Harmonic Response Analysis of 220 kV Oil-Immersed Transformer Winding And Core Under Preload

Power transformers are important equipment in the power system, but various faults are inevitable in the actual operation. If the transformer winding is deformed, it will lead to a decrease in the insulation and mechanical properties of the transformer, which in turn can cause transformer failure. In this article, a 220 kV three-phase oil immersed power transformer is taken as the research object. The vibration models of the transformer winding and core under different preloading forces are established using ANSYS Workbench. The structural modal analysis is carried out to obtain the natural frequencies and modal shapes of orders 1 to 6. Then, the mode superposition method is used for harmonic response analysis to obtain the analysis results. The results show that under the influence of preloading force, the modal vibration mode of the transformer structure remains basically unchanged, but the corresponding modal frequencies of each order change with the preloading force. Based on the results of modal analysis and harmonic response analysis, the reasonable setting of preload force for transformer windings can be guided, which can be used to identify weak links in the operation of transformers, and to reduce the impact of short circuit electromagnetic force and magnetostrictive vibration on transformers by setting reasonable factory preload force.