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Method for estimating voltage sag frequency caused by transformer commissioning

A voltage sag, transformer technology, applied in transformer testing, measuring current/voltage, instruments, etc.

Active Publication Date: 2020-10-27
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0027] The technical problem to be solved by the present invention is to provide a method for estimating the frequency of voltage sags caused by transformer operation, objectively estimate the remanence of the transformer and the closing angle to calculate the voltage sags, and use the proposed method of segmental statistics to solve the problem of The overestimation problem of this kind of non-rectangular sag, and finally get the estimation result of grid voltage sag frequency that is more realistic

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  • Method for estimating voltage sag frequency caused by transformer commissioning
  • Method for estimating voltage sag frequency caused by transformer commissioning
  • Method for estimating voltage sag frequency caused by transformer commissioning

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Embodiment Construction

[0093] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0094] The invention includes the steps of establishing the magnetization curve of the transformer, determining the probability distribution of the closing angle and residual magnetism, calculating the voltage sag caused by the no-load closing of the transformer, and evaluating the frequency of the voltage sag caused by the transformer being put into operation, wherein each large The steps and their sub-steps are elaborated as follows:

[0095] First, establish the magnetization curve of the transformer

[0096] Transformer excitation inrush current can be calculated by core flux and magnetization curve Φ-i. The magnetization curve of a transformer is a highly nonlinear curve reflecting the magnetization characteristics of the iron core, which cannot be directly measured. Although a more accurate transformer magnetization curve can b...

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Abstract

The invention discloses a method for estimating voltage sag frequency caused by transformer commissioning. The method comprises the steps of: establishing a transformer magnetization curve; determining probability distribution of a closing angle and residual magnetism; calculating voltage sag caused by no-load closing of a transformer; and evaluating the voltage sag frequency caused by transformercommissioning. According to the method, the maximum entropy principle is applied, the probability distribution of the residual magnetism of the transformer is objectively and accurately evaluated byutilizing the relationship among the closing angle of the transformer, the residual magnetism and the maximum instantaneous magnetic flux, and the unreliability of estimating the residual magnetism according to experience in a traditional method is overcome; the non-rectangular sag caused by the transformer is subjected to equivalent frequency statistics by utilizing a multi-segment amplitude-duration function, so that the over-estimation of the sag by a traditional frequency statistics method is avoided.

Description

technical field [0001] The invention relates to the technical field of voltage sags, in particular to a method for estimating the frequency of voltage sags caused by transformer operation. Background technique [0002] The causes of voltage sag mainly include short circuit (including lightning strike) and switching of large-capacity equipment, such as transformer operation. In previous assessments of the frequency of voltage sags, regardless of factors such as the distribution of fault locations and the coordination of relay protection, the frequency of voltage sags caused by short circuits was only evaluated, and the voltage caused by transformer operation was usually ignored. Pause. Theoretical research and monitoring data show that a huge inrush current is generated when the transformer is switched on without load, and the voltage sag caused by this current to the busbars with a short distance cannot be ignored. [0003] Secondly, the operating principle of the three-ph...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/62G01R19/00
CPCG01R19/0053G01R31/62
Inventor 汪颖李顺祎肖先勇
Owner SICHUAN UNIV