3/2开关接线方式下基于能量制动的抗电流互感器饱和措施

结合一起3/2开关接线方式下,发生区外故障时由于电流互感器(TA)饱和导致差动保护误动作的案例,分析了3/2开关接线方式下TA饱和对比例电流差动保护的影响,得出了基于差动量和制动量比例制动特性的电流差动保护在区外故障出现TA饱和时动作概率会很大的结论。根据在TA线性传变区内差动电流和制动电流能够正确反映区内外故障的思想,提出了基于能量制动的抗TA饱和措施,并且针对3/2开关接线方式下的特殊电气结构,提出了在该接线方式下的一种新的制动能量表达方式,能够对由于区外故障导致的TA饱和进行可靠识别并闭锁差动保护。仿真分析表明,针对3/2接线方式下可能出现的TA饱和现象,提出的抗TA饱和措施能够显著提升电流差动保护的抗TA饱和性能。

Energy Resistance Based Anti-saturation Scheme with Breaker-and-a-half Configuration

Based on an analysis of the effects of the current transformer saturation on line current differential protection with breaker-and-a-half configuration, it is concluded that the probability of normal ratio line differential relay''s mal-operation will be greatly increased without any extra anti-saturation strategy during an external fault. According to an investigation of the current characteristics in the transformer''s linear transform area, a new energy resistance based anti-saturation scheme is proposed which can detect the current transformer saturation and relay''s mal-operation during an external fault. Also, a new expression for energy resistance formula is presented which can increase the new scheme''s accuracy and sensitivity in breaker-and-a-half configuration. It is shown by simulation results that the scheme proposed can appreciably increase the anti-saturation ability of line current differential protection.