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Maximum alternating and zero sequence braking method for preventing transformer protection from malfunction

A technology of transformer protection and phase-to-phase current, 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: 2007-11-21
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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 the zero-sequence current, and provides a method of maximum phase-to-phase current and zero-sequence braking to prevent transformer protection from malfunctioning, using a transformer Y 0 The maximum value of the phase-to-phase current obtained after Y / Δ conversion of the three-phase current on the side and the zero-sequence current on this side constitute a ratio braking element. When the ratio value is less than the setting value, a braking signal is output to control the ratio differential protection of the transformer. verb: move

Method used

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

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Embodiment 1

[0012] A maximum phase-to-phase current and zero-sequence braking method for preventing maloperation of transformer protection, which can be realized by a circuit of maximum phase-to-phase current and zero-sequence braking components for preventing transformer protection maloperation in FIG. 1 . The element is composed of subtractors 11-13, filters 21-24, maximum value circuit 3, multiplier 4 and comparator 5, wherein the positive input terminals of the subtractors 11-13 are respectively input into the transformer Y 0 The three-phase current instantaneous value signals ia, ib, and ic on the side, and the negative input terminals are respectively input into the transformer Y 0 The output terminals of the commutation three-phase current instantaneous value signals ib, ic, and ia on the side are respectively connected to the input terminals of filters 21-23, and the input terminals of the maximum value seeking circuit 3 are respectively connected to the output terminals of filters...

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Abstract

The maximum value of three-phase current at Y0 side of transformer obtained after being made Y / delta transform and the zero sequence current at the same side 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 method for relay protection of a power system, in particular to a method for maximum phase-to-phase current and zero-sequence braking to prevent 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...

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