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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
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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 • Induction Generator Effect • Subsynchronous Torsional Interaction • Subsynchronous Control Interaction
Challenges • Low magnitude of oscillation • Low frequency range • Tight response time requirement (Speed) • High amplitude of fault current • Avoid 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
Signal processing techniques • Fourier Transform • Short time Fourier transform • Wavelet transform
Real world event Generator current waveform for a real world SSR case
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.