Coordinated power system frequency regulation by PMSG-based offshore wind farm

This paper proposes a new control scheme for variable speed wind turbines with permanent magnet synchronous generators (VSWT-PMSG) based offshore wind farm (WF), which is connected to the main onshore grid through voltage source converter (VSC) based high voltage DC (HVDC) transmission system, to decrease the frequency fluctuations of the onshore grid. A centralized droop controller for VSWT-PMSGs is designed in order that the offshore WF can control the frequency oscillations of the main grid in which a large scale of WF composed of fixed speed wind turbines with squirrel cage induction generators (FSWT-SCIGs) is installed. In the proposed system, control of the frequency oscillations is performed by adopting the deloading operation. The simulation analysis is performed on a model system composed of synchronous generators (SGs), FSWT-SCIGs based WF, and VSWT-PMSGs based offshore WF to show the effectiveness of the proposed coordinated control system.