基于差动电流与制动电流比值的抗电流互感器饱和新方法

Novel Method for Current Transformer Saturation Countermeasure Based on the Ratio of Differential Current and Restraint Current

根据差动电流与制动电流的比值在内部故障和外部故障电流互感器(TA)饱和时的不同变化特征,提出了一种区分内部故障和外部故障TA饱和的新方法——比率制动系数法。同时,为解决内部故障TA也发生饱和时差动保护的开放问题,在比率制动系数判据的基础上又增加了差动电流极性判据。EMTP仿真计算表明,该方法不仅能明确区分内部故障和外部故障TA饱和,而且在内部故障TA也发生饱和以及在转换性故障时,差动保护也能够快速开放。比率制动系数法特征清晰,原理简单,具有良好的应用前景。

Based on the different variation characteristics of the ratio of differential current and restraint current during internal fault and external fault with current transformer saturation, a new saturation criterion called ratio restraint coefficient method is presented. Meanwhile a criterion of identifying the change of the differential current＇ s polarity is added to solve the problem of opening the differential protection during the internal fault with current transformer saturation. The simulation results using EMTP clearly indicate that the proposed method can not only accurately identify the internal fault and external fault with current transformer saturation, but also open the differential protection quickly during the internal fault with current transformer saturation and even the transitional fault. The proposed method with clear characteristics and simple principle is a promising current transformer saturation criterion in field application.