Fault positioning method for overhead line-high voltage cable mixing line

Abstract

The present invention provides a fault positioning method for an overhead line-high voltage cable mixing line, comprising the steps of: (1) respectively measuring three-phase voltage and current phasors of M and N end points at two sides of the line, respectively calculating negative sequence voltages, negative sequence currents, positive sequence voltages and positive sequence currents of the two sides through a symmetrical component method; (2) judging a fault type according to the negative sequence voltages; (3) if the fault type is asymmetric fault, respectively calculating a negative sequence voltage amplitude of each point along the line through the three-phase voltage and current phasors of two-terminal electrical quantities M and N sides, and determining that the points with the equal negative sequence voltage amplitude are fault points; (4) if the fault type is three-phase symmetrical fault, performing fault positioning through a method for comparing positive sequence voltage amplitude variations, and determining that the points with the equal positive sequence voltage amplitude variation are fault points. The fault positioning method of the present invention aims at parameter characteristics of the overhead line-high voltage cable mixing line, does not require synchronous two-terminal electrical quantities, does not need to perform fault section judgment in advance, does not have a pseudo root identification problem, and can adopt various quick search algorithms in the process of fault position search.

Description

technical field [0001] The invention relates to a method in the field of relay protection of an electric power system, in particular to a fault location method for an overhead line-high voltage cable hybrid line. Background technique [0002] With the development of our country's urban construction and the needs of the environment, the overhead line-high voltage cable hybrid line is more and more widely used in power transmission and distribution projects due to its unique advantages. When a fault occurs on an EHV transmission line, it is of great significance to accurately locate and remove the fault as quickly as possible, reduce the loss caused by the fault to the power equipment and system, and improve the reliability and safety of the power system operation. [0003] The research on fault location of ultra-high voltage hybrid lines can be divided into two categories: traveling wave method and fault analysis method according to different ranging principles. [0004] The...

AI Technical Summary

Problems solved by technology

At present, there are mainly the following kinds of algorithms for fault analysis and distance measurement of hybrid lines: (1) The fault point search algorithm based on the voltage amplitude of the fault point, etc., the algorithm principle is simple, but there are large calculations and false positives in the calculation of line distribution parameters. root identification problem

(2) Establish a ranging function based on the voltage and current equation of the fault point to solve the fault location. This method is generally complicated for hybrid lines, and the calculation accuracy is greatly affected by the accuracy of electrical quantity collection. The problem with low robustness of the results

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