Reduced Order Model Based on Combined POD/LDEIM-Q for Nonlinear Thermoelectric Coupling

The insulation evaluation in converter transformer is a nonlinear thermoelectric coupling problem whose numerical solution is time consuming. To decrease the computation cost, a discrete empirical interpolation method (DEIM) is usually utilized to approximate the nonlinear term with a reduced order model (ROM), but it suffers sometimes from the unstable convergence problem. In this article, a local DEIM based on QR factorization (LDEIM-Q) is proposed. It has a better error bound and can avoid the unexpected instabilities. The LDEIM-Q is combined with the proper orthogonal decomposition (POD) to deal with the nonlinear thermoelectric coupling. A converter transformer model is taken as an example to validate our method in terms of accuracy and efficiency.