Coordinated control for multi terminal DC grids connected to offshore wind farms

This article deals with power flow coordination of a HVDC grid used to connect offshore wind farms to several mainland grids. The coordination of the DC grid is achieved thanks to a centralized control which monitors and sends proper setpoints to manage power flow. This controller is equipped with a dedicated algorithm which enables to guarantee as much as possible the desired power transfer and cope with wind power forecast errors. Moreover, this HVDC grid controller is used as interface for the AC transmission system operator to redistribute power flow among grid side converter stations in order to de-risk AC contingencies and avoid wind power spillage. Simulations results obtained from an EMT model of a five-terminal MTDC grid with Modular Multilevel Converters prove the effectiveness of the proposed methodology in normal operation as well as the system restoration after a wind farm disconnection.