基于小波能量统计法的HVDC换相失败故障诊断

将小波变换应用于高压直流输电系统换相失败的故障诊断中,基于多分辨率分析分别对不同故障情况下的直流电压、直流电流、交流电压和交流电流等暂态信号进行分解,提取每一层的特征;根据各层小波能量统计,定义2个故障诊断指标作为辨识各种故障的判据,并针对这2个指标分别设置4个阈值以诊断直流线路故障和不同原因引起的换相失败故障。仿真结果表明,该方法不仅能准确区分换相失败故障和直流线路故障,而且能判断引起换相失败的原因。

Fault Diagnosis of Commutation Failures in the HVDC System Based on a Method of Wavelet Energy Statistics

This paper proposes a method to identify different causes leading to commutation failures in the HVDC system based on wavelet transform.By using the technique of wavelet multi-resolution analysis(MRA),the transient signals generated by faults are decomposed into different resolution levels,with the features of each extracted.Based on the wavelet energy statistics,two auxiliary parameters are defined as the criteria for the identification;four thresholds are then set to distinguish between different faults.Simulation results indicate that the proposed approach makes it possible to perform definite identification of commutation failures from DC line faults and normal operations.Furthermore,discrimination in AC short circuit faults and missing firing faults,which cause commutation failures,can also be made.