基于电流分布系数的母差保护非故障相饱和判别

Non-fault phase saturation discrimination for busbar differential protection based on current distribution coefficient

当发生母线区外故障,故障支路的非故障相电流互感器(CT)出现饱和时,为防止母差保护误动作,提出基于电流分布系数识别故障支路非故障相饱和的方法,识别出非故障相饱和后闭锁母差保护。采用该方法计算母线区外故障时电源支路的故障相电流分布系数及"母线二次故障"时电源支路的"二次故障"相电流分布系数,并对比两者计算结果。若计算结果不一致,说明"二次故障"为非故障相饱和;若计算结果一致,说明"二次故障"为母线区内或区外故障。实时数字仿真(RTDS)结果表明,在不降低母差保护动作速度的前提下,该方法能快速准确识别故障支路非故障相饱和,可靠防止母差保护误动。

When an external fault of busbar occurs,the current transformer( CT) of non-fault phase is saturated. In order to prevent the busbar protection from mal-operating,the method to identify the non-fault phase saturation of the faulty branch based on the current distribution coefficient is proposed. After identifying the non-fault phase saturation,the busbar protection is blocked. The method calculates the external fault phase current distribution coefficient of the power branch and the secondary fault phase current distribution coefficient of the power branch,and compares the calculation results of the two current distribution coefficients. If the calculation results are inconsistent,it means that the secondary fault is saturated by the non-fault phase. If the calculation result is consistent,it means that the secondary fault is internal or external. The real time digital simulation( RTDS) results show that the method can quickly and accurately identify the non-fault phase saturation of the faulty branch without reducing the operating speed of the busbar protection,and reliably prevent the busbar protection from maloperating.