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Positive and zero sequence fault component braking method for preventing transformer protection from malfunction

A transformer protection and fault component technology, applied in emergency protection circuit devices, electrical components, etc., can solve problems such as the inability to completely eliminate the influence of zero-sequence current, and achieve the effect of preventing misoperation

Inactive Publication Date: 2005-05-11
ZHEJIANG UNIV
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  • Summary
  • Abstract
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  • Claims
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Problems solved by technology

[0003] The technical problem to be solved by the present invention is aimed at Y 0 The side three-phase current conversion method cannot completely eliminate the influence of zero-sequence current, and provides a positive-sequence and zero-sequence fault component braking method to prevent transformer protection from malfunctioning, using transformer Y 0 The fundamental positive-sequence current fault component on one side and the fundamental zero-sequence current fault component on this side constitute a ratio brake element. When the ratio value is less than the set value, a three-phase brake signal is output to brake the ratio differential protection of the transformer.

Method used

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  • Positive and zero sequence fault component braking method for preventing transformer protection from malfunction

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Embodiment 1

[0010] A positive-sequence and zero-sequence fault component braking method for preventing transformer protection maloperation, which can be realized through the circuit block diagram of a positive-sequence and zero-sequence fault component braking component for preventing transformer protection maloperation in FIG. 1 . The element is composed of memories 11-14, subtractors 21-24, fundamental wave positive sequence filter 1, filter 2, 01, multiplier 3 and comparator 4, wherein the input terminals of memories 11-13 and the subtraction The positive input ends of the devices 21-23 are respectively input into the transformer Y 0 side three-phase current instantaneous value signal i a i b i c The output ends of the memory devices 11-13 are respectively connected to the negative input ends of the subtractors 21-23, and the output ends of the subtractors 21-23 are respectively connected with three input ends of the fundamental positive sequence filter 1; The output terminal of seq...

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Abstract

The positive sequence current failure components of first harmonic at Y0 side of transformer and the zero sequence current failure components are used to build up the rate break component. When the rate value is less than setting value, the break signal is outputted to break the rate differential protection of relating transformer. The invention can avoid miss -protection caused by ground fault of Y0 side when error of three-phase current transformer is disagreeing.

Description

technical field [0001] The invention relates to a power system relay protection method, in particular to a positive sequence and zero sequence fault component braking method for preventing transformer protection malfunction. Background technique [0002] The existing power transformer differential protection device uses a ratio braking element, that is, through the ratio of differential current and through current, to identify external faults and internal faults; at the same time, through inrush current and overexcitation braking elements, that is, through Analyze the waveform or harmonic content of the differential current to identify the inrush current and over-excitation current to achieve the purpose of identifying internal faults. to Y 0 / Δ wiring power transformer, in order to prevent Y 0 The zero-sequence current of the ground fault outside the side area causes the differential protection to malfunction. At present, Y 0 The method of transforming the side three-pha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/045
Inventor 徐习东
Owner ZHEJIANG UNIV
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