Numerical Simulation and Analysis of a Saturated-Core-Type Superconducting Fault Current Limiter

The saturated-core-type superconducting fault current limiter (SCSFCL) is an important device to limit increasing fault currents in electrical power grids. However, there have been few numerical simulations carried out to simulate the properties of the superconducting DC coil in the SCSFCL, but such modeling is indispensable to the design and analysis of such devices. In this paper, a simulation method to simulate the SCSFCL with COMSOL Multiphysics is presented, and the AC losses of the DC coil in the normal, nonlimiting state, which is its usual operating state, are simulated and analyzed for the first time. A strategy to simulate the AC loss of the superconducting coil with a three-dimensional (3-D) model is given first. The nonlinear electric and magnetic problems are decoupled first. Next, the model is divided into smaller models for separate calculations. The 3-D model is further simplified into a 2-D model based on the worst case scenario for a conservative design. The AC loss distribution within the coil is given and the relationship between the AC loss and an AC component of the current is analyzed, and it is found that the outermost coil regions have much larger AC loss than the coils near the centre.