The Enhanced Average Model of the Smart Transformer with the Wye-Delta Connection of Dual Active Bridges

Abstract

Nowadays, many power electronics converters (PECs) are connected to the distribution grid, increasing the energy quality requirements in point of common coupling (PCC). One of the promising solutions to improve the energy quality is a smart transformer (ST) characterised by additional benefits in relation to the classical transformer throughout the possibility to implement advanced functionalities in PCC. However, the ST contains a lot of power semiconductor switches, making a problem for simulation software and the computer hardware when the control algorithm and all the ST functionalities are investigated. Usually, the solver algorithms in simulation software are used to create many linear time-varying states spaces, which increases exponentially with the number of switches. Therefore, very important is a model averaging process of the selected advanced ST topology, which is the aim of the paper. The proposed ST average model is compared with full switching models of each ST power conversion stage. It allows for decreasing the simulation time a dozen times, enabling the control algorithm analysis with a full ST model. The proposed solution and results prove steady-state and dynamic behaviour of the average model and provide a comprehensive averaging process for a novel multiple active bridge direct current/direct current (DC/DC) converter inside the ST.