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Differential protection method for extra-high voltage transformer

A differential protection and transformer technology, applied in emergency protection circuit devices, electrical components, etc., can solve problems such as differential protection misoperation, and achieve the effect of improving reliability

Inactive Publication Date: 2015-01-28
XUJI GRP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a differential protection method for UHV transformers to solve the problem of differential protection misoperation due to excitation inrush current when UHV transformers are airdropped

Method used

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  • Differential protection method for extra-high voltage transformer
  • Differential protection method for extra-high voltage transformer
  • Differential protection method for extra-high voltage transformer

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Embodiment Construction

[0033] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0034] The UHV transformer differential protection method provided by the present invention is mainly used in the UHV relay protection device of the smart grid. By judging the symmetry of the UHV transformer public winding current waveform in real time, it is possible to prevent the inrush current from causing a difference when the transformer is air-dropped. Misoperation of manual protection to improve the reliability of the protection device. When the UHV transformer is air-dropped, there will be excitation current on the common winding side, and both the main transformer protection device and the voltage regulation compensation transformer protection device need to introduce the common winding CT, so the excitation inrush current can be identified by judging the symmetry of the common winding current waveform.

[0035] UHV transformer CT ...

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Abstract

The invention relates to a differential protection method for an extra-high voltage transformer, and belongs to the technical field of power system relay protection. The differential protection method includes: firstly locking differential protection that has not been started, then judging harmonic content of a difference stream which has been started the differential protection, and if harmonic contents of three-phase difference streams are all low, directly opening three-phase differential protection; otherwise, judging that current amplitude of each phase of a common winding is more than a no-flow threshold, judging symmetry of the current more than the no-flow threshold, and only opening differential protection of the phase which meets the requirement of symmetry. No-load and no-load faults of the transformer are identified through comparing symmetry of current waveforms of the common winding of the extra-high voltage transformer, so that the differential protection does not operates mistakenly when in a normal no-load test and acts quickly when a faulty transformer is in the no-load test, and reliability of a protection device is improved.

Description

technical field [0001] The invention relates to a method for differential protection of an ultra-high voltage transformer, which belongs to the technical field of relay protection for power systems. Background technique [0002] The structure of the UHV transformer in the 1000kV UHV AC test demonstration project is very different from that of the 500kV autotransformer. Due to the structure, the protection configuration of the UHV transformer is quite different from the traditional transformer protection configuration. In the UHV transformer protection configuration, separate differential protections are configured for the main transformer and voltage regulation and compensation transformer. The excitation inrush current when the transformer is air-dropped is the unbalanced current of the differential protection. In order to prevent the maloperation of the transformer differential protection, the second harmonic content in the differential current is usually used to identify...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/045
Inventor 邓茂军倪传坤李宝伟李旭李文正程天保席颖颖胡沙沙
Owner XUJI GRP
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