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Alternating 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: 2007-11-21
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 phase-to-phase and zero-sequence braking method to prevent transformer protection malfunction, using transformer Y 0 The phase-to-phase current on one side and the zero-sequence current on this side constitute a ratio brake criterion. When the ratio value is less than the set value, the phase-to-phase brake signal is output to brake the ratio differential protection of the corresponding phase transformer.

Method used

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  • Alternating and Zero Sequence braking method for preventing transformer protection from malfunction
  • Alternating and Zero Sequence braking method for preventing transformer protection from malfunction
  • Alternating and Zero Sequence braking method for preventing transformer protection from malfunction

Examples

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Embodiment 1

[0011] A phase-to-phase and sequence braking method for preventing maloperation of transformer differential protection, which can be realized by a circuit of phase-to-phase and zero-sequence braking components for preventing transformer protection malfunction as shown in FIG. 1 . The element is composed of subtractors 11-13, filters 21-24, multipliers 3, comparators 41-43, and the positive input terminals of the subtractors 11-13 are respectively input into the transformer Y 0 side three-phase current instantaneous value signal i a i b i c , the negative input terminals respectively input the transformer Y 0 side commutation three-phase current instantaneous value signal i b i c i a , the output ends of which are respectively connected to the input ends of the filters 21-23; the input end of the filter 24 inputs the zero-sequence current instantaneous value signal 3i of this side o , its output end is connected with an input end of multiplier 3; Another input end of mult...

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Abstract

The method includes following steps: the inter-phase current obtained from Y0 side of and transformer and the zero sequence current are used to build up rate break component; when the rate value is less than setting value, the break signal of the phase 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 of phase-to-phase and zero-sequence braking to prevent maloperation of transformer protection Background technique [0002] The existing power transformer longitudinal 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 vertical differential protection to malfunction. Currently, Y 0 The method of transforming the s...

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
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