Inrush current modeling of three-limb core-type power transformers based on efficient analytical-numerical hybrid method

Abstract

This study proposes a time-domain analytical-numerical method in order to precisely assess the three-phase three-limb core-type transformer inrush current considering the nonlinear behavior of the iron core. The proposed method focuses on acquiring equations for inrush current and also the magnetic core flux by the application of a simulation-based iterative approach. In this regard, multiple integral equations are solved taking the time intervals into account. Then several derivations and integrations of matrix terms are substituted into the obtained results so as to simplify the solution process. The proposed method is simulated in MATLAB environment. It is shown that the proposed method provides remarkable enhancements in computation time accompanied by excellent accuracy compared with methods based on numerical methods. The simulation results obtained by the proposed analytical-numerical method are also compared with experimental tests to indicate a close and reasonable agreement.