Phased-ultrasonic receiving-planar array transducer for partial discharge location in transformer

Partial discharge (PD) location in transformers is very important, and many methods that have been brought forward in past decades have a limitation theoretically, namely, they cannot locate multiple PDs in electrical equipment. In this paper, a new PD location method based on UHF and ultrasonic-phased arrays receiving theory has been presented, which has a possibility to locate multiple PDs. According to the method, a phased-ultrasonic receiving-planar array sensor that possesses 16 x 16 elements is designed; and, based on the phased-array theory, the characteristics of the plane sensor are studied. The laboratory experimental tests on the plane sensor element indicates that it has a good performance within the frequency band of the main ultrasonic energy produced by PD in transformer oil. Location tests are conducted on one or two piezoelectric ultrasonic sources in oil, which are both simulated as PD sources and triggered by an electrical pulse whose front is considered as a time benchmark in the locating algorithm. The test results show locations to one and two PDs can be realized in a single measurement, which lays a foundation for locating PDs in a power transformer in service