Transformer Partial Discharge Location by Optimized Ultrasonic Propagation Path Search

Partial discharge detection and location are vital to diagnose insulation conditions of power transformer. Ultrasonic detection has the advantages of anti-interference, low loss and flexible application, and has been widely applied in partial discharge location. However, the propagation paths of ultrasonic signal are complex in transformer structural components. Conventional locating method by direct wave shows a large error. In this paper, an optimized ultrasonic propagation path search method is proposed by considering the transformer interior structure and propagation paths of ultrasonic. The method is employed to determine an optimal arrangement of ultrasonic sensor in transformer tank, and the determined time differences are transferred into particle swarm optimization algorithm to solve location equations. A locating verification of two partial discharge sources is implemented on a 35 kV experiment transformer, and the optimized ultrasonic propagation path search method shows higher locating accuracy of partial discharge. The average locating errors of two sources are 12.6 cm and 23.9 cm respectively, which are smaller than that of conventional methods (17.4 cm and 45.9 cm by GA, 47.5 cm and 43.6 cm by ICA).