基于对称分量变换的暂态电流极性方向比较保护算法

研究了一种新的基于暂态电流极性比较的方向保护技术.使用对称分量变换对三相暂态电流行波信号进行解耦,然后用其电流模量小波变换后的模极大值极性关系,辨识区内或区外故障:线路内部故障时线路两端的电流模量小波变换模极大值极性相同,而线路外部故障时则相反.该算法用单一模量对各种故障类型都可以给出正确的结果,较好地克服了以往采用Clark变换和Karrenbauer变换使用单一模量情况下对某些故障不能正确反应等缺陷.EMTDC仿真实验证明了算法的可行性.

Current Traveling Wave Polarity Comparisonal Protection Algorithm Based on the Transformation of Symmetrical Component

A new directional protection technique based on transient polarity comparison is proposed in the paper. In the proposed technique, an algorithm based on symmetrical component transformation is used to decouple the three phase transient current signals. The transient traveling wave signals of fault currents are firstly captured and the modal transformation of symmetrical components of the signals is then derived. The polarities of modulus maxima of the wavelet transform at both ends of protected line are compared. Whether a fault is inside or outside the protected line section can be determined based on the comparison of the polarity signals. Theoretical analysis and simulation results prove that the proposed technique is more reliable than that of the existing ones and is able to solve the problems for some special fault conditions for which the conventional polarity comparison technique based on single modulus may fail. It is also able to offer a higher sensitivity under all types of faults.