摘要
变压器外部故障切除后,暂态磁通可能超过变压器铁心的饱和点,从而产生一定的恢复性涌流。同时,外部故障过程中电流可能有很大的非周期分量,使CT进入饱和区。这两方面因素均有可能使差动保护在故障切除后误动。该文首先对变压器磁链进行理论推导,然后建立变压器和CT模型进行仿真,并通过实验验证结果。进一步推导得出了影响恢复性涌流大小的因素,研究了各种状态下涌流对差动保护的影响以及CT饱和的作用。最后综合考虑涌流和CT饱和,分析保护误动的主要原因。
After an external fault of transformer is cleared, the transient flux may enter into the saturation region, and a recovery inrush may be produced. At the same time, the aperiodic component in the fault current usually has a high value during the fault, so that the CT may also enter into the saturation region. Both of them may cause the maloperation of the differential protection. In this paper, the flux of the transformer is obtained by theoretical derivation, then models of transformer and CT are built for simulation, and an experiment is done to prove the results. The factors that affect the inrush are analyzed. The influence on the inrush of the differential protection is investigated and the saturation of CT is studied as well. At last, considering the inrush and the saturation of CT together, the main cause of the maloperation is discussed.
出处
《继电器》
CSCD
北大核心
2006年第1期5-9,14,共6页
Relay
关键词
外部故障
恢复性涌流
CT饱和
差动保护
误动
external fault
recovery inrush
saturation of CT
transformer differential protection
maloperation
