A full-line quick-action protection method for UHV DC lines based on principal component cluster analysis of pole-line fault current curve clusters

Abstract

The invention relates to an ultrahigh-voltage direct-current line whole-line quick-acting protection method based on polar fault current curve cluster principal component clustering analysis, and belongs to the technical field of power system relay protection. When a line fails, the polar current curve clusters of a measuring end under the condition of a fault within the whole line and under a forward fault outside the protected area are respectively acquired through electromagnetic transient simulation, and three sampling points before the fault and seven sampling points after the fault are selected as sample data to perform PCA clustering analysis. In the PCA clustering space, a 'line fault' forms a clustering center, an 'inverter side' fault forms a clustering center, and q1=0 is taken as the boundary for both the 'line fault' and the 'inverter side' fault. For a positive line, the fault is a fault inside the line when q1>0, and the fault is a positive fault outside the protected area when q1<=0. For a negative line, the fault is a forward fault outside the protected area when q1>0, and the fault is a fault inside the line when q1<=0. When the line fails, the projection value of test sample data on a PC1 coordinate axis is calculated, and whether the fault is a line fault is judged according to the value of q1. A large number of simulation experiments show that the method is reliable and effective.

Description

technical field [0001] The invention relates to a full-line snap-action protection method of an ultra-high voltage direct current line by utilizing the principal component cluster analysis of the pole line fault current curve cluster, and belongs to the technical field of electric power system relay protection. Background technique [0002] At present, the existing main protection of the DC line includes traveling wave protection and low voltage protection, both of which use the single-ended information of the line, which is often difficult to detect and respond to the high-impedance ground fault of the line, and as a backup for detecting and responding to the high-impedance fault Protection has a great influence on the control system of the longitudinal differential protection, and generally cannot play the role of backup protection. [0003] At present, the DC transmission line protection that has been put into operation in my country is mainly based on the so-called trave...

AI Technical Summary

Problems solved by technology

Since the transmission distance of UHVDC lines is usually long, the causes of line faults are very complicated, such as lightning strikes on the line causing insulator flashover, common short circuit, bird damage, icing, de-icing bounce, mountain fire faults, and nonlinear time-varying caused by line-to-tree discharge For high-resistance faults, it is often difficult to characterize and analyze these faults with explicit mathematical relationships, so it is difficult to reliably achieve full-line quick action only by adjusting the protection setting.

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