基于直接测量的换相失败检测及预测方法研究

A Method of Commutation Failure Detection and Prediction Based on Direct Deasurement

换相失败是高压直流输电系统逆变侧换流阀较易发生的典型故障,连续换相失败会对电网造成严重危害,传统基于交流或直流运行参数的间接判断法存在响应时间慢、误判率高等缺陷。此处首先分析了换相失败机理,换相失败后晶闸管阀将继续导通,不会承受正向电压,而实际关断角小于最小关断角是导致换相失败的根本原因之一。利用换相失败后晶闸管阀电压波形特征,提出了通过设置采样窗口,直接测量晶闸管阀电压来检测换相失败故障的方法,同时测量晶闸管阀的实际关断角,用于评估换相失败风险。搭建了基于RT-LAB的闭环测试平台,验证了此处所提换相失败检测方法和关断角测量功能,为解决高压直流输电换相失败故障奠定了坚实的技术基础。

Commutation failure is a typical fault that is easy to occur on the inverter side of high-voltage direct current transmission system.The continuous commutation failure will cause serious damage to the grid.The rapid and accurate detection and prediction of commutation failure is the key technology to improve the ability of converter valve to resist commutation failure.First,the commutation failure mechanism is analyzed.The thyristor valve will continue to conduct after the com-mutation failure and will not withstand the forward voltage.The actual turn-off angle is less than the minimum turn-off angle is the root cause of the commutation failure.Based on the characteristics of the thyristor valve voltage waveform after the commutation failure,a method for detecting the commutation failure fault by setting the sampling window and directly measuring the thyristor valve voltage is proposed.At the same tim e,the actual turnoff angle of the thyristor valve is measured to evaluate the risk of commutation failure.A closed-loop test platform based on RT-LAB is built to verify the commutation failure detection method and turn-off angle measurement function proposed,which lays a solid technical foundation for solving the failure of high-voltage direct current transmission commutation failure.