The Simulation Research Of The New Converter Transformer Winding Vibration Under DC Magnetic Bias

In the direct current (DC) transmission system program, the DC magnetic biasphenomenon is relatively serious, leading to the large amount of harmonic current andreactive power not only can cause adverse to power quality and grid system, etc,butalso will damage the devices of the converter substation, especially the convertertransformer. Traditional filtering methods only think in terms of power grid, harmoniccurrent caused by DC magnetic bias, through transformer winding can increaseelectromagnetic force and electromagnetic vibration. Its main performance is:winding vibration lead to out of audible noise limit of converter transformer;Insulation structure damage reduce the service life of converter transformer.The new converter transformer studied in this paper is applying with inductivefiltering technology, which designed to greatly reduce the harmonic magnetic flux ofcore, thereby suppressing the vibration of the transformer windings, to achieve thepurpose of reducing noise.The work of this paper is a part of the project HarmonicInfluence Mechanism and New Method of Restraining on Converter TransformerVibration (51077045),supported by the National Natural Science Foundation.Thefundamental research in this thesis can be summarized as follows.Studied the work mechanism of the new converter transformer and itselectromagnetic properties. By the introduction of the filtering mechanism of the newconverter transformer, and to compare with traditional converter transformer undersoftware simulation situation, to show the new converter transformer has advantagesin the electromagnetic characteristics. And by analyzing two different softwaresimulation results to confirm the feasibility of finite element analysis, which lay thefoundation for analyzing the DC magnetic bias;Derived inhibition mechanism of the new converter transformer under DCmagnetic bias. Based on transformer DC magnetic bias mechanism, combined withthe equivalent circuit model of the new converter transformer, to analyze theinhibition mechanism and to provide a theoretical basis for the subsequent simulationconclusions;Used software co-simulation to study the inhibitory effect of the new convertertransformer on its winding vibration under DC magnetic bias. Transient dynamics andfinite element analysis method to study the excitation current, magnetic flux leakage distribution, electromagnetic force and vibration of transformer winding under DCmagnetic bias.In this article, through systematic analysis to reveal the new convertertransformer has well inhibitory effect of winding vibration under DC magnetic bias,shows its good prospect of engineering application.