Acquiring method of DC (direct-current) bias magnet ratio total losses curve of transformer core material

Abstract

The invention discloses an acquiring method of a DC (direct-current) bias magnet ratio total losses curve of a transformer core material and relates to measurement of material magnetic variables. The method comprises the following steps of: firstly processing a device used in the method disclosed by the invention through a variable-voltage transformer, a transformer core model, a DC current source, a digital oscilloscope, a power analyzer and a power frequency AC (alternating-current) power supply; and then, operating the device according to six steps to obtain a DC bias magnet ratio total losses curve of a measured transformer core material under the action of a DC bias magnetic field when any given DC exciting current Idc acts within a range of 0.1-2A. An AC-DC serial excitation mode identical to that of DC bias magnet of an actual transformer is utilized in the method disclosed by the invention to simulate the DC magnetic flow in an overlapped iron core material under a DC bias magnet working condition, thereby completely meeting the actual condition of DC bias magnet of a power transformer, and the acquired DC bias magnet ratio total losses curve of the transformer core material is close to a real value.

Description

technical field [0001] The technical scheme of the invention relates to the measurement of the magnetic variable of the material, in particular to the method for obtaining the DC bias ratio total loss curve of the transformer core material. Background technique [0002] With the continuous development of my country's UHVDC transmission technology, the problem of transformer DC bias has become increasingly prominent, and has become an urgent problem to be solved in engineering practice. It is very necessary for transformer manufacturers, power system management and construction departments to study the influence of DC bias on AC transformers, which has attracted the attention of transformer designers and researchers at home and abroad. [0003] The transformer DC bias phenomenon refers to the DC magnetic flux in the transformer core for some reason, which makes the transformer core present positive and negative half-cycle asymmetrical saturation and a series of electromagneti...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the excitation method of the system adopts the parallel loading method of AC excitation and DC excitation, which is inconsistent with the series excitation method when the DC bias problem occurs in the actual power transformer in online operation, and the obtained transformer core The DC bias ratio of the material to the total loss curve deviates far from the true value, resulting in errors in the measurement results

Even if the system adopts a series excitation method that is consistent with the actual working conditions, since the measurable materials of the system are very different from those used in the actual transformer, the working magnetic flux density is too low, which is not enough to explain the DC power of the power transformer. Reality under Bias Conditions

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