Combined With The Adaptive And Multiple Criteria In Neutral Indirectly Grounded Fault Line Selection Method

In the low voltage distribution network in China, The use of arc suppression coil grounding system is universal. Aiming at the single-phase grounding fault which has A higher probability of occurrence in such system, The fault line selection method using steady state information are difficult to meet the requirements anti-interference and sensitivity, and the fault transient information based line selection method make use of a kind of information when a fault occurs, failed to make full use of transient characteristics of fault time, and easy to produce the dead, even with the intelligent algorithm to fusion, The adaptability is poor and the line selection of the border region is difficult to ensure the success rate. So it is necessary to conduct in-depth analysis of fault line selection method.This paper established the NES transient model of single phase to ground fault to describe the random and fuzzy degree of the transient process, To make quantitative analysis of transient characteristic quantities. The paper use energy ratio coefficient and impedance ratio coefficient to full feature domain for quantitative analysis, and use Wavelet packet multi band polarity method, decaying DC component method and UoIo decomposition coefficient method to complement each otherTo improve the success rate in fault line selection of the border region, With the adaptive weight coefficient function and the adaptive transient characteristics of fault time, the paper fuses transient of various fault conditions line selection method, and form the weighted optimum distance and weighted distance to degradation to minimum fuzzy optimization model, the paper also use MATLAB analysis and simulation verification, so that it can guarantee the full feature domain three kinds of fault types can meet the requirements of the no dead area, which type of line selection area can have better effect, and also have good discreteness. Compared to the traditional fuzzy comprehensive evaluation model, the membership function has better objectivity, the result is more concise, and at the same time, more practical, Compared to the fault line selection method which relies on a large number of actual fault current data for training,not only in the signal processing level is improved, but also easier to meet the practical needs.