A Distance Protection Method for Fail-Open Components in Oscillating Blocking

Abstract

The invention relates to a distance protection method for a fault-opening element in oscillation locking, comprising the following steps: collecting three-phase current and three-phase voltage at the installation place of the protection; judging whether to enter the oscillation locking state; if and Go to the penultimate step, otherwise, go to the next step; if the current asymmetry m≥0.65, open the distance protection; otherwise, go to the next step; if the oscillation center voltage Either one satisfies Delay 200ms to open the distance protection section I, and open the distance protection section II instantaneously; otherwise, go to the next step; if Either one satisfies Delay 200ms to open distance protection stage I, and instantaneously open distance protection stage II; otherwise, block distance protection; if Either one satisfies , open the distance protection with a delay of 150ms; otherwise, go to the next step; if Either one satisfies , delay 150ms to open the distance protection; otherwise, block the distance protection. The method improves the sensitivity of the fault-opening element in the oscillation blocking, so that the distance protection can operate correctly when the fault passes through a relatively large transition resistance.

Description

technical field [0001] The invention relates to a protection method in the field of relay protection of electric power systems, in particular to a distance protection method for fault open components in oscillation blocking. Background technique [0002] Distance protection is widely used in power systems of different voltage levels as backup protection of transmission lines and transformers. [0003] When the power system oscillates, the measurement impedance changes periodically, and there is a possibility of misoperation of the distance protection. For the distance protection sections I and II, due to the short action time, the microcomputer protection device adopts an oscillation blocking element to prevent the distance protection sections I and II from oscillating. Malfunction during the process, for the distance protection section III, because the action time is long, rely on the action delay to avoid the oscillation, if a fault occurs during the oscillation blocking p...

AI Technical Summary

Problems solved by technology

For asymmetric fault open components, when the line is under heavy load operation, when a ground fault occurs through a large transition resistance, the current asymmetry degree m does not meet the conditions, and the distance protection cannot be opened, resulting in the protection not being able to operate correctly

For symmetrical fail-open elements, the oscillating center voltage Generally, two stages are adopted, and there are overlapping action areas between the two, and the opening time is inconsistent. When a three-phase short circuit occurs through the transition resistance, the opening time is longer, which affects the rapidity of protection.

[0005] To sum up, the existing fault-opening components in oscillation blocking have low sensitivity when dealing with faults through large transition resistance under heavy load and three-phase faults through transition resistance. In serious cases, the distance protection cannot be opened, resulting in protection failure

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