HVDC换相失败小波故障诊断方法

Fault Diagnosis Based on Wavelet for Commutation Failures in HVDC

将小波变换应用于高压直流输电(HVDC)系统换相失败的故障诊断中,基于多尺度分析分别对不同故障情况下的直流电流进行分解,并利用尺度能量和尺度熵这两种小波处理方法提取故障特征,分别定义两个故障诊断指标作为辨识各种故障的判据,然后针对这两个指标分别设置4个阈值以诊断直流线路故障和换相失败故障.仿真表明,在不同的HVDC系统故障情况下,暂态信号小波尺度能量和尺度熵的分布都具有一定的规律性,可分别作为判断系统故障的有效依据,提出的判据能准确地对换相失败故障做出诊断.

This paper proposes a method to identify different causes of commutation failures in the High-Voltage Direct Current Transmission （ HVDC ） system. By using the technique of wavelet multi-resolution analysis （ MRA）, the transient signals generated by the faults are decomposed into different resolution scales. Then, the features of each fault are extracted using the wavelet signal processing methods such as scale energy and scale entropy. Moreover, two auxiliary parameters are defined as the criteria for the identification, and four thresholds are set to distinguish the commutation failures from DC line faults. Simulated results indicate that there exist certain distribution regularities for the scale energy and scale entropy of transient signals with different HVDC faults, and that the criteria based on these regularities can make effective and reliable diagnosis of commutation failures.