dc systems, energy conversion & storage matchmaking event de... · frequency (1mhz .. 2mhz),...

DC Systems, Energy conversion & Storage

Matchmaking Event

25th April 2018

Efficient Energy Conversion Electromechanics and Electric Mobility

DC Grids and Storage for Smart Cities High Voltage DC Systems

High Voltage DC Diagnostics and Monitoring High Voltage DC Materials and Components

2

D C E & S

DC Systems, Energy Conversion & Storage

Master’s Thesis Proposal

Efficient Energy Conversion DC systems, Energy conversion & Storage

HARMONIC MODELLING IN OFFSHORE WIND POWER PLANTS

Type of project: MSc thesis

Scope: Computer modelling of an Offshore Wind Power Plant for harmonic studies

Problem definition:

Due to the increasing penetration of power electronics, harmonic emissions are becoming a prevalent

phenomenon in electric power grids. The increased bandwidth of converters might overlap with these

harmonics, creating unexpected and undesired interactions.

In the case of Large Offshore Wind Power Plants (OWPPs), the concern for power quality is higher due to

several reasons. First, the existence of numerous harmonic sources in these systems. Second, the fact that

offshore wind power plants are typically connected to weak points in the grid, whose sizeable equivalent

impedance might interact with the OWPP. Third, the high capacitance of the long submarine transmission

cables which might create unexpected resonances.

Typically, wind turbines have been modelled as simple harmonic current sources, neglecting possible

interactions in between converters. Even if more complex models have been lately applied, deep knowledge of

what converter parameters (in the control structures and in the physical parameters) are most influential

needs to be developed.

Methodology:

Model a real case study of an Offshore Wind Power Plant

Sensitivity analysis of the parameters of the system

Research Objectives:

Feasibility of the harmonic modelling of a full Offshore Wind Power Plant in Matlab Simulink

Determination of the most influential parameters on harmonic behaviour

Contact details:

PhD student: Lucia Beloqui Larumbe ([email protected])

Supervisor: Dr. Zian Qin ([email protected]),

Prof. Dr. Eng. Pavol Bauer ([email protected])

mailto:[email protected]



3

D C E & S




IMPEDANCE-BASED HARMONIC MODELLING FOR OFFSHORE WIND POWER PLANTS


Scope: Computer modelling of a small Offshore Wind Power Plant (OWPP) with a novel method in order to

check its feasibility for harmonic studies in steady state and transient operation

Problem definition:


phenomenon in electric power grids. In the case of OWPPs the concern for power quality is higher due to





Lately, a new method for the modelling of the wind turbines has appeared: Impedance Based Method (IBM).

The potential of this modelling method is substantial, but before its application it is necessary to determine its

limitations.

Methodology:

Model a small case study of an OWPP in Matlab Simulink with detail (PWM model)

Model the same case study using the Impedance Based Method (IBM)

Comparison in steady state(s)

Further development of the Impedance Based Model into a transient model


Detect the limitations of the IBM in steady state

Feasibility of using the IBM, a priori designed for small-signal analysis, for transient analysis

Contact details:







4

D C E & S




ANALYSIS AND MITIGATION OF HARMONICS IN OFFSHORE WIND POWER PLANTS

Type of project: Extra Project (15 ECTS)

Scope: Literature review and computer simulations

Problem definition:


phenomenon in electric power grids. The increased bandwidth of converters might overlap with these

harmonics, creating unexpected and undesired interactions.

In the case of Large Offshore Wind Power Plants (OWPPs), the concern for power quality is higher due to





Lately, considerable changes are occurring in the analysis techniques used in Industry and Academia. In

parallel, several new mitigation techniques, especially through the control of power electronic converters, have

been developed.

Methodology:

Review the analysis techniques used nowadays for harmonic studies in OWPPs

Review the mitigation techniques used nowadays for harmonic emissions and resonances

Small verifications of the concepts through computer simulations in Simulink

Report

Possibility of publishing a conference paper

Contact details:







5

D C E & S




OPTIMUM CONCEPT FOR A 1MHZ CONTROLLER AND DRIVER, TO DRIVE THE 1MHZ, 27W,

MOBILE POWER SUPPLY ARCHITECTURE, IN SILICON-ON-INSULATOR PROCESS (SOI)


Scope: Concept for high speed drivers and control in silicon on insulator process

Problem definition:

A 1 MHz, 27W, high power density, flyback power converter will have an active synchronous rectifier at the

secondary side. A correct timing between primary side and secondary side is essential. An active clamp in the

flyback topology will ease this timing requirement. However, it requires a control of an extra floating switch at

the primary side, just like a half-bridge topology. At 1MHz this not straight forward at all. A combination of high

frequency (1MHz .. 2MHz), high voltage (600V) and fast dv/dt, together with our SOI technology, has not been

explored yet.

The challenge for this master thesis is to develop this high side and low side driver structure + related control,

to design it, and to create a test-chip. Finally, this test-chip will be merged into the 27W architecture described

above.

Methodology:

Work out architecture for 1MHz controller concept

Simulation of controller and driver stage

Realize floorplan

Test-chip design

Measurements on test-chip


Feasibility of high frequency switching control for AC/DC converter

Explore the boundaries of the used silicon on insulator technology

Contact details:

Company supervisor: Ferdinand Sluijs, [email protected]

Advisor: Arjan van den Berg, [email protected]

University supervisors: Pavol Bauer, [email protected]

Kouchi Zhang, [email protected]

Advisors: Jianning Dong, [email protected]

Zian Qin, [email protected]







6

D C E & S




TEST BENCH AUTOMATION DEVELOPMENT FOR POWER APPLICATIONS

Type of project: MSc internship or thesis

Scope: Automatic characterization of new controller ICs for Smart Power Chargers

Project description:

A complexity of the NXP’s mixed signal controllers requires an extensive testing of their functionality and

performance.

Focus of the project will be on:

1. creating and debugging Matlab scripts for controlling of the external instrumentations such as remotely controlled oscilloscopes and data acquisition units as well as communicating with the device under test using I2C.

2. Creating interface between the existing IC validation test benches and Simulink models. 3. Creating automated reports based on the Excel and Excel VBA.

Requirements:

• Knowledge of the scripting languages preferable Matlab and VBA is required. • Knowledge of Simulink modelling is desired • Some experience in statistics and data processing methods as well as I2C or other interfaces

would be advantageous. • Good report writing ability is required.


Automation of characterization of key parameters in power applications, including reporting

Use the results in models for circuit and system simulations

Contact details:


Advisor: Dimitri Grigoriev, [email protected]

University supervisor: Pavol Bauer, [email protected]

Advisors: Zian Qin, [email protected]

Jianning Dong, [email protected]






7

D C E & S




OPTIMUM CONCEPT FOR A MULTI-OUTPUT, UNIVERSAL MAINS, 1MHZ, 27W, MOBILE

POWER SUPPLY WITH A POWER DENSITY OF >25W/INCH3


Scope: Concept and model of 1MHz adapter in mobile applications with high power density

Problem definition:

Nowadays smart phone chargers become more and more intelligent and powerful. The primary reason is to

reduce charging time. The current sweet spot is 27W charging power. The phone and adapter will “talk” to

each other to select the optimum voltage / current combination. Traditionally a standard flyback topology is

chosen. Together with a secondary side synchronous rectifier and protocol controller an efficient, intelligent

charger can be built. Going to higher switching frequencies will enable us to increase the power density as

(power) components will become smaller. Multiple physical domains are involved:

Electrical domain, especially how to overcome switching losses that will become dominant in 1MHz

applications. The wide input and output voltage range is a challenge. What do new types of switches

like GaN bring?

Thermal domain, the temperature constraints will not change. So how to solve the thermal issues

when we make the charger smaller?

Magnetic domain, how to create the optimum isolated transformer for the 1MHz frequency range.

And that can meet the EMI regulations at the same time.

Methodology:

Simulate and model the targeted adapter

Build the adapter

Measurements and comparison against model


Feasibility of a predictive adapter model with wide input and output voltage range

Influence of the parasitic components at high frequency operation

Contact details:


Advisor: Arjan van den Berg, [email protected]

University supervisor: Pavol Bauer, [email protected]

Advisors: Zian Qin, [email protected]

Jianning Dong, [email protected]






8

D C E & S




RESONANT CONVERTER WITH GAN SWITCHES (100 - 300W)


Feasibility study and demo project for a 100 – 300W mains isolated resonant converter, wherein for size & loss

reduction the traditional Si-MOSFETs are replaced by GaN switches, and a high switching frequency. There is

already a controller for a very high efficient resonant power supply, but further improvement is still highly

wanted.

Scope:

Reduction of size and losses in a power supply saves energy and raw materials. For size reduction a high

switching frequency is a must.

Problem definition:

There is ongoing request for reduction of waste energy and reduction of size of power supplies for various

applications Also from an environmental point of view this is highly preferable. One of the key issues for this is

switching at very high frequency. Present day Si MOSFETs have only limited capabilities to switch at high

frequency. GaN switches promise to overcome this limitations, as they have low on-resistance, low

capacitances, easy drive and fast switching. Before proposing this to the market a feasibility study must be

carried out to verify whether the new switches indeed live up to their promises.

Methodology:

1. study the behaviour of the normal operation of a resonant converter. 2. make a rough model for the losses n the GaN switch to verify optimal frequency setting 3. design a resonant converter for 1 MHz, incl. the mains filter for CM noise 4. build the converter 5. measuring efficiency etc. and verify EMC behaviour


study hf switching with GaN in a mains isolated resonant converter (

investigation of influence of parasitics in this type of converters

verify optimal usage of GaN switches

Collaboration with Industry: Yes. The study is preferably done at the NXP premises in Nijmegen, in an expert-

group on world class flyback and especially also world class resonant converters

Contact details:

NXP: Ferdinand Sluijs, ([email protected])

Supervisor at TUDelft: Frans Pansier ([email protected])



9

D C E & S




REPLACEMENT OF OPTOCOUPLER BY RF COMMUNICATION THROUGH TRANSFORMER


In mains isolated converters most often the control information is transferred by means of an optocoupler. Can

this be replaced by a rf signal using the existing transformer?

Scope:

In a mains isolated flyback converter reducing component count and increasing efficiency simultaneously. The

numbers of chargers etc for mobile equipment is huge. Any reduction of power consumption and component

count help reducing pollution, and reduces the consumption of raw materials

Problem definition:

In most isolated converters the control info is transferred from secondary side to primary side using an

optocoupler. This coupler consumes energy, and adds to cost. The questions arises: can the transfer of

information be done with components that needs to be used anyhow, esp. the transformer. A transformer can

be used for transferring power, but also for transferring information. Can this be done with the same

transformer? A potential candidate is to use an rf signal to be coupled to the transformer to do this. The

bandwidth of the communication must be large enough and the communication should be bidirectional,

paving the way for more sophisticated features.

Methodology:

6. study the behaviour of the normal operation of a flyback converter as used for chargers 7. study the possibility of transferring power and hf information using the same transformer, including

constraints on frequency span, sensitivity for noise, etc. 8. proposal for the way the information is transferred by means of a hf signal (e.g.: pulses (with

protocol), fm modulation, etc.) 9. building prototype, and assessing feasibility (efficiency, performance,cost etc.)


knowledge on multi-purpose use of transformers for power supplies

knowledge on interaction of hf signals and switched mode power transfer in transformers

optimisation of efficiency and size of power supplies with mains isolation

Collaboration with Industry: Yes. The study is preferably done at the NXP premises in Nijmegen, in an expert-

group on flyback converters

Contact details:

NXP: Ferdinand Sluijs, ([email protected])

Supervisor at TUDelft: Frans Pansier ([email protected])



10

D C E & S




OFFSHORE WIND FARM ELECTRICAL OPTIMISATION AND GRID COMPLIANCE

ASSESSMENT


Scope:

Offshore wind farm (OWF) optimisation by analyzing and comparing different options for collector system, system voltage, offshore high voltage station (OHVS) and assessment of grid compliancy. Problem definition:

The cost of energy from offshore wind has fallen by 32% since 2012 and is now below the joint UK government

and industry target of GBP 100 per megawatt hour (MWh) four years ahead of schedule, according to a

report delivered by the Offshore Renewable Energy (ORE) Catapult on behalf of the Offshore Wind Programme

Board (OWPB). "Subsidy-free" offshore wind is getting a lot of attention after contracts in Germany and the

Netherlands were signed without direct government incentives.

Optimisation of the technical aspects is key in achieving OWF cost reduction and this is what this project will

explore, where the main components of an OWF and key technical constraints will be considered as input

parameters.

Methodology:

Model the offshore wind farm and optimise the electrical configuration in MATLAB

Analyze grid compliancy based on one of the ENTSO-E countries codes

Create an integrated fully functional friendly MATLAB with an in-built GUI


Optimisation of offshore wind farm electrical system based on CAPEX and OPEX by considering: the number and siting of Offshore High Voltage Stations (OHVS), the layout of both the interarray and the export cables as well as the selection of electrical components in terms of voltage level and capacity.

Case study of optimizing an OWF and checking grid code compliancy. Theory will have to be complemented with simulation studies to give a systems perspective and a better understanding for techniques involved in meeting grid code demands.

Delivery of a MATLAB model with a GUI functionality which can be used for any wind farm to achieve the above mentioned objectives.

Contact details:

Company contact: Maria Kalogera, [email protected]

University supervisor: Prof. Pavol Bauer, [email protected]

http://crmfreport.com/



11

D C E & S




MAXIMISATION OF ENERGY PER AREA AND LOAD FACTOR IN UTILITY SCALE SOLAR PV


Scope:

Utility scale solar farm maximization of power generation per area and load factor by analyzing and comparing different options for mounting systems, ground coverage ratios (GCRs), including tracking systems and east-west mounting systems, module types and DC-AC ratios. Problem definition: The installation of utility scale solar farms is accelerating globally. While the focus so far has been mostly on reducing cost, in the future land area will become a more important constraint. In fact, in some densely populated countries, including the Netherlands, land availability for solar PV is already limited, leading to sharply rising land prices. This induces a pressure to maximise PV installation (and hence energy generation) per unit area. A related pressure is for higher AC load factors, ie maximizing the power generation in the morning and evening hours, as opposed to maximizing the harvesting around noon.

Methodology:

Investigate and compare options for maximizing Energy per Area and AC Load Factor (literature review, expert interviews)

Model different utility scale PV farm designs in the software package PV Syst, for a number of global reference locations

Report optimal PV farm designs given the competing drivers of low cost, high EpA and high AC load factor


Present utility scale PV farm designs for maximum Energy per Area and AC load factor, to determine where the practical limits for the parameters are.

Propose an optimal lay-out for a number of locations and circumstances, including the Netherlands and a number of international reference locations

Delivery of a PV Syst models and power generation profiles for these designs and locations.

Contact details:

Company contact: Domnick, Andreas, [email protected]

University supervisor: Prof. Pavol Bauer, [email protected]

Nishant Narayan, [email protected]

Gautham Ram Chandra Mouli, [email protected]





12

D C E & S




IMPROVING CONVERTER RELIABILITY IN ACTIVE SPEED STALLED TIDAL TURBINES

Type of project: Extra Project

Scope: Improving converter reliability is essential to minimizing the cost of energy from tidal turbines. Wide

fluctuations in speed of tidal turbines (<300kW) due to the turbulence in tidal velocities can impose heavy

thermal loading on the power converter. This is especially true for fixed-pitch turbines. The converter loading

has a significant impact on its lifetime, and hence, the maintenance cost of the tidal turbine.

Problem definition: Investigate the influence of the speed fluctuations in a fixed-pitch tidal turbine on the

converter lifetime. Investigate the different solutions (control strategy, converter topology, etc.) for prolonging

the mean time to failure.

Methodology: The converter current is calculated by coupling the turbine mechanical model with

electromechanical models for the generator and the converter. Based on the converter currents, a thermal

model is used to estimate the thermal cycling in a tidal power converter, and mean life to failure is estimated.

Different speed control strategies, converter topologies, etc. can then be compared based on the mean time to

failure.


Influence of tidal turbulence on the converter lifetime in a fixed-pitch turbine.

Comparison of different converter topologies based on their lifetime.

Suggesting optimal topology or speed control strategy for maximum lifetime.

Collaboration with Industry: Yes

Contact details:

PhD candidate: Faisal Wani ([email protected])

Supervisor: Dr. Jianning Dong ([email protected])



13

D C E & S




WIND POWER OUTPUT PREDICTION CONSIDERING COMPONENT DEGRADATION

Type of project: MSc Thesis

We are getting old…

Photo courtesy: Tim Strous

Scope: This project aims at wind power output prediction considering degradation of different components in

wind turbine, while concentrating on the electrical generator system.

Problem definition: As the share of wind power grows large, operation and maintenance (O&M) cost reduction

becomes a catching and demanding topic. Power output prediction is an important part to schedule O&M to

reduce cost. The power output depends on many factors. The degradation of different components, e.g.

blades, power electronics and generators leads to efficiency and availability reduction, but has not been well

understood. This project will explore the influence of component degradation on wind turbine availability, so

that the wind power output can be predicted with quantification of uncertainty. Special attention will be paid

on power electronics converters and wind generator.

Methodology: The project includes literature review, modelling and simulation.


Overview of the state of art of wind turbine degradation and availability research.

Model the availability of the generator system considering degradation.

Case study of power output prediction of an offshore wind turbine.

Collaboration with Industry: No.

Contact details:

PhD student: Udai Shipurkar ([email protected])

Daily Supervisor: Dr. Jianning Dong ([email protected])

Supervisor: Prof. Pavol Bauer ([email protected])




14

D C E & S




SOLID-STATE HYBRID CIRCUIT BREAKER – TOPOLOGY COMPARISON


Scope: The two main challenges of meshed low voltage DC grids today are the flexible control

of power flow and the short-circuit protection. The conventional approach to deal with both problems is to incorporate galvanically isolated DC-DC converters with integrated short-circuit protection, which are rated for the full power rating of the grid. In this thesis, we develop an approach based on the combination of a converter which has a partial power rating with respect to the grids power rating and a circuit breaker with full rating with respect to the grid.

Problem definition: Power electronic converters have a limited over-current withstand capability. The breakdown voltage of the semiconductor devices cannot be exceeded at any time. Oversizing the converters for higher currents and/or voltages is possible, but expensive. It is more efficient to develop fast and reliable circuit breakers to protect the converters from the short-circuit effects.

Methodology: In the first phase the student will familiarize with the protection practices and the concept of

partially rated converters for power flow control through literature study. The core of the work load is

evaluating different circuit breaker topologies for the power flow control converter.


Define a set of appropriate circuit breakers for partially rated power flow control converter

Analyse and compare the circuit breakers using simulation

Laboratory prototype testing with the partner institution (optional)

Collaboration with Industry: It is an option, Fraunhofer-IISB

Contact details:

PhD student: P.Purgat ([email protected])

Supervisor: dr. Zian Qin([email protected])

prof. P. Bauer ([email protected])




15

D C E & S




DESIGN AND OPTIMIZATION OF THE ELECTRICAL SYSTEM FOR AN AIRBORNE WIND

ENERGY WINCH


Scope: Design and optimization of the electrical system for an airborne wind energy winch. The winch should

be optimized for power generation (reel-out), reel in and temporary energy storage.

Problem definition: The system generates electric power by converting the pulling of the kite in to a rotary

motion and driving a generator. The system should also function as a motor to pull back the kite to the start

position, with a fraction of the energy which was generated. In order to ensure a continuous power output also

an energy storage system is installed. The current 100 kW system is a test system. MSc Thesis would consists of

the preliminary design of the commercial system, including configuration (DC, AC), component selection,

optimization and economical aspects.

Methodology: Optimisation and field test of current system, simulation of improved system, economic analysis


Investigate limitations current 100 kW system

Requirements commercial system

preliminary design of commercial system

Collaboration with Industry: Yes, Kitepower (spin-off TUDelft)

Contact details:

Daily Supervisor: Jianning Dong, [email protected]

Supervisor: Joep Breuer, Technical Manager, Kitepower, [email protected]



16

D C E & S




LEARNING WITH THE LAB-SCALE MODULAR MULTILEVEL CONVERTER


Scope: The available lab scaled modular multilevel converter (MMC) can be used to gain knowledge on real

time digital simulator (OPAL-RT) and other hardware operation.

Problem definition: Experiment with the available lab-scaled MMC to understand the operation principles. Its

operation will then be tested by applying different control strategies.

Methodology: Laboratory work is expected.


Learn and test different PWM techniques and generate the required carrier wave to switch the

submodules. .

Apply simple control schemes, for instance capacitor balancing to test the proper operation of the

available lab-scale MMC.

Collaboration with Industry: <No>

Contact details:

PhD student: <A. Shekhar, [email protected]>

Supervisor: <Zian Qin; Pavol Bauer>

1.


17

D C E & S




MODULAR MULTILEVEL CONVERTER AS STATCOM


Scope: This project explores the use of modular multilevel converter (MMC) for harmonic elimination1. The

concept is to be applied to mitigate the power quality issues and highlight the trade-offs and challenges

therein.

Problem definition: Develop schemes to detect and mitigate medium voltage grid current and voltage

harmonics by operating a MMC as STATCOM. Different harmonic detection and current injection strategies

need to be implemented and compared in terms of power quality conditioning.

Methodology: Simulations as well as experimental work is desired. The student is expected to learn about the

operation of the MMC and develop control techniques to comply with different grid requirements at medium

voltage level.


Identifying the methodology to detect harmonics at the point of common coupling (PCC).

Determining how fast the convertor needs to react while keeping its internal balancing.

Showing the operation of MMC as STATCOM for harmonic elimination experimentally.

Compare different methods of achieving harmonic elimination using MMC and 2 level VSC.


C ontact details:

PhD student: <A. Shekhar, [email protected] >

Supervisors: <L. M. Ramírez-Elizondo; Zian Qin; Pavol Bauer>

1 E. Kontos, G. Tsolaridis, R. Teodorescu and P. Bauer, "High Order Voltage and Current Harmonic Mitigation Using

the Modular Multilevel Converter STATCOM," in IEEE ACCESS, vol. 5, pp. 16684-16692, 2017.

2.


18

D C E & S




MODULAR MULTILEVEL CONVERTER (MMC) WITH DYNAMIC DC LINK VOLTAGE


Scope: It is possible to increase the dc link voltage without increasing the voltage ‘seen’ by the converter

switches in a MMC. This improves the efficiency of the system without investing in higher rated components.

Problem definition: Develop a control strategy for operating the dc link with dynamic voltage while keeping the

MMC energy within the rated limits to obtain efficiency and capacity improvement.

Methodology: The student is expected to prove this idea through simulations and implement it experimentally

in the available lab scale converter. The fundamental equations will be given to the student for the

implementation of this concept, for which familiarity with MATLAB is important.


Show through simulations that the energy in the MMC can be controlled such that the dc link voltage

can be dynamically raised without increasing the voltage seen by the submodule capacitors and

switches.

Define boundaries within which this concept can be applied.

Determine the achievable efficiency/capacity gains of operating the MMC with dynamic dc link

voltage.

Implement the concept in the available lab-scale MMC prototype to justify the claimed gains.


C ontact details:

PhD student: <A. Shekhar, [email protected] >

Supervisors: <L. M. Ramírez-Elizondo; Zian Qin; Pavol Bauer>


19

D C E & S




MODELLING AND GATE DRIVER DESIGN OF SILICON CARBIDE (SIC) DEVICES


Scope: modelling of Silicon Carbide (SiC) power switches

Problem definition:

SiC has wider bandgap compared with Silicon (Si), which brings SiC devices advantages like higher blocking

voltage, non-reverse recovery, faster switching speed, etc. Because of these advantages, it is promising to use

SiC power devices instead of Si based ones for better performance. But due to the different characteristics

between the two devices, one cannot expect much improvement of the performance by simply replacing the

latter with the former ones in circuit. Therefore, in order to use the SiC device in a proper way and push its

performance to the limit, a better understanding of its characteristics is needed before a SiC device dedicated

gate driver can be designed.

Methodology:

Build a double-pulse testing platform

Study the switching behaviour

Extract the values of the parasitics

Study the impact of the environment, e. g. voltage and temperature, on the parasitics


Modelling of the SiC devices

Propose gate driver design and application criteria for the SiC devices

Contact details:

Supervisor: Dr. Zian Qin ([email protected])




20

D C E & S




BATTERY EMULATOR FOR TESTING PE INTERFACE MODULES


Scope: Design a laboratory setup that can replicate the behaviour of an electrical battery storage unit.

Assemble, program and test the emulator under power electronic (PE) interface conditions.

Problem definition: With the growing interest in nano-grids and a wider utilisation of energy storage units, the

accompanying PE converters that are required to interface and control the power flow need a platform on

which they can be tested. Actual high-power batteries are hazardous to experiments with, while off-the-shelf

emulators are costly and can function in a limited range. The solution therefore is to custom design converters

that can be programed to behave as a battery under both charging and discharging conditions. By

implementing a topology similar to the one in the figure, a wide range of conditions can be achieved by

combining various switches, resistors and quantity of commercially available safer-batteries or power sources.

The task is therefore to design, assemble and program such a setup for laboratory implementation.

Methodology: Assemble a converter based on the layout given in the figure. Choose the appropriate

components and design its PCB board. Program the available controllers to operate the switches in the device.

Test the battery emulator via simulations on a system model and finally laboratory experimentation on the

setup.


Identify the key features of a battery emulators.

Design and assemble the emulator based on these features.

Test the operations of this converter via simulation and experimentation.

Collaboration with Industry: No

Contact details:

PhD student: Mladen Gagic, [email protected]

Supervisor: Prof. dr. J.A. Ferreira, [email protected]



21

D C E & S




DUAL ACTIVE BRIDGE MODULE FOR MULTILEVEL APPLICATIONS


Scope: Modify a DAB converter to operate as a module in a Multilevel system. By reconfiguring certain

elements on an existing prototype, the module should be able to communicate with other modules while

interfacing certain loads/sources.

Problem definition: Conventional MMC and other Multilevel systems usually implement modules that do not

provide galvanic isolations between their input and out. By modifying existing DAB converters we can

reconfigure them to operate as modules as part of a broader system. The inclusion of certain sensors and

communication ports may also be necessary to achieve access to control parameters and compatibility with

other modules. Reprogramming the DAB converter to function as a module will also be required. Simulation on

a system model and finally experimentation on a laboratory setup will serve as a testing platform and

validation of the expected converter performance.

Methodology: The methodology for this thesis will include getting familiar with the layout and design of the

existing DAB converters. Afterward a reconfiguration process by adding or removing certain elements will be

required. Adjusting the controls for multilevel operations and testing them via simulations should precede the

final experimental verification of the module.


Analyse the design and operational principle of DAB converters.

Reconfigure existing DAB converter to operate as an isolated module in a Multilevel system.

Test and analyse the performance of this module via simulation and experimentation on a laboratory

setup.


Contact details:





22

D C E & S




HIGHER RATED PV EMULATOR


Scope: Based on the available converters that replicate the power curves of PV cells, the goal is to redesign

them in order to achieve a higher power rating and possibly a more accurate performance.

Problem definition: There are various methods of extracting data from systems that incorporate PV sources.

However, in laboratory environments, where available space is usually limited, any setup needs to be compact

and highly robust. Therefore, by implementing the tools and equipment that are at hand, the task will be to

modify an existing PV emulator for the purpose of testing other converters intended to interface a PV sources.

These emulators function by operating the switch in the linear (active) region while being supplied by a

conventional DC power source. In order to scale up the power rating of the emulator, the student should

reconfigure and possibly reprogram the converter by choosing the proper components and adjusting the

controls to suit their switching needs. Simulations and experimentations should be carried out during the

design process.

Methodology: After getting familiar with the basic design and operating principle of the existing emulator, a

process of redesign should follow. This process includes choosing which elements to preplace and adjusting the

controller to suit them. Assembly, simulation and experimental testing can than take place.


Identify key feature of the PV emulator.

Reconfigure the emulator and modify the controls to suit a high power rating.

Test the operations of the converter.


Contact details:





23

D C E & S




MULTI-FREQUENCY ACTIVE FILTERING


Scope: Design, build and test a modular series and/or parallel active filter for operation in multi-frequency

micro-grids. This converter will be assembled with pre-existing component submodules equipped with

sufficient sensors and control capabilities. The appropriate control strategy needs to be chosen and then tested

under various conditions.

Problem definition: As part of a novel Multi-frequency micro-grid, the inclusion of a certain components that

provide an enhanced power quality is an important feature. Active filters are common-place in various AC and

DC systems and applications. However, the presence of additional (superposed ) frequencies provides a new

layer of control that needs to be addressed. The physical filtering module (composed from pre-existing

submodules )may require only certain modifications. The main goal is to put forward and test a control strategy

that can actively track and mitigate various harmonics present in the system via the available sensors and

control devices.

Methodology: In order to achieve active filtering under these conditions, certain steps should be followed. This

includes proposing a control strategy based on the available voltage and current measurements. Afterwards,

the control strategy should be tested via a simulations on a Matlab model of the system. Finally, the active

filter should be assembled, tested and evaluated on a laboratory setup.


Identify the requirements of MF active filtering.

Propose a control strategy for the MF Active Filter.

Test and evaluate the MF Active Filter via simulation and laboratory experimentation.


Contact details:





24

D C E & S




MULTI-FREQUENCY POWER MEASUREMENT BOARD


Scope: Design, assemble and test a PCB board capable of high-precision measurements of electrical power flow

on various frequencies (including DC) in a MF micro-grid. By incorporating various sensors and available

controllers, a multi-port device should be assembled and programed to track the power flow on individual

frequencies going through it.

Problem definition: In a novel Multilevel, Multi-frequency power systems that is currently being designed,

measurement of power flow is more challenging. This is due to the presence of at least one or more AC

frequencies that are superposed on a DC offset. Power tracking of multiple frequencies can be achieved by a

measurement board containing the proper voltage/current sensors, conditioning circuits and available

controllers. Along with the necessary choice of hardware, the proper algorithms need to be incorporated

within the controller.

Methodology: Firstly a method of isolating and calculating the relevant parameters within the limits of the

available controllers needs to be suggested. This method should then be tested and verified via simulations on

a model MF system. Afterwards, the process of designing the actual prototype board can begin along with the

programing of the controller. Finally, the Measurement Board should be tested on a laboratory setup of the

system.


Propose a MF power measuring method.

Design a device to accommodate the required components.

Test the measuring accuracy of the program via simulation and experimentation.


Contact details:





25

D C E & S




POWER ELECTRONIC BUILDING BLOCKS FOR VARIOUS CONVERTER TOPOLOGIES


Scope: Implementing existing power electronics submodules to design, assemble and test various common

converter topologies. These include conventional isolated and non-isolated DC/DC and DC/AC converters.

Problem definition: An ideal opportunity for any student that wishes to get hand-on experience with operating

various topologies of widely implemented PE converters. With existing PE “building blocks” ( sub-modules) with

pre-installed switches, sensors and control components a wide assortment of converters can be assembled.

Using standard testing practises, these converters need to be tested under various loads and/or source

conditions. A performance analysis should be presented as part of the final report.

Methodology: Firstly, the student needs to get acquainted with the operating principles of the individual

submodules. After this, a number of possible converter topologies should be suggested along with their control

principle. Finally, adjusting the controller, followed by various experiments under certain conditions will be

carried out in order to demonstrate the PE Building Blocks performance.


Identify possible converter topologies.

Experiment with different combinations of PE building blocks.

Test and analyse the performance of the submodules for different topologies.


Contact details:





26

D C E & S




DESIGN AND EVALUATION OF SIC SWITCHING SUBMODULE


Scope: Using available SiC MOSFET switches and high-frequency drivers, the goals is to design a high-

performance half-bridge submodule (SM) for use in “building block” design application. This SM should also

include various sensors, snubbers and communication ports in order to properly function as part of a broader

system.

Problem definition: SiC and other wide band-gap devices are still relatively novel in terms of applications. Due

to their high performance potential, SiC switches could be pushed to high-frequency operation. This is ideal in

some aspects but creates problem in various other domains such as EMI and stress on other components of the

converter. Therefore a proper design is required for modules implementing SiC MOSFETS. This needs to take

into account both the layout and choice of adjacent components. Final incorporation, testing and evaluation of

the SiC switching SM in actual converter topologies (DC/DC, DC/AC) will be carried out.

Methodology: The utilisation of SiC MOSFET switches on a submodule level requires experimentation with

different layouts and design approaches in order to achieve an optimal solution. Several iterations may be

necessary before an acceptable result can be achieve. Simulations and experiments in laboratory setups will be

used in the design phase and final evaluation.


Identify the potential benefits and challenges of implementing SiC MOSFET switches.

Design a half-bridge SM that mitigates most of the challenges.

Analyse and evaluate the performance of these submodules.


Contact details:





27

D C E & S


Electromechanics and Electric Mobility DC systems, Energy conversion & Storage


BATTERY SIZING OF EVS FOR ON-ROAD DYNAMIC CHARGING (WIRELESS)


Figure[1]: Dynamic wireless EV charging and dynamic SOC profile

Scope: Dynamic charging of EVs with inductive coupling based wireless power transfer is an attractive research

area. It allows smaller and lighter batteries to be used, due to frequent charging using the charging

infrastructure embedded under roads.

Problem definition: The research challenge in this field is to optimally design a dynamic EV charging system

considering a stochastic driving cycle along an intercity highway. The trade-off between investment cost of a

dynamic IPT system and the reduction of the battery size and extension of the battery life needs to be

investigated.

Methodology: The methodology to arrive at a good design are the following:

Literature review of battery lifetime models and dynamic EV charging system layout

Problem Formulation of a multi-objective techno-economic framework

Sensitivity analysis of stochasticity of driving cycles on battery sizing and lifetime

Research Objectives: The pertinent research objectives are highlighted below:

Quantification of battery size reduction by dynamic charging

Quantification of battery lifetime extension

Multi-objective optimization of techno-economic model


Contact details:

PhD student: S. Bandyopadhyay [email protected], LB 03.640,

Supervisor: Dr. Jianning Dong [email protected], LB 03.630, Prof. Pavol Bauer

[email protected] , LB 03.600




28

D C E & S




OPTIMAL COIL TOPOLOGY FOR DYNAMIC WIRELESS CHARGING OF EVS


Figure[1]: Dynamic wireless EV charging and possible coil topologies

Scope: Dynamic charging of EVs with inductive coupling based wireless power transfer is an attractive research

area. The main design challenge of this field is to provide a constant power profile to an in-motion EV.

Therefore, it is necessary to research different coil topologies to select the optimal topology for this

application.

Problem definition: Dynamic IPT systems need to provide a constant power profile for moving EVs. The EV

battery health will deteriorate if pulsed power is used. This design specification needs innovative solutions like

power buffering and misalignment tolerant coil topologies. This research is focused on optimal coil topology

which will ensure low power pulsations.


Literature review of coil types used in dynamic IPT systems

Electromagnetic model of a lumped multi-coil dynamic IPT system

Optimization and comparison of different coil shapes


Optimal coil topology for dynamic IPT systems

Coil layout and internal spacing guidelines

Multi-objective optimization for efficiency maximization and cost minimization


Contact details:







29

D C E & S




THERMAL MODEL OF WIRELESS INDUCTIVE COUPLERS FOR EV CHARGING


Figure[1]: Wireless inductive coupler arrangement and thermal model

Scope: The possible flexibilities and potential of wireless charging makes it a prime candidate of replacing

conventional wired charging of EVs. However, as the power increases the loss density and thermal behaviour

become the limiting factor. That’s why quantifying the power density limits of the inductive couplers is very

important for designers.

Problem definition: Wireless inductive power charge-pads use materials like litz wire, ferrites and aluminium

which are relatively more expensive than normal copper wires and insulations needed for wired charging.

Charge-pads are of different shapes like DD coils, circular coils , rectangular coils and their loss distribution can

be different depending on core layouts. The goal of this thesis will be to find the thermal weak-links and thus

the power density limits of the charge-pads with or without cooling.


Thermal modeling using finite element analysis and as well as lumped parameter modeling

Optimization of coil shapes and experimental validation of models


Coil sizing guidelines based on power transfer and airgap specifications

Design trade-offs w.r.t power density and thermal considerations

Comparison of coil shapes based on thermal limits


Contact details:







30

D C E & S




DESIGN A CONVERTER FOR EV CHARGING SYSTEMS


Scope:

This MSc assignment entails the design of a PFC converter for electric vehicle charging applications (marked in

red). This part of the power module can be matched to the isolated DC/DC converter that has been developed

in a previous Msc. Assignment (marked in green).

Problem definition: Long term GaN is needed to stay competitive. The prices of the devices are expected to be

on par with current conventional technologies while SiC will always be a bit more expensive. The emphasis is

on technology prototype development I.E. hardware, understanding the week points of the technology. The

sooner we can take new technologies for a spin “outside of the lab”, the better. The prototype will not

immediately be ready for large scale production.

Methodology:

Set general requirements (input voltage: 200V-15% - 240V+10%, 420Vout +/- 20Vripple due to PFC, EMC, power factor, THD, etc.)

2 months literature study -> 1 chapter

2 months simulating 3-5 topologies -> 1 chapter

Refine requirements

Select 1-2 topologies for possible implementation

2 months detailed design of these 1-2 topologies -> 1 chapter

2 months implement, test and benchmark-> 1 chapter

1 month write report


Compare different topologies and implement a technology prototype, utilizing GaN (and SiC diodes)

This prototype will possibly be benchmarked against other implementations

This new design should give a benefit for: 1 cost (eventually), 2 efficiency, 3 power density

Contact details:

Company contact: [email protected]

University supervisor: Gautham Ram Chandra Mouli,

([email protected]); Zian Qin ([email protected])




31

D C E & S




DESIGN AND MODELLING OF ELECTRIC MACHINE FOR ELECTRICALLY ASSISTED SHORT –

RANGE CIVIL AIRCRAFT


Scope: Facing the environmental pressure, the aviation industry has to come up with innovative technologies

to reduce its environmental footprint. An electrically assisted propulsion system (EAPS) which embeds an

electrical machine in a conventional turbofan engine can reduce the size and emission of the engine, and

increase the overall efficiency.

Problem definition: The thesis project aims to design a high power density electrical machine which can

operate in parallel with the turbofan engine for short-range mission. Requirements of electrical machines will

be investigated from mission profile, in cooperation with aerospace engineering faculty. Tradeoff between

reliability, efficiency and power density should be made with a preliminary design tool set. Physics based model

should be built for detailed design and analysis of the electrical machine.

Methodology: The project includes electrical machine modelling and simulation based on FEA, circuit and

analytical calculation.


Integrative design of electrical machine based on mission profile.

Development of preliminary design tool set for electrical machines in EAPS.

Physics based modelling of PM machine for EAPS.


Contact details:



Dr. Arvind Gangoli Rao ([email protected])




32

D C E & S




DYNAMIC MODELLING OF A CANNED PERMANENT MAGNET MACHINE


Stator can

Rotor can

Sea water

Scope: Canned permanent magnet machines can be used as motors in marine propellers and as generators in

tidal or wave energy turbines. The canned stator and the rotor structure of these PM machines may not only

cause additional eddy current losses but also influence the dynamic characteristics of the canned PM machine.

Problem definition: The main goal of this thesis is to characterize the impact of the additional inductive effects

of the conductive canned structure on the steady-state and the dynamic characteristics of the PM machine.

Comparisons must be made with the dynamic characteristics of the PM machine with non-conductive glass

fibre cans.

Methodology: The candidate needs to understand the steady-state and dynamic performance of the canned

PM machine, and identify main differences compared to the conventional PM machines. The differences in

operational characteristics can be reflected in terms of the additional differential equations in the circuit model

of the canned PM machine. The developed model needs to be verified against the finite element simulations.


Develop a mathematical model for a canned PM machine for steady state and dynamic analysis.

Verification of the equivalent circuit model against finite element simulations.

Influence of can parameters on the performance of the canned PM machine.


Contact details:

PhD candidate: Faisal Wani, [email protected]

Supervisor: Dr. Jianning Dong, [email protected]



33

D C E & S




FOREIGN OBJECT MODELLING AND DETECTION IN DYNAMIC INDUCTIVE CHARGING OF

ELECTRIC VEHICLE


Scope: The goal of the project is to analyse and assess the effect of conductive or magneto-conductive objects

placed near the dynamic charging system and seek ways to detect them.

Problem definition: Dynamic inductive charging of electric vehicles means the electric vehicle (EV) is charged

through contactless inductive power transfer while driving. The performance of inductive power transfer (IPT)

system might be affected by conductive or magneto-conductive foreign objects having a limited size (typically

road side refuse, e.g. aluminium cans). The project will evaluate the effects of foreign objects on electrical

waveforms and efficiency of the dynamic IPT system. Method to detect the foreign objects from electrical

quantities will be investigated and implemented.

Methodology: Finite element method and circuit analysis will be used to study the effects of foreign objects.

Analog or digital circuits will be designed and implemented to detect the foreign objects.


Modelling the foreign objects in DIPT system

Evaluation of foreign objects on DIPT performance

Methodology to detect the foreign objects


Contact details:


Soumya Bandyopadhyay ([email protected])





34

D C E & S




HARDWARE-IN-LOOP SIMULATION OF ELECTRIC VEHICLE POWERTRAIN


Flux Density (T)

Scope: This project aims at development of a hardware-in-loop simulation system of electric powertrain of

electric vehicles.

Problem definition: Hardware-in-loop (HIL) or power-HIL simulations are essential for cost-effect and time-

effective developments of modern powertrains in electric vehicles and electric aircrafts. Control algorithms can

be tested through mathematical dynamic models of electrical machines and power electronics without building

real prototypes. The models of power electronics converters can be replaced with real converters to be tested

if power-HIL is involved. To fully represent the dynamic performance of the powertrain, magnetic saturation,

losses and temperature rise of motors, dynamics of the transmission system, battery and vehicle aerodynamics

should be considered. Comprehensive models should be built and integrated in the real time simulation

platform. Various driving profiles and control algorithms will investigated to validate the effectiveness of the

developed models.

Methodology: Finite element method will be used to generate the dynamic models of electrical machines.

MATLAB/Simulink and OPAL-RT will be used to implement the real-time simulation.


Dynamic modelling of different components in EV powertrain

Real time simulation platform of EV powertrain

Comparison of control algorithms using developed simulation platform


Contact details:





35

D C E & S




LAB SETUP DEVELOPMENT FOR COURSE ET4291 CONTROL OF ELECTRICAL DRIVES

Type of project: Extra project (15 ECTS)

Scope: This project aims at development of a lab setup which can be used for laboratory work for course

ET4291 Control of Electrical Drives.

Problem definition: Currently there are only computer simulations available in the course ET4291 Control of

Electrical Drives, which does not meet the requirements of fast growing applications such as electric vehicles

and renewable energy. The extra project will develop a lab setup which enables implementation and

measurements of real life electrical drives for students. A permanent magnet synchronous machine and an

induction machine will be connected back-to-back. Two three-phase converters will be used to drive both

machines. One of the converters will work in torque control mode for generating. The other one will work in

speed control mode for motoring. Control algorithms will be developed with TI DSP and MATLAB/Simulink.

Methodology: First control blocks should be developed through hardware in loop simulation. Then interface

circuits between DSP and converters should be designed and implemented. Hardware implementation and test

of the system will be carried out afterwards.


Choice of components and system topologies.

Hardware in loop simulation of the drives.

Implementation of the lab setup.


Contact details:





36

D C E & S




PWM-INDUCED LOSSES IN FLOODED GENERATORS FOR TIDAL TURBINES


Stator can

Rotor can

Sea water

Scope: The project is an ideal opportunity for any student who wishes to understand how turbine

characteristics affect the generator performance and vice-versa. Flooded generators are proposed as a solution

to improve the reliability in tidal turbines. Materials, such as stainless steel , when used as a can experience

additional eddy current losses in the cans. Can losses may be significantly influenced by the PWM harmonics

introduced by the converter controlling the generator speed.

Problem definition: Estimate the can loss contribution to the total power loss in the flooded permanent

magnet generator. The can losses should account for the influence of the variation in tidal current velocity due

to the turbulence in the sea state.

Methodology: A tidal turbine experiences wide speed fluctuation about the reference speed due to low inertia

of tidal turbines and turbulence in tidal current velocities. The speed fluctuations can be calculated by coupling

the generator model (could be finite element, depending on the preference of the student) to the turbine

mechanical model e.g. in MATLAB Simulink. The speed control of the generator/turbine is achieved by using a

pulse-width modulated back-to-back converter. The model developed to estimate can losses must be used to

understand important can loss characteristics and trends, dependency on other system parameters, and

suggest ways to mitigate these losses.


Develop models to calculate the eddy current losses in a Canned machine.

Account for losses due to dynamic speed variations caused by turbulence in the sea state.

Influence of turbine and machine parameters, and the control strategies on the can losses.


Contact details:

PhD candidate: Faisal Wani, [email protected]

Supervisor: Dr. Jianning Dong, [email protected]



37

D C E & S



DC Grids and Storage for Smart Cities DC systems, Energy conversion & Storage

CONTROL OF DC NANOGRID CLUSTER BUILT WITH MULTI-PORT CONVERTERS


+ 350 Vdc -350 Vdc

MPC #1

PV system

EV

DC House #1

MPC #2

PV system

EV

DC House #2

MPC #n

PV system

EV

DC House # n

Figure[1]: (a)Quad-active Bridge Architecture and, (b) 4-legged transformer

Scope: Research on DC buildings and houses is gaining momentum in recent literature. Multi-port converters

(MPC )integrating multiple sources and loads are designed to realize the dc nanogrids as shown in Fig. 1(b).

Connecting the DC houses with MPCs to the utility grid can be an interesting research topic.

Problem definition: The research challenge in this field is to device a hierarchical control strategy for clustering

the DC nanogrids to form a resilient and reliable DC microgrid.


Literature review on control of nanogrid clustering

Control model of the DC bi-polar nanogrid cluster and the QAB converter


Combining the dynamic model of the MPC and the DC nanogrid cluster

Analysis of the resilience and availability of the dc grid

Energy management optimization to reduce operational cost


Candidate details:

PhD student: S. Bandyopadhyay [email protected] LB 03.640, Nils van der Blij [email protected] LB 03.690

Supervisor: Dr. Laura Ramirez Elizondo [email protected], LB 03.570 , Prof. Pavol Bauer [email protected] , LB 03.600





38

D C E & S




DESIGN OPTIMIZATION OF HF TRANSFORMER FOR A MULTI-PORT CONVERTER


Figure[1]: (a)Quad-active Bridge Architecture and, (b) 4-legged transformer

Scope: DC residential grids consist of multiple sources and bi-directional loads. An integrated multi-port

converter, which utilizes a single power conversion stage to interconnect all ports, instead of the individual dc-

dc conversion stages, can be introduced in order to make the whole grid simpler. Thus, cost, size, and volume

can be reduced due to less amount of devices and associated circuits. The reduced conversion step results in

higher power density and efficiency.

Problem definition: The research challenge in this field is to optimally model and design the high frequency

transformer to couple all the windings of the QAB converter.


3D and 2D FEM model of the transformer

Detailed loss model and evaluation power density limits of the transformer


A simplified equivalent circuit of the HF transformer

Loss model of the HF transformer

Multi-objective optimization and laboratory implementation


Candidate details:

PhD student: S. Bandyopadhyay [email protected]

Supervisor: Prof. Pavol Bauer [email protected] , LB 03.600



39

D C E & S




DC-GRID DESIGN FOR LOW-VOLTAGE DISTRIBUTION


Scope: Investigate and develop a dc-grid design based on current and future converter technologies.

Problem definition: DC grids play an important role in the energy transition as they allow the connection of

renewable energy sources, storage batteries and large consumers such as heat pumps and electric vehicles to

the grid in a single conversion step. This reduces the capital cost of the devices, increases the conversion

efficiency and allows flexible power management. However, standards are currently lacking, resulting in

different voltage levels and grid configurations for the implemented pilot projects. A wide range of possible

solutions makes it hard to come up with a concessive grid design.

Methodology: The goal of the thesis is to investigate and develop a dc-grid design. The design has numerous

degrees of freedom such as the voltage level and configuration (from bipolar 350 V to unipolar 1,5 kV), the

maximal length of the feeders, the integration of distributed or central storage to reduce load and generation

peaks etc. An important factor is the choice of the converter, both contemporary IGBT-based converters with

low-frequency insulation transformers and SiC-converters with high frequency transformers should be

considered. The grid is developed for several scenarios such as a distribution grid for residential connections, as

well as an industrial environment with a much higher load duration and high PV penetration.


Cost-effective dc-grid design at high efficiency

Impact of voltage level and grid topology and losses and voltage profile

Impact of converter technology on grid topology and efficiency

Collaboration with Industry: Dynniq Energy

Contact details:

Company contact: Sven De Breucker ([email protected])

University: L. M. Ramirez-Elizondo ([email protected])



40

D C E & S




FORECASTING MODELS & THEIR IMPACT ON THE PERFORMANCE OF A DC HOUSE


Battery

Controller

EV

Loads

PVPV

Scope: The goal of this project is to 1) forecast the yield of PV system based on the past data; 2) decide the

system operation in the future; 3) study the forecasting impact of the performance on the DC house.

Problem definition: With the increasing penetration of PV power system into the DC house, the problem

caused by fluctuation and intermittency of PV power output draws more attention. And this will also affect the

load consumption, especially during the peak time. What’s more, the data of PV irradiance is extensive, so

finding out the best method to forecast is also fundamental, such as stochastic method, fuzzy logic method,

machine learning.

Methodology:

Extensive literature review on DC house and forecasting algorithms

Design System architecture including the PV sizing, battery sizing and load profile

Model of the designed DC house system


Find the most appropriate forecasting algorithm

Apply the forecasting algorithm to the designed system

Analyse case studiesbased on performance (efficiency) with and without forecasting


Contact details:

PhD student: Na Li, [email protected];


Victor Vega Garita, [email protected]

Supervisors: Pavol Bauer, [email protected]

Laura Ramirez Elizondo,[email protected]




41

D C E & S




SYSTEM SIZING & IMPACT OF DEMAND SIDE MANAGEMENT ON THE OFF-GRID DC

HOUSE


Battery

Controller

EV

Loads

PVPV

Scope: Demand side management (DSM) can be used to improve the utilization and efficiency of renewable

energy, especially in some places where there is no access to electricity. The goal is to design an autonomous

household system, decide its size, study the demand side management strategy and its impact on the energy

system sizing for an off-grid DC house.

Problem definition: Considering a typical DC house includes PV, battery and smart controller and some loads.

Because the PV yield doesn’t match with the demand, especially during peak hours, it is very important to

allocate the energy generated by PV system appropriately.

Methodology:

Extensive literature review on DSM for an off-grid DC house

Study the DSM strategies and decide the best one for this system

Model the off-grid DC house system


Evaluate the system size including PV, battery and load profile

Apply the DSM strategy in the designed system

Analyse case studies: system performance and sizing with and without DSM


Contact details:

PhD student: Na Li, [email protected];


Victor Vega Garita, [email protected]

Supervisors: Pavol Bauer, [email protected]

Laura Ramirez Elizondo, [email protected]




42

D C E & S




SELF-SUFFICIENT OFF-GRID DC-APPLIANCES WITH ENERGY STORAGE AS A MODULAR

SOLUTION FOR CLIMBING UP THE RURAL ELECTRIFICATION LADDER


Fig. 1 Energy ladder in the context of rural electrification

Scope: 1.2 billion people around the world lack access to affordable electricity. Energy access is not a binary

metric as regarded in the past, but consists of multiple levels of electricity demand at different levels of the so-

called rural electrification ladder.

Problem definition: Solar Home Systems (SHS) seem to be a promising off-grid solution to power the off-grid DC

appliances. However, the optimal system sizing of SHS become obsolete when users move up the electrification

ladder. Therefore a modular solution needs to be adopted, which could be in the form of self-sufficient off-grid

DC loads.

Methodology: The research mainly consists of optimizing the system size of SHS for various levels of

electrification with and without the use of self-sufficient appliances. The student will be involved in modelling

and simulating SHS on MATLAB for different scenarios.


Comparing the optimal system sizing with and without self-sufficient DC loads in the system

Quantifying the costs and benefits of having storage-integrated DC loads

Comparing the load modularity with other modular architecture options


Contact details:

PhD students: Nishant Narayan<[email protected]>

Supervisor: Zian Qin< [email protected]>



43

D C E & S




POWER FLOW CONTROL IN LVDC GRIDS USING LOCAL ENERGY STORAGE


Scope: The LVDC grid faces two major bottlenecks- protection and power flow control. At the TU Delft partially

rated power flow control converter was proposed. The converter is developed with the Fraunhofer-IISB to

achieve the state-of-the-art hardware. The scope of this project is development and application of the novel

control methods for the developed device.

Problem definition: The power flow control converter (PFCC) can be enhanced with a local storage. However,

in doing so the energy storage control problems are included in already complex control of the PFCC. The main

focus of this thesis will be to develop the control of the partially rated power flow control converter with local

energy storage.

Methodology: The student needs to familiarize with the power flow control in LVDC grids and associated

challenges. After developing the control models in Matlab/Simulink, the algorithms will be applied in the FPGA

and tested in the laboratory.


Literature review of the power flow control and energy storage in LVDC grids

Developing the control algorithms for the partially rated power flow control converter

Application & Testing of the developed control methods in the laboratory

Collaboration with Industry: Optional

Contact details:

PhD student: Pavel Purgat, [email protected]

Supervisor: Dr. Zian Qin, [email protected],

prof. Pavol Bauer, [email protected]




44

D C E & S




MODELLING, STABILITY, CONTROL AND MANAGEMENT OF DC DISTRIBUTION GRIDS


Microgrid

MicrogridNanogrid

Energy Storage System

Renewable Energy Sources

Electrical Loads

Fault Isolation Device

Microgrid

MV Grid

~

Scope: To aid the broad adoption of DC distribution grids more research is required on the modelling, stability,

control and management of dc distribution grids. Many topics within these categories are available for master

students.

Problem definition: Distribution grids are subjected to changes such as the increasing participation of

distributed energy resources (DER), segmentation of the grid, and increasing participation of consumers and

producers. This poses significant challenges with respect to stability and control. It becomes attractive to

employ DC distribution systems since they have several advantages to AC distribution systems. DC distribution

grids do not require the synchronization or reactive power governance, and do not have issues with harmonic

and inrush currents. Moreover, the interconnection of dc (micro)grids is significantly simpler. Furthermore, dc

distribution grids are also foreseen to have advantages over ac in terms of efficiency, distribution lines, and

converters .

Methodology: These topics mainly involve literature research, analytical derivations, simulations and/or

programming. However, design/experimental topics are also available.

Examples of available topics are:

Steady state (load flow) analysis of DC distribution grids

Transient analysis of DC distribution grids

Small-signal stability of DC distribution grids

Centralized/Decentralized/Distributed control of DC distribution grids

Demand Side Management in DC distribution grids

Cost of Flexibility in smart grids

Blockchain for Smart Grids

Collaboration with Industry: In some cases possible.

Contact details:

PhD student: Nils H. van der Blij ([email protected])

Supervisor: Laura M. Ramirez-Elizondo ([email protected])



45

D C E & S




DESIGN AND EXPERIMENTAL VERIFICATION OF DC DISTRIBUTION GRID CONTROL


Scope: It is essential for the broad adoption of DC distribution grids to design and experimentally verify the

research done on the modelling, stability, control and management of DC distribution grids. Different projects

are available to design converters or do experimental work.

Problem definition: Distribution grids are subjected to changes such as the increasing participation of

distributed energy resources (DER), segmentation of the grid, and increasing participation of consumers and

producers. This poses significant challenges with respect to stability and control. DC distribution grids are

foreseen to have advantages over ac in terms of efficiency, distribution lines, and converters . However, more

theoretical and experimental work is required to research and prove these advantages.

Methodology: These topics either mainly involve the design of suitable converters and/or the execution of

experiments. Moreover these projects entail literature research, simulations and programming.

Examples of Research objectives:

Design of a DC distribution system

Design of the communication between power electronic converters

Simulation of DC distribution systems

Conduct experiments regarding the control of DC distribution grids

Converter (PCB) design

Programming power electronic converter’s microcontroller

Collaboration with Industry: In some cases possible.

Contact details:

PhD student: Nils H. van der Blij ([email protected])

Supervisor: Laura M. Ramirez-Elizondo ([email protected])



46

D C E & S




BATTERY MANAGEMENT STRATEGIES

Type of project: MSc thesis/Extra Project

Fig. 1 Battery management system board (left), and battery tester (right).

Scope: Energy Storage, especially batteries, have become an indispensable part of sustainable energy systems.

From PV Systems and Electric Vehicles to grid-scale applications, batteries play a vital role.

Problem definition: Batteries are often the first components to fail in an energy system, owing to short

lifetimes and demanding, complex trade-offs in their operational parameters. A battery management system

(BMS) needs to be designed for the most common battery technologies like Lead-acid gel, and Lithium Iron

Phosphate. The BMS should be capable of achieving controlled voltage balancing across the different battery

cells. Consequently, capacity fading rates can be observed.

Methodology: The research consists of firstly understanding the operational battery parameters and their

interdependencies. Secondly, the student will use dedicated hardware for BMS implementation, including TI

board (EM1401), and Arbin battery tester (LBT22043). Additionally, the student will devise test-case patterns

for charging and discharging the battery, along with implementation of Ah-counting through the available

hardware.


Develop test-case patterns for charging and discharging different batteries.

Implement Ah-counting and controlled voltage balancing for the different battery cells.

Analyse the expected different capacity fading rates between battery technologies.


Contact details:

PhD students: Yunhe Yu, Victor Vega-Garita, Nishant Narayan

Supervisor: Zian Qin < [email protected]>,

Pavol Bauer, <[email protected]>



47

D C E & S




LEARNING WITH THE BATTERY MANAGEMENT SYSTEM

Type of project: Extra Project/ SIP 2

Scope: The available battery cells and battery management circuit in the lab can be used to obtain the

knowledge of battery management system

Problem definition: Battery cells are always connected in series for a higher terminal voltage. Due to the

inconsistencies of the battery cells in terms of impedance, status of health (SOH), self-discharging, heat

dissipation, a battery management system is necessary to make sure the load is properly shared among the

cells and thereby maximize the lifetime of the entire battery stack.

Methodology: Laboratory work is expected


Build up the platform to test the battery management system

Able to control the charging/discharging current of the battery stack

Able to observe or estimate the parameters of the batter cells, e.g. capacity, state of charge,

temperature


Contact details:

PhD students: Yunhe Yu, Nishant Narayan, Victor Vega Garita

Supervisors: Zian Qin, <[email protected]>

Pavol Bauer, <[email protected]>



48

D C E & S



High Voltage DC Systems DC systems, Energy conversion & Storage

DISTRIBUTION GRIDS WITH FLEXIBLE DC LINKS


Scope: The existing ac link between two substations needs to be converted to partial dc link system2. Think of

how to interconnect the system to have maximum infrastructural utilization and showcase the operational

modes of the new system3. Provide grid support to the distribution network using this flexible ac-dc link.

Problem definition: Design and simulate a grid integrated flexible dc link for power redirection, reactive power

support, harmonic elimination and other ancillary services to improve the operability of the existing medium

voltage ac distribution network.

Methodology: Ability to simulate state space model and control strategies in MATLAB is required.

Understanding of modular multilevel converters (MMC) is to be developed. Enthusiastic student may use the

available laboratory prototype of MMC to implement his/her findings.


Show how parallel ac-dc link topology can operate with converter based voltage regulation.

Develop various grid supporting ancillary services using MMC, such as active power redirection,

reactive power support, fault ride through, harmonic elimination, etc.

Prove the working of the developed optimal ac-dc load sharing algorithm.

Analyse the proposed system feasibility with an economic/functionality study.


Contact details:

PhD student: <A. Shekhar, [email protected]>

Supervisor: <L. M. Ramírez-Elizondo, Pavol Bauer>

2 Aditya Shekhar, Epameinondas Kontos, Laura Ramírez-Elizondo, Armando Rodrigo-Mor, Pavol Bauer, Grid capacity and efficiency

enhancement by operating medium voltage AC cables as DC links with modular multilevel converters, In International Journal of Electrical Power & Energy Systems, Volume 93, 2017, Pages 479-493, ISSN 0142-0615, https://doi.org/10.1016/j.ijepes.2017.06.012. 3 Aditya Shekhar, Epameinondas Kontos, Laura Ramírez-Elizondo and Pavol Bauer, “AC Distribution Grid Reconfiguration using

Flexible DC Link Architecture for Increasing Power Delivery Capacity during (n-1) Contingency,” IEEE SPEC, 2017.

Outer

Substation AInner City

Substation B5-20 km

Operate the Overloaded MVAC

Underground Cable Under DC Conditions

MV/LV

Radial In-city

Distribution

<

Photograph>


49

D C E & S




SMALL-SIGNAL ANALYSES FOR INVESTIGATING SLOW CONTROL INTERACTIONS BETWEEN

POWER ELECTRONIC ELEMENTS IN MODERN ELECTRICAL POWER SYSTEMS


Scope: Multi-infeed and interaction of power electronics

Problem definition: For reliably integrating power electronic elements in modern power systems, the interoperability of the elements with the network and amongst each other needs to be ensured. The wide range of potential interaction phenomena can only be covered by a bundle of complementary approaches.

In a first step Siemens has proposed a methodology to investigate slow control interaction phenomena of a single VSC HVDC with the network in the linearized state space of complex systems based on small-signal analyses, i.e. modal analysis (eigenvalues and eigenvectors of the state matrix, etc.) and linear analysis tools (Bode, Nyquist, etc.).

For this thesis the proposed method shall be refined and extended to “multi-infeed” configurations addressing the interaction of multiple power electronic elements.

MATLAB and Simulink will be employed for the analyses of the linearized differential equations.

Methodology:

Enhance and extend proposed methodology to multi-infeed configurations in MATLAB/Simulink


Evaluate and understand interaction of slow control functions

Identify potential controller interaction

Find risk factors for detrimental controller interaction

Collaboration with Industry: SIEMENS. Probably a 3 month internship + 6 month Thesis (Erlangen, Germany)

Contact details:

Company: Sebastian Höhn, [email protected]

University: Lucia Beloqui Larumbe, [email protected]



50

D C E & S




SMALL DC LINK SUBMODULE FOR MODULAR MULTILEVEL CONVERTERS


Scope: Studying the methods to achieve small dc link of the submodule for MMC.

Problem definition: The modular multilevel converter (MMC) is the key technology of high voltage direct

current (HVDC) that enables power transmission through an extra-long distance. The submodule in MMC, as a

single phase dc-ac inverter, inherently suffers from second-order power ripple, which needs a large dc link

capacitor bank to overcome passively. The large dc link composed of electrolyte capacitors is bulky, heavy and

with short life, it is therefore a crucial challenge especially when the number of the arm converters is

tremendous, e.g. 300.

Methodology:

Build the MMC model

Deploy different modulation strategies in the MMC

Compare the impact on power ripple of the submodule


Find out the modulation strategy that can achieve the lowest power ripple in submodule

Evaluate the feasibility of using hardware method to reduce the power ripple in submodule

Contact details:

PhD student: Aditya Shekhar ([email protected])


Prof. Dr. Eng. Pavol Bauer, ([email protected])

Large capacitor bank




51

D C E & S



High Voltage DC Diagnostics and Monitoring DC systems, Energy conversion & Storage

ARBITRARY VOLTAGE WAVEFORM FOR INSULATION TESTING PURPOSE

Type of project: <MSc thesis>

Scope: <To determine the extra information that can be extracted about dielectric condition when arbitrary

voltage waveform is used for diagnostics, instead of traditional AC or DC voltage >

Problem definition: < Partial Discharge (PD) measurement and dielectric spectroscopy are powerful tools used

for diagnostic of high voltage equipment . PD and DS measurement are often done at AC 50 Hz sinusoidal

voltage. While there are a lot of study regarding this type of measurement, still a comprehensive figure about

the insulation condition cannot be derived out of these measurements. On reason is that only limited amount

of information related to dielectric aging state would be present in PD and DS measurement when they are

done using 50 Hz sinusoidal waveform. The goal for this project is to investigate PD and DS measurement using

arbitrary voltage waveform and on oil-impregnated paper insulation to investigate whether it is possible to

extract valuable information about aging state of the paper insulation.

Methodology: <The work is mostly experimental work which has to be carried out at high voltage laboratory.

PD and DS measurement will be performed at different arbitrary voltage waveform and the measurement

results should be compared with AC 50 Hz voltage waveform>


<literature review of PD and DS measurement techniques>

<preparation of experimental set-up for investigation of aging status of oil-impregnated paper,

including how to generate arbitrary high voltage waveform, and how do PD and DS measurement >

<comparison of PD and DS measurement between arbitrary voltage waveform and AC 50 Hz>

Collaboration with Industry: < No>

Contact details:

Supervisor: < Mohamad Ghaffarian Niasar, [email protected]>

Rob Ross, [email protected], Peter Vaessen [email protected]

Xiaolei Wang, “Partial Discharge Analysis of Stator Insulation at Arbitrary Voltage Waveform Stimulus”, PhD thesis, 2015


52

D C E & S




FEASIBILITY STUDY OF TRANSFORMER NOISE MAPPING BY MEANS OF VIDEO/IMAGE

PROCESSING>

Type of project: <Extra project>

Scope: < In this project feasibility study of transformer noise mapping using video files and image processing

techniques should be investigated.>

Problem definition: < A video file captured of an object can reveal significant amount of information about that

object. These information can be extracted if proper image processing technique is used. Recently it has been

shown that vibration of overhead line conductor can be extracted using signal processing of captured video

files from a vibrating conductor. Noise generated from a transformer can be used as a diagnostic tools to assess

the performance of the transformer. High amount of acoustic noise can also be disturbing for the people living

nearby a substation and hence requires action to reduce the noise level. Acoustic noise measurement and

creation of a noise map for a transformer is therefore of interest. Conventionally this is done by means of

microphone that are moved around the transformer and a colour map representing the magnitude of the

noise with respect to the location of the noise is created. This kind of map can be used to interpreting the

reason behind high amount of noise and possible active damping arrangement to suppress the disturbing

acoustic noise in the environment. Acoustic noise generated by a transformer is equivalent to vibration of the

transformer body. This vibration is different at different locations on the transformer tank. This subtle vibration

can be extracted out of colour change of a video file taken from the transformer.>

Methodology: <The work mostly involves MATLAB coding and video/image processing. An algorithm should be

developed to extract tiny motion through colour change of images in a video files. Simple experimental setup

with known noise sources will be used to test the developed algorithm>


<literature review of available motion magnification techniques>

<Development of a motion magnification algorithm suitable for extraction of tiny colour changes in an

image and verification of the code through experiment>


Contact details:


Source: http://electrical-engineering-portal.com/transformers-are-never-silent


53

D C E & S




DIAGNOSTICS AND MONITORING OF HVDC CONVERTER TRANSFORMER


Scope: <To understand aging mechanism of oil-impregnated paper exposed to DC and AC stress at the same

time >

Problem definition: < Converter transformer is an important part of a HVDC link. Any unexpected failure of

such transformer can be very costly due to the cost of transformer itself and the cost of power interruption.

Condition monitoring of such transformer is therefore very crucial. To be able to properly interpret partial

discharge measurements recorded from a converter transformer it is necessary to understand how each

dielectric component inside a converter transformer behave to different stresses. Paper insulation inside a

converter transformer is stressed by DC and AC electric field at the same time while on a conventional

transformer the insulation is only stressed by AC electric field. Partial discharge behaviour of a converter

transformer is therefore different than a conventional transformer and hence the interpretation would be

different.

Methodology: < In this project life time of paper insulation material should be investigated under simultaneous

DC and AC electric stress. Evaluation of PD over the life time should be recorded and interpretation of the

results must be provided.>


<literature review of insulation system used in HCDC converter transformer and a summary of

available tests used to ensure a proper made converter transformer >

<Life time of oil-impregnated paper stressed with AC, DC and combined AC and DC stresses>

<Experiment of Impulse breakdown strength when oil-impregnated paper is aged with AC voltage

superimposed with pulsed stresses>


Contact details:



Source: ABB


54

D C E & S




ELECTRIC & MAGNETIC FIELDS ON HYBRID OVERHEAD TRANSMISSION LINES


Scope: Analysis of the electric and magnetic fields on hybrid overhead transmission lines with the help of Finite

Element Methods.

Problem definition: One challenge, while designing hybrid overhead transmission lines, i.e. tower structures

that consist of both HVAC and HVDC circuits, is the combined effect of the electric and magnetic fields along

the line route.

Methodology: This project would include a) a literature review and b) basic simulation of electric and magnetic

fields with the help of Finite Element Methods and modelling in COMSOL Multiphysics software package.


Literature review and incentivization of applied standards worldwide;

Modelling of electric and magnetic fields in COMSOL Multiphysics.


Contact details:

Company: Konstantinos Velitsikakis, [email protected]

University supervisor: Peter Vaessen, [email protected]

Mohamad Ghaffarian, [email protected]




55

D C E & S




DESIGN OF A CONTROL SYSTEM FOR PARTIAL DISCHARGE ONLINE MONITORING OF

HVDC GAS INSULATED SYSTEMS


Scope: To design a control system for continuous online monitoring of partial discharges for offshore HVDC GIS

substations, including the design of special algorithms for signal processing and automatic configuration of the

acquisition parameters.

Problem definition: partial discharges are one of the most efficient ways to monitor the insulation condition of

HVDC Gas Insulated Systems (GIS). Due to renewable energy integration, offshore HVDC substations are

increasing in number and power delivery. Remote online monitoring systems are crucial for the early detection

of insulation defects which can lead to faults and ultimately cause big economic, social and environmental

losses. Remote monitoring systems must be able to operate autonomously. For that purpose, signal processing

is used to extract information from the collected data. New algorithms and control strategies need to be

developed for an automatic and reliable operation of remote monitoring systems.

Methodology: This project includes: a) literature review; b) design of algorithms and control strategies; c)

implementation on acquisition systems using Labview software; d) high voltage experiments for validation.


Review of existing signal processing methods of noisy signals.

Development of adaptive algorithms for automatic trigger level determination.

Efficient implementation of algorithms in embedded control systems using Labview and control of fast

acquisition oscilloscope cards.

Verification of the system performance by means of high voltage tests.

Contact details:

University supervisor: Armando Rodrigo Mor, [email protected]

Luis Carlos Castro Heredia, [email protected]

Fabio Muñoz Muñoz, [email protected]




56

D C E & S




DESIGN OF ALGORITHMS FOR AUTOMATIC DISCRIMINATION OF NOISE AND PARTIAL

DISCHARGE SIGNALS.


Scope: To design algorithms for automatic discrimination of noise and partial discharge signals to be used in

autonomous and remote online partial discharge monitoring systems.

Problem definition: partial discharges (PD) are one of the most efficient ways to monitor the insulation

condition of high voltage assets. Online monitoring systems are used for continuous monitoring of equipment

for long periods of time, ranging from weeks to years. Nowadays, all the existing systems require human

supervision since measurements are heavily affected by noisy signals and external interferences. The lack of

algorithms for automatic discrimination of pulses hinder the expansion of autonomous and reliable monitoring

systems. Therefore, new signal processing tools are needed to be able to discriminate real PD pulses from noise

pulses and any other source of external interference. This research project focuses on the creation of an

algorithm for reliable discrimination of partial discharge pulses based on their shape and frequency

components. Development of algorithms based on machine learning, neural networks, fuzzy logic and other

advanced processing tools is expected.

Methodology: This project includes: a) literature review; b) design of algorithms; c) implementation of

algorithms on acquisition systems using Labview software and/or Matlab; d) high voltage experiments for

validation.


Review of existing signal processing methods for PD discrimination.

Development of algorithms for automatic recognition of PD pulses.

Efficient implementation of algorithms in embedded control systems using Labview and/or Matlab.

Verification of algorithms performance by means of high voltage tests.

Contact details:

University supervisor: Armando Rodrigo Mor, [email protected]

Luis Carlos Castro Heredia, [email protected]

Fabio Muñoz Muñoz, [email protected]




57

D C E & S



High Voltage DC Materials and Components DC systems, Energy conversion & Storage

BREAKDOWN MECHANISM OF HIGHLY VISCOUS DIELECTRIC LIQUID


Scope: <The scope of this thesis is to model pre-breakdown phenomenon occurring in highly viscous dielectric

liquids >

Problem definition: <Streamer formation is the pre-breakdown mechanism in dielectric liquids. Based on the

applied voltage it can be classified as positive or negative streamer. Mechanisms of breakdown is different for

each of the streamer type. In the case of negative streamer, streamer is initiated due to formation of

microbubbles adjacent to the needle tip. The bubble itself forms subsequence to a current pulse injected to the

liquid due to an electronic avalanche. The current pulse create a high temperature zone inside the dielectric

liquid which vaporizes the liquid and forms the micro bubble. The bubble would further expands and reach a

maximum size. Thereafter the bubble contracts and vanishes. Due to columbic and electrophoretic forces the

bubble may detach from the needle tip and float into the liquids. Current pulses recorded from the negative

polarity shows a pulse train typically increasing in magnitude. The goal of the project if to simulate these

complex, Multiphysics phenomenon. >

Methodology: <The work include initial laboratory measurement in which corona discharge on a point-plane

geometry immersed in the dielectric liquid must be recorded at positive and negative voltage polarity with fast

and slow detection systems. A FEM model that simulate the pulses of corona discharges has to be developed >


<literature review of existing theory and publication about breakdown mechanism of dielectric liquids

and simulation methods that have been used>

<experimental work to record corona discharge under positive and negative polarities which slow and

fast detection circuit>

<Development of a FEM model that simulate the pre-breakdown phenomenon >


Contact details:



Source: Henrik Frid, et al. “Simulation of Microbubbles…”


58

D C E & S




DESIGN OF A CAPACITIVE VOLTAGE PROBE FOR SURFACE CHARGE MEASUREMENT


Scope: < A capacitive voltage probe for measurement of surface charges has to be designed and constructed.

The device will be used to experiment charge decay on surface of different dielectrics. A model representing

the phenomena of charge decay should be developed and verified with the experimental results.>

Problem definition: <Surface charges may accumulate on the surface of DC insulator and alter electric field

distribution. In gas insulated substations due to field emission from the enclosure, electric charges are injected

to SF6 and deposits on the surface of the spacer. In outdoor polymeric insulator surface charges are formed on

the insulator due to corona activity. The presence of surface charges may decrease the breakdown strength of

the insulator, leading to failure of HVDC component (in the event of lightning impulses) and hence interrupting

power transmission. Therefore understanding how surface charges form and decay on the surface of insulator

is very important for HVDC insulation design. >

Methodology: <The work consist of design and construction as well as simulation and experimental validation.

Experimental work will be done in high voltage laboratory with the help of constructed capacitive probe.

Simulation should be performed with COMSOL Multiphysics>


<to understand how electric charge and surface potential can be measured >

<To design a circuit capable of measuring surface potential due to surface charges, verification with

circuit analysis software (e.g. PSPICE)>

<construct the capacitive voltage probe>

<experimental work and measurement of surface charge decay on different insulation>

<development of a FEM model to simulate surface charge decay phenomena>


Contact details:



Xiaolei Wang, “Partial Discharge Analysis of Stator Insulation at Arbitrary Voltage Waveform Stimulus”, PhD thesis, 2015


59

D C E & S




MODELLING OF CHARGE DECAY IN HVDC CABLES


Scope: <To develop a model that can demonstrate charge decay and recovery voltage phenomenon on HVDC

cables >

Problem definition: <Space charges can accumulate in DC cables and alter the electric field distribution in the

cable. Space charge build up and decay depends on insulation parameters, temperature, and environment.

Charge decay can happen very quick or can take many days. When voltage is removed from a DC cable, trapped

space charges can remain in the insulation for a long time. A de-energized cable can therefore develop

potential difference between conductor and the sheath due to the available space charges. This is important

from the safety point of view as such electric potential can be lethal. In this project a finite element model and

a circuit model will be develop to demonstrate how the potential decay occurs when the voltage is removed

from the cable. The model must be validated by means of experiment.>

Methodology: <The work consists of development of a numerical model that can simulate charge decay and

voltage recovery phenomenon in HVDC cables. The work also involve experimental work which will be done in

high voltage laboratory. >


<literature review of mechanism of charge decay and voltage recovery measurement as a diagnostic

method>

<Development of a FEM model in COMSOL Multiphysics that simulate charge decay in HVDC cable.

Development of a circuit model that can represent voltage recovery phenomenon>

<Comparison of the developed model with experiment>


Contact details:



E. Kuffel, W et al, High Voltage Engineering Fundamentals.


60

D C E & S




MODELLING OF A FAST ACTUATOR FOR HVDC BREAKER APPLICATION


Scope: <Development of a FEM model that accurately predicts operation of a Thomson coil >

Problem definition: <To interrupt HVDC current three main technologies are available. In the first technology

power electronic switches are used to interrupt the current. This technology offers a very fast operation (~1𝜇𝑠)

however the on-state loss is rather high which makes the technology expensive to operate. The second

technology is purely mechanical. The on-state loss for this technology is minimized but the operation time of

the switch is rather high (~60m𝑠). In the third technology a combination of both methods are used in which the

on-state operation has almost a minimal loss while the operation time is reduced significantly (~5m𝑠)

compared to purely mechanical switch. To achieve an ultra-fast actuation a Thomson coil can be used. The coil

is connected to a capacitor bank and the armature is connected to the breaker push-pull rod. By discharging

the capacitor bank through the coil, the armature experienced a force which moves it away from the coil. The

phenomenon involves number of physics that are coupled. Electromagnetism, heat transfer, Newton motion

laws, and solid state mechanic equations. The involved physics must be solved together in order to accurately

model the behaviour of the actuator.>

Methodology: <The work is mostly focused on computer simulation. After development of the model, a small

scale Thomson coil has to build to verify accuracy of the constructed model. The experimental part will be done

in high voltage laboratory of TU Delft.>


<literature review of the existing HVDC circuit breaker mechanisms and understanding operation

cycle of each method >

<To be able to couple different physics in COMSOL Multiphysics software>

<Development of a FEM model that can accurately predict the operation of a Thomson coil>

<experimental verification of the constructed model on a small scale Thomson coil>


C ontact details:



Magnus Callavik et al, Hybrid High-voltage Direct Current Breaker


61

D C E & S




MODELLING OF SUPERCONDUCTING TAPES AND CABLES


Scope: < The scope of this project is to develop a finite element model for calculating AC losses in the

superconducting tape with different tape size and cable design. >

Problem definition: < Superconductors are materials that can conduct a stationary electrical current without

resistance. Alternating magnetic fields and transport currents cause dissipation of energy in superconductors.

The energy dissipation is called AC loss. The magnetic field penetrates the material in the form of flux lines. The

magnetic-field variation inside the material induces an electric field E according to Faraday’s law. The electric

field drives “screening currents” in the material. The screening currents determine the magnetic-field

distribution in the superconductor according to Ampere’s law. The screening currents dissipate energy given by

E.J. The energy is delivered by the external magnetic field and is supplied by the power source which generates

the magnetic field. The energy is required for depinning and moving the flux lines, which is a dissipative

process. The energy is converted into heat that must be removed by the high cost and low efficiency cooling

system. AC loss is therefore an undesirable phenomenon.>

Methodology: < The research is included the modelling of the cable in COMSOL Multiphysics® software and

calculating the AC loss (the energy which is required for depinning and moving the flux lines).>


< Model the superconducting cable in COMSOL Multiphysics® software.>

< Calculating the AC loss and validating with the available publications.>

< Reducing the AC loss by changing the configuration of the superconducting tapes.>


Contact details: Babak Gholizad, [email protected]

Mohamad Ghaffarian Niasar, [email protected]

Rob Ross, [email protected]

Source: Marijn Pieter Oomen, PhD thesis




62

D C E & S




BREAKDOWN STRENGTH OF SOLID INTERFACE WITH ARTIFICIAL DEFECTS UNDER

DIFFERENT AC WAVEFORMS

Type of project: < Extra Project>

Scope: The scope of this project is to investigate the breakdown strength of solid interface with artificial

defects under different AC waveforms.

Problem definition:

The largest part of the failures in the cable systems occurred in the cable accessories, especially at the interface

between cable insulation and accessory insulation. Defects might be introduced to the interface during the

installation process, or created at the interface due to the aging process. Beside the normal operating AC

voltage, the cable systems are also subjected to other types of AC voltage waveforms, such as the transient

over-voltage caused by switching or lightning impulses, or the AC sinusoidal waveforms with different

frequencies that are applied during after-laying tests, or the AC voltages with harmonics caused by power

electronics in the system. Degradation can be ignited or accelerated by such AC waveforms within the defects

at the interface, which will finally lead to breakdown. This work is to study the breakdown strength at the

interface with defects under the different types of AC waveforms.

Methodology:

this project will be mainly carried out in the high-voltage laboratory of TUD. AC voltage waveforms need to be

determined and generated. Material samples need to be prepared with introducing defects. Statistical analysis

will be performed after breakdown measurements.


To learn the different AC voltage waveforms that may stress on the cable accessories

To prepare the samples and fabricate the defects at the solid interface

To measure the breakdown strength of the samples and analyse the results


Contact details:

PhD student: Jiayang Wu [email protected]

Supervisor: Armando Rodrigo Mor [email protected]



63

D C E & S




PARTIAL DISCHARGE CHARACTERISTICS AT SOLID INTERFACE WITH ARTIFICIAL DEFECTS

UNDER SUPERIMPOSED VOLTAGES IN MATERIAL SCALE

Type of project: <Master Thesis>

Scope: The scope of this research is to investigate the characteristics of partial discharges at the interface of

cable insulation materials with defects under superimposed waveforms.

Problem definition:

Although the HV cable systems should be well designed in order to withstand operation and transient

conditions, failures may still occur especially in the cable accessories. It can be expected that many failures are

initiated by partial discharge activities within the defects, which are caused by installation or aging process.

Therefore, investigation of partial discharges can give useful information about the conditions of cable

accessories and predict the probable failures. On the other hand, impulse voltages caused by switching

operations or lightning strikes, can ride over the operating AC voltage to form the superimposed voltage, which

increase the stress on network components and may trigger partial discharges. Thus, a study on partial

discharge characteristics under superimposed voltages is needed in order to provide information for failure

prediction.

Methodology:

this project is focused on the partial discharge behaviour at the interface of cable accessories. Experiments

need to be performed in the high-voltage laboratory with generating superimposed voltage waveforms,

preparing material samples with defects and performing PD measurements.


To generate superimposed voltages (with switching and lightning)

To prepare the samples and fabricate the defects at the solid interface

To measure the partial discharge parameters of the samples

To analyse the results and interpret the mechanism

Collaboration with Industry: <TenneT>

Contact details:

PhD student: Jiayang Wu [email protected]

Supervisor: Armando Rodrigo Mor [email protected]



64

D C E & S




MODELLING ELECTROMECHANICAL INSTABILITY MODE IN ELECTROACTIVE POLYMERS

USING FINITE ELEMENT METHOD (FEM)

Type of project: Master Thesis (45 ECTS)

1 Electromechanical stress concentration (from S.Park,2012)

Scope: The scope of the project is to determine in which conditions the electromechanical instability (Pull-in

instability) failure occurs in dielectric elastomer that is typically used in artificial muscles or energy wave

harvesting.

Problem definition: Dielectric electroactive polymers (DEAP) are a class of smart insulating material used in

actuators or energy harvesting devices. When a DEAP membrane is exposed to high electric fields, it deforms

due to Coulomb forces created on its surface. This translates in transforming energy from an electrical domain

to a mechanical one. And vice versa, since reversibility of the process.

The applied force may not be homogeneous all over the surface due to localized stress concentration: these

areas are the weakest spots of the system. It is important to understand how these spots arise in order to

prevent this failure mode.

Methodology: The project includes: a modelling part in which the mechanical and electrical stresses are

coupled and described by a set of non-linear equations; a simulation part in which a standard finite-element

(FEM) discretization is used to evaluate the model on different 3D geometries. Research Objectives:

Designing a model that fully describes the electromechanical coupling of DEAP

Understanding conditions that make electromechanical instability failure mode occur


Contact details:

PhD student: Alessandro Iannarelli, [email protected]

Supervisor: Rob Ross, [email protected]; Pavol Bauer, [email protected]




65

D C E & S




PERFORMANCE REDUCTION STUDY OF ELECTROACTIVE POLYMER USED IN ENERGY

HARVESTING GENERATOR OR ARTIFICIAL MUSCLES

Type of project: Master Thesis (45 ECTS)

Scope: The scope of this study is to determine the cause of performance reduction in energy harvesting

generator or artificial muscle due to repetitive and uninterrupted use.

Problem definition: Dielectric electroactive polymers (DEAP) are a class of smart insulating material used in

actuators or energy harvesting devices. When a DEAP membrane is exposed to high electric fields, it deforms

due to Coulomb forces created on its surface. This translates in transforming energy from an electrical domain

to a mechanical one. And vice versa, since reversibility of the process.

During its operation, such material undergo a huge number of deformation cycles. From previous experiments,

it has been observed that the actuation displacement for a DEAP system changes over time albeit the voltage is

kept the same. The actuation jump again back to its max when the device is kept at rest for some time. T make

a reliable and robust system that can work for long time continuously, it is important to know which are the

causes of this loss of performance in time.

Methodology: The project includes: quantitative observation of displacement change over time. This will done

both with visible and IR camera imaging ; Measurement of the conductivity of silicone thin film; Measurement

of possible space charges formation.


Quantify the speed of performance reduction over time.

Verify the possibility of space charge formation in thin silicone film.

Possibly understand the performance reduction cause and formulate a solution.

Contact details:

PhD student: Alessandro Iannarelli, [email protected]

Supervisor: Rob Ross, [email protected]; Pavol Bauer, [email protected]




66

D C E & S




DESIGN OF A COAXIAL SAMPLE FOR CALIBRATION AND CHARACTERIZATION OF SPACE

CHARGE ACOUSTIC MEASUREMENTS


Scope: Design of a sample resembling a full size HVDC cable, capable of emulating trapped electric charges at

different radius of the cable’s dielectric bulk. The calibrated sample should be compatible with the acoustic

methods used at Space Charge measurements.

Problem definition: HVDC networks are widely increasing their presence in the transmission network due to

the new developments and achievements of HVDC power converters. Therefore, measurement of the Space

Charge phenomena in HVDC components is becoming more relevant. The availability of different space charge

measurement methods brings the necessity of calibration and characterization of measurement equipment in

order to reach standardized measurements. This brings the necessity of a reliable calibrated sample to

reproduce the same charge values in different tests and equipment.

Methodology: The research involves full understanding of the acoustic methods for space charge

measurements. The student will make a design of the coaxial calibration sample and proceed to its

construction and validation tests.


Develop a design for a space charge calibration sample.

Construction and testing of the sample prototype.


Contact details:

PhD student: Guillermo Mier, [email protected]

Supervisor: Armando Rodrigo Mor, [email protected]



67

D C E & S




INTEGRATED ULTRASOUN SENSOR FOR THE CALIBRATION OF PRESSURE WAVE

PROPAGATION METHODS IN SPACE CHARGE MEASUREMENTS OF HV CABLES


Scope: Design a electroacoustic sensor that will be coupled to a HV cable sample during PWP measurements.

The use of this sensor should be capable of predict the measured space charge values at different trapped

charge values.

Problem definition: HVDC networks are widely increasing their presence in the transmission network due to

the new developments and achievements of HVDC power converters. Therefore, measurement of the Space

Charge phenomena in HVDC components is becoming more relevant. One of the challenges involving the

measurement of SC in HVDC cables is the need of a HV at the inner conductor for calibration purposes; which

brings the necessity of very long cables for the construction of terminations, as well as the incapacity of

measuring SC in post-mortem tests. The capacity to measure the propagating pressure wave at different points

of the cable allows to calibrate without the HV at the inner electrode.

Methodology: The research involves full understanding of the PWP method for space charge measurements.

Selection of the most appropriate sensor according to the electrical and mechanical requirements. The process

involves simulations and extensive laboratory work.


Selection and design of the sensor.

Validation of the design by laboratory testing.

Methodology to calibrate PWP method with the measured pressure waves.


Contact details:

PhD student: Guillermo Mier, [email protected]

Supervisor: Armando Rodrigo Mor, [email protected]



68

D C E & S




CELLULOSIC INSULATION IMPREGNATED WITH ENVIRONMENTALLY FRIENDLY LIQUIDS

USED IN LARGE POWER TRANSFORMERS AND REACTORS.


Scope: Study on the lightning impulse withstand properties of transformer insulation impregnated with

environmentally friendly liquids.

Problem definition: Due to the efficiency and durability, a modern power transformer is one of the most

sustainable elements of the power system. The market demands as well as legal regulation force the increase

in using environmentally friendly materials in the high voltage components. Royal SMIT Transformers considers

replacing the mineral oil by the environmentally friendly liquids (esters) in the produced power transformers.

On the one hand, such action would decrease the environmental footprint of the produced transformers even

more. On the other hand, it must be ensured that the use of new insulating liquid will not jeopardize the

reliable operation of the transformer for the period of e.g. 40 years. The proposed research will be the first

step to verify the latter.

Methodology: The investigation will consist of both theoretical and practical parts:

Literature study on the breakdown phenomena and withstand capabilities of esters.

Lightning impulse testing of the inter-turn insulation impregnated ester.

Statistical analysis and comparison of the obtained values with those obtained for mineral oils

(reference to the previous research, e.g. MSc thesis of A. Ionut – TU Delft, 2011)


Define the withstand capabilities of cellulosic insulation impregnated with ester.

Compare the breakdown characteristics of mineral oil to the properties of ester when considering the

two liquids as impregnating medium for high voltage transformers.

Collaboration with Industry: Royal Smit Transformers

Contact details:

Supervisor SMIT: Lukasz Chmura, [email protected]

Supervisor SMIT: Maarten Deutekom, [email protected]

TUD Supervisor: Armando Rodrigo Mor, [email protected]



69

D C E & S




LIGHTNING IMPULSE PROPAGATION WITHIN A NEW TYPE OF WINDING– STEP 1.


Scope: Study on the lightning voltage distribution in the next generation of transformers and reactors.

Problem definition: Part of the factory acceptance test for extra high voltage transformers and reactors is

Lightning Impulse (LI) testing. During such test, the voltage distribution along the winding depends on electrical

parameters of the winding (capacitance, inductance and resistance). The later, in turn, are related to the

physical dimensions of the winding and the ratings of the transformer. It is widely known that the lightning

impulse voltage does not distribute linearly along the winding. The challenge lies in understanding the details

of voltage distribution across the winding during the lightning impulse. As an example, a 230 kV reactor can

contain up to 2000 meters of copper wire per winding. Such length in combination with very short rise-time of

a lightning impulse might additionally introduce the travelling wave effect and oscillations within the winding.

Methodology: Major steps:

Literature study on the transient behaviour within transformer windings.

Inventory of parameters governing the voltage distribution along the winding during LI test.

Winding model development and simulation of the LI voltage distribution.

Measurement of LI voltage distribution on a real winding and model verification.

Research objective:

Develop a tool/model which will help to determine the LI voltage distribution along the winding of

when considering dimensions and number of turns differ.

Collaboration with industry: Royal Smit Transformers

Contact details:

Supervisor SMIT: Lukasz Chmura, [email protected]

Supervisor SMIT: Maarten Deutekom, [email protected]

TUD Supervisor: Armando Rodrigo Mor, [email protected]


70

D C E & S




INTEGRITY OF EARTHING GRIDS OF HIGH VOLTAGE SUBSTATIONS


Scope: Modelling of earthing grids and developing a method to access the integrity of the earthing grid after it

has been installed and is operational.

Problem definition: Earthing system in substations are used to safely carry the short circuit currents in case of

faults to ground conditions. A properly designed earthing grid ensures that the ground and equipment

potentials remain within a safe limit. Earthing grids are made of a mesh of copper conductors buried under the

substation. Therefore, it becomes a challenge to assess the quality of an earthing grid after the system has

been installed. This project aims to the evaluation of various ways for assessing the integrity of an earthing grid

after it has been installed and is operational.

Methodology: This project would include a) a literature review, b) detailed simulation of cases in SES CDEGS

software package and c) field measurement(s) to verify the simulations.


Review of existing methods for assessing the integrity of earthing grids;

Modelling of substation earthing grids in SES CDEGS;

Verification of measurement results.

Contact details:

Company: Konstantinos Velitsikakis, [email protected]

University supervisor: Peter Vaessen, [email protected]

Mohamad Ghaffarian, [email protected]




71

D C E & S




MODULAR MULTILEVEL CONVERTER BASED ARBITRARY VOLTAGE WAVEFORM

GENERATOR FOR DIELECTRIC TESTING


Scope: To construct a MMC based arbitrary voltage waveform generator for dielectric testing purpose

Problem definition: Random wave shape generator can bring revolutionary change in the high voltage testing

techniques. For example, the partial discharge’s (PD) appearance and its specific features are greatly

influenced by the testing voltage waveform and frequency; this is because different physical processes may be

stimulated by different durations of the applied waveform. To be able to implement such diagnostics tool, the

first step is to design a generator capable of generating arbitrary voltage waveform. Voltage amplifier that can

generate arbitrary voltage waveform is already commercially available (up to 50 kV), however they are

expensive and the output power is limited. The idea of this project is to design and construct a MMC capable of

generating arbitrary voltage waveforms.

Methodology: To simulate, design and construct a MMC arbitrary voltage waveform generator


literature review of MMC technology, design, limitations, control methodology, etc.

to make a computer model for MMC capable of generating arbitrary voltage waveform

to construct a small scale (1 kV) MMC based arbitrary voltage waveform generator

Collaboration with Industry: Yes, DNVGL

Contact details:

Supervisors:

Mohamad Ghaffarian Niasar, [email protected]

Peter Vaessen, [email protected]

Source: Wikipedia



dc systems, energy conversion & storage matchmaking event de... · frequency (1mhz .. 2mhz),...

Documents