故障分量提取及故障选相的新方法

提出了一种中低压中性点不接地系统故障分量提取的新算法，该算法既能提取短时的暂态故障分量，也能提取长时间稳定的故障分量，对速断、定时限及过电流保护都适用，可极大地改善延时保护的性能；在此基础上给出了自适应电流保护中系统阻抗准确计算的方法；针对目前利用相电流差故障分量选相存在灵敏度不够高的缺陷，提出了利用相电流之和的故障分量来进行故障选相的高灵敏度选相算法。

A NEW METHOD FOR FAULT COMPONENTS EXTRACTION AND FAULT PHASES SELECTION

This paper proposes a new method to extract fault components in small current neutral grounding system. Both short-time fault components and long-time ones can be gotten by this method. Fault components are firstly introduced into definite time and over-current protective relays and it can significantly improve the performance of time-delay protection. Based on this method a scheme to accurately calculate system impedance is put forward. In order to overcome the low sensitivity of the fault phase selection method adopting fault components of phase current difference, a high sensitivity phase selection method based on the fault components of phase current sum is presented.