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Method for identifying magnetizing inrush current by utilizing current waveform characteristics

A technology of feature recognition and excitation inrush current, applied in the direction of electrical digital data processing, special data processing applications, instruments, etc., can solve problems such as differential protection misoperation, achieve the effect of improving applicability, reducing influence, and highlighting inrush current characteristics

Inactive Publication Date: 2016-06-08
XI'AN POLYTECHNIC UNIVERSITY
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  • Summary
  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0012] The purpose of the present invention is to provide a method for identifying the magnetizing inrush current using the characteristics of the current waveform, which solves the problem of differential protection misoperation in the prior art

Method used

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  • Method for identifying magnetizing inrush current by utilizing current waveform characteristics
  • Method for identifying magnetizing inrush current by utilizing current waveform characteristics
  • Method for identifying magnetizing inrush current by utilizing current waveform characteristics

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Embodiment

[0061] Assuming that the number of sampling points in the power frequency cycle is N, use the data window of one power frequency cycle to calculate the first group of maximum and minimum values. If the inrush current criterion is satisfied, count Num=1; in order to improve the reliability of inrush current discrimination, Then move N / 4 data windows point by point sequentially, and continuously calculate the maximum value and minimum value group of the current change rate that satisfies the inrush current criterion in the data window, and then count Num when the time difference is satisfied. The inrush current can be reliably confirmed when the criterion is met for the first time, and the reliable blocking of the transformer differential protection can be realized.

[0062] The method of the invention utilizes the waveform characteristics of the three-phase current change rate of the transformer winding, and proposes an excitation inrush current identification method utilizing t...

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Abstract

The invention discloses a method for identifying a magnetizing inrush current by utilizing current waveform characteristics. The method comprises the following specific steps: step 1: acquiring a three-phase current i phi(k) of a transformer winding, and performing differential treatment on the current of each phase, wherein phi is equal to A, B or C; step 2: calculating a change rate i'd phi(k) of the three-phase current within a power frequency period T, then determining sampling points of a maximum value i'd phi.max(k1 phi) and a minimal value i'd phi.min(k2 phi) of the change rate of the three-phase current, and calculating a time interval t phi of the extreme values of the change rate of the three-phase current; and step 3: identifying the inrush current and an internal fault by utilizing criteria. According to the method for identifying the magnetizing inrush current by utilizing the current waveform characteristics, the influence of a direct-current component is reduced; and the method is simple and small in calculation amount, so that differential protection misoperations are reduced.

Description

technical field [0001] The invention belongs to the technical field of relay protection for electric power system transformers, and in particular relates to a method for identifying excitation inrush current by using current waveform features. Background technique [0002] Transformers are important equipment in power plants and substations, and their safe and reliable operation is of great significance to the continuous and stable operation of the entire power system. The longitudinal differential protection is one of the main protections of the transformer protection, and the excitation inrush current of the transformer is the main source of the maloperation of the transformer differential protection. The excitation inrush current is not the fault state of the transformer, so how to accurately identify the inrush current and internal faults and ensure the safe and stable operation of the transformer is of great significance. [0003] How to accurately identify inrush curr...

Claims

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Application Information

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IPC IPC(8): G06F19/00
CPCG16Z99/00
Inventor 邵文权乔妮吴淑
Owner XI'AN POLYTECHNIC UNIVERSITY
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