利用暂态电流的谐振接地电网故障选线自适应新方法

谐振接地系统(NES)发生单相接地故障时,由于故障电流小及接地点电弧不稳定等原因,其零序故障电流准确获取和定值整定困难,使其故障线路的检出仍是难题。在分析小电流接地系统单相电弧接地故障时各线路零序暂态电流特征的基础上,提出一种基于暂态电流的故障选线自适应方法。利用所有健全线路暂态电流与故障线路暂态电流之差为最小值的原理,构成故障选线算法。新方法不仅能消除故障电流小和接地点电弧不稳定影响,而且还能在短线故障时,克服健全长线电容电流的影响,有很强的抗干扰能力,毋需整定,不涉及极性和方向的判断,具有自适应性,可大大改善保护对故障线路检出性能。大量的数字仿真结果表明,该方法有效。

An adaptive approach to selecting fault circuit in arc suppression coils system using transient current

For the reasons of grounding current being too little and the electric arc of fault position being not stable, to obtain the zero-current of fault circuit and to tune the parameters of equipments in little current grounding system with arc suppression coils are difficult. The fault circuit selection in this system is always a complex and difficult issue. It was presented an adaptive fault circuit selection method based on transient current. Because the difference of transient current in the normal circuits and the fault circuit is the lowest, this fault circuit selection method is based on this principle, which can erase the influences of the small current and the unstable electric arc , and can also erase the influence of capacitive current on normal long circuit when the fault is on the short circuit. The method also has considerable immunity to noise. With great adaptability to various faults happened in the systems with arc suppression coils and considerable immunity to noises and no requirements of pre-setting, the overall performance of the protection can be upgraded by this method. The results of digital simulation show that the proposed method is effective and reliable.