Finite-Element-Based Nonlinear Physical Model of Iron-Core Transformers for Dynamic Simulations

摘要

A finite-element (FE)-based transformer physical phase variable model is proposed. In this model, the effects of nonlinear magnetization on inductances are included by considering the inductance variations with the amplitude of the ac flux as well as its phase angle during a complete ac cycle. Such a consideration is represented by 2-D inductance tables. The magnetizing currents at various magnetization levels are used to calculate the inductances then build the table. The magnetizing currents are determined using circuit-coupled FE analysis of the transformer with sinusoidal voltage supplies. The structure of the inductance table is given and the procedure of inductance table lookup during dynamic simulation is provided. Simulink implementation of the FE-based transformer phase variable model is performed. The validity of the presented technique is verified through comparing the magnetizing current waveforms obtained from the FE-based phase variable model and those from an FE model. The significance of the proposed FE-based phase variable model is in its accuracy and its applicability for dynamic simulation of interconnected components in a power system.