Date of Defense
16-4-2025 9:30 AM
Location
F1-1164
Document Type
Dissertation Defense
Degree Name
Doctor of Philosophy in Electrical Engineering
College
COE
Department
Electrical and Communication Engineering
First Advisor
Dr. Rachid Errouissi
Keywords
Renewable energy, disturbance observer, DC-DC boost converter, backstepping control, feedback control, grid tied inverter, back-to-back converter
Abstract
Renewable energy systems face significant challenges in ensuring stability, efficiency, and reliability due to model uncertainties, unmeasured disturbances, and grid variabilities. This thesis addresses these challenges through the development and experimental validation of disturbance observer-based control (DOBC) strategies for power converters. The first study focuses on DC-DC boost converters, employing a backstepping-based DOBC to achieve zero steady-state error, robust stabilization, and compensation for control saturation without requiring anti-windup schemes. Experimental results confirmed the controller effectiveness under diverse load types and operating conditions. The second study presents a robust current control scheme for grid-tied inverters with LCL filters, combining state-feedback control with a disturbance observer (DOB) to ensure high tracking accuracy and closed-loop stability under both balanced and unbalanced grid voltages. Simulations and experiments validated its adaptability and superior performance, even in the presence of parametric uncertainties. The third study extends DOBC to PMSG wind turbine systems, introducing a reconfigurable control framework that dynamically interchanges the roles of machine-side and grid-side converters based on grid conditions. This innovative approach ensures seamless transitions between balanced and unbalanced grid voltages, with robust performance demonstrated through real-time implementation. Collectively, the research provides a comprehensive framework for designing and implementing advanced control strategies to enhance the stability, efficiency, and sustainability of renewable energy systems.
Included in
DISTURBANCE OBSERVER-BASED CONTROL FOR POWER CONVERTERS IN RENEWABLE ENERGY SYSTEMS
F1-1164
Renewable energy systems face significant challenges in ensuring stability, efficiency, and reliability due to model uncertainties, unmeasured disturbances, and grid variabilities. This thesis addresses these challenges through the development and experimental validation of disturbance observer-based control (DOBC) strategies for power converters. The first study focuses on DC-DC boost converters, employing a backstepping-based DOBC to achieve zero steady-state error, robust stabilization, and compensation for control saturation without requiring anti-windup schemes. Experimental results confirmed the controller effectiveness under diverse load types and operating conditions. The second study presents a robust current control scheme for grid-tied inverters with LCL filters, combining state-feedback control with a disturbance observer (DOB) to ensure high tracking accuracy and closed-loop stability under both balanced and unbalanced grid voltages. Simulations and experiments validated its adaptability and superior performance, even in the presence of parametric uncertainties. The third study extends DOBC to PMSG wind turbine systems, introducing a reconfigurable control framework that dynamically interchanges the roles of machine-side and grid-side converters based on grid conditions. This innovative approach ensures seamless transitions between balanced and unbalanced grid voltages, with robust performance demonstrated through real-time implementation. Collectively, the research provides a comprehensive framework for designing and implementing advanced control strategies to enhance the stability, efficiency, and sustainability of renewable energy systems.