Experimental Study on Influence of Soil–Structure Interaction on Seismic Performance of UHV Transformer

Abstract

ABSTRACT Ultra-high voltage (UHV) transformer has a high seismic vulnerability. The transformers are usually directly connected to the shaking table to conduct an experiment to study its seismic performance, without considering the effect of the foundation soil on the upper equipment. In the present study, the transformer was scaled down based on the dimensional theory. Then, a soil box that can effectively eliminate the boundary effect is designed and a method that can simulate the site category is proposed. Finally, shaking table tests were conducted on rigid foundations and type I site for the scaled-down model, the seismic response of equipment under different site types is obtained. The results imply that under the rigid foundation, the transformer body response is larger with the seismic wave input in the X+Z direction compared to the seismic wave input in the X-direction; as the seismic acceleration increase, the acceleration and strain of bushings gradually ascend, and the response of bushing with Y direction earthquake wave input is significant than that with X direction earthquake wave input. Under type I site condition, with the earthquake excitation increase, the acceleration amplification effect for transformer body caused by the soil–structure interaction decreases gradually; the response of high voltage bushing under earthquake waves is more significant compared with medium and low voltage bushing; with the earthquake excitation increases, the acceleration of high voltage bushing is 1.13 to 1.40 times that of rigid foundation connection, and the strain response is 1.01 to 1.26 times that of rigid foundation connection. The research findings can be applied in the seismic field of UHV transformers to improve the level of seismic design.