Equivalent study of stray magnetic field of extra-large current transformer based on finite element simulation

At present, the extra-large current transformer (ELCT) lacks an equivalent method for on-site stray magnetic field interference at the generator outlet. In order to solve the problem that it is impossible to effectively test the on-site stray magnetic field interference resistance performance of ELCT. This paper studies the feasibility of simulating the equivalent field interference of the leakage magnetic field generated by eccentric busbar current and verifying the thermal effect of ELCT's balanced winding through three-dimensional finite element simulation. First, a super-large current test platform and a corresponding simulation model are established, and the accuracy of the simulation model and the fitting magnetic hysteresis curve is verified by comparing the simulation and experiment. Then, the spatial and temporal distributions of the magnetic field environment in the six-phase conductor with a neutral point and the eccentric busbar situation of the ELCT core are simulated. Based on the distribution of the magnetic field, the method of interference equivalence in the magnetic field of the core is obtained by using the eccentric busbar test method. The shielding performance and heating conditions of two groups of balanced windings with different arrangement directions are simulated and compared. The simulation results show that the distribution of the magnetic field in the core has important reference significance for optimizing the thermal effect of the balanced winding; the eccentric busbar test method can simulate the degree of interference from the scattered magnetic field under the actual conditions and meet the testing needs for verifying the heating condition of ELCT.