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Sampling point differential protection misoperation prevention method

A technology of differential protection and sampling points, which is applied in the direction of automatically disconnected emergency protection devices, emergency protection circuit devices, electrical components, etc., can solve problems such as misoperation and excessive DC component attenuation, and achieve improved reliability and enhanced Effects on Stability and Reliability

Active Publication Date: 2015-11-04
XUJI GRP +3
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Problems solved by technology

[0004] The purpose of the present invention is to provide a sampling point differential protection anti-maloperation method to solve the problem that when the fault single CT outside the area is saturated, the unsaturated CT current contains a large DC component and flows through the small current converter of the protection device. Misoperation of Differential Protection at Sampling Point

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  • Sampling point differential protection misoperation prevention method
  • Sampling point differential protection misoperation prevention method
  • Sampling point differential protection misoperation prevention method

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Embodiment Construction

[0028] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0029] For faults in the zone, the absolute values ​​of most sampling points of differential current and braking current are basically equal, and the absolute values ​​of current sampling values ​​after differential are also basically the same. For external faults accompanied by CT transient saturation and unsaturated CT current is very large and contains a large DC component, the differential operation can basically eliminate the attenuated DC component in the differential current, highlighting the discontinuity of the differential current; while for the braking current, Due to the contribution of the non-saturated CT current, there will be no discontinuity after the difference, and it can effectively play a braking role at the discontinuity of the differential current. Therefore, the present invention first performs differential element ca...

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Abstract

The invention relates to a sampling point differential protection misoperation prevention method, belonging to the technical field of relay protection of power systems. The method comprises the following steps of: firstly, performing difference calculation to differential current and brake current sampling points, and judging whether the differenced differential current and brake current sampling values meet a rate brake condition, wherein influence of unsaturated CT attenuation direct current component on the synthesized differential current may be weakened through a difference algorithm; and judging whether a criterion for opening sampling point differential protection is satisfied according to ratio of the sampling values of the differenced differential current and brake current. The method solves a problem of misoperation of sampling point differential protection caused by too fast attenuation of the direct component when external fault single CT is saturated and unsaturated CT current contains large direct current component and flows through a low current converter of a protection device. Meanwhile, by the method, sampling point differential protection causes no misoperation when waveform is abnormal, and causes reliable operation when normal failure happens, thus, reliability of sampling point differential protection is improved.

Description

technical field [0001] The invention relates to a method for preventing maloperation of sampling point differential protection, which belongs to the technical field of relay protection of electric power systems. Background technique [0002] The relay protection device requires that the faulty equipment can be reliably removed when the system fails to ensure the safe and stable operation of the system, but the damage caused by the incorrect action (including refusal and misoperation) of the protection device is also huge. [0003] When a metal fault occurs outside the area, if the fault closing angle is small and the single CT is transiently saturated, the unsaturated CT current is large and contains a large DC component. At this time, when the unsaturated CT current flows through the current converter inside the protection device , will cause the small current converter of the protection device to experience rapid DC attenuation after a period of time (generally about 100ms...

Claims

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Application Information

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IPC IPC(8): H02H7/26H02H3/26
Inventor 姚东晓倪传坤邓茂军马和科吕利娟陈继瑞李旭汪华永原琳席颖颖张景丽张哲王东兴茹东武
Owner XUJI GRP
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