Signal Detection And Calibration For Partial Discharge Based On UHF Technology

As an effective detection methods, partial discharge(PD) detection is widelyapplied to detecting insulating state of power cables and accessories. Sincetraditional partial discharge detection is performed offline, in recent years, UHF PDdetection methods are cause for more concern. In this paper, a UHF capacitivecoupling sensor for on-line partial discharge detection has been developed for UHFcapacitive coupling method, and a series of studies about110kV power cables andcable joints have been made.A UHF capacitive coupling sensor has been made, and the sensor is suitable foron-line partial discharge detection, it will not affect the performance of the cableinsulation. The actual performance of the sensor has been proved through input andoutput characteristics experiment, it has good response to characteristics of the inputsignal, and can measure the real UHF signals effectively. In order to study thepropagation of UHF signal in the power cables, three defects has been produced inthe cable joints to generate partial discharge, and measure it with the sensor. Andsum up that PD UHF signal frequency range is different, by observing in thespectrum of the PD UHF signal with different defects, it has a certain reference valueto determine the type of fault. Meanwhile, there is overlapping between the differentfrequency range, it relates to the location of the defect and the shape. In order toquantify PD signals, a calibration experiment has been conducted. In order tocompare the conventional method with the new method of the type, obtained thedifferences of the two methods in PD detection and calibration, and the advantage ofthe UHF method in partial discharge detection and calibration has been verified.