Optimized control of hybrid excitation wind generators using advanced sliding mode strategies

Abstract

Wind power is a sustainable and reliable solution to the growing global demand for electricity, driven by the shift toward renewable energy sources. Hybrid Excitation Synchronous Generators (HESG) stand out among emerging technologies for their ability to efficiently transform wind energy into clean power. Unlike conventional systems, the HESG uniquely combines dual-excitation mechanisms, integrating permanent magnet excitation with winding field operations, providing superior adaptability, reduced complexity, and enhanced performance under variable wind conditions. However, controlling HESGs under nonlinear and variable wind conditions presents challenges that demand advanced control strategies to ensure optimal performance and power quality. The study aims to optimize HESG flux by refining the design of the direct current excitation coils and permanent magnets, ensuring higher system reliability and efficiency. To address these challenges, the study introduces Smooth function based $3^{\text{rd}}$order sliding mode control (SF-TOSMC), chosen for its ability to handle system nonlinearities, reduce chattering, and improve stability. The proposed SF-TOSMC replaces the discontinuous "sign" function with a continuous "smooth" function, significantly enhancing stability and improving overall system performance. The control strategy was validated through MATLAB simulations and compared to proportional integral (PI) and second-order sliding mode control (SOSMC), achieving a 72 % reduction in harmonic distortion for grid-injected current and an overall efficiency of 97.9 % under unpredictable wind conditions, outperforming SOSMC (92.3 %) and PI (83.3 %). These findings underline the effectiveness of SF-TOSMC in overcoming HESG control challenges, demonstrating its transformative potential in enhancing energy efficiency, grid stability, and cost-effectiveness in renewable energy applications.