Calculating the current distribution in power transformer windings using finite element analysis with circuit constraints

The paper is concerned with the formulation of an A-V finite element method to simulate the electromagnetic field and current distribution in the windings of power transformers with nonnegligible circulating current. The algorithm combines field analysis and network analysis of the electric circuit in a way that is most efficient for the practical design of transformers. Vector potential A is the variable concerned with the magnetic field and its effect. The eddy current in each conductor is treated by the generally used method, whereas the choice of the terms for the electric circuit is modified so that the transpositions of transformer windings, variant electric circuit connections in or out of windings and sinusoidal excitation, can be formulated easily and systematically under the multiprojection finite element method that is employed to approximate the three-dimensional field. Furthermore, the resulting bandwidth of the coefficient matrix can be reduced when the equation is solved by the elimination method. Validation was verified by experiment