基于形态学的特高压直流输电线路单端电流方向暂态保护

Single-end current direction transient protection based on morphology for UHVDC transmission line

提出一种基于形态学的特高压直流输电线路单端电流方向暂态保护方法,根据故障电流行波方向判定故障发生在本侧区外,或者本侧区内/对侧区外,根据边界及线路对高频信号的衰减特性判定故障发生在本侧区内还是对侧区外。利用整流侧保护安装处获取的故障暂态电流信号结合多分辨形态梯度(MMG)变换,提取电流信号在突变点的极性,提出电流方向元件原理及判据。对整流侧保护安装处检测到的暂态信号进行形态谱运算,并将形态谱归一化后的值转换到频域,通过比较在频域内的形态谱判断故障在对侧区外还是本侧区内。仿真结果表明所提方法能准确区分本侧区外、本侧区内和对侧区外故障,实现特高压直流输电线路全线保护。

A kind of single-end current direction transient protection based on morphology is proposed for UHVDC transmission line. It judges whether the fault occurs in the out-zone of own side according to the traveling wave direction of fault current;if not,it further judges whether the fault occurs in the in-zone of own side or the out-zone of opposite side according to the decay characteristics of line and line boundary vs. the high frequency signal. Combined with MMG（Multi-resolution Morphological Gradient） transform,the fault transient signal acquired by the rectifier-side protection is used to extract the polarity of current signal at the catastrophe point,based on which,the principle and criterion of current direction element are proposed. The morphological spectrums of the transient signal acquired by the rectifier-side protection are calculated,normalized and converted into frequency domain,which are then used to judge whether the fault occurs in the out-zone of opposite side or the in-zone of own side by comparison. The simulative results show the proposed method can identify the in-zone,out-zone faults of own side and the out-zone fault of opposite side accurately,realizing the protection of whole UHVDC transmission line.