Improved optimal torque control for large scale floating offshore wind turbines based on interval type-2 fuzzy logic system

Abstract

As floating offshore wind turbines (FOWTs) evolve toward large capacities, the dynamic response lag caused by large rotor inertia become increasingly significant in the wind energy conversion system (WECS). This paper introduces a novel torque compensation method to enhance the traditional optimal torque control (OTC) response speed. In this improved OTC (IOTC) scheme, the impact of the floating platform pitch motion on aerodynamics is considered. The influence of the torque compensation on system responsiveness and stability is also analyzed. Based on this analysis, an interval type-2 fuzzy logic system (IT2-FLS) is designed to adapt the compensation coefficient adaptively. Multiple simulation experiments are performed on a 15 MW FOWT model to verify the effectiveness of the proposed method. The results show that the proposed approach surpasses traditional OTC and optimal tip speed ratio (TSR) methods in terms of power output. Additionally, introducing the IT2-FLS enhances power stability compared to fixed compensation coefficients and type-1 fuzzy logic systems (T1-FLS).