Adaptive reclosing judgment method for single-phase grounding fault of power transmission line

Abstract

The invention discloses an adaptive reclosing judgment method for a single-phase grounding fault of a power transmission line, and the method comprises the steps: collecting three-phase voltages and three-phase currents of one side of the power transmission line at two moments, and enabling the three-phase voltages and three-phase currents to serve as input; calculating the corresponding positive and negative zero-sequence voltage and current phasors through employing the measured voltages and currents at the two moments; Building equations for two types of possible faults (perpetual single-phase grounding fault and instantaneous single-phase grounding fault) based on a power transmission line distribution parameter model, and describing the relation of voltages and currents of two sides of the power transmission line, and obtaining two systems of nonlinear equations; taking the power potential, equivalent system impedance, fault distance and transition resistance of a measurement point opposite side system as unknown quantities, solving the built systems of nonlinear equations, respectively obtaining fault range finding results of the two systems of nonlinear equations, solving the ratio of the fault range finding results, determining that the perpetual single-phase grounding fault happens if the ratio is less than a threshold value, and locking the reclosing function, or else determining that the instantaneous single-phase grounding fault happens, and carrying out the reclosing.

Description

technical field [0001] The invention relates to the field of power system protection and control, in particular to an adaptive reclosing judging method for a single-phase ground fault of a transmission line. [0002] technical background [0003] Automatic reclosing technology is widely used on transmission lines with a voltage level above 110kV. It can automatically restore power supply for instantaneous ground faults. However, if it is a permanent ground fault, the implementation of reclosing will have a secondary impact on the power system, affecting the system. stability. Therefore, adaptive reclosing technology has received extensive attention. [0004] The existing adaptive reclosing technology mainly uses the fault characteristics induced by the faulty phase line after the trip of the circuit breaker on both sides of the faulty phase line due to the latent supply current and interphase coupling of the non-faulty phase line to identify whether there is a stable groundi...

AI Technical Summary

Problems solved by technology

Turn the problem of fault location into the identification of line topology, using two phase-to-ground faults after a single-phase ground fault occurs on the transmission line and before the circuit breakers on both sides trip, and after the fault phase circuit breakers on both sides of the line trip and before reclosing. The single-ended electrical quantity under the time section describes the monitored line equation, and the amount of information is doubled, so the fault distance can be accurately obtained, but it cannot solve the problem of adaptive reclosing discrimination. During the research process, it was found that the two time sections Information, assuming that the fault is an instantaneous ground fault and a permanent ground fault respectively, the following equations are used to calculate the fault distance, and the fault distance measurement error can directly reflect the difference of the fault type. The main reason is the stable fault branch Whether there is will directly affect the voltage stability of the fault phase line at time 2, and the stability will directly lead to the size of the ranging error, so the fault ranging algorithm can be further extended to an adaptive reclosing algorithm

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