一种220kV线路零序后备保护整定优化方案及其风险概率分析

基于后备保护优化的目标和零序后备保护作用定位，把配置了至少一套光纤电流差动保护的线路视为主保护完善的被配合线路，不用考虑与之配合的线路零序后备保护定值与被配合线路的零序后备保护定值之间的配合关系，即默认与主保护配合，按照此种原则整定的点称之为基准点，基准点之外的定值按照时间级差逐级配合。从失配风险和高阻接地时差动保护拒动概率两个方面进行分析，表明实际电网中按照该方案整定的零序保护发生越级动作的概率极低。在广东电网中的应用情况说明该方案优化效果明显。

Analysis on Zero Sequence Backup Protection Setting Optimization Scheme for 220 kV Lines and Its Risk Probability

Based on target of backup protection optimization and positioning of zero sequence backup protection, this paper proposes to regard lines which is at least equipped with a set of fiber current differential protection as cooperated lines pro- vided with complete main protection. It is not needed to consider cooperative relationship between the definite value of zero sequence backup protection of lines matched up with cooperated lines and that of cooperated lines which is acquiescent to be matched up with the main protection. According to the above principle, the setting point is called datum mark beyond which the definite value is set to realize gradual cooperation based on time differential. By analyzing mismatch risk and refused movement probability of differential protection at the time of high resistance grounding, it indicates the probability of by- passing movement of the zero sequence protection set according to this scheme in practical power grid is very low. Application in Guangdong power grid indicates that this scheme is good in optimization effectiveness.