Optimal control for an HVDC system with series connected offshore wind turbines

This paper studies an HVDC system based on pulse-width-modulated current source converters (PWM-CSC) which is suitable for series connection of offshore wind turbines. A high-frequency link based on reduced matrix converter is proposed as energy conversion system in each wind turbine. An optimal linear quadratic regulator is designed in order to reduce the complexity of the inner-loop and to improve its dynamic performance. Operation features of this control are tested in stationary state and transient conditions.