Location of partial discharge in transformer oil using circular array of ultrasonic sensors
Partial discharge (PD) in transformer oil is one of the major causes of electrical insulation failures in oil transformers. An accurate location of PD provides important information required for detection and elimination of insulation defects. To improve accuracy of PD location, a new location method is proposed in this paper based on using circular array of ultrasonic sensors (CAUS) and implemented as follows. First, the fast independent component analysis (FastICA) algorithm is used to de-noise PD signal obtained by CAUS. Second, the total least square (TLS) algorithm is used to transform the wide-band signal obtained by CAUS to the narrowband one. Third, the mode excitation algorithm and the fast direction of arrival (FastDOA) algorithm are combined together to find three different directions of arrival (DOA) of the signal from PD to CAUS. Next, using the azimuth and pitch angles of these three DOAs, the PD location is determined in the center of a sphere whose surface tangents to these three DOAs in three different planes. Finally, the improved genetic algorithm is used to obtain accurate coordinates of the PD source. An experimental system of PD-location has been developed, which consists of (i) CAUS made of 8 sensors evenly placed along a circle, and a single sensor placed in the center of the circle, (ii) classic three-capacitance PD model, (iii) 16-channel synchronous data collector, (iv) oil tank, and (v) computer. The preliminary experimental results show that the accuracy of PD location after denoising is better than that before de-noising.