634 / 2019-04-10 20:22:17

Analysis to Influences and Countermeasures of Non-periodic DC Component on Line Protection

non-periodic DC component,circuit breaker arc extinguishing,single-phase auto-reclosing,CT saturation,differential protection

This paper analyzes that the non-periodic DC component may cause the circuit breaker to fail to isolate the fault when the internal fault occurs. For this typical accident, the scheme of accelerated inter-tripping the opposite after auto-reclosing, single-phase auto-reclosing check three-phase live voltage, cooperating of re-closing time on both sides and the permanent fault detection of single-phase line are proposed. This paper also analyzes that the non-periodic DC component may cause CT saturation, which has an influence on the split-phase current differential protection, and may cause misoperation of line protection during the external fault. It is necessary to increase the CT ratio and improve the ability of protection against severe saturation.