fast methods for transient stability prediction in power systems
TRANSCRIPT
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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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