| Laminated cores of power transformer and reactor play an important role in the high voltage power transmission system.However,the vibration and noise not only affect the environment,but also reduce the service life of equipment and the reliability of the power grid operation.To study the electromagnetic vibration of laminated cores and find an effective method of decreasing noise,the magnetic characteristic of silicon steel sheets is firstly measured,and the electromagnetic mechanical coupling of laminated cores is studied by multi physical fields numerical analysis and experiment.The main points of this thesis are as follows:(1)The magnetization and magnetostriction characteristics of silicon steel sheets are obtained by the SST and MST 500 under different excitation which includes sine wave,stress and harmonic.The influence of stress and harmonics on magnetization and magnetostriction of silicon steel sheet is studied.(2)Based on the coupling analysis of electromagnetic field and structural force field,a numerical model for magneto-elastic coupled of laminated cores is adopted.Because different types of load have a different effect on the electromagnetic vibration,analysis and tests of the electromagnetic vibration of the transformer are carried out,which considered different loads,such as no-load,resistive load and non-linear load.And the vibration considering magnetostrictive effect with various harmonics is analyzed by magneto-mechanical coupling method in three phase dry SG-10 transformer.A prototype with different load conditions of vibration measurement system is built to study the harmonic components and analyze the spectrum,especially under nonlinear load condition.The calculation and test results are in good agreement,which verifies the feasibility of the method.(3)Based on the measurement data of 3D magnetization characteristic of laminated silicon steels,a 3D magnetoelastic calculation method of laminated cores including magnetic anisotropy is adopted.The magnetic field,stress and mechanical vibration can be obtained from the 3D magnetic-mechanical analysis of reactor core.Then the calculated results are compared with those not considering 3D magnetic properties.Finally,the experimental results of single-phase saturated reactor prototype prove the validity of the numerical model and analysis method.The research work of this thesis is helpful to improve the calculation accuracy and optimize reactor products in the design stage,which can shorten the development cycle and test cost. |
