Backstepping Controller Design for the Medium and Low Voltage Stages of Smart Transformer

Smart Transformer (ST) is a smart device allowing the integration of renewable energy resources, energy storage systems and electric vehicle charging stations into the grid. The ST plays a manager role between the different parts of the Smart Grid (SG), due to its features, namely, bidirectional power control, automatic voltage regulation, power quality improvement and advanced communication services. The three-stage topology of the smart transformer is considered as the most appropriate one for SG requirements. To improve the ST performance, several controller strategies such as, Proportional-Integral controller, predictive controller, and linear-quadratic-regulator, have been proposed. These controllers, practically, show good performance, but they are not robust to parameter variations and grid perturbations. To overcome these limitations, a nonlinear adaptive Backstepping controller is proposed in this paper. The accurate design steps of Backstepping controller are presented and investigated. The effectiveness of the proposed controller is validated through simulations results.