11
Modular Power Electronics for Modular Power Electronics for Renewable Distributed Energy Renewable Distributed Energy
Dr. Bill KramerDr. Bill KramerDr. Sudipta ChakrabortyDr. Sudipta Chakraborty
IEEE Colorado Symposium on Electronics for Sustainable EnergyMarriot Hotel, Boulder, Colorado
May 17, 2008
22
OutlineOutline
• Background• PE for distributed energy resources (DER)
– PV, fuel Cell– Wind, microturbines, IC engines– Battery, flywheel
• Modular power electronics– Integrated power electronics modules– Topologies for distributed resources– Control requirements
• Conclusions
33
BackgroundBackground
• Increasing importance of distributed resources• Renewable portfolio standards• DER consists of
– Renewable sources (PV, wind) – Non-renewable sources (Fuel cell, microturbines,
IC engines)– Storages (Battery, flywheel)
• Requirements for specific power electronics (PE) for consumer applications and/or grid connection
44
Barriers for PEBarriers for PE
• Addition of PE with distributed resources– Increased cost (up to 40% of capital cost)– Decreased reliability (typically 5 years life)
• Technology challenges– Lack of standardization– Lack of modularity and scalability– Lack of DER system package
• California Energy Commission (CEC) PIER program
55
Power Electronics for DERPower Electronics for DER
• Depends on specific DER– Type of generation (DC or variable AC)– Bidirectional (storages)
• Different PE topologiesDC – DC (Buck, Boost, Isolated)DC – AC (Inverter)AC – DC (Rectifier)AC – AC (Cycloconverter, Matrix converter)Combinations AC-DC-AC, DC-DC-AC
66
PV TopologiesPV TopologiesCentralized PV
Cascaded DC-DC and DC-AC
AC-Module
77
Fuel Cell TopologiesFuel Cell Topologies
UtilityHigh Frequency Inverter
High Frequency AC-AC Converter
High Frequency AC Link
Fuel Cell Stack
Central Inverter
Cascaded DC-DC and DC-AC
Cascaded DC-AC and AC-AC
88
PE for PV and Fuel CellPE for PV and Fuel Cell
3 Phase Transformer Utility
3-Phase Inverter
PVFuel Cell
Single Inverter
Isolated DC-DC Converter and Inverter
99
Wind TopologiesWind Topologies
GearBox G
Blades &Rotor
Synchronous Generator Rectifier Inverter Utility
Partially Rated PE
Full-scale PE
1010
Microturbine TopologiesMicroturbine Topologies
G
High FrequencyGenerator
UtilityRectifier High Frequency Inverter
High Frequency AC-AC Converter
High Frequency Link
Microturbine
DC-link Power Converters
HFAC-link Power Converter
Direct AC-AC converter
1111
IC Engine TopologiesIC Engine Topologies
• IC engines typically connected by fixed speed synchronous generator
• PE offers the advantage of having variable speed operation - optimizes fuel usage for varying loads
Full-scale PE Partially Rated PE
1212
PE for Wind, Microturbine, IC EnginePE for Wind, Microturbine, IC EnginePartially Rated Back-to-back Converters
Full-scale Back-to-back Converters
1313
Controller ExampleController Example
High FrequencyGenerator
Active PWM Rectifier IGBT PWM InverterCommon DC Bus
3 PhaseTransformer Utility
ABCDQ
ABCDQ
uvui
dv qv
θ
θ
di qi
+ -*di
*qi -+
-+
-+
DQ-PLL
PowerRegulator
refP
refQ
outP
outQ
CurrentRegulator
dD
qD
SPWM Modulation
DQABC
G
Microturbine
GatingControl
+
dcV
-*
dcVPI
PWM Modulation
GatingControl
+- *ω
ω
PI++
Load
Fuel Governor(Speed)
Fuel Governor
(Temperature)
+-*T
T
),min( tg FF gF
tF
FuelLimiter
ω
Fuel Valve Actuator
-
*fw
fw
Fuel InputTo
Microturbine
1414
Battery Storage TopologiesBattery Storage Topologies
Single Inverter Cascaded DC-DC and DC-AC
Hybrid System with Battery and Wind
1515
PE for Battery StoragePE for Battery Storage
Battery
Battery
Battery
Battery
Battery
Battery
High Frequency Transformer
DC Bus
Bidirectional DC-DC Converter and Inverter
Isolated Bidirectional DC-DC Converter
1616
Flywheel Storage TopologiesFlywheel Storage Topologies
DC-link Power Converters
HFAC-link Power Converter
1717
PE for Flywheel StoragePE for Flywheel Storage
Back-to-back Converters
Back-to-back PDM Converters
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Modular Power ElectronicsModular Power Electronics
• Power Electronics Building Block (PEBB) – Integration of power devices, gate drives, and
other components to functional blocks• Adoption of functional building blocks that can
be used for multiple applications results in – High volume production– Reduced engineering effort
• The value of integration can be enhanced with the standardization of interfaces of the power blocks, control and communications
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Integrated PE ModulesIntegrated PE Modules
• Modular design approach revolves around integrated power electronics modules (IPEM)
• IPEM consists of – PE switches– DC-link capacitors– Sensors– Gate drivers– Heat sink – DSP controller
• Semikron SKAI• American Superconductor
PM1000 Integrated Heat Sink
Auxiliary Power
Local Controller (Optional)
Coolant In
Coolant Out
DCSide
ACSide
Gate Driver Protection
Measurements
Power Poles
Communications
Auxiliary Power Source
2020
Modular Topologies for DERModular Topologies for DERCascaded DC-DC and DC-AC Converters
Back-to-back Converters
Bidirectional DC-DC and DC-AC Converters
2121
Generalized IPEMGeneralized IPEM--based PEbased PEDG Source DC-Link Generation (IPEM 1) Utility Connection (IPEM 2)
PV, Fuel Cell
Utility
Wind, Microturbine,
IC Engine, Flywheel
+-
Battery
S1 S2
S3 S4
NO*
NO*
* Non-operational
IPEM 1 External Circuits
S1 S2 S3
S4
IPEM 1
S5 S6
S1 S2
S3 S4
NO*
NO*
IPEM 1 External Circuits
* Non-operational
+
-
S1 S2 S3
S4 S5 S6
IPEM 2
I1 I2 I3
SOURCE
INTERFACE
DC
BUS
INTERFACE
UTILITY
INTERFACE
S1 S2
S3 S4
IPEM 2
Single Phase
Three Phase
NO*
NO*
* Non-operational
Single Phase
Three Phase
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Controller for Modular PEController for Modular PE
• Dual converters provide flexibility of designing comprehensive control objectives
• In general, the source converters are used for DC bus voltage control
• Grid connected converters are used in constant current control or constant power control
• DC bus voltage regulation is also frequently used for grid converters
• Additionally, for the fuel based systems, such as microturbines, fuel cells and IC engines; external controller can be designed for optimization of fuel
2323
Typical Control FunctionsTypical Control Functions
DE Systems
IPEM 1 IPEM 2 Additional
PV Maximum peak power tracking
Power flow to grid n.a.
Wind Generator speed, current, flux
DC bus voltage, current to utility
n.a.
Microturbines DC bus voltage Power flow to grid Fuel usage
Fuel Cell DC bus voltage Power flow to grid Fuel usage
IC Engine DC bus voltage Power flow to grid Fuel usage
Battery-Charging Battery terminal voltage DC bus voltage Operational mode
Battery-Discharge DC bus voltage Power flow to grid Operational mode
Flywheel Generator torque, speed, DC bus voltage
Power flow to grid n.a.
Control Functions
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Standardization RequirementsStandardization Requirements
• Standardization is required for power flow and signal distribution network
• This in turn allows for distributed controller approach
• By using control software that is functionally divided into hierarchical levels and by standardizing interfaces between levels - application software becomes independent of the hardware specifications of power stage
• The standardization of communication interface allows division of PE system into flexible, easy-to-use, multifunctional modules, which can significantly ease the task of system integration
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Conceptual Modular PE SystemConceptual Modular PE System
IPEM
(Rectifier)
IPEM
(Inverter)
Heat Sink Heat Sink
Passive Filters and
Transformer
Gate Driver
Heat Sink Heat Sink
Local Controller
Integrated Cooling
DC BusGWind Turbine
GeneratorUtility
Coolant In Coolant Out
Measurements MeasurementsLocal Controller
Gate Driver
EMIFilter
2626
ConclusionsConclusions
• PE adds large installation costs for DER system • PE designs are specific to the DE technology, still
they possess some common functionalities• IPEM based back-to-back converter topologies
- a viable PE interface that can operate with different DE systems with small or no modifications
• However, to reach the goal of modularity, challenges in defining the power and communication interfaces, are to be addressed
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AcknowledgementsAcknowledgements
• California Energy Commission (CEC) • National Renewable Energy Laboratory
The National Renewable Energy Laboratory is a national laboratory of the U.S. Department of Energy (DOE) managed by Midwest Research Institute for the U.S. Department of Energy under Contract Number DE-AC26-99GO10337. This report was prepared as an account of the work sponsored by the California Energy Commission and pursuant to the M&O Contract with the United States Department of Energy (DOE). Neither Midwest Research Institute, nor the DOE, nor the California Energy Commission, nor any of their employees, contractors or subcontractors, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacture, or otherwise does not necessarily constitute or imply is endorsement, recommendation, or favoring by Midwest Research Institute, or the DOE, or the California Energy Commission. The views and opinions of authors expressed herein do not necessarily state or reflect those of Midwest Research Institute, the DOE, or the California energy Commission, or any of their employees, or the United States Government, or any agency thereof, or the State of California. This report has not been approved or disapproved by Midwest Research Institute, the DOE, or the California Energy Commission, nor has Midwest Research Institute, the DOE, or the California Energy Commission passed upon the accuracy or adequacy of the information in this report.
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Questions ?Questions ?
IPEM
(Rectifier)
IPEM
(Inverter)
Heat Sink Heat Sink
Passive Filters and
Transformer
Gate Driver
Heat Sink Heat Sink
Local Controller
Integrated Cooling
DC BusGWind Turbine
GeneratorUtility
Coolant In Coolant Out
Measurements MeasurementsLocal Controller
Gate Driver
EMIFilter