Real time marine current turbine emulator: Design, development and control strategies

This paper is a contribution to the development of real time emulators, applied for marine current energy conversion. The main components of the emulator are: an electromechanical sub-system (ES) and an informatics subsystem (IS); structure based on "hardware-in the-loop" (HILS) simulation techniques. The ES is composed from three electrical drives: an asynchronous machine that emulates the marine turbine, an asynchronous generator, used to study the energy conversion and grid connection, and a break, which develops extra loads and variable moment of inertia. The IS is a supervising and control subsystem and is composed from a computational unit and different interface devices. The studied system is a fixed speed marine current generation system based on Double Fed Induction Generator (DFIG). The stator of the generator is directly connected to the grid while the rotor is connected through a back-to-back converter which is dimensioned to stand only for a fraction of the generator rated power.