Range finding method for single-phase earth fault of line based on actual measurement of transition resistance

Abstract

The invention discloses a range finding method for a single-phase earth fault of a line based on actual measurement of transition resistance. The method includes the steps of measuring fault phase voltage, fault phase current, fault phase negative sequence current and zero sequence current at the protective installation part of a power transmission line, describing the physical characteristics of voltage and current transmission of the power transmission line by using a distributed parameter model, calculating the transition resistance at the single-phase earth fault point of the power transmission line, and sequentially calculating the transition resistance and transition resistance difference function value of each point on the power transmission line by using a one-dimensional searching method. Accurate range finding for the single-phase earth fault of the power transmission line is realized by using the characteristic that the transition resistance difference function value at the fault point of the power transmission line reaches the minimal value, which theoretically eliminating the influence of the factors including distribution capacitance, transition resistor and load current, and ensuring high range finding precision. The method is a searching method which means no false solution problem of equation solving methods and misconvergence problems of iterative methods, and the method is highly practical.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a single-phase ground fault distance measurement method based on the actual measurement of transition resistance. Background technique [0002] Divided from the electrical quantity used for distance measurement, fault location methods can be divided into two categories: double-ended ranging and single-ended ranging. The double-terminal fault location method is a method to determine the fault location of the transmission line by using the electrical quantity at both ends of the transmission line. It needs to obtain the electrical quantity of the opposite end through the channel, so it is highly dependent on the channel, and it is also vulnerable to the double-terminal sampling value in actual use. Synchronization effects. The single-ended ranging method is a method that only uses the voltage and current data at one end of the transmission line to de...

AI Technical Summary

Problems solved by technology

In the case of medium and low-resistance short-circuit faults, due to the obvious drop in voltage along the line, the error in estimating the voltage phase angle of the fault point by using the negative-sequence current phase angle at the observation point has little effect on the ranging results; but in the case of high-resistance short-circuit faults, Because the voltage difference of each point along the line is very small, the error in estimating the voltage phase angle of the fault point by using the negative sequence current phase angle at the observation point plus the influence of the transient process, the distance measurement error of this method is relatively large

Images