Zero sequence overcurrent protection method, system and device and computer readable storage medium

A zero-sequence overcurrent and protection device technology, applied in emergency protection circuit devices, electrical components, etc., can solve the problems of non-prominence, reduced excitation inductance, endangering the safety of power grid operation, etc., and achieve the effect of avoiding misoperation

CN109119971AActive Publication Date: 2019-01-01GUANGDONG POWER GRID CO LTD +1
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2019-01-01

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Abstract

The invention discloses a zero sequence overcurrent protection method, system and device and a computer readable storage medium. The method can obtain the linear relation between the zero-mode inrushcurrent waveform and the unsaturated core magnetic density and three-phase remanence magnetic density through a zero-mode inrush current analytic equation comprising the saturated mutual inductance ofa transformer, high-voltage side self-leakage resistance, low-voltage side self-leakage resistance, system zero sequence reactance, system voltage, system magnetic density, unsaturated core magneticdensity and remanence magnetic density; can determine the value of the unsaturated core magnetic density in each phase of the three phases through an unsaturated core magnetic density expression. Therefore, after the zero-mode inrush current parameter is substituted into the zero-mode inrush current analytic mode, the zero-mode inrush current waveform can be obtained, thereby achieving the mathematical analysis of the zero-mode inrush current waveform, achieving the analysis of the influence of transformer parameters of different structure types on the magnitude of the zero-mode inrush current. The method can reproduce the waveform when the zero-mode inrush current occurs, and can set the protection criterion of a zero sequence overcurrent protection device, and avoids misoperation of thezero sequence overcurrent protection device.
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Description

technical field

[0001] The present invention relates to the technical field of electric power system relay protection, in particular to a zero-sequence overcurrent protection method, system, device and computer-readable storage medium. Background technique

[0002] The transformer is an important equipment for transferring energy and transforming voltage in the power system. When the transformer is closed with no load or the voltage recovers after the external fault is removed, a large excitation inrush current will appear in the transient process. Free DC component, the transformer core intermittently enters saturation during this process, the exciting inductance decreases sharply, and a large current will appear; in the process of transformer commissioning, there may be cases where the transformer differential protection does not operate and acts as a backup protection The phenomenon of zero-sequence protection action tripping is related to the zero-sequence component caus...

Examples

Embodiment Construction

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0047] The embodiment of the present invention discloses a zero-sequence overcurrent protection method, see figure 1 As shown, the method includes:

[0048] S1: Obtain the zero-mode inrush current parameters of the transformer;

[0049] S2: Using the zero-mode inrush current parameters, the zero-mode inrush current analytical formula and the unsaturated core magnetic density expression, the zero-mode inrush current waveform is obtained;

[0050] ...