1 real time digital simulation rtds ® power systems simulation in real time

1

Real Time Digital Simulation

RTDS®

Power Systems Simulation in

Real Time

2

RTDS Technologies Inc.Company:

• Based in Winnipeg, Canada

• Established in 1994

- 40 °C

3

History:

• Manitoba HVDC Research Centre (1980s)

• Funding from Manitoba Hydro

• World’s 1st real time digital simulator

• 1st commercial installation in 1993

• Created a independent company - RTDS Technologies in 1994

RTDS Technologies Inc.

4

RTDS Technologies:

• over 100 installations• over 400 units• 23 countries• clients include leading …

– electrical power utilities– electrical equipment

manufacturers– research and learning

institutions


5

RTDS Technologies Inc.RTDS Simulator Users:

Electrical power utilities

Electrical equipment manufacturers

Research and learning institutions

% of Clients per Sector

32.38%

37.14%

30.48% % manufacturers

% research

% utility

% Racks per Sector

33%

27%

40% manufacturer

research

utility

6

Real Time Digital Simulation

• Electromagnetic transient solution (EMTP type simulation)

• Based on the Dommel algorithm• Trapezoidal rule of integration• New solution produced each timestep

• Continuous hard real-time response must be achieved and sustained if physical control and protection equipment is to be included in the simulation study

• Dedicated high speed processing and signal communication required to achieve real-time

• The RTDS Simulator• A combination of specially designed parallel

processing hardware and detailed, efficient solution algorithms


Time scales of power system phenomena

10-7 10-5 10-3 10-1 101 103 105

Lightning

Switching

Subsynchronous resonance

Transient stability

Long term dynamics

Tie-line regulation

Daily load variation

Timescale (seconds)

HVDC, FACTS, etc.

Generator control

Protection

Prime mover control

LFC

Operator actions

1 cycle 1 sec 1 min 1 hr 1 day

Impulsive transients

Oscillatory transients

Short-duration variations

Long-duration variations

Imbalance, harmonics, inter-harmonics, notching, noise

Voltage fluctuations

Frequency variations

Electromagnetic transient modeling and simulationElectromagnetic transient modeling and simulation

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RTDS Technologies Inc.Simulation Techniques:

Loadflow & Short Circuit50/60 Hz only

Transient Stabilitysimulation cannot

capturesubsynchronous

phenomena.

~0 Hz

Electromagnetic Transients - EMTP/EMTDC/ATP

Special Models andSmaller Timesteps

Region often neglected by non-real timeelectromagnetic transient simulations

(short duration simulations)

Frequency

Real Time Electromagnetic Transients - RTDS

0 Hz to 2-3 kHz (dt = 50 us)

Continuous real time simulationscover the entire frequency range

?

0 Hz to 2-3 kHz (dt = 50 us)

~50/60 Hz

RRLBRK

BRK

0.1 [H]

1.0 [uF]

0.1 [H]

1.0 [uF]

Capbank : Graphs

0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450 0.500 ... ... ...

-300

-200

-100

0

100

200

300

kV

Vcap

-2.00

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

kA

RLIa RLIb RLIc

Transients and Steady State

• Transient solution

– Harmonics– Non-linear effects– Frequency

dependent effects

• Steady state solution

– RMS Value

• Transient – High frequency

– Damped (short duration)

RRLBRK

BRK

0.1 [H]

1.0 [uF]

0.1 [H]

1.0 [uF]

Capbank : Graphs

0.190 0.200 0.210 0.220 0.230 0.240 0.250 0.260 ... ... ...

-300

-200

-100

0

100

200

300

kV

Vcap

-2.00

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

kA

RLIa RLIb RLIc



1 unit 80 MVA

1 unit = 150 MVA

#1 #2

VTIT 3

IfEfEf0

Vref

Exciter (ST3A)

Vref0

Ef0

W2

S2M

S / Hinhold

out

TM01

1.0D -

F

+

W2

*13.333

G1 + sTD -

F

+

G1 + sT

S / Hinhold

outTM01

L2N

P+jQ

#1 #2

Ia

L2N

TM0

S / Hinhold

out

G1 + sTD -

F

+

G1 + sT

*13.333

W

D -

F

+

#1 #2

Neuclear plant : Con...

P1

25.4618

Q1

66.1229S

Te

3

AV

Tm

Tm0

Ef0

Tmw

Ef If

1.0

TM0

S / Hinhold

out

S2M

TIME

TIME

S2M

L2N

W

Ef

P = 25.46Q = 66.12V = 1.004

VA

E132

Ef0

VTIT 3

IfEfEf0

Vref

Exciter (ST3A)

Vref0

Ea

TLine_01

P = 143.8Q = 76.1

V = 1.003

VA

STe

3

AV

Tm

Tm0

Ef0

Tmw

Ef If

ABC->G

TimedFaultLogic

TLine_02

BR

KB

RK

OOS Investigation

x 4.00 4.50 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 ... ... ...

0.970

0.980

0.990

1.000

1.010

1.020

1.030

1.040

1.050

1.060

1.070 W W2

-150

-100

-50

0

50

100

150

200

250

300 P1 P2

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50 E132

Transient stability problem• Fault / clearance

• Slow Transients (electro-mechanical)

• Electrical transient occurs when there is a rapid exchange or flow of energy from one element to another

– Interaction of energy stored in electric fields of capacitances and magnetic fields of inductances in electrical power systems

– Initiated by a change to the network topology (connections)

• Switching Events

– Opening and closing

• Faults

– Inception and clearance

• Lightning

• Others

Electromagnetic transients

RRLBRK1

0.001 [H]

3

BRK

#1 #2TLine1

T

Ea Eb

#1 #2

OpenMain : Graphs

0.170 0.190 0.210 0.230 0.250 0.270 ... ... ...

-300

-200

-100

0

100

200

300

y

Ea

Main : Graphs

0.170 0.190 0.210 0.230 0.250 0.270 ... ... ...

-300

-200

-100

0

100

200

300

y

Eb

Electromagnetic transients

Basic R-L-C networks

0.005 3BRK 1

RL

10.0

1/[2(pi).SQRT(LC)] =1.299 kHz

0.1950 0.1975 0.2000 0.2025 0.2050 0.2075 0.2100 0.2125 0.2150 ... ... ...

-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0

Ic

-300

-200

-100

0

100

200

300 Ec

Oscillatory transients:

• Both L and C involved

• Damping is due to resistance

• System losses• Loads

Load Flow / Transient Stability • Each solution based on

phasor calculations

Electro-Magnetic Transients

• Direct time domain solution of Differential Equations

Transient vs. Steady State

R L

I

R=

0 V

• Period of natural frequency is about 1.5 ms• Period of natural frequency is about 1.5 ms

Time StepTime Step

HL 0.11 000,1001R FC 05.02 005.012R

e v1 v2

L1

R1

R12

C2

i2

i1

• Time step of 1.0 ms• Time step of 1.0 ms

Time StepTime Step

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0 0.01 0.02 0.03 0.04 0.05

Time (s)

• Time step of 5 micro-seconds• Time step of 5 micro-seconds

Time StepTime Step

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0 0.007 0.014 0.021 0.028 0.035 0.042 0.049

Time (s)

• Time step of 70 micro-seconds• Time step of 70 micro-seconds

Time StepTime Step

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0 0.007 0.014 0.021 0.028 0.035 0.042 0.049

Time (s)

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Simulation:

Non Real Time:• Simulation of the system’s response over 1 second may require several

seconds or even minutes of computer time

• Wide range of available non real-time programs (PSCAD, EMTP, etc.)

• Solution speed is not hard real-time, hence interpolation can be used in large closely connected networks with numerous switches

Real Time:• Simulation of the system’s response over 1 second must be completed in

exactly 1 second.

• Hard real-time provides equidistant updates from each timestep

Non Real Time vs. Real Time

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实时仿真Real Time Simulation

• 实时：仿真系统中完成一个物理现象的时间与电力系统中完成该现象的时间完全一样；

• 时间域中的电磁暂态分析；• 实时仿真应在所仿真的整个系统，而不是在部分的仿真系统进行；• 实时仿真应能连续地长时间进行；• 实时仿真装置应能与实际的电力系统元件（例如与控制保护系统）相连

接来完成闭环试验或是能在电力系统中运行；• Real Time:The time to complete a physical phenomena should be exactly the

same as it happened in a real power system;

• It is in time domain, electromagnetic transient analysis;

• The real time simulation is in full simulated system, not in part of the simulated system;

• The real time simulation can operate continuously;

• The real time simulation can connect to the real power system equipments （ e.g. relay or control system) for a close loop test or can operate in the power system;

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动模与数模仿真Analog and Digital Real Time Simulations

• 两种实时仿真：– 动模与数模

• 三个时间里程碑：– 1880 年代， 1970 年代， 1989 年

• 动模在世界上已有百年的历史，在国内至少有 50 年历史 ;• 实时数字仿真只有 19 年历史 ;• 目前实时数字仿真的安装地点约为动模的一倍 ; 仿真规模在数十倍以上；• Two Kinds of Real Time Simulation:

• Analog and Digital • Three Milestone Years:

• 1880’ 1970’ 1989• Analog Real Time Simulation Has 100 year’s History worldwide and more than 50

Year’s History in China• Real Time Digital Simulation Has only 19 year’s History • Digital/Analog ： The Location Number: 2 ， Simulated Scale: Tens Times

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国外实时数字仿真的里程碑（供讨论）Milestone of Real Time Simulation (for

discussion)• 美国国家专利 2323588, Waldo E. Enns 交流网络仿真装置，申请 1940.11.6. 批准

1943.7.6 ；• IEEE 论文 Hermann W. Dommel 教授 ,1969.4.4.

– 单相和多相网络中电磁暂态的数字仿真

• 世界上第一台实时数字仿真装置诞生： 1989 年， Manitoba HVDC 研究中心（ RTDS 技术公司） ; Dennis Woodford, Rick Kuffel, Rudi Wiercks, Trevor Maguire, James Giesbrecht

• US Patent 2323588, Waldo E. Enns, Applied 1940.11.6 ， Approval 1943.7.6

– Apparatus for A.C. Network Analysis

• IEEE Paper April 4, 1969, Hermann W. Dommel

– Digital Computer Simulation of Electromagnetic Transient in Single-and Multiphase Networks

• Manitoba HVDC Research Center (RTDS Tchnologies Inc), 1989, Dennis Woodford, Rick Kuffel, Rudi Wiercks, Trevor Maguire, James Giesbrecht

– The Birth Day of First Power System Real Time Digital Simulator Worldwide

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经验与教训（一）What We Learned from the History Review (1)

• 电力工业的发展是实时仿真的主要推动力 ;

• 科技的进步是实时仿真的基础（电工理论基础，电力系统理论和技术以及计算机技术） ;

• 正确的技术路线和市场化 ;

• 坚持不懈的研究与开发 ;

• The Real Time Simulation Is Driven by The Development of Electric Power Industry;

• Science & Technology’s Progresses are the Base of the Real Time Simulation (Theories & Technologies of Electric and Computer);

• Right Technical Plan/Path and Marketing;

• Continue R&D;

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经验与教训（二）What We Learned from the History Review (2)

• 如同任何其它历史（经济，技术，政治等等）实时仿真的历史也有历史的创造者，推动者和见证者– - 今天每一个人都可以为自己参与了这个实时仿真的技术发展史而自豪

• 回顾历史可以让我们知道自己从何而来，现在何处，以及将要去往何处。– - 实时仿真技术从发展至今尚处成长期，它值得我们为其努力。

• As Other Histories (Economy, Technical etc), Real Time Simulation Technology Has Its History Creators, Promoters and Witnesses. – Every Body in This Room Can Proud For His Involving In This History

• Review History Let Us Know Where We Are From, Where We Are and Where We To Go:– Real Time Simulation Technologies Are Still Growing. It Is Worth For Us to

Continue Work For It.

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对未来应用的建议Suggestions For The Applications in Near Future

• 继续为交直流大电力系统服务仍是一段时期内实时仿真的主要方向 ;• 重视实时仿真在再生能源和负荷管理的应用 ;• Continue Work for the AC/DC Power Systems• Put Attention to Renewable Energy and Demand Management

27

RTDS

Simulation

Hardware

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RTDS Hardware:

• Custom parallel processing computer

• Hardware is modular, allowing users to increase computing capability as required

• Main interface with the hardware is through user-friendly software

• Ample, convenient input and output allowing connection of physical devices

Simulation Hardware

29

A Rack:

A unit of hardware is called a ‘Rack’ and typically includes:• 1~6 RISC Processor Cards (GPC)• 1 Inter-Rack Communication Card (IRC)• 1 Workstation InterFace Card (WIF)

Simulation Hardware

30

Parallel Processing – Sharing the burden of calculation:

Simulation Hardware

> t

31

Small Scale Simulations:• Reduced # of processors• Transportable to site

Large Scale RTDS Simulations:• Large scale studies• Complex simulation case• One large or several smaller

simultaneous simulations

Simulation Hardware

32

Simulation HardwareModular Hardware:

• Easy expansion• Maximum availability• Easy maintenance• Full Compatibility

Processing power

GPC

33

Simulation HardwareCustomer Driven Development:

Giga Processor Card - GPC:

• Introduced January 2005

• Additional Power utilizing two IBM 750GX Power PC’s each running at 1 GHz

• Multiple timestep operation supported

3PC RPC GPCProcessor ADSP 21062 IBM PPC750CXe IBM PPC750GXPrecision 40-bit 64-bit 64-bitProcessors per card 3 2 2

MFLOPS per processor 80 600 1000MFLOPS per card 240 1200 2000( MFLOPS = millions of floating-point operations per second )

34

Simulation HardwareRISC Processor Card (GPC):

• GPC Network Solution– 1 GPC processor handles 54 nodes

in a single lumped circuit, as well as 12 embedded valve groups

– presently dimensioned for 56 single-phase switches (i.e. breakers and/or faults)

TPC 3PC GPC27 6 0.5

No. of cards required to perform solution of 54 node network

37

Workstation InterFace Card - WIF:

• Each rack contains a single WIF with its own unique Ethernet Address

• Connects to workstation via standard Ethernet LAN

• Provides timestep clock

• Provides communications to load, start and stop simulation case

• Enables user interaction with simulation

• Provides data exchange coordination and data record capability

Simulation Hardware

38

Workstation InterFace Card - WIF:

• 50 MHz MPC860T/DT processor

• 10/100 Base TX Ethernet interface

• 1 million point plot memory

• Bus logic to control local rack simulation

• Global bus for Multi-rack simulation

• RS-232C Diagnostic/Configuration Port

• LED display on the faceplate to show configuration information

Simulation Hardware

39

Inter-Rack Communication Card - IRC:

• Connection via RJ-45 jack

• Connection paths which mimic the power system

• No need to change connections

• High speed communication between racks

• Direct connection to six other racks

Simulation Hardware

40

Flexible and Expandable I/O for the GPC:

•GTAI (12 channel, isolated 16-bit analogue input card)

•GTAO (12 channel, isolated 16-bit analogue output card)

•GTDI (64 channel, isolated digital input card)

•GTDO (64 channel, isolated digital output card)

•GTFPI (interface to digital and high voltage interface panels)

•GTNET (Ethernet Interface System)

The GT family of I/O cards can be daisy chain connected to a single GPC fiber port (fewer GPC cards needed to accommodate I/O connection).

Simulation Hardware

41

High Precision Analogue Output Card - GTAO:

• Twelve (12) synchronized 16-bit output signals per card

• Output range +/- 10 volts peak (0.3 mV resolution)

• Fully compatible for 12 channel update of small timestep (~ 2μs) simulation signals

• Connects to GPC via fiber optic connection – daisy chain connection allowed to other GTIO cards

• Rail mounted with access from rear of cubicle

• Signal selection and scaling in Draft

Simulation Hardware

42

High Precision Analogue Input Card -GTAI:

• 12 channel input card with 16 bit A-to-D converters

• Provides optical isolation of input signals from external devices to the RTDS

• Interfaces to GPC via fiber optic connection

• +/- 10 V true differential analog input



• Signal selection and scaling in Draft

Simulation Hardware

43

GPC Digital Input - GTDI:

• Required for digital input to small timestep simulations

• 64 digital input signals per card



• Signal selection in Draft

Simulation Hardware

44

GPC Digital Output - GTDO:

• Required for digital output to small timestep simulations

• 64 digital output signals per card




Simulation Hardware

45

GPC Front and High Voltage Panel Interface - GTFPI:

• Interface to 16 digital input and 16 digital output low voltage channels

• Interface to 16 dry contacts




Simulation Hardware

装置开关输出回路接线图

开关量输出回路

47

GPC Network Communication - GTNET:

• GTNET – GSE IEC 61850 binary messaging

• GTNET – SV IEC 61850-9-2 sampled values

• GTNET – Playback very large data playback

• GTNET – DNP DNP SCADA interface

Simulation Hardware

48

Digital Interface Panel:

• Interconnect signals between the RTDS external equipment

• 16 digital input and 16 digital output via 4mm banana plug adapters mounted on front of the cubicle

• Signals from the GPC connect to the digital interface panel via the GTFPI card

Simulation Hardware

49

High Voltage Interface Panel:

• 16 solid state contacts rated for up to 250 Vdc

• Used to send status signals from the RTDS Simulator to external equipment at station level voltage (max. 250 Vdc)

Simulation Hardware

50

Amplifiers:

• External amplifiers are used to provide secondary level voltages and currents

• Amplifiers are connected in the test loop between the RTDS Simulator and the equipment under test

• Various amplifiers solutions have been used (Omicron, Analogue Associates/Techron/Crown, Doble, etc.)

Simulation Hardware

51

RTDS

Simulation

Software


52

RTDS Software:

Graphical User Interface • RSCAD

Power and Control System

Software• Component Model Libraries &

Compiler

Simulation Software

53

RSCAD Graphical User Interface:

FILEMAN TLINE RUNTIME

DRAFT CABLE MULTIPLOT

Simulation Software

54

RSCAD Graphical User Interface Software:

• JAVA Based• Runs on PC under Windows and on

Sun Workstation under Unix• Single line diagram drawing format• Hierarchy structure for circuit layout• Integrated Load Flow• Software can be installed on any

number of customer computers• PSS/E conversion function

Simulation Software

55

Circuit Construction in RSCAD / DRAFT:

• Circuit assembly

• Data entry

3 phase drawing models single line drawing mode

Simulation Software

56

Component Editing:

Simulation Software

57

Running the Simulation in RSCAD / RUNTIME:

• True real time performance provides ability to operate the simulated power system interactively

• Simulator control

• Monitoring

• Data acquisition

• Manual mode

• Automatic mode

Simulation Software

58

Automated Batch Mode Testing:

• Script file– High level programming language with

C like structure– adaptive via if, for, and while statements– user-defined subroutines– customize reporting of result analysis– automated plot printing

• Efficient means of running numerous cases

Simulation Software

59

Comprehensive library of component models available:

Power System Control System

Component Model Library Component Model Library

Simulation Software

Machine Models

• The simplest model is that of a constant speed ( frequency) machine consisting of an ideal voltage source behind an appropriate impedance. For an electromagnetic transient study this would most likely be the machine subtransient reactance.

E`` X``

This type of machine model would be appropriate in a study

where the transmission line being protected was represented

by lumped impedances and the time scale of interest was several cycles. The relay bandwidth would be restricted to 50/60Hz and dc offset components. e.g.

jXE``

jX``R

Machine

jx

Trans. Line Infinite BB

RRelay

For longer time periods involving possible power swings then the transient reactance would replace the subtransient reactance and the machine inertia would have to be represented by at least a single equivalent mass. The moment of inertia, J, is for both the turbine generator and exciter combined.

X`

E`

Inertia, JTm

Te

Swing Example

Here is a study involving a full dqo machine model with single

mass inertia and a single pole open and reclose feature at the relay

location R. There are two 100km distributed parameter lines

with a single phase fault half way along one of the lines.

Multi-mass machine models

• Single mass inertia models are probably OK for hydro turbine sets.

• Steam turbines on the other hand have multiple stages (HP, IP, LP) plus the generator and exciter and may be much larger than the hydro sets.

• Shafts have been damaged by mechanical resonances excited by sub-synchronous frequencies on the electrical network.

AVR’s, governors & PSS’s

• In studies where the inertia of the set is relevant then we need to also include other devices which produce effects in the time window of interest.

• Governors are in general very slow except in cases of “fast valving” on a steam set.

• Automatic voltage regulators and Power Sytem Stabilisers will certainly be in play during power swing conditions.

Conclusions

• Choose a model which suits the time scale of interest.

• Where possible, compare any simulation results with recordings to check for model validity.

• Models for internal faults are not generally available and are actively being researched at the present time.

Transformer Models

• Can be modeled in RTDS in three fundamental ways– The Ideal transformer model– The Linear transformer model– The built-in saturable transformer model

Ideal Transformer Model• Ideal Transformer

– Ignores leakage flux• Assumes flux is confined in the core

– Neglects Magnetizing Currents• Assumes no core reluctance

Simple Transformer

+

-

+

-

i1

Ac

V1

i2

V2

N1

N2

Ideal Transformer Equations

V Nd

dt1 1

V Nd

dt2 2

V

V

N

N1

2

1

2

I

I

N

N1

2

2

1

Linear Transformer Model

• In this case the magnetizing branch is included in the model as an inductive branch.

Saturable Transformer Model

• Uses a star-circuit representation

• User could include saturation data

Transformer ModelTransformer Model

n:1n:1IdealIdeal

TransformerTransformer

LsLsRpRp LpLpLmLm RsRs

Volt

ag

eV

olt

ag

e

CurrentCurrent

Operating pointOperating pointfor for current transformerscurrent transformers

Linear regionLinear region

Non-Linear regionNon-Linear region

V-I curve knee pointV-I curve knee point

Transformer V-I Curve CharacteristicTransformer V-I Curve Characteristic

More in Section 10More in Section 10

Saturation voltageSaturation voltage

Operating pointOperating pointfor for voltage transformersvoltage transformers

ii LL

((tt ))

((t -t - t)t)

iiLL(t- (t- t) t)

slopeslope

knkn

Non-linear Element Represented as Non-linear Element Represented as

Piece-Wise Linear Piece-Wise Linear -i-i Function Function

tttttitik LLn iiLL(t)(t)

Saturable Transformer Model

• The model requires as a minimum the following data– The voltage rating of each winding– The leakage impedance of each winding– The transformer connectivity information

Transmission Line Models

• RTDS users must know– What kind of models are available– Applicability of the various models for steady

state or transient studies– Advantages and disadvantages of each model

EMTP Line Models for Steady State Studies

• Line models for steady state studies– Exact-pi model– Nominal-pi model

Exact-Pi Model

• Exact-pi model– It is a lumped-parameter model– The model includes hyperbolic corrections– Frequency independent– Best model for steady state studies

1/Y series

Y shunt /2 Y shunt /2

Exact-Pi Models

• It is a multi-phase line model and it takes into account– Skin effect and– Circuits in the same right-of-way

• Not good for transient studies

Nominal-Pi Model

• Derived from the exact-pi model – Ignores hyperbolic corrections

• Takes into account– Skin effect and

Nominal-Pi Model

• Multi-phase line model

• Frequency Independent

• No time step limitations

• Not good for transient Studies– Could be used if multiple Nominal-pi sections

are cascaded together

Nominal-Pi Model

• Model Limitations– Cannot be Used for “Electrically Long Lines” – Limited to lines with length < 150 Km at 60 Hz– Limited to lines with length < 5 Km at 2 kHz

RTDS Line Models for Transient Studies

• Line models for transient studies– Nominal-pi model– Frequency independent distributed parameter

line model– Frequency dependent distributed parameter line

model


• Nominal-pi– Not recommended for transient studies– Produces reflections at the cascading points– Computationally expensive– Sections must be kept very short { 5-10 km for

frequencies up to about 2 kHz}


• Constant parameter distributed line model– Bergeron model– Model assumes that R’, L’, & C’ are constant– L’ & C’ are distributed and the losses R’*l are

lumped in three places– Shunt losses are ignored


• Frequency dependent transmission line model– Represents accurately the distributed nature of all line

parameters– Frequency Dependent – Transformation matrix is real and constant– Most accurate for use in transient studies


• The DP and FD models– Use traveling wave solutions and are valid over a

wider frequency range– Require transformations between phase and modal

domain– Keep track of modal waves traveling at different

speeds– When the modal propagation time ( or “travel time” )

of a line is less than the chosen simulation time−step Δt, the line cannot be represented using these general travelling wave models.

Conclusions

• Use pi-exact model for steady state studies

• Use fd-line models for lines of main interest in your study

• Use cp-line models for lines of secondary interest

Section 10 Section 10

Relay Input SourcesRelay Input Sources

npnp CT loadCT load(burden)(burden)

nsns

ipip

isis

BurdenMagnetizingBranch

ip Rp Lp LsRs is

IdealCT

ip’ Rp Lp LsRs isEs

im

imr imx

LmRmRl

ip’ isEs

im

LmRb

Currentsource

1010

100100

10001000

CT ratio error [%]

600/5 A, C100 CTwith 1.5 total load resistance

Ideal CT

10 100 1000

CT Primary Current [A] (referred to the secondary)

CT

Sec

ond

ary

Cu

rren

t [A

]C

T S

econ

dar

y C

urr

ent

[A]

CT Saturation for Symmetric Fault CurrentsCT Saturation for Symmetric Fault Currents

0.1 1 10 10010

100

Exciting Current [A]

Vol

tage

[V

]

1523

3548

7

LmLm is nonlinear inductor, is nonlinear inductor, specified in piecewise linear form specified in piecewise linear form

-I-I data points are not readily available data points are not readily available

ATPATP provides a routine provides a routine SATURATIONSATURATION to to

convert convert VVrmsrms-I-Irmsrms characteristics characteristics

into into -I-I set set

9.2 9.2 Digital Models of Digital Models of

Coupling Capacitor Voltage TransformersCoupling Capacitor Voltage TransformersCCVTCCVT

A CCVT Circuit ConnectionA CCVT Circuit Connection

HV

C

C1

2

L

R

GG C

R RLL

R

G RC

LR

C

L

y

y

R

y

Z

1

2d1

d1

d1

1

2

ps

p

r

2

s

3

b

h

T

F

FF3

a

a

Cp

d1 C C p

p

R

C

L

Cs

s

x

x

x

R

1

3

138kV

5kV/115V/66.4V

SW1

A 138 kV CCVT DesignA 138 kV CCVT Design

Voltage Transformer Voltage Transformer Digital ModelsDigital Models

n:1n:1IdealIdeal

TransformerTransformer

LsLsRpRp LpLp

CpCp

RmRm LmLm RsRs

103

Component Builder:

Simulation Software

104

Applications


105

Closed-loop testing of protection systems:

Applications

106

Applications

Protection systems test methods:• Synthetic testing

– Typical of test set used for routine testing– No true power system signals used– “Synthetic” waveforms are often unrealistic and in

some cases misrepresent how a relay will function in service

107

Applications

Protection systems test methods:• Playback testing

– Uses recorded or simulated power system signals– Waveforms only valid until the relay trips– Only one relay can be tested

108

Applications

Protection systems test methods:• Closed loop testing

– Requires a real time simulator to provide realistic power system signals

– Closed loop response allows complete interaction between the relay and the simulated power system

– Multiple devices (relays and/or controllers) can be tested as if connected to an actual power system

109

ApplicationsClosed-loop testing of protection systems:

Standard electrical connection

Digital to AnalogueConverters

V VII

Relay #2Relay #1

125 Vdc

Digital I/O Digital I/O

PowerAmps

125 Vdc

PowerAmps

110

ApplicationsClosed-loop testing of protection systems:

Interconnection via IEC 61850 GOOSE and Sampled Values

GTNET - SV

Relay #1

GTNET - GSE

GTNET - SV

Relay #2

STATIONBUS

PROCESS BUS

111

Closed-loop testing of protection systems:

• Proven power system representation

• Advanced instrument transformer models

• Script files for automated testing and customized reporting

• Hardware interface

• Interaction studies providing a true test for multiple relays and other devices

• Suitable for low level testing of single relays and multiple relays

• Flexible amplifier solutions

Applications

........

........

R

Real-Time Digital SimulatorRTDS

DIGITAL INPUT / OUTPUT CHANNELS

1 10 11 12 13 14 15 16

DIGITAL INPUT / OUTPUT CHANNELS

2 543 6 7 8 9

1 10 11 12 13 14 15 162 543 6 7 8 9

RTDS Simulator

Voltage and Current

Amplifiers

Protective Relay(s)

Interfacing to Protective Relays

Amplified Voltages and Currents (Sec. Levels)

Trip and Reclose Signals

Voltage and Current Signals (low level)

112

Closed-loop testing of protection systems:• Manufacturers

• ABB Automation – Sweden • Dong Fang - China• AREVA T&D – England • SiFang - China• Basler Electric – USA • Guodian Nanjing Automation - China• GE Multilin – Canada • LGIS – South Korea• Siemens AG – Germany • NxtPhase T&D - Canada• SEL – USA• TMT&D - Japan

• Utilities• REE – Spain • Guangxi EPRI - China• PG&E –USA • East China EPRI - China• KEPCO – Korea • Fujian EPRI – China• FURNAS – Brazil • Sichuan EPRI – China• CCGroup – China • North China EPRI - China• SEC – Saudi Arabia

• Universities / Research & Test Institutes• China EPRI – China • CPRI – India• Kinectrics – Canada • NTU – Singapore• University of Bath – England • University of Western Ontario – Canada• Wuhan University – China • Xuchang Relay Institute - China

Applications

113

Closed-loop testing of control systems:

Applications

114

ApplicationsTesting of Excitation Controllers:

Static Exciter Test Circuit

MainGenerator

590 MVA22 kV

Per unit conversion8.2 V = 1 p.u.

ControlledRectifier

50 km22 kV : 230 kV

MainGrid22 kV : 560 V

DECS300

V

I

AUX. POWER

AMPS

Low Voltage+/- 10 Vpk.

25 V / V5 A / V

RTDS Simulator

Omicron

Static Exciter

Low Voltage< 24 Vdc.

RTDS Analogue Output

RTDS DigitalInput

115

Closed-loop testing of control systems:

• True real time required

• Large amount of data exchange – 100’s of digital and analogue I/O

channels needed

• Improved firing for power electronics

• Real time network solution – more breakers

• Switched filter component – more breakers with fewer nodes

Applications

From RTDS to Controls

From Controls to RTDS

-commutating bus voltages-dc current & voltage-winding currents-breaker status

-firing pulses-block/bypass signals-control variable monitoring

Interfacing to HVDC Controls

Digital and AnalogueSignals

Digital and AnalogueSignals

116

Commercial Control System Studies:

• HVDC (High Voltage Direct Current)

• SVC (Static Var Compensator)

• TCSC (Thyristor Switched

Series Cap.)

• Generator (Exciter, Governor, PSS)

• STATCOM (3-level, PWM ~1200 Hz)

Applications

117

Closed-loop testing of control systems:• Manufacturers

• ABB Power Systems – Sweden • Fuji - Japan• AREVA T&D – England • Hitachi - Japan• Basler Electric – USA • Kinkei - Japan• Siemens AG – Germany • Medensia – Japan• Nokian Capacitors – Finnland • XJ Corporation

• Utilities• KEPCO – Korea • Fujian EPRI – China• FURNAS – Brazil • South Central Power China - China• Manitoba Hydro – Canada • TNB - Malaysia

• Universities / Research & Test Institutes• CPRI – India • Kinectrics - Canada• BDCC – China • Xian High Voltage Apparatus Research Institute - China

Applications

118

• efficiency of real time• frequency response

from 0-3kHz with one tool• detailed control - power

system interaction investigation

• Ongoing R & D to combine two types of equivalence techniques

ApplicationsGeneral Power System Studies & Education:

119

General Power System Studies & Education :• Utilities

• KEPCO – Korea • Chugoku EPCo – Japan• Kansai EPCo – Japan • Takaoka EPCo – Japan• Tohoku EPCo – Japan • Manitoba Hydro – Canada• BC Hydro – Canada • LADWP - USA

• Universities / Research & Test Institutes• CPRI – India • ChangWon University – South Korea• Clemson University – USA • Florida State University (CAPS) – USA• J Power – Japan • TU Delft / TU Eindhoven – The Netherlands• University of Manitoba – Canada • University of Western Ontario – Canada• University of Wyoming – USA • University of Missouri-Rolla – USA• University of Cassino – Italy • University of Durban – South Africa

Applications

120


Validation

121

Validation:

• In-house

• Independent validation by customers

• Commercial studies

• Industry benchmark cases Electromagnetic Transient Electromechanical Transient Transient Stability Load Flow / Steady State

Validation

122

Comparisons between RTDS and various references:

• EMTDC, EMTP, and Netomac

Non real time electromagnetic transient simulation

• PSS/E, Y-Method, Netomac, and BPA

Transient stability

• PSS/E, Netomac, and BPA

Load flow

• CIGRE and IEEE

Benchmark cases

• Actual power system measurements

Validation

123

Commercial Studies:

AC DCBus Split Filters

Loads

220 kV

Songo

GMPC+

EC f P

PLC SignalTransmission

GPS

BrakingResistorsCahora Bassa

Mozambique

533 kV DC

South Africa

330 kV AC

1500 km

400 kV AC

Matimba Apollo

InterconnectedGrids Signal Processing

for Control andProtection

Bindura

Zimbabwe

PAC

PDC

0

0

1.5

1.5

0

1.5

RTDS

FieldTest

HVDC Current ( kA )

0

1.5

Siemens

Grid Master Power Controller

ESKOM, South Africa

Validation

Analog Graph

x 0.150 0.175 0.200 0.225 0.250 0.275 0.300 0.325 0.350 ... ... ...

-800.000k

-600.000k

-400.000k

-200.000k

0.000

200.000k

400.000k

600.000k

bus

volta

ge

MV1 EA Vas5

-600.000k

-400.000k

-200.000k

0.000

200.000k

400.000k

600.000k

bus

vol

tage

MV1 EB Vcs5

-600.000k

-400.000k

-200.000k

0.000

200.000k

400.000k

600.000k

bus

volta

ge

MV1 EC Vbs5

Advanced Graph Frame

x 0.150 0.175 0.200 0.225 0.250 0.275 0.300 0.325 0.350 ... ... ...

-3.0k

-2.0k

-1.0k

0.0

1.0k

2.0k

3.0k

4.0k

lin

e #

2

DM2 IA Ias4

-2.0k

-1.5k

-1.0k

-0.5k

0.0

0.5k

1.0k

1.5k

lin

e #

2

DM2 IB Ics4

-2.0k

-1.5k

-1.0k

-0.5k

0.0

0.5k

1.0k

1.5k

line #

2

DM2 IC Ibs4

Voltages Currents

Near the fault bus

Fault recordings

Model validation

125

Recent

Developments


126

Recent Developments

Requirements:

more accurate power system modelling

Resources:

more powerful processors

Led to

Further developments in RTDS real time simulation

Continued development in both hardware and softwareContinued development in both hardware and software

Aimed at meeting changing needs of power system Aimed at meeting changing needs of power system engineers and of the power system itselfengineers and of the power system itself

127

Recent DevelopmentsRecently developed models for GPC card:

Phase Domain Transmission Lines

UMEC Transformer

Voltage Source Converters

128

Simulation:Simulation:

Non Real Time:

• Solution process is not hard real-time, hence interpolation can be used even in large closely connected networks with numerous switches

Real Time:

• Hard real-time required, hence interpolation cannot be applied in large closely connected networks with many switches

• VSC Bridge; Adequate valve firing resolution provided by small time-steps

• Main Network; simulation is more efficient with larger time-steps

• Conflicting requirements

• Multiple timestep approach chosen

Recent Developments

Challenge of VSC modellingChallenge of VSC modelling

The main network ---

Requires a normal time step of approximately 50 μs

The VSC model ---

Requires a firing resolution of a few microseconds

129

Recent DevelopmentsVSC Sub-Network

• Efficient EMT simulation programs often utilize the concept of sub-networks

• Individual sub-networks can be solved in parallel

• Taking this approach we map VSC bridges into individual sub-networks

• The VSC sub-network interfaces with the main circuit

• The interface is similar to well known “hybrid” analogue/digital real-time simulation methods

• VSC interface is fully digital and eliminates difficulties with D/A and A/D conversions as well as amplifiers used in the hybrid simulator

• Small time-step solution in the VSC sub-network is interfaced to large time-step solution of the main network

V

VoltageAmplifier

D/A

A/D

I

CurrentMeasurement

V

RTDSSimulator

Main Network(50 us)

STATCOM

Analog VSC Model(continuous solution)

I

CurrentMeasurement

V

RTDSSimulator

Main Network(50 us)

STATCOMRTDSSimulator

+-

Discrete Time-StepVSC Model

(1.4 to 2.0 us)

130

Recent DevelopmentsExample Simulation Test Case

Small time-step execution time minimized by linking pre-created machine language modules

Doubly fed induction machine with saturation

Six-pulse two-level bridge (two units)

Three-phase high pass filter bank

Three-phase RL branch

Capacitor branch

Three-phase interface transformer

Network solution equations

= 0.4 sec

= 0.22 sec (per unit)

= 0.09 sec

= 0.05 sec

= 0.025 sec

= 0.11 sec

= 0.2 sec

Total small time-step execution time

~ 1.32 sec

Small time-step used in example case

~1.67 sec

131

Recent DevelopmentsExample Simulation Test Case

Validation of real-time results against PSCAD non real-time simulation with 50 sec time-step

RTDS PSCAD

132

Recent DevelopmentsMore Recent Work

Real Time Simulation of 3-level STATCOM with 36 valves

133


Conclusion

134

ConclusionImpact of Real Time Digital Simulation Techniques:

Real time digital simulation: • represents an important advancement in the understanding of power system

operation and performance

• allows more organizations to establish affordable and manageable in-house simulation facilities

• combines the accuracy of digital models with the real time response of traditional analogue simulators

• provides a mechanism to rigorously study and test the performance of new and existing protection and control devices prior to installation in the actual power system

• provides detailed knowledge of power system performance before, during, and after an event

• increases confidence and reliability in the design, implementation and operation of the electrical network and its complex components

135

Additional Information:

• Our website

www.rtds.com

• Technical publications– Multiple volumes of published papers available dating back to 1991

• Technical documentation and tutorials– Including on-line reference

RTDS Technologies welcomes any questions or comments. Please do not hesitate before, during and after installation to contact us.


136

Generator ControlsGeneric controls:• Controllers based on PSS/E models

Stabilizers Exciters

EXAC1AVREXAC1AAVREXAC2AVREXAC3AVREXAC4AVREXDC2AVR

EXST1AVREXST1AAVREXST2(A)AVREXST3AVREXPIC1AVR

IEE2STPSSIEEESTPSSPSS2A

Governor / Turbine

GASTGOVHYGOVGOVIEESGOGOVIEEEG1GOVIEEEG2GOVIEEEG3GOVTGOV1GOV

137

Generator ControlsDetailed exciter simulation:• Static exciter with detailed rectifier circuit

138

Generator ControlsDetailed exciter simulation:• Automatic voltage regulator

139

Generator ControlsDetailed exciter simulation:• Protection

Under ExcitationLimiter

Stator Current Limiter

Volts per HertzLimiter

Over ExcitationLimiter

1 real time digital simulation rtds ® power systems simulation in real time

Documents

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