基于非最严苛电网运行方式的超高压线路距离保护整定方法

分析了西北电网三起因保护拒动而导致的故障范围扩大事故，指出现有基于最严苛电网运行方式的超高压线路后备保护整定可能导致保护定值灵敏性不足、无法可靠动作的问题。提出了基于非最严苛电网运行方式的超高压线路距离保护整定方法，距离II段采用接近于实际的检修方式进行整定，距离III段采用考虑对侧故障可靠切除后的运行方式进行整定。该整定方法在改善配合关系的同时，能够最大限度地发挥距离保护对本线和相邻设备的后备作用。实际算例验证了该整定方法的有效性。

A distance protection relay coordination method for EHV transmission lines based on non most severe grid operation mode

This paper analyzes three power grid fault range enlargement accidents in the Northwest Power Grid caused by the failure of protection to operate on command. It is pointed out that one of the reasons for this is the insufficient sensitivity of line protection setting because of the existing backup protection coordination method which is based on extreme grid operation modes. A method for coordinating the settings of distance protection for extra-high-voltage lines based on non-extreme grid operation modes is proposed. In this method, zone II of the distance protection is coordinated based on modes close to actual maintenance situations, while zone III is coordinated using the mode where the opposite-side fault is successfully removed. This method can clarify the coordination relationship of adjacent relays and thus optimize a relay''s backup protection function for the line where it is installed and its downstream equipment. The effectiveness of the proposed method is verified through experiments. This work is supported by National Natural Science Foundation of China (No. 51777081).