Design of a Simulation Startup Model for a Marine Current Turbine

Abstract: This project is aimed at developing a simulation model in Simulink for a new startup system controlling the marine current turbine at Uppsala university's research facility in Söderfors. The goal is to design a circuit that is able to switch between feeding power to and extracting power from the synchronous machine in order to control the rotational speed of the turbine. The technical solution consisted of two separate circuits combined into the final system. First, the synchronous machine is run as a BLDC motor where power is fed to the motor in order to accelerate the turbine. Then, at a specified rotational speed threshold the BLDC circuit is disconnected and the turbine continues to accelerate by picking up power from the water alone. Lastly, when the rotational speed reaches the desired setpoint for the rotational speed the synchronous machine is connected to a DC load. By controlling the power extracted in the load with a PI controller the rotational speed of the turbine stays at the setpoint value. Results from the simulation model shows that it is possible to control the startup process of the turbine with such a system. In future projects improvements can be made regarding removing current spikes, more smooth power usage and faster PI controllers. To further develop the startup system the next step would be to translate the simulation model into LabVIEW code in order to test it at the site in Söderfors.