Research on Online Monitoring of PT Short Circuit Fault Based on 4PT Neutral Point Voltage

The 4PT(Potential Transformer, PT) wiring is widely used in 10kV, 35kV and other ungrounded systems to realize real-time voltage monitoring, and the PT may trigger winding short-circuit faults such as turn-to-turn and layer-to-layer due to some reasons during long-term operation. In this paper, a PT short-circuit fault online monitoring method based on 4PT neutral secondary voltage is proposed. First of all, the typical 4PT wiring mode, the secondary three-phase voltage, zero sequence voltage value of the theoretical analysis; then the PT short circuit fault phenomenon and the occurrence of short circuit faults after the PT electrical characteristics of the changes in a detailed analysis; next analyze the PT short circuit fault on the 4PT wiring mode of the impact of the voltage, current, and put forward the PT short-circuit fault on-line monitoring method; finally, through the test, the simulation on the Finally, the online detection method of PT short-circuit fault proposed in this paper is verified through test and simulation, which confirms the correctness of the theoretical analysis and the feasibility of the method. The online monitoring method proposed in this paper is able to monitor the health status of PT in real time and accurately without withdrawing PT from operation or dismantling it, which effectively avoids the grid impact and economic loss caused by PT explosion and other faults that can not be detected in time and continue to run after a short-circuit fault occurs in the PT.