Research on high voltage capacitor partial discharge detection with portable oscillating wave circuit

Abstract

At present, the partial discharge(PD) detection of high voltage power capacitor usually employs a resonant circuit which requires a very bulky reactor, and a PD detector with ultrasonic sensors. One of the problems with this approach is difficult experimental setup. Another is the limitation of PD signal analyze and get further valuable information, due to the properties of ultrasonic signal itself. This paper reports on a new user-friendly and effective way to carry out PD test of HV power capacitor. This system contains a supply module, a specially made sampling impedance and a PD pulse collector. The supply module, consists of high voltage DC power generator, protection resistance, damping resistance, semiconductor switch, which is integrated designed, characterized by small size, light weight, and low power consumption. The specially made sampling impedance which is employed to obtain PD signals could be applied to the detection of capacitor samples with different capacity, and the impedance can be directly connected to the end of the capacitor without the influence of large current signal. And the PD pulse collector is different from PD detectors under stable voltage, which needs to grasp the PD signal accurately in several cycles of the test loop oscillation, and the signal acquisition is required to be continuous. Compared with the previous approach, the oscillating wave circuit with specially made impedance reported in this paper, showed much more portability for large power capacitors PD detection, and the results provided chances for time and frequency domain spectrum analysis, which could be helpful to identify the PD type of HV power capacitors.