Method for partial discharge localisation in air-insulated substations

Partial discharge (PD) localisation in air-insulated substations (AIS) can be used to assess insulation condition efficiently. The localisation results of previously published methods were in the form of coordinates or bearings, and showed large errors on coordinates. Further research is required if the fault is to be pinpointed. In this study, a novel localisation method based on directional antenna and multi-point measurement is proposed to improve the accuracy of localisation result and inform the possible error distribution, which reflect the fact that where the PD ultrahigh frequency signal radiates from is not a point but the non-metallic area of the source equipment. Through the single point measurement, the bearing of the PD source is obtained. With the multi-point measurement, an accurate result and its error distribution are made available. An onsite test in a 220kV testing AIS was performed, and compared with an existing method. The results show that the proposed method is more accurate than the existing method, and it is efficient to locate the faulty equipment with additional information of the error distribution.