A device and control method for evaluating and degaussing the residual magnetism of a power transformer

Abstract

The invention discloses a device for evaluating and degaussing the residual magnetism of a power transformer. The main circuit includes: a filter capacitor and a resistor R0 are connected in parallel at both ends of a switching power supply, a main switch T5 is connected in series at the forward end of the switching power supply, and a rear end of the main switch T5 is connected in series. In parallel, there are switch T6 and resistor R1 series branch, switch 1 and switch 2 series branch, switch 3 and switch 4 series branch; the drive circuit is connected with main switch T5, switch T6, switch 1, switch 2 and switch 3 1. The driving end of the switch 4 is connected, and the control circuit is connected with the driving circuit, and is used to issue instructions to the driving circuit. In order to realize accurate and fast degaussing, the present invention provides a reference basis, is more intelligent, can realize fast and complete degaussing, and greatly improves the degaussing time and degaussing effect on site.

Description

technical field [0001] The invention relates to a device and a control method for evaluating and demagnetizing residual magnetism of a power transformer, and belongs to the technical field of power system safety control. Background technique [0002] After the power transformer is out of operation and after the DC resistance test, there will be residual magnetism. The amount of residual magnetism depends on the winding current before the switching action, the strength and time of the DC current passing through the winding. The influence of transformer core remanence mainly includes the following aspects: [0003] (1) When the residual magnetism of the transformer is large, the excitation inrush current generated by no-load charging may lead to a large difference between the input and output currents of the transformer, causing the transformer differential protection to malfunction. [0004] (2) The impact excitation inrush current formed when the transformer is charged with...

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Problems solved by technology

[0003] (1) When the residual magnetism of the transformer is large, the excitation inrush current generated by no-load charging may cause a large difference between the input and output currents of the transformer, causing the transformer differential protection to malfunction

[0004] (2) The impact excitation inrush current formed when the transformer is charged with no load will cause the mechanical force between the windings, which may gradually loosen the fixings and deform the windings, thus forming hidden dangers

[0005] (3) The excitation inrush current contains a variety of harmonic components and DC components, making the transformer a harmonic source in the power grid, which reduces the power supply quality of the power supply system; at the same time, the high-order components in the harmonics are harmful to sensitive power in the power system. Electronic components will also have a strong destructive effect

However, in the actual degaussing process, it is difficult to reflect the change of the residual magnetism, and the degaussing effect cannot be guaranteed.

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