Method for partial discharge detection in transformer bushings based on RF sensor array

Abstract

When partial discharge occurs in the main equipment of a substation, it generates radio frequency electromagnetic waves with frequencies ranging from tens of MHz to GHz. These electromagnetic waves generated by internal partial discharges can propagate through non-metallic parts of the equipment (such as insulating bushings and transformer gaps) into the external space, providing a theoretical basis for conducting non-contact partial discharge detection outside the substation equipment. Based on this principle, this paper proposes a non-contact broadband radio frequency partial discharge detection technique. This technique employs an array composed of multiple broadband RF sensors, utilizes gigahertz high-speed sampling detection, and combines waveform feature identification with time difference of arrival localization methods to identify and accurately locate discharge signals and interference signals. Through experimental cases involving bushing partial discharges, this paper validates the feasibility and effectiveness of this technique in detecting partial discharges in bushings. In the bushing tests, the array records the PD pulses and separates them from several obvious interference components. The obtained positions are close enough to the preset discharge and interference locations for fault judgment at site. Because the sensors are installed outside the equipment, the measurement does not require a temporary electrical connection to the bushing or transformer tank. This makes the method more suitable for cases where a suspected insulation defect needs to be checked without interrupting the operating condition of the apparatus.