Distribution network feed out circuit fault circuit selection method by using HHT detection technology

Abstract

The present invention is a distribution network cable-line mixed fault circuit selection method by using HHT detection technology. The invention uses HHT singularity detection technology to calibrate fault occurring time accurately, and implements circuit selection according to a principle that, when a fault occurs transient fault zero-sequence current component of the fault circuit and the regular circuit is opposite in direction. The specific method is using HHT to proceed EMD decomposition to the sampling signal of before and after 1 / 4 period each circuit fault zero-sequence current that is morphological filter pretreated, obtaining highest frequency IMF component of each circuit fault zero-sequence current and proceeding a first-order backward difference treatment to the IMF component, comparing the polar mutation of the fault zero-sequence current IMF component at fault moment, and then forming a circuit selection criterion. Analysis and simulation of the principle shows that, using fault information of 1 / 4 period after the fault to select circuit can provide an accurate and reliable circuit selection result and avoid effects of paraphrase and CT saturation on circuit selection accrracy.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a fault line selection method of a distribution network feed-out line detected by HHT. Background technique [0002] With the rapid development of urban construction, the proportion of cable lines in the distribution network has increased, and there are more and more cable-line hybrid lines. Laying cables can not only increase the transmission capacity and reduce the size of substation outlets, but also reduce the operation and maintenance costs and construction difficulty per unit transmission capacity. When a single-phase ground fault occurs in the distribution network, due to the large ground capacitance of the cable, it will cause a large transient ground capacitance current, making the similarity between healthy lines worse, and the line selection method based on correlation analysis will invalidated. But at the same time, the transient quant...

AI Technical Summary

Problems solved by technology

Many scholars have done a lot of research on distribution network fault line selection, but due to the small amount of fault steady state, coupled with the complexity of the power grid itself and the load, it is difficult to extract effective fault signals in actual engineering

Compared with the steady-state quantity, the magnitude of the transient quantity of the distribution network fault is ten to dozens of times larger. Therefore, scholars pay more attention to the study of the transient characteristics, and propose many However, these methods have not completely solved the problem of single-phase ground fault line selection in distribution network.

Images