Study on a Partial Discharge Detection Method for Transformers Adopting the End Shield as UHF Sensor

Power transformer is one of the most important equipment in power system. Its reliability directly affects the safe operation of power network. A partial discharge (PD) detection method for transformers adopting the end shield of the bushing as ultra-high frequency (UHF) sensor is developed in this paper. The bushing end shield can be used as the internal UHF sensor to measure the PD UHF signals. The experiments are carried out on an 80kV transformer model with three types of defect models set inside. The validity and sensitivity of this method are proved by experiments with AC voltage. The results show that the proposed method has high detection sensitivity and it can measure the PD signals without additional sensor. The UHF method has good anti-interference performance and is not affected by corona discharge outside the transformer. This PD detection method solves the problem that the internal UHF sensor has security risks while the external sensor is susceptible to interference. It provides a new method for PD detection of transformers in field.