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Based on the MSc thesis works of my former MSc students, Mr Binod Shrestha entitled “A Fast Method for Out-of-Step Protection Using State Plane Trajectories Analysis”, December 2011, and Mr. Parikshit Sharma entitled “Fast Methods for Transient Stability

Prediction in Large Power Systems and Wind Integrated Power Systems”, February 2013.

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University of Saskatchewan RTDS

Number of PhD Students: 3.

Number of MSc students: 7.

Power System Protection & Control.

Transient Stability Prediction, Voltage Stability

Prediction.

Website:

http://www.ece.usask.ca/eceresearch/faculty/rag404/

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• Introduction

• State Deviation Method

• Experimental Results Using HIL With RTDS

• Conclusions

Contents

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Introduction

Figure 1 : Interconnected power system representation

Normal operating condition

Disturbances

Voltage and frequency are within limits.

Faults, loss of major transmission lines etc. Generator

Sub-Station

Transmission

Line

Load

Breaker

Transformer

EA δ1 EB δ2

Pe1Pe2

377.0

377.0

2

StableUnstable

Speed of the generator

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Effects of Power Swing

Kestrel Power ISOCH

Record (2003 black out)

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Kestrel Power ISOCH Record

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Effects of Power Swing

Prone to mal operation

Transient Stability Prediction

Distance Relays

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Two Blinder Scheme

Outer BlinderInner Blinder

Load

region

Δt

Impedance changes at different rates during faults and power

swings

Stable swing

Unstable swing

Fault

Blinder based Technique

Prone to mal-operation.

Needs update of settings

Disadvantages

Requires number of offline

stability studies

Slower Detection Time

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Swing center voltage (SCV)

Other methods

R-R dot scheme

Intelligent systems based methods

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Extended equal area criteria

Frequency deviation of voltage method

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Voltage rating of breakers

Vs

VR

Vs

Vs

Vs

Vs

VsVB

VB

VB

VBVB

VB

VB

Vs

Voltage across the breaker = 1.3 or 1.5 times Vpeak

During short circuit breaking:

Voltage across the breaker = 2 or 2.5 times Vpeak

During loss of synchronism:

All the breakers are designed for either 2 or 2.5 times the rated voltage

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Phasor representation of voltage during power swing

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State Deviation Technique

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Equilibrium points

Single Machine Infinite Bus (SMIB)

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Proposed State Deviation Method (contd.)

Case-I : Stable Swing

Case-II : Unstable Swing

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State Deviation Method (contd.)

Transient Stability Prediction Procedure

System-wide transient stability prediction

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Experimental Testing

Real Time Digital Simulations (RTDSTM)

Real time simulations

(@ 50 μs)

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Experimental Set-up

AD 1836 96 kHz audio codec

with input & output RCA

jacks were used.

Demodulated signals consist

of 48000 samples/sec.

Power/speed deviation

signals @0.2-10 Hz.

Downsampled by 240 times

(ie 200 samples/second).

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Hardware-in-the Loop (HIL) Testing (contd.)

Test system (IEEE 39-bus test system)

Represents New England Power System and interconnection with

rest of the US and Canada

US and Canada

Interconnection

equivalent

18IEEE 39-bus test system

Three phase fault

applied at bus 15

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Stable Power Swing (fault at bus 15 for the duration of 100 ms)

State Deviation Method (Hardware Implementation)

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State Deviation Method (Hardware Implementation)

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Line 1-2 8-9

Angle Diff. 76.8o 68.8o

Unstable Power Swing (fault at bus 15 for the duration of 120 ms)

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Test system (IEEE 39-bus test system)

Represents New England Power System and interconnection with

rest of the US and Canada

US and Canada

Interconnection

equivalent

18IEEE 39-bus test system

Three phase fault

applied at bus 26

State Deviation Method (Hardware Implementation)

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State Deviation Method (Hardware Implementation)

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Stable Power Swing (fault at bus 26 for the duration of 140 ms)

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State Deviation Method (Hardware Implementation)

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Line 1-2 8-9

Angle Diff. 74.87o 74.39o

Unstable Power Swing (fault at bus 26 for the duration of 160 ms)

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Summary of Simulation Results

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Conclusions

Faster than existing methods.

State Deviation Calculation Time on DSP < 21μs.

(observed from real time testing).

Methods could be applied for Out-of-Step Protection of

Generators as well as System-Wide Transient Stability

Prediction.

Method could successfully predict multi-swing instability.

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