A homologous waveform comparison method based on angular step search and its application

To address potential risks in analog signal acquisition by relay protection equipment， this paper proposes a homologous waveform comparison method based on angular step search for automatically identifying anomalies in analog signals. First， the third-order Lagrange interpolation algorithm is employed to unify the sampling rates of waveforms with different source rates. Next， a reference waveform and the analog signal channel to be aligned are selected. Preliminary alignment of waveforms is achieved using the absolute time at the zero point， followed by fine alignment using the absolute value of the sampling value difference as the criterion， implemented via an angular step search method. Subsequently， anomalies in the analog signal channel are identified by comparing waveform phasor differences combined with sampling value differences. Furthermore， a homologous waveform comparison framework is developed， and the method is applied in practical engineering scenarios. Finally， case study results demonstrate that the proposed method achieves waveform alignment and identifies anomalous analog channels even under frequency offset conditions， proving its value for engineering applications.