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Transformer CT (current transformer) breaking discriminating method and device and differential protection method and device

A judging method and technology of judging device, which are applied to measuring devices, instruments, measuring electrical variables, etc., can solve the problems of poor reliability and rapidity of transformer differential protection action, and inaccurate judgment of transformer CT disconnection.

Active Publication Date: 2017-05-31
XUJI GRP +3
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  • Application Information

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Problems solved by technology

[0005] The object of the present invention is to provide a transformer CT disconnection discrimination method and device, which are used to solve the problem of inaccurate transformer CT disconnection discrimination. The present invention also provides a transformer differential protection method and device based on CT disconnection discrimination. It is used to solve the problem of improving the reliability and rapidity of transformer differential protection action

Method used

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  • Transformer CT (current transformer) breaking discriminating method and device and differential protection method and device
  • Transformer CT (current transformer) breaking discriminating method and device and differential protection method and device
  • Transformer CT (current transformer) breaking discriminating method and device and differential protection method and device

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Embodiment Construction

[0111] The present invention will be described in detail below with reference to the accompanying drawings.

[0112] Embodiment of transformer CT disconnection judgment method:

[0113] like figure 1 As shown, the current transformers on each side of the transformer are CT1, CT2, CT3 and CT4. by figure 1 Taking the CT2 disconnection of the medium and high voltage side as an example, the medium voltage side of the transformer is selected as the reference side, and the steps of the method for judging the disconnection of the transformer CT are as follows:

[0114] Step A: Obtain the three-phase phase current on the high-voltage side of the transformer, the zero-sequence current, and the three-phase phase current before N cycles.

[0115] Step B: Calculate the zero-sequence current 3I of the current three-phase phase current converted from the high voltage side of the transformer to the reference side of the transformer 0 , the current effective value of the three-phase curre...

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Abstract

The invention relates to a transformer CT (current transformer) breaking discriminating method and device and a differential protection method and device, wherein the differential protection method comprises the following steps of judging whether a differential protection starting condition is met or not; if the starting condition is met, judging the PT at each side of a transformer is abnormal or not; further judging whether CT breaking occurs at each side of the transformer according to the PT abnormal condition of each side of the transformer; if the CT breaking occurs at a certain side of the transformer, closing the differential protection; otherwise, starting the differential protection. The methods and the devices provided by the invention have the advantages that whether the CT breaking occurs or not can be fast and accurately discriminated; if the CT breaking occurs, the differential protection is closed; the differential protection maloperation is avoided; if the CT breaking does not occur, the differential protection is opened; the differential protection refuse operation is avoided; the accuracy of differential protection is obviously improved.

Description

technical field [0001] The invention relates to a transformer CT disconnection judging method and device, and a differential protection method and device, belonging to the technical field of power system relay protection. Background technique [0002] As the main protection of components or lines, differential current protection is mainly based on the principle of balance of total current flowing into and out of the protected equipment, and the action speed is fast. As the power system has higher and higher requirements for the selectivity, sensitivity, quick interruption and reliability of the protection function, differential protection has been widely used in the power system. When a CT disconnection or an internal fault occurs, the differential protection will have a large unbalanced differential current. Therefore, it is necessary to quickly and accurately identify the CT disconnection or an internal fault, so as to block or open the differential protection accordingly....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/06
CPCG01R31/72
Inventor 陈继瑞李宝伟樊占峰马和科姜自强汪花永李书圣张哲原琳王东兴王中玉李旭席颖颖孟利平
Owner XUJI GRP
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