Internal Oil Flow of Transformer Based on Multiphysics Coupling Characteristic Analysis

The misoperation of gas protection in transformer out-of-zone faults will seriously affect the security and stability level of power system. In this paper, the oil flow characteristics in transformer under different operating conditions are analyzed by multi-physical field coupling simulation. The principle of common gas protection relays and their causes of misoperation are analyzed. A numerical simulation model of multi-physical field inside transformer is established. The inner core and winding of transformer are modeled and simulated by ANSYS Maxwell 3D and ANSYS Fluent software. The variation of multiphysical field in normal operation, out-of-zone fault and in-zone fault of transformer is obtained. The changes of magnetic field and electromagnetic stress, oil flow and outlet pressure of inner winding and core of transformer are analyzed. This study provides a new basis for formulating measures to improve the reliability of gas protection operation.