Comparative Study of Detection Method on Partial Discharge in Oil Under DC Voltage

In order to compare the effectiveness of the different DC partial discharge detection methods, a set of DC partial discharge detection system in the oil is designed and built. This paper applies electrical measuring methods and ultrasonic methods to test the partial discharge signals. Electrical measuring methods use wideband current sensor, non-inductive resistance and detecting impedance. Ultrasonic methods use ultrasonic probe and preamplifier for collection of the signals. DC partial discharge of needle-plane electrode model in transformer oil is tested with above four ways. The experimental results show that electrical measuring methods are vulnerable to interference such as DC power which is difficult to identify partial discharge signals. Ultrasonic sensor has strong ability of resistance to electromagnetic interference, by selecting the appropriate detection frequency band range, we can realize the accurate identification and detection of partial discharge.