Method for enhancing differential protection performance by coordination of mutation quantity fault discrimination and fuzzy harmonic analysis

Abstract

The invention relates to a method for enhancing differential protection performance by the coordination of mutation quantity fault discrimination and fuzzy harmonic analysis, which utilizes different characteristics of difference current and braking current mutation quantity to distinguish the internal and external faults of an area under different fault conditions. After a fault type is distinguished by the discrimination method, a fuzzy harmonic analysis criterion is combined to enhance the accuracy of fault discrimination so as to enhance the reliability and sensitivity of differential protection. The method is already adopted in a complete set of protection device of a DSA serial transformer and both the simulation results and the site practical situation indicate that the method has good prevention effect on reasons which easily cause differential misoperation, such as TA saturation, sympathetic surge, AD abnormity, and the like.

Description

technical field [0001] The invention relates to a new method for comprehensively improving the reliability of differential protection by using a novel fault discrimination method combined with harmonic analysis criteria. Background technique [0002] At present, the transformer protection in our country has basically adopted the microcomputer transformer differential protection device, but the accurate operation rate of the protection is generally not high. According to the current relevant data statistics, the current correct operation rate of the transformer differential protection is only about 75%. Can not meet the needs of on-site safe operation. At present, the main reasons for the misoperation of ratio differential protection include the following points [0003] 1. TA saturation outside the area. Although the products of various companies have anti-TA saturation measures, it may still cause protection misoperation during the TA saturation process, or the protection ...

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Problems solved by technology

[0003] 1. TA saturation outside the area. Although the products of each company have anti-TA saturation measures, it may still cause protection misoperation during the TA saturation process, or the protection will refuse to operate or delay action when a fault occurs after TA saturation.

[0004] 2. Inrush current, the research on inrush current is gradually in-depth, but differential malfunction caused by inrush current occasionally occurs

[0005] 3. Internal AD failure, multiple on-site wave recordings found that when the protection internal AD fails, the existence of some "bad points" leads to differential misoperation

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