Research on on-line PD monitoring system for large power transformer

This paper presents a new set of on-line partial discharge (PD) monitoring system for large power transformer. Four sets of 500 kV power transformers can be monitored automatically at the same time, and then fault warning and localization are made by software. Various methods are used to reject interference in order to increase the monitoring sensitivity of PD. The on-line calibration technique, the pulse injection through capacitive tapping, is applied for measurement of apparent discharge. The earthing fault of transformer was found while the system commissioning. Now this system has been in operation steadily for more than two years. As one of main prevision maintenance testing item, on-line PD monitoring systems are paid more attention by engineers both in China and abroad. Up to now, some on-line systems had already been put in operation in Canada, Japan and China. They have already got many good results and accumulating a lot of good experiences. On base of summarizing forefather's works, a new type of JFY-2 on-line PD monitoring system for large power transformer has been developed by Jilin electric power research institute joint with Tsinghua university.