Optimised Active Disturbance Rejection Control for Grid-Connected Floating Offshore Wind Turbines Under Wave Disturbance

To mitigate the pronounced power fluctuations in floating offshore wind turbine (FOWT) systems induced by complex wind and wave conditions, this study proposes a novel grid-connected control strategy that integrates Wave Disturbance Compensation (WDC) and active disturbance rejection control (ADRC). The objective of this strategy is to reduce the total harmonic distortion (THD) of grid-connected voltage and current in the presence of non-stationary disturbances. The WDC module suppresses low- frequency wind-wave-induced fluctuations through a feedforward compensation mechanism, while the ADRC controller conducts real-time disturbance estimation and rejection, thereby enhancing the robustness and operational stability of the system. To further improve control performance, an enhanced Whale Migration Algorithm, termed WMA–Lévy–Spiral, incorporating Lévy flight and a spiral contraction strategy, is developed for the global optimisation of ADRC parameters. A co-simulation platform for a 5 MW FOWT was constructed using Simulink and OPENFAST, with the system’s dynamic behaviour visualised via ParaView. Simulation results demonstrated that the proposed method reduced the THD of grid-connected voltage and current to 2.46% and 0.91%, respectively. Moreover, hardware-in-the-loop (HIL) experiments further verified the practical feasibility and effectiveness of the proposed control system.