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Fuzzy Identification Method of Magnetizing Inrush Current in Differential Protection of Transformer

A technology of exciting inrush current and differential protection, applied in emergency protection circuit devices, instruments, measuring electrical variables, etc., can solve problems such as errors and inaccurate reliability

Inactive Publication Date: 2016-12-28
JIANGSU UNIV OF SCI & TECH
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Problems solved by technology

[0005] The purpose of the present invention is to provide a fuzzy identification method for excitation inrush current in differential protection of transformers, so as to solve the problem that the existing general fuzzy theoretical method for transformer protection can only identify a single criterion, and when each criterion is used independently, there will be certain error, technical problem of inaccurate reliability

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  • Fuzzy Identification Method of Magnetizing Inrush Current in Differential Protection of Transformer
  • Fuzzy Identification Method of Magnetizing Inrush Current in Differential Protection of Transformer
  • Fuzzy Identification Method of Magnetizing Inrush Current in Differential Protection of Transformer

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Embodiment Construction

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0044] First, some basic concepts and formulas that need to be used are given to facilitate understanding later.

[0045] The definition of fuzzy set: a fuzzy set A on the universe U means: for any element x∈U in the universe U, a number f in the closed interval [0,1] is specified A (x)∈[0,1] corresponds to it, f A (x) is called the degree of membership of x to A. That is, a mapping f is defined A :

[0046] f A : U→[0,1],

[0047] f A (x)

[0048] Definition of membership function: It is used to describe the characteristic function of fuzzy set and can take values ​​continuously in the closed interval [0,1]. The membership function uses f A (x) where A represents a fuzzy set and x is an element of A. The membership function satisfies: 0≤f A (x)≤1. f A The larger the value of (x), the more likely x belongs to A. if f A The value ...

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Abstract

The invention discloses a method for fuzzy identification of excitation inrush current for differential protection of transformers. Based on fuzzy theory, the fuzzy measurement method of 2 can be added, which can achieve the complementary advantages of various inrush current criteria, comprehensive waveform discontinuity angle criterion and waveform symmetry criterion. According to the low voltage criterion, the criterion set is formed, and the influence of each criterion on the excitation inrush current criterion is adjusted through the weighting coefficient. Even if a certain criterion is not perfect and makes an error, it will only lead to the shift of the membership function of the fuzzy quantity, and will not cause an error in the final result, which solves the problem of relatively high frequency of wrong actions caused by a single criterion, and improves the protection of transformers. performance.

Description

technical field [0001] The invention relates to a fuzzy theory-based method for identifying excitation inrush current of differential protection of transformers, belonging to the technical field of relay protection for power system equipment. Background technique [0002] At present, transformer protection is realized by differential protection, but this method has certain defects. The reason is that when the transformer is closed with no load or the external fault is removed, the terminal voltage suddenly rises and the iron core is quickly saturated, and the excitation circuit will generate a peak value of up to The excitation inrush current of 6 to 8 times the rated current will become a source of differential protection unbalanced current, so auxiliary criteria are needed to help distinguish. [0003] Functionally speaking, transformer differential protection should have the following two functions: one is to distinguish the excitation inrush current and internal fault cu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/045G01R19/00
Inventor 曾庆军卢梦宁王彪
Owner JIANGSU UNIV OF SCI & TECH