Subspace Correction Method for Computing Magnetic Shields in Large Power Transformers

In a large power transformer, magnetic shields of the oil tank are made of grain-oriented silicon steel laminations. The thickness of a lamination is 0.3 mm and the thickness of its coating film is only 4 μm. Accurate solution of non-linear eddy current problem in such a multi-scale structure is very challenging. This paper proposes a subspace correction method (SCM) to solve the nonlinear eddy current problem in the lamination system. The method can compute 3-D eddy currents in the steel laminations and is very efficient for large-scale simulations. Numerical experiments on the TEAM benchmark model P21^c-M1 show good agreements between the calculated and measured data and demonstrate the competitive behavior of the SCM.