Residual magnetism evaluating method and system based on region-variable integration in voltage attenuation process

Abstract

The invention discloses a region-variable integration residual magnetism evaluating method based on a voltage attenuation process. The region-variable integration residual magnetism evaluating methodis characterized by comprising the following steps that S1, by detecting the voltage jump moment of a transformer port, the on-off moment of a transformer interval breaker is determined; S2, the on-off moment of the transformer interval breaker serves as the starting point, by selecting an integrating range, core terminal voltage is integrated, and the transformer core residual magnetism is calculated; S3, external disturbance generated during integration is denoised, primary-side voltage is reconstructed for secondary-side voltage passing through a voltage transformer, CVT output voltage canbe subjected to transfer function backward processing, and the residual magnetism is evaluated after voltage waveform reconstruction. During actual operation, when a transformer is switched on or off,or the transformer is subjected to some preventive tests, because a transformer core has the hysteresis characteristic, magnetic flow can remain in the core, that is the transformer residual magnetism is generated. Under general conditions, once the residual magnetism is generated, the residual magnetism can exist in the core for a long time but cannot disappear naturally.

Description

technical field [0001] The invention relates to a voltage attenuation evaluation method, in particular to a residual magnetism evaluation method and system based on variable area integration of the voltage attenuation process. Background technique [0002] Due to the hysteresis characteristic of the iron core of a power transformer, the iron core often retains residual magnetism during the transformer removal process. As a result, excitation inrush currents will be generated when the transformer is switched on without load, which will endanger the safety of equipment and systems, and even cause power outages and grid failures. Related studies have found that figure 1 As shown, the greater the residual magnetism of the iron core after the transformer is removed, the stronger the excitation inrush current generated when the switch is switched on, and the more serious the overvoltage phenomenon. Accurate residual magnetism evaluation plays a very important role in formulating...

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Problems solved by technology

Calculation models widely used in academia include Preisach model, Product model, and Stoner-Wohlfarth model, etc., but the above models all involve some parameters that cannot be directly measured, and their practicability is poor

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