Self-adaption route selection method for single-phase ground fault of power distribution network based on transient zero sequence current

Abstract

The invention relates to the field of distribution network relay protection, in particular to an adaptive line selection method for distribution network single-phase grounding faults based on transient zero-sequence current frequency distribution. Firstly, the wavelet decomposition of the zero-sequence current before and after the fault is performed and the single-branch reconstruction is performed on the characteristic frequency band of each line, and then the instantaneous value of the zero-sequence current in the reconstructed signal of each line is compared with the corresponding instantaneous value of other lines. If the other lines are different, add 1 to the counter. After comparing all the sampling points, get the line with the largest counter value; then perform a symbol comparison of the reconstructed data on the line with the characteristic frequency band (4, 0), if the point with the same symbol accounted for more than 60%, and the difference with other line counter values ​​does not exceed 5, then the line is judged as a faulty line; otherwise, the line with the largest determined counter value is judged as a faulty line. The line selection method provided by the invention can effectively utilize the information contained in the fault transient process, and can greatly improve the reliability of fault line selection.

Description

technical field [0001] The invention relates to the field of distribution network relay protection, in particular to an adaptive line selection method for distribution network single-phase grounding faults based on transient zero-sequence current frequency distribution. Background technique [0002] my country's 3-66kV distribution network adopts the non-direct grounding method of the neutral point. Because the current flowing through the grounding point is small when a grounding fault occurs, it is called a small current grounding system (NUGS). It includes the neutral point ungrounded system (NUS), the neutral point through the arc suppression coil grounding system (NES, also known as the resonant grounding system) and the neutral point through the resistance grounding system (NRS). [0003] After a single-phase ground fault occurs in a small-current grounding system and reaches a steady state, the non-fault line only flows through its own ground capacitance current, which...

AI Technical Summary

Problems solved by technology

Although this solves the problem of inaccurate wavelet frequency division, the frequency distribution of transient quantities of different lines is not always completely consistent because the frequency components and size of transient quantities are affected by various factors such as network parameters and fault times. Therefore, in some cases, it is very difficult to select a frequency segment where the transient quantities of each line are relatively concentrated for line selection

Images