Analysis on a Resonance Faults Incident of 35kV Capacitor Voltage Transformer

Capacitor voltage transformers (CVTs), as important online monitoring devices, have been widely used in power systems. Monitoring overvoltage waveforms through CVTs provides crucial information for fault location and troubleshooting. However, However, the internal dynamic and nonlinear components of CVTs, primarily designed for power frequency voltage measurements, can distort wideband lightning overvoltage waveforms, complicating fault analysis. This paper analyzes a typical power frequency resonance fault recorded by a 35 kV line CVT, examining the waveform distortions and ferroresonance process caused by the CVT fault under lightning overvoltage conditions. Simulation results show that when the damping circuit of the CVT is damaged, prolonged lightning waves can cause sustained power frequency resonance that cannot be eliminated. The research offers valuable references for analyzing similar overvoltage incidents.