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Method for different protection using wave-shaping method

A technology of differential protection and waveform shaping, applied in the field of power system, can solve problems such as AC current waveform deformation and incorrect differential protection action

Inactive Publication Date: 2008-09-24
BEIJING SIFANG JIBAO ENG TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the above-mentioned defects that the differential protection action is incorrect due to the deformation of the AC current waveform, and propose a method for differential protection using the waveform shaping method

Method used

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Embodiment Construction

[0015] figure 1 It is a schematic flow diagram of the method of the present invention. Such as figure 1 As shown, a kind of method that utilizes waveform shaping method to carry out differential protection proposed by the present invention is realized through the following technical scheme, and described method comprises steps:

[0016] Firstly, starting from step S101, when the differential protection is started, whether the protection device will trip the circuit breaker or not, enter the following judgment process;

[0017] In step S102, the instantaneous current value in the differential protection device is sampled. When the AC waveform is deformed but its zero-crossing point is still available, according to whether the instantaneous current value reaches the predetermined value W, it is judged whether it is possible to start the differential protection due to the current transformer caused by saturation.

[0018] The predetermined value W is determined according to th...

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Abstract

A method for differential protection by waveform shaping includes: a differential protection device samples the current waveform of a current mutual-inductor to get a transient value to shape the deformed AC waveform to square to sum vectors of other side current except that of the saturated mutual-inductor to get the composed current vector to compare the above basic square waveform phase with that of the composed current basic waveform to get the cosine of its included angle. If taking the positive current direction to the transformer as the positive then the rest cosine value is positive, which refers to internal fault the differential protector is switched-on, or the outside fault, the protector is switch-off.

Description

technical field [0001] The present invention relates to the field of power systems, and more particularly to a method for relay protection. Background technique [0002] In the power system, the current differential protection that is often used is a relay protection based on the difference between the current flowing into the protected element and the current flowing out of the protected element. Because of its sensitivity and easy implementation, it is generally used as the main protection of the protected components. This protection technology is often used to protect important components such as transformers, engines, busbars, and reactors. Its refusal to move (should act but not act) and misoperation (should not act and act) will cause the equipment to stop working or be damaged, which will bring huge losses to the national economy. [0003] At present, most of the differential protection adopts the proportional braking characteristic of the broken line to prevent the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H3/26
Inventor 李静正刘建飞张忠理肖海华
Owner BEIJING SIFANG JIBAO ENG TECH
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