Method and circuit for measuring state before reclosure of fault line

Abstract

The invention provides a method and a circuit for measuring the state before reclosure of a fault line. The method comprises steps as follows: after the line trips, measured impedance is obtained through measurement on a measurement line; the fault state of the measurement line is judged according to the measured impedance, wherein the fault state comprises an instantaneous line fault and a permanent line fault; logical judgement of reclosure of the line is realized according to the fault state of the measurement line; when the fault state of the measurement line is the instantaneous line fault, reclosure is performed in a detection no-voltage manner; when the fault state of the measurement line is the permanent line fault, reclosure is not performed. When a power transmission line fails,the line state before reclosure is measured through matching of an online monitoring device with a relay protection device, the reclosure condition is opened when conditions are met, otherwise, reclosure is closed, and the closing success rate of reclosure is increased.

Description

technical field [0001] The invention relates to the field of fault detection, in particular to a method for measuring the state before reclosing of a fault line and the field of circuits. Background technique [0002] In the context of large power grid construction, ultra-high voltage, long-distance, high-power, and cross-regional transmission of electric energy has been formed. It is inevitable that the transmission line will trip due to a fault during operation. In order to quickly restore power transmission, blindly reclose the tripped line for a trial transmission. In this state, it often overlaps with the permanent fault line, causing the second equipment damage and system shock. [0003] In order to ensure fast recovery of power supply, after the line fault trips, the reclosing function is often used to test power transmission to the faulty line. Since the state of the line fault is unknown, 30-45% of the reclosing fails. [0004] There are hazards on the line due to...

AI Technical Summary

Problems solved by technology

[0005] 1. Affect the service life of the circuit breaker: When the recloser recloses on the permanent fault line, the strong short-circuit current is before closing (discharge before the contact of the moving and static contacts), during closing (discharging during the contact of the moving and static contacts) and The re-tripping (discharge during the contact separation of the moving and static contacts) caused by the failure not disappearing, the fault current is many times larger than the closing and opening current under normal operation, and the burning of the moving and static contacts of the circuit breaker is more serious, reducing the performance of the circuit breaker

[0006] 2. Affect the safe and stable operation of the power grid: when the switch is closed with a fault, the system will be impacted again. Due to the impact, the power quality of the user will be affected, the thyristor conductor of the DC transmission line will be closed, and the Acc (automatic adjustment system) will be disturbed. and other adverse effects

[0007] 3. Destroy the insulation level of some equipment: when the fault line overlaps again, the electromotive force generated by the large fault current will damage the insulation of generators, transformers, busbars and transmission lines, thus affecting the safe and stable operation of the power grid

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