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Transformer longitudinal error protecting method with zero sequence ratio brake

A technology of ratio braking and longitudinal differential protection, which is applied in the direction of emergency protection circuit devices and electrical components, and can solve the problems that zero-sequence current cannot be completely eliminated

Inactive Publication Date: 2008-02-06
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 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 transformer differential protection method with zero-sequence ratio braking is provided. The braking current representing the through current and the transformer Y 0 The zero-sequence current of this phase is weighted and summed to form the braking current containing zero-sequence current of this phase. The braking current of this phase containing zero-sequence current and the differential current of this phase are used to form the braking element of this phase ratio. When the differential current is greater than the braking current containing When the braking current of the zero-sequence current is greater than the minimum operating current, the operating signal of the corresponding phase-ratio braking element is output

Method used

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  • Transformer longitudinal error protecting method with zero sequence ratio brake
  • Transformer longitudinal error protecting method with zero sequence ratio brake
  • Transformer longitudinal error protecting method with zero sequence ratio brake

Examples

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Embodiment 1

[0016] A transformer longitudinal differential protection method with zero-sequence braking, which can be realized through the circuit block diagram of a transformer longitudinal differential protection ratio braking component with zero-sequence braking in Figure 3. This element consists of multipliers A1, B1, C1, O1, adders A3, B3, C3 and comparators A4, B4, C4. One of the input terminals of the multipliers A1, B1, and C1 respectively inputs the filtered braking current signal I representing the crossing current in the longitudinal differential protection of the transformer. za , I zb , I zc , and the other input terminal enters the ratio brake coefficient K Z =0.5, its output end connects an input end of adder A3, B3, C3 respectively; An input end input transformer Y of multiplier 01 0 Filtered zero-sequence current signal 3I 0 , and the other input terminal enters the zero-sequence braking coefficient K 0 =0.15, its output end is respectively connected to the other inp...

Embodiment 2

[0018] A transformer longitudinal difference protection method with zero-sequence braking, which can be realized through another circuit of transformer longitudinal difference protection ratio braking element with zero-sequence braking shown in Fig. 4 . The element is composed of subtractors A11, B12, C13, multipliers A21, B22, C23, O2, adders A31, B32, C33, A41, B42, C43 and comparators A51, B52, C53. Among them, the positive input terminals of the subtractors A11, B12, and C13 respectively input the filtered braking current signal I representing the through current of the transformer differential protection za , I zb , I zc , and the negative input terminal respectively inputs the brake inflection point current value I in the longitudinal differential protection of the transformer reso =1.2×I n , I n In order to convert to the rated current of the transformer on this side; one input terminal of the multiplier A21, B22, C23 is respectively connected to the output terminal...

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Abstract

This invention discloses a longitudinal deviation protection method for a transformer with a zero sequence rate brake, which weights to get the sum of the brake current representing the through current and a zero sequence current of the transformer Yo to get the brake current containing zero sequence current of said phase and uses the brake current containing zero sequence current and related phase differential current to constitute said phase rate brake element. When the differential current is greater than the brake current containing the zero sequence current and larger than the smallest action current, the action signal of related phase rate brake element is output.

Description

technical field [0001] The invention relates to a relay protection method of a power system, in particular to a transformer differential protection method with zero-sequence ratio braking. Background technique [0002] The current longitudinal differential protection of power transformers consists of components such as differential quick-break, ratio differential, excitation inrush current detection, and over-excitation detection. According to DL / T 684-1999 "Large Generator Transformer Relay Protection Setting Calculation Guidelines", the block diagram of transformer longitudinal differential protection is shown in Figure 1, and the principle wiring example of longitudinal differential protection is shown in Figure 2. Usually using a current transformer for Y 0 Y / Δ transformation is performed on the three-phase current on the side to eliminate the influence of zero-sequence current. Obviously, after the transformation, each current does not contain the zero-sequence compon...

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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