【摘要】 微机保护被广泛使用后,电流互感器的二次负荷由阻感性变为电阻性,且故障切除时间缩短,使P类电流互感器残留剩磁大大增加,常引起下次故障时,电流差动保护区外误动和距离Ⅰ段延时动作。文中通过实例和理论分析,说明了剩磁和一次电流非周期分量对电流传变的不同影响,建议220kV及以下电压等级线路保护使用PR类电流互感器,以消除剩磁对保护的影响,同时能够保证距离Ⅰ段范围内故障的快速切除。对于PR类电流互感器,在考核互感器饱和对保护的影响时,只需考虑非周期分量引起的暂态饱和,因此依据"故障发生5ms后电流互感器出现暂态饱和"对保护进行考核是合理的。更多还原

【Abstract】 As the extensive application of the microcomputer protection,the secondary load of the current transformer changes from resistance and inductance load to resistance load,and the fault clearing time is shorter,making the remanence of the P class current transformer increase greatly.Too much remanence often leads to the maloperation of the differential current protection for the external fault and the time-delay operation of zone Ⅰ of the distance protection.Based on the practical and theoretical analysis,this paper explains the different impacts of the remance and the non-periodic component in the primary current on the current transferring and proposes that PR class current transformers should be used in the 220 kV line protection to eliminate remanence’s impacts and to insure the rapid operation of zone Ⅰ of the distance protection to clear off the internal fault.For the PR class current transformer,it is only need to consider the transient saturation induced by non-periodic component for the examination of current transformer saturation’s impact on protection,so choosing "the transient saturation of the current transformer comes forth at 5 ms after the fault" as the examining standard is reasonable.更多还原