多时态的三相相地增量电流矢量关系特征及选线应用

为提高配电网单相接地选线定位的正确率,通过对小电流接地在多时态三相增量电流的构成和矢量关系特征的分析研究发现:1)反映小电流接地本质特征的分量电流为双负序电流,并总结出其矢量关系特征;2)检验增量电流至少在一个时态内有无双负序电流矢量关系特征,能够确定是否疑似接地线路;3)检验增量电流至少在后暂态有无该特征,能够辨识真伪单相接地;4)可能出现的暂态谐振电流的首半波或非周期分量电流,与工频增量电流在接地相的首半波同极性。据此,设计了在多时态比较三相相地增量电流矢量关系特征的接地选线和防误辨识方法。该方法排除了零序谐振电流的影响,广泛适用于各类型配电网的高、中、低阻接地选线。经多方案仿真和模拟实验验证,该方法适用有效。

Vector Relation Characteristics of Three-phase Phase-earth Increment Current in Multiple Time-state and Its Application in Fault Line Selection

In order to improve accuracy of phase-earth grounding and positioning of distribution network, through analysis of main components and vector relationship characteristics of the incremental current in the three-phase with small current grounding, it was found that, 1) the essential characteristics of small current grounding are double negative sequence current and its vector relation characteristics are summarized;2) checking whether the incremental current has the characteristics of double negative sequence current vector in at least one time-state can determine the suspected ground circuit;3) verifying whether the incremental current has the characteristics at least in the post-transient states can identify the single-phase grounding true or false;4) the first half or non-periodic component current of the transient resonant current that may occur is of the same polarity as the first half of the grounding phase. Based on these, a method of grounding line selection and error prevention identification is designed by comparing the vector relation characteristics of three-phase phase-earth increment current. The method eliminates the influence of zero-sequence resonant current, making it suitable for groundin g monitorin g of high-, medium-, and low-resistance transition resistors of all types. Results of simulation and experiments have all confirmed effectiveness of the proposed method.