基于小波包和包络线的行波相关法单端故障测距研究

针对行波相关法时间窗不固定导致单端行波故障测距可靠性低的问题,提出将小波包和包络线结合的新方法。首先利用db1小波基对故障行波信号进行小波包多尺度的分解重构,验证了在不同尺度下正反向行波初始波头的宽度都是相同的;以正反向行波初始波头的宽度作为行波相关法中时间窗宽度,使时间窗宽度成为一个定值。其次,利用包络线把正反向行波中前两个不同极性的波头变为单极性波头,最后通过相关算法处理实现单端行波故障测距。所提方法使行波相关法中的时间窗宽度不再受故障距离、过渡电阻等因素的影响,且经包络线处理后的正反向波避开了相关函数出现多余极值。经PSCAD和MATLAB仿真分析,与传统行波相关法相比,所提方法明显提高了单端故障测距的可靠性。

Traveling wave correlation method for single terminal fault location based on wavelet packet and envelope

Aiming at the time window of traveling wave correlation method is not fixed, and the reliability of single-ended traveling wave fault location is low, a new method combining wavelet packet with envelope is proposed. Firstly, the wavelet packet decomposition and reconstruction of the fault traveling wave signal are carried out by using the db1 wavelet basis, and the width of the initial wave head of the forward and backward traveling waves is the same at different scales. The width of the initial wave head of the forward and backward traveling wave is used as the time window width in the traveling wave correlation method, so that the time window width becomes a fixed value. Secondly, the first two poles of the forward and backward traveling waves are converted into unipolar wave head by using the envelope. Finally, the single ended traveling wave fault location is realized by the related algorithm. The proposed method makes the time window width in the traveling wave correlation method no longer affected by the fault distance and transition resistance, and the forward and backward waves after the envelope processing avoid the excess extremum of the correlation function. Compared with the traditional traveling wave correlation method, this method can obviously improve the reliability of single ended fault location by PSCAD and MATLAB simulation analysis.