for Subsynchronous Resonance Detection

pancakesbootAI and Robotics

Nov 24, 2013 (3 years and 10 months ago)

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Copyright © SEL 2012

A Comparison of Different Signal Selection
Options and Signal Processing Techniques
for Subsynchronous Resonance Detection

Yu Xia, PhD, Member, IEEE

Normann Fischer, Senior Member, IEEE

Schweitzer Engineering Laboratories

Outline


Existing Subsynchronous Resonance
(SSR) detection methods


Signal input options


Signal processing tools


Application results


Conclusions

Background


Series compensated lines


Types of SSR

1.
Induction Generator Effect

2.
Subsynchronous Torsional Interaction

3.
Subsynchronous Control Interaction

Challenges



Low magnitude of oscillation



L
ow frequency range



T
ight response time requirement (Speed)



H
igh amplitude of fault current



A
void false trips (Security)



Recognize SSR (Dependability)

Existing SSR detection methods



Tex Relay




Torsional motion relay



Armature current relay


Microprocessor based methods


Patent by Southern California Edison



Patent by ABB



ERLphase method

Input signal options


Negative sequence current



Voltage across the series capacitors



Generator terminal currents and voltages



Generator speed

DFT result for voltage and current of
the capacitor bank

0
20
40
60
80
100
120
0
5
10
15
20
X: 35.4
Y: 19.27
Frequency, Hz
Voltage, kV
DFT result of voltage and current of the capacitor bank
X: 60
Y: 17.9
0
20
40
60
80
100
120
0
0.05
0.1
0.15
0.2
X: 60
Y: 0.1624
Frequency, Hz
Current, kA
X: 35.4
Y: 0.1029
Signal processing techniques


Fourier Transform


Short time
Fourier transform


Wavelet transform

Heisenberg boxes (STFT)

Heisenberg boxes (WT)

DFT, STFT and WT

Real world event

0
0.2
0.4
0.6
0.8
1
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
Time, sec
Current, A
Generator current waveform for a real world SSR case

Application results (FT)

0
20
40
60
80
100
120
0
50
100
150
200
250
300
350
400
X: 25
Y: 380.9
Frequency, Hz
Magnitude, A
DFT result of IA
X: 60
Y: 176.3
X: 95
Y: 32.94
Application results (STFT)

Application results (WT)

Conclusions (1)


Existing SSR detection methods were
reviewed.


Different signal selection options and signal
processing techniques were compared.


Existing methods either do exclusively time
domain analysis or exclusively frequency
domain analysis.

Conclusions (2)


STFT and WT decompose the signals in
both time and frequency domain.


WT overcomes the drawbacks of FT and
show a clear relationship between the
magnitudes of different frequency
components and time.

Questions?