Cable insulation electric tree degradation detection method based on leakage current integral charge

Abstract

The invention discloses a cable insulation electric tree degradation detection method based on a leakage current integral charge. The method comprises the steps that an electric tree detection circuitbased on the leakage current integral charge technology is built; a time-varying curve of a capacitor voltage is obtained based on a circuit, and the time-varying curve of the capacitor charge quantity through the capacitance value is reversely deduced; linear fitting is conducted on capacitor charge data sampled for 500-600 seconds to obtain a fitting function; a time demarcation point of whicha deviation between the charge quantity and the fitting function is greater than or equal to 5% is judged, and a slope k of charge to time between the time demarcation point and 600 seconds is calculated; when k is larger than or equal to 10-10, it is judged that an electric tree is generated, and otherwise no electric tree is generated; and when the value of k is between 10-10 and 10-9, an electric tree degradation level is low, and when k is greater than 10-9, the electric tree degradation is serious.

Description

technical field [0001] The invention relates to the field of degradation detection of power cable insulation materials, in particular to a method for detecting degradation of cable insulation electrical branches based on leakage current integral charge. Background technique [0002] Power cables are key electrical equipment in new energy grid-connected and urban power supply systems. During the service of power cables, the aging, degradation and breakdown of cable insulation under complex working conditions are important factors affecting the reliable operation of power cables. Under the action of a long-term electric heating field, a dendritic discharge channel will appear between the semiconducting layer and the insulating layer in the cable, and a series of chemical and physical reactions caused by partial discharge in the micropore or channel will continuously degrade the surrounding materials and maintain the dendrite. The continuous development of the channel seriously...

AI Technical Summary

Problems solved by technology

The traditional test method is mainly used for laboratory analysis and research. Under the actual cable operation condition, it is greatly affected by the interference of field and environmental conditions, which seriously affects the accuracy of the evaluation of the insulation state of the power cable.

Determining the real aging state of insulation by partial discharge characteristic parameters requires long-term on-line monitoring, and relies on analysis methods of characteristic parameters and electrical tree development state, and the diagnostic accuracy is limited

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