Study on Algorithm of fault recording analysis combining its time-domain waveforms and phase-domain trajectories

Abstract

When the period of a sinusoidal waveform is taken as a baseline, after sampling time of fault recording are transformed into polar angles and its instantaneous values are transformed into polar diameters, the recording is transformed from its time-domain waveform in a rectangular coordinate system into the phase-domain trajectory in a polar coordinate system. In the paper the recording is analyzed base on the combination of the time-domain waveform and the phase-domain trajectory of the fault recording to mine fault feature parameters for reformulating the recording, and then the reformulated recording is used to substitute the original one to achieve various fault analysis functions in power systems. A short-circuit current containing a dc component being taken as an example, the algorithm consisting of separating, reformulating and adjusting various components from the current waveform are researched. By the algorithm the programs are created in Matlab, after their running the post-adjustment reformulated waveforms with high accuracy are obtained, and their curves of absolute errors pre- and post-adjustment are plotted. The relational problems, such as the calculation of the phase angles of samples and their errors, the accuracy of the reformulated waveforms, etc., are discussed. The research results show that there is a high correlation between the reformulated waveform using the algorithm proposed in the paper and the original one for the fault recording with only dc components, and it can be used to substitute the origin one within an error range.