Study On The Method Of Using Induction Filter To Reduce The Noise Of Converter Transformer

The influence of noise generated by transformers on the environment is attracting more and more attention.The noise of transformer comes from many aspects such as winding and core.Magnetostriction of silicon steel sheet is the main cause of transformer's vibration and noise.The harmonic in converter transformer can aggravate the magnetostriction of silicon steel sheet,resulting in the increase of transformer noise.The traditional grid side filtering method can reduce the harmonic content of the power grid,but it can't effectively weaken the vibration and noise of the converter transformer.In this paper,a noise reduction experiment of converter transformer based on inductive filtering technology is studied.This method can weaken the harmonic magnetic flux in the iron core,so that the vibration of the silicon steel sheet of the converter transformer can be suppressed so as to reduce the noise of the transformer.The work of this paper is a part of the project Harmonic Influence Mechanism and New Method of Restraining on Converter Transformer Vibration(51077045,and national network 5216A014007V),supported by the National Natural Science Foundation.The fundamental research can be summarized as follows.First,the finite element model of four-column single-phase converter transformer is established,and the modal and corresponding mode shapes are obtained by modal simulation.The theory of magnetostrictive properties is analyzed,an d the influence of the harmonic magnetic flux on the magnetostriction of silicon steel sheet is discussed.We elicit the acoustic theory and demonstrate the correlation between the harmonic magnetic flux and the transformer noise from the acoustic angle.Secondly,We explain the basic principle of inductive filtering technology,design the parameters of induction filter,and build a DC transmission model based on inductive filter commutation transformer.The test results show that the inductive filtering technology has a good inhibitory effect on the core harmonic flux,which lays a theoretical foundation for subsequent experimental research of inductive filter technology to suppress the vibration and noise of converter transformer.Then,we set up an experimental platform for vibration and noise measurement of induction filter converter transformer.The vibration and noise level of the unfiltered device,the traditional filter and the inductive filter are tested respectively,and the core flux measurement results are compared and analyzed.The experimental data show that the induction filter technology can effectively reduce the vibration and noise of the converter transformer,and the effect of noise reduction is better than the traditional filtering method.We analyze the vibrational spectrum diagram and exclude the effect of structural resonance on the experimentFinally,in order to simulate the DC bias phenomenon of converter transformer in HVDC transmission,We controll conduction angles of some thyrist ors are different from that of the other thyristors to form an equivalent DC current.The vibration and noise of induction filter converter transformer under DC bias is measured.The test results also show the effect of the induction filter technology on t he vibration and noise reduction of the transformer.