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Split-phase zero sequence braking method for preventing transformer protection from malfunction

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

Inactive Publication Date: 2008-02-06
ZHEJIANG UNIV
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  • Abstract
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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 a phase-separated zero-sequence braking method to prevent transformer protection malfunction is provided. The transformer Y 0 The 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 brake signal of this phase is output to brake the ratio differential protection of the corresponding phase transformer.

Method used

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  • Split-phase zero sequence braking method for preventing transformer protection from malfunction

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Embodiment 1

[0011] A phase-separated zero-sequence braking method for preventing maloperation of transformer differential protection, which can be realized through the circuit block diagram of a phase-separated zero-sequence braking component for preventing transformer protection maloperation in FIG. 1 . The element is composed of filters 11-14, multipliers 2, and comparators 31-33, where the input terminals of filters 11-13 are respectively input into the transformer Y 0 side three-phase current instantaneous value signal i a i b i c , the input terminal of the filter 14 is input to the transformer Y 0 side zero-sequence current instantaneous value signal 3i 0 , its output terminal is connected to an input terminal of multiplier 2; the other input terminal of multiplier 2 inputs the setting value K=0.5, the negative input terminals of comparators 31-33 are connected with the output terminals of multiplier 2, and its positive input The terminals are respectively connected to the outpu...

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Abstract

The method includes following steps: phase current at Y0 side of transformer and the zero sequence current of this side are used to build up the rate breaking 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 relay protection method for a power system, in particular to a phase-separated zero-sequence braking method for preventing transformer protection maloperation. 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 side thr...

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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