Remanence evaluating and demagnetizing device of power transformer and remanence evaluation and demagnetizing control methods

Abstract

The invention discloses a remanence evaluating and demagnetizing device of a power transformer. In a main circuit, two ends of a switch power are respectively connected with a filter capacitor and a resistor R0 in parallel, a forward end of the switch power is connected with a main switch T5 in serial, a switch T6 and a resistor R1 serial branch, a switch 1 and a switch 2 serial branch, a switch 3and a switch 4 serial branch are connected at the rear end of the main switch T5 in parallel, a drive circuit is connected with drive ends of the main switch T5, the switch T6, the switch 1, the switch 2, the switch 3 and the switch 4, and a control circuit is connected with the drive circuit and is used for sending an instruction to the drive circuit. The device provides reference for rapid, accurate demagnetization, is more intelligent, can demagnetize rapidly and thoroughly, and greatly shortens field demagnetization time and improves demagnetization effect.

Description

technical field [0001] The invention relates to a device and a control method for evaluating and demagnetizing the residual magnetism of a power transformer, belonging to the technical field of power system safety control. Background technique [0002] After the power transformer is out of operation and the DC resistance test will produce 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 the residual magnetism of the transformer core mainly includes the following aspects: [0003] (1) When the remanence 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 during the no-load charging of th...

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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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