采用波形识别的直流50Hz保护优化改进策略

结合近几年来南方电网多次出现的变压器空投涌流引起直流50 Hz保护动作事件,仿真研究了励磁涌流、和应涌流及故障电流波形特征差异性,在不降低保护灵敏度的原则下,提出了一种基于波形识别的直流50Hz保护优化改进策略,并在高压直流PSCAD/EMTDC控制保护仿真模型的基础上结合优化改进策略自定义创建直流50Hz保护闭锁模型,从交流系统强度变化、换流变压器空载合闸角变化、换流变压器铁芯剩磁变化三个角度对所提出的优化策略进行仿真验证。结果表明,所提出的基于波形识别的直流50Hz保护优化改进策略能正确地实现直流50 Hz保护的闭锁和解锁,在不影响直流系统安全稳定运行的情况下很好地解决了变压器空投涌流引起直流50Hz保护误动的问题。

Optimization and Improvement Strategy for Direct Current 50 Hz Protection Using Waveform Recognition

Combined with direct current(DC)50 Hz protection action events caused by transformer inrush current occurred in China southern power grid in recent years, the waveform characteristics difference of inrush current, sympathetic inrush current and fault current are simulated and studied. Under the principle of without reducing sensitivity of the protection, an optimization and improvement strategy for DC 50 Hz protection based on waveform recognition is proposed. A DC 50 Hz protection lockout model is designed and developed in the PSCAD/EMTDC control and protection simulation model based on the optimization and improvement strategy. The proposed strategy is verified by means of simulation from the change of the alternating current system strength, no-load closing angle of converter transformer and core remanence of converter transformer. The results show that the proposed strategy can realize the blocking and unlocking of DC 50 Hz protection correctly, which solves the misoperation problem of DC 50 Hz protection caused by inrush current of the transformer without affecting the safety and stability of the DC system, and it has some reference significance to the research work and protection design.