基于保护特性的P类电流互感器选型

为深入了解P类电流互感器饱和特性，防范互感器饱和导致保护不正确动作，通过理论推导和计算详细分析了铁芯剩磁、故障电流非周期分量、时间常数等因素对电流互感器暂态饱和特性的影响。分析结果表明关于保护用电流互感器给定暂态系数不宜低于2的选型规定不能满足线路保护和变压器保护的要求。根据分析结果，针对不同保护装置技术要求给出了保护用P类电流互感器的选型建议，并综合考虑电网实际情况，从电流互感器、保护装置、电网运行等方面提出了防范措施。

Selection of P Type Current Transformer Based on Protection Characteristic

In order to investigate the saturation characteristic of class P current transformer and formulate measures to prevent protection malfunction caused by transformer saturation, the impacts on current transformer transient saturation characteristic of core remanence, fault current non-periodic component, time constant and other factors are analyzed in detail through theoretical derivation and calculation. The analysis results show that current selection provisions of specified transient factor not less than 2 for protection current transformer cannot meet the line protection and transformer protection requirements. According to analysis results, advice is proposed on protection class P current transformer selection for the technical requirements of different protection devices. Considering actual situation of power network, preventive measures are also proposed from the aspects of current transformer, protection device and power grid operation.