Abstract:The measurement and diagnosis of partial discharge (PD) is accepted as one of the most valuable means for assessing the quality of high voltage power apparatus and its running status. However, the current partial discharge monitoring mainly based on equipment, which needs multi-process test equipment, high cost, and large maintenance engineering. This paper introduced the use of four antennas array to receive ultra-high frequency (UHF) signal, and define 3-D coordinate system, then located PD source in the field of the substation, Furthermore, this paper discussed the principles of the location algorithm based on time difference, analyzed the origin of its location error, then the connection of location error and the placement of antenna array and the error of time difference has been discussed theoretically. Finally, this paper provided the optimal placement of the radio frequency antenna array.