Fault recording data analysis based on combinational filter and time-frequency transform

An analysis algorithm based on CF(Combinational Filter) and TFT(Time-Frequency Transform) is proposed for fault recording data.The sampling value correction error due to asynchronous sampling is analyzed and it is proposed to use difference method to eliminate the error for achieving ideal filtering.Being immune to the effect of asynchronous sampling,TFT has ideal frequency characteristics.Because of its complex band-pass filter characteristics,it outputs the fundamental complex phasor without the components of other bands.Because the time-frequency bandwidth of TFT can be flexibly adjusted,shorter calculation data window is thus obtained.Simulative results indicate that,with better dynamic performance and anti-interference capability,the proposed algorithm filters effectively the aperiodic components,measures accurately the magnitude,frequency and phase of fundamental with the fixed sampling rate.