Performance study of control strategies applied to smart transformer model based on a five-level cascaded H-bridge rectifier

Abstract

This paper proposes a Smart transformer (ST) model comprising a five-level Cascaded H-Bridge (CHB) rectifier at its medium voltage stage, dual active bridge converters at its high-frequency stage, and a four-leg inverter at its low voltage stage. Indeed, the CHB rectifier enables the improvement of ST modularity and the integration of many Renewable Energy Sources (RESs). Nevertheless, the high integration of RESs can lead to voltage fluctuations due to their intermittent energy production which can affect the ST behavior. Therefore, a robust controller is required to improve the ST's dynamic performance. In this context, vector-oriented control, Sliding Mode Control (SMC), and adaptive backstepping control are studied in this paper. To select the most appropriate controllers, a series of simulations under anomalous conditions, including voltage variations, parametric variations, and fault occurrence, are performed using Matlab software. The obtained simulation results demonstrate that SMC provides the best performance and the greatest robustness.