Analysis of Low Voltage Crossing Event Caused by Pollution Flashover of 220kV Transmission Line

Pollution flashover is one of the important reasons for the decrease in insulation strength of transmission lines. The occurrence of pollution flashover in transmission lines is mainly due to the special climate of the environment in which they are located, and the dissolution and conductivity of attachments on the surface of insulators, significantly reducing the insulation level of insulators. The paper uses PSCAD transient simulation software to model and simulate the 220kV Jinmou Second Line operated and maintained by an energy supply company. The results show that the B phase of the 220kV Jinmou Second Line did indeed experience a tripping phenomenon. Through on-site investigation, it was found that the insulators were heavily contaminated and did not comply with regulations. Under the influence of heavy fog weather, pollution flashover is prone to occur. Subsequently, through the analysis of the action of the feed pump frequency converter, it was found that the accident occurred indirectly due to the load fluctuation range exceeding the controllable range of the frequency converter during the restart process, resulting in overcurrent protection actions of the 1st and 2nd frequency converters; And the water supply of boiler 4 did not meet the demand, resulting in boiler shutdown. Based on the analysis of the case, prevention and control measures for differential transformation of insulators and optimization of the feed pump frequency converter were proposed.