| In order to optimize the structure of power equipments and realize active vibration and noise reduction,it is necessary to accurately calculate and master the vibration characteristics of its core.According to the complexity of operating conditions,the vibration characteristics of shunt reactor,two-stage magnetic valve controllable reactor,anode saturable reactor and high frequency transformer core are studied in this paper.The main work is as follows:(1)The magnetostriction and magnetization characteristics of silicon steel sheets under different service conditions,such as power frequency,harmonic,DC bias,and non-sinusoidal excitation,are measured by laser testing system.The magnetostriction and magnetization characteristics curves of silicon steel sheets in different magnetization directions are compared and analyzed,which provides data basis for vibration calculation of power equipments' core.(2)Based on the improved essential magnetostrictive model,a magneto-mechanical coupling model considering magnetostrictive force,Maxwell electromagnetic force and winding force is established.The vibration and force characteristics of the core and winding of a high voltage shunt reactor are calculated,and the influence of air-gap cushion with different Young's modulus on the core vibration is studied.In order to compare the influence of magnetostrictive force and Maxwell electromagnetic force on core vibration,the transformer model(core without air gap)and shunt reactor model(core with air gap)with same core shape and winding structure designed and manufactured by Tianwei Baobian Electric Co.,Ltd.Technology Center are calculated and compared quantitatively.Finally,the calculated results are verified by experiment.(3)According to the magnetostrictive essential model,the vibration mechanism of the core of the two-stage magnetic valve controllable reactor under DC bias is analyzed,and the external circuit model of the two-stage magnetic valve reactor is simplified.Based on the measured data of magnetostriction and magnetization characteristics of silicon steel sheets under DC bias,the magnetic flux density,stress,displacement distribution and vibration of the core of the two-stage magnetic valve reactor with or without DC bias are calculated and analyzed.The test platform of two-stage magnetic valve reactor is built to test the vibration law of its core under different working conditions.The test results verify the validity of finite element calculation model.(4)The magnetic field,force and displacement distribution of the core of the anode saturable reactor are calculated.The results show that the vibration of the anode saturable reactor core is much larger than that of other power equipments.In order to reduce the noise of anode saturable reactor core,a method of polyurethane damping elastomer noise reduction is proposed.The single core of the anode saturable reactor used in Jinping-Jiangnan(±800kV/4750A)HVDC transmission project is taken as the research object.The polyurethane damping elastomer is applied to the core.The results show that the effect of polyurethane damping elastomer on reducing vibration and noise of the core is very clear.It provides a solution for reducing vibration and noise of anode saturable reactor.(5)To solve the problem that amorphous and nanocrystalline sheets are too thin and brittle to measure their magnetostrictive properties by using magnetostrictive measuring equipment,a magnetostrictive inversion method based on magnetic ring vibration is proposed in this dissertation.The results of magnetostriction measurements of silicon steel,amorphous and nanocrystalline materials show that the magnetostriction of amorphous materials under different frequencies is much larger than that of silicon steel and nanocrystalline materials.In view of the large magnetostriction of amorphous materials,the vibration and noise of an amorphous high frequency transformer under sinusoidal and non-sinusoidal excitation are measured and analyzed in combination with its natural frequency.This part of the research results provide theoretical basis and experimental data for magnetostrictive measurement of new magnetic materials and consideration of natural frequency and non-sinusoidal excitation in the design stage of high frequency transformer. |
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