Experimental research on incipient fault voltage disturbance model of power cable insulation

• The sub-cycle voltage disturbance caused by the incipient fault is obtained through experiment. • The waveform and occurrence frequency characteristics of the voltage disturbance are analyzed. • The model and disturbance characteristics indexes of incipient fault sub-cycle disturbance are proposed. Incipient fault is the precursors of permanent cable fault. Analyzing and modeling the transient power disturbances caused by incipient fault is an important prerequisite for accurately identifying incipient cable fault. In this paper, a large number of sub-cycle voltage disturbances caused by the incipient fault are obtained by performing an applying voltage test on a 10 kV cable with local insulation defects. Then, for the voltage signal with disturbance, the time domain analysis method is used to extract the disturbance, and Hilbert transform method and curve fitting method are used to analyze the variation trend of the disturbance. Three stages of the disturbance are obtained: normal stage, fault excitation stage, disturbance attenuation stage. Then an incipient fault sub-cycle voltage disturbance model is proposed and sub-cycle disturbance characteristic indexes which are fault excitation starting time and fault excitation duration are extracted; The validity of the model is analyzed by the reproduced experimental waveform, and the disturbance propagation characteristics along the line are analyzed by PSCAD simulation.