Numerical Computation of the Vibroacoustic Behaviour of an Oil-Immersed Power Transformer

Abstract

This paper presents a numerical calculation method that allows for the simulation of the mechanical and acoustic behaviour of a transformer tank. In order to simulate the vibroacoustic behaviour of an oil-immersed power transformer, an acoustic-mechanical coupled three-dimensional finite-element method model of a transformer was setup. The simulation is performed in the frequency domain at frequencies adjacent to the driving frequency. A vibration source closely resembling the actual active part of the transformer is placed within the oil-filled tank that mechanically represents an acoustic cavity with flexible steel boundaries. Via a fluid-structure interface the vibration source generates acoustic waves in the oil medium which partly transmit through the tank wall structure and partly reflect within the steel transformer tank again via a fluid-structure interface. The vibrating tank is then coupled with the external acoustic air medium and the corresponding sound field is calculated and evaluated according to IEC 60076-10. This numerical computation allows for the direct calculation of the complete vibrational and acoustic behaviour of a transformer.