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

A technology of transformer protection and zero-sequence braking, applied in emergency protection circuit devices, electrical components, etc., can solve the problem that the influence of zero-sequence current cannot be completely eliminated.

Inactive Publication Date: 2008-05-14
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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 braking method to prevent transformer protection misoperation, using transformer Y 0 The fundamental positive-sequence current on one side and the fundamental zero-sequence current on this side form a ratio braking element. When the ratio value is less than the setting value, a braking signal is output to brake the ratio differential protection of the transformer.

Method used

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

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Embodiment 1

[0012] A positive-sequence and zero-sequence braking method to prevent maloperation of transformer differential protection, which can be achieved by figure 1 A positive-sequence and zero-sequence brake component circuit to prevent transformer protection malfunction is realized. The component is composed of fundamental wave positive sequence filter 1, filter 2, 01, multiplier 3 and comparator 4, where the three input terminals of fundamental wave positive sequence filter 1 are respectively input into transformer Y 0 side three-phase current instantaneous value signal i a i b i c , its output terminal is connected to the input terminal of filter 2; the input terminal of filter 01 is input to the transformer Y 0 side zero sequence current instantaneous value signal 3i o , its output terminal is connected to an input terminal of multiplier 3, and another input terminal of multiplier 3 inputs the setting value K=0.9, and its output terminal is connected with the negative input ...

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Abstract

The positive sequence current of first harmonic at Y0 side of transformer and the zero sequence current at the same side are used to build 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 relay protection method of a power system, in particular to a positive-sequence and zero-sequence braking method for preventing maloperation of transformer protection. 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-phase curr...

Claims

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Application Information

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