摘要
分析了不同运行方式、零序互感强弱及不同故障位置下同塔双回线路外部接地故障和内部接地故障时零序电流的分布规律。外部接地故障主要考虑了同塔双回线路零序阻抗不同的影响,内部接地故障则主要考虑了双回线路并列运行、一回线路充电热备用、一回线路接地挂检等运行方式下零序互感及故障位置的影响。由于同塔线路间零序电流同向流动的"零序助磁"与反向流动的"零序去磁"效应,造成零序电流分布规律的异变,极端情况下将导致零序电流I段保护的超越。结合广东电网实际算例,提出了避免零序电流I段保护超越的整定措施,零序I段的整定应考虑运行方式、互感强弱及故障位置的综合影响,以避免同塔线路故障,相邻健全线路零序电流I段受互感影响而超越误动。
The distribution regularity of zero-sequence current, which appears during external and internal grounding faults occurred in double-circuit transmission lines on the same tower under different operation modes, different zero-sequence mutual inductance and different fault locations, is analyzed. For external grounding faults, the impact of different zero-sequence impedance of double-circuit transmission lines on the same tower is mainly considered; for internal grounding faults, the impacts of zero-sequence mutual inductances and fault locations under following conditions are considered： parallel operation of both transmission lines; one transmission line is energized and in the stand-by state while the other one is artificially grounded for the maintenance. The effects of ＂zero-sequence magnetic assist＂ and ＂zero-sequence degaussing＂, which are caused by the flowing of zero-sequence currents of both transmission lines on the same tower in the same direction and by those in the opposite direction respectively, lead to variation of distribution regularity of zero-sequence currents, and in extreme circumstance the out-of-limit of the first zone of zero-sequence over-current protection may occur. Based on practical calculation examples of Guangdong power grid, the setting measures are put forward to avoid the out-of-limit of the first zone of zero-sequence over-current protection for double-circuit transmission lines on the same tower. It is also proposed that in the setting of the first zone of zero-sequence over-current protection for double-circuit transmission lines on the same tower, the comprehensive effects of operation modes of double-circuit transmission lines on the same tower, the extent of zero-sequence mutual induction and fault locations should be taken into account to avoid the malfunction of the first zone of zero-sequence over-current protection of adjacent healthy transmission lines due to the affect of mutual induction while grounding fault occurs in another circuit of transmission lines
出处
《电网技术》
EI
CSCD
北大核心
2011年第11期212-217,共6页
Power System Technology
关键词
同塔双回线路
零序电流
分布特性
零序互感
double-circuit transmission lines on the same tower
zero-sequence current
distribution characteristics
zero-sequence mutual inductance
