@ARTICLE{Riemer_Björn_Multi-harmonic_2015, author={Riemer, Björn and Hameyer, Kay}, volume={vol. 64}, number={No 1 March}, journal={Archives of Electrical Engineering}, pages={129-138}, howpublished={online}, year={2015}, publisher={Polish Academy of Sciences}, abstract={This paper presents a methodology for the calculation of the flux distribution in power transformer cores considering nonlinear material, with reduced computational effort. The calculation is based on a weak coupled multi-harmonic approach. The methodology can be applied to 2D and 3D Finite Element models. The decrease of the computational effort for the proposed approach is >90% compared to a time-stepping method at comparable accuracy. Furthermore, the approach offers a possibility for parallelisation to reduce the overall simulation time. The speed up of the parallelised simulations is nearly linear. The methodology is applied to a single-phase and a three-phase power transformer. Exemplary, the flux distribution for a capacitive load case is determined and the differences in the flux distribution obtained by a 2D and 3D FE model are pointed out. Deviations are significant, due to the fact, that the 2D FE model underestimates the stray fluxes. It is shown, that a 3D FE model of the transformer is required, if the nonlinearity of the core material has to be taken into account.}, type={Artykuły / Articles}, title={Multi-harmonic approach to determine load dependent local flux variations in power transformer cores}, URL={http://www.journals.pan.pl/Content/85058/PDF/11_paper.pdf}, doi={10.1515/aee-2015-0012}, keywords={flux distribution, local flux variations, multi-harmonic FEM, nonlinear FEM, power transformer}, }