Tault component transformer longitudinal error protecting method with maximum side zero sequence ratio brake

Abstract

This invention discloses a longitudinal deviation protection method for a fault component transformer with the largest side zero sequence rate brake, which weights the fault component of the brake current representing the through current and the maximum value in the fault components of the zero sequence currents of the neutral point earth sides of the transformer to get the fault component of the brake current containing zero sequence current, the fault component of which and that of the differential current of a related phase are used to make up of a fault component rate brake element of said phase, when the component of the differential current is greater than that of the brake current containing zero sequence current and greater than the minimum action current, a signal of the fault component rate brake element of said phase is output.

Description

technical field [0001] The invention relates to a relay protection method of a power system, in particular to a longitudinal difference protection method of a fault component transformer with maximum-side 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 differential protection is shown in figure 1 As shown, the wiring example of longitudinal differential protection principle 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 doe...

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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 fault component transformer longitudinal differential protection method with maximum side zero-sequence ratio braking is provided. component and the maximum value of the fault components of the zero-sequence current on the grounding side (or branch) of each neutral point of the transformer are weighted and summed to form the fault component of the braking current containing zero-sequence current, using the braking current containing zero-sequence current The fault component of the current and the fault component of the differential current of the corresponding phase constitute the fault component ratio braking element of this phase. When the fault component of the differential current is greater than the fault component of the braking current containing zero-sequence current and greater than the minimum operating current , output the action signal of the fault component ratio braking element of this phase

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