Unsymmetrical fault relay protection method of distributing line

Abstract

The invention discloses an unsymmetrical fault relay protection method of a distributing line, which comprises the steps of firstly performing fault detection and detecting whether faults occur on the distributing line based on the current and the voltage; secondly performing unsymmetrical fault recognition and recognizing whether the faults are unsymmetrical faults based on the relation between three-phase current and the voltage; thirdly performing fault direction judgments and judging fault directions based on the relation between the voltage and the current; fourthly performing time limiting protection which comprises time limiting excess current protection and time limiting low voltage protection, measuring a relation motion of the current and the setting current, and measuring a relation motion of the voltage and the setting voltage; and fifthly performing mutation protection which comprises current mutation protection and voltage mutation protection and judging whether a mutation motion of the voltage or the current occurs based on a setting time and within a setting time range. The unsymmetrical fault relay protection method of the distributing line can achieve rapid and selective isolation of unsymmetrical faults of single-power supply type and radial distributing lines.

Description

technical field [0001] The invention relates to the field of power systems, in particular to a method for relay protection of distribution lines. Background technique [0002] Distribution lines (also known as feeder lines, feeders) are an important part of the power distribution system. After the distribution line fails, automatically detecting and cutting off the faulty section is the premise to ensure the reliability of power supply for users. [0003] At present, there are two main categories of distribution line fault isolation. One is current protection, which also includes current quick-break protection and definite time over-current protection. When a fault occurs on the distribution line, based on the increase in current, the current quick-break protection isolates the fault instantaneously, and the definite time overcurrent protection isolates the fault after a set time delay. The current quick-break protection can quickly isolate the fault, but it will inevitab...

AI Technical Summary

Problems solved by technology

Based on the fault isolation method of the feeder terminal unit and the communication network, the determination of the fault section depends on the information interaction between the communication network and the feeder terminal unit, and the reliability of fault isolation is poor

[0004] To sum up, the existing distribution line fault isolation methods cannot meet the user's requirements for safe and reliable power supply

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