Abstract

This paper proposes a method for predicting the load noise of high-voltage (HV) transformers. When the transformer is loaded, the electromagnetic force is generated by the interaction between electric and magnetic fields. This force, the so-called Lorentz force, induces the vibration of the winding structure causing the load noise of transformer. Therefore, calculating the Lorentz force plays a crucial role in predicting the load noise. Herein, a 3-Dimensional equivalent magnetic circuit network (3-D EMCN) is applied to calculate the Lorentz force, instead of 3-Dimensional finite element analysis (3-D FEA) to shorten the computation time. Subsequently, considering the relationship between the sound pressure and the Lorentz force, the calculated force can be applied in the equation for the sound pressure level (SPL), which represents the relative sound pressure on a logarithmic scale. The formula for the sound pressure varies depending on the sound source model. The source model of load noise can be represented as a dipole source because the structure of the transformer windings is considered as an unbaffled speaker. The transformer parameters identified to affect the load noise are additionally considered for more accurate prediction of load noise. The parameters identified to increase the load noise are simply multiplied to the equation, whereas those with the opposite effect are multiplied inversely. Finally, after this compensation process, the accuracy of the load noise prediction equation is calculated as the standard deviation of the differences between the experimental and calculated results.

Highlights

  • The rapid growth of the entire industry and recent interest in sustainable development have increased the requirements for electrical power supplies and demand for high-voltage (HV) transformers

  • The electromagnetic force, the so-called Lorentz force which is the main source of load noise is calculated

  • After the appropriate form of the sound pressure that can be applied to the structure of the transformer is obtained, the relationship between the Lorentz force and the sound pressure level (SPL) will be shown as an initial load noise prediction equation

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Summary

INTRODUCTION

The rapid growth of the entire industry and recent interest in sustainable development have increased the requirements for electrical power supplies and demand for high-voltage (HV) transformers. The accuracy of the 3-D EMCN is important for accurate predictions of the load noise of HV transformers This can be verified by comparing the calculation results of the 3-D EMCN for the Lorentz force with those of 3-D FEA under the same load conditions. After the appropriate form of the sound pressure that can be applied to the structure of the transformer is obtained, the relationship between the Lorentz force and the SPL will be shown as an initial load noise prediction equation

EXPRESSION OF SPL
COMPENSATION AND VERIFICATION OF THE PREDICTION EQUATION FOR LOAD NOISE
VERIFICATION OF LOAD NOISE PREDICTION EQUATIONS
CONCLUSIONS

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