A Precise Power Frequency Notch Filter for Abnormal State Perception in Power System

Relay protection relies on non-power frequency information to determine the state of power system in some situations. It necessitates the use of precise and effective notch filters to eliminate the power frequency component that might confuse the non-power frequency measurement process. The conventional filters may amplify or suppress the non-power frequency signals when removing the power frequency one, causing signal distortion. This paper presents a digital infinite impulse response (IIR) notch filter design based on triangular transform. The frequency response of the filter is optimized by the pole position displacement, which reduces the distortion of the filtered signals. The proposed notch filter's robustness is then increased by using the cross-panning method to extend the filter's window length. The filter is validated by MATLAB simulation of harmonics analysis and applied in experimental tests of grounding parameter calculation of distribution networks. The result demonstrates that the filter can raise the accuracy and dependability of signal processing. It can be useful for abnormal state perception of novel power systems like fault identification, harmonic tracing, and disturbance feature extraction.