互联系统振荡造成保护误动的分析及其对策

ANALYSIS OF MALOPERATION OF PROTECTLIVE RELAYING CAUSED BY POWER SYSTEM OSCILLATION AND ITS COUNTERMEASURE

随着电网规模的日益扩大,仅按简单系统进行保护的单一整定,即只计算故障后某一瞬间(如故障后t=0s)的电流和电压周期分量,而不考虑故障切除后互联系统机电暂态过程对保护动作的影响,已不能满足快速、正确地切除系统故障、维护互联系统稳定运行的要求。通过对由川南系统与沱江电网构成的互联电网电流保护误动作的研究,提出了分析互联电网电流保护动作的一般方法和原则,尤其是故障切除后分析保护误动时,必须同时考虑互联电网的电磁暂态过程和机电暂态过程。通过分析,得到了出线保护整定值与联络线保护整定值之间的关系,可供整定互联电网联络开关保护整定参考。

With the increasingly enlargement of the scale of electrical power system, the requirement of maintaining stable operation of interconnected power system by cutting off the fault quickly and correctly cannot be satisfied by traditional setting mode of protective relaying which only considers the situation of simple power system, i.e., only calculating the periodical component of current and voltage at a certain moment after the fault occurred, but not considering the influence of electromechanical process on the action of protective relaying in interconnected system after the fault was switched out. Through the research on the maloperation of overcurrent protection in an interconnected power network consisting of South Sichuan power system and Tuojiang power system, the general method and principle of analyzing the action of overcurrent protection in an interconnected power system are presented in this paper, especially, in the analysis of protection's maloperation after the fault was switched out, the influence of electromagnetic transient process and electromechanical process should be considered simultaneously. By means of the analysis in this paper the relation between the setting value of outgoing line and that of tie line is obtained which is available for reference in the setting of the protection for tie switch of interconnected power network.