Control Strategies for Tidal Stream Turbine Systems - A Comparative Study of ADRC, PI, and High-Order Sliding Mode Controls

Abstract : Due to the characteristics of predictability and high energy density in tidal current resources, tidal stream turbine generation systems have been developed in the last decades around the world. Speed control would be necessary to perform the maximum power point tracking (MPPT) task under varying marine current conditions. Considering that various disturbances or parameter uncertainties may deteriorate the system performance, the active disturbance rejection control (ADRC) strategy seems to be an interesting solution for controller designs. In this paper, an ADRC strategy is applied in the speed control loop for realizing MPPT under disturbances of current velocity and turbine torque. The system performance of the proposed ADRC is compared with PI and high-order sliding mode (HOSM) control strategies. The operation under swell wave disturbance is also carried out. This simulation-based comparative study shows the effectiveness and advantages of the ADRC controller over conventional PI controller in terms of quick convergence, overshoots elimination, and better performance under disturbances.