Analysis of decreasing resistance to short circuit impact under dc bias of transformer

Due to unipolar operation and non-linear load, the AC transformer grounded by the DC current intrusion, the vibration displacement of the transformer winding is increased, and the short-circuit impact resistance of the winding is greatly reduced, which seriously threatens the safe operation of the transformer. In this paper, the vibration characteristics of the windings and pads under DC bias are analyzed by calculating the layered refinement model of the windings. On this basis, the reasons for the decline in short-circuit impact capability are analyzed to provide a basis for solving the problem.