Dispatching and frequency control strategies for marine current turbines based on doubly fed induction generator

This paper presents the modeling and development of a dispatchable large-scale marine current turbine (MCT) farm equipped with power fluctuation compensation and primary frequency control schemes. The proposed control strategies rely on the regular and highly predictable power extraction from the marine currents, which are essentially governed by astronomical forces. Therefore, a mathematical model for prediction of marine current speed is developed and validated with the recorded measurements. Subsequently, the effect of velocity disturbances caused by the swell effect is studied and a battery energy storage station (BESS) control strategy for power fluctuation mitigation is proposed with reduced BESS capacity. Additionally, the provision of frequency control for MCT based on BESS has been discussed. The performance of the BESS-based frequency control strategy has been analyzed and compared with that of frequency control based on the combination of inertial response and deloaded operation. The simulation results depict that both these strategies can effectively enable MCTs to participate in primary frequency control, however, provision of frequency control based on BESS is more feasible in terms of profitability and reduction in fossil fuel consumption.