220kV站用变压器保护改进方案的研究

对于220kV变电站中站用变压器，其35kV母线短路电流大，用于继电保护的电流互感器变比大，而站用变压器容量小、变压比大，低压侧故障折算到35kV侧电流较小。一般继电保护装置难以满足要求。文章提出了站用变压器在较小电流情况下，如何启动保护跳闸的方法，从而使站用变压器保护即使在较小故障电流情况下仍然可以切除故障，防止扩大事故，保障变电站安全运行。

Research on Improved Scheme of Station Transformer Protection in 220kV Substation

For the station transformer in 220kV substation, its short-circuit current of 35Kv Dusbar anct the variable ratio of current transformer used for relay protection are larger than normal, while the station transformer capacity is small, transformation ratio is large, and the current of low voltage side fault con- verting 35kV side is smaller, then general relay protection device is difficult to meet the requirements. In this paper, a way how to start the protection trip is put forward on the condition of station transformer＇s smaller current. Thus, station transformer protection can remove the fault when the fault current is small, avoiding the expansion of accident and guaranteeing the safe operation of substation.