振荡中故障选相元件的研究

Faulty phase selector during power swing

目前实用的选相元件在系统振荡时可能会误选相,有必要研究能适用于振荡时的选相方案。分析了振荡中再故障时故障回路测量阻抗不变的特征,并在此基础上提出了一种适用于振荡的新型选相元件。该元件结合常规的零、负序故障分量分区和阻抗值比较方法,采用阻抗变化率的判别从可能的故障类型中识别出真正的故障回路,解决了系统振荡时选择性和速动性之间的矛盾。理论分析和EMTP数字仿真计算表明,新的选相方案在性能上较常规选相方案有明显的改善,可以完全克服阻抗法故障识别在振荡中选相的失配问题,并且该方案原理简单,动作可靠,具有很高的工程应用价值。

As the currently used faulty phase selector may work Improperly during power swmg,a novel faulty phase selector adaptable to power swing is proposed based on the result of analysis that the impedance of faulty phase is invariable during power swing. Based on the traditional sectioning method of zero and negative sequence fault components and the impedance comparison method,the impedance variance ratio is applied to select the faulty phase from possible fault types during power swing with better balance between selectivity and rapidity. Theoretical analysis and EMTP-based simulation show that,the proposed phase selection method,simple and reliable,is evidently superior to the traditional method in faulty phase selection during power swing.