Stability improvement of an integrated offshore wind farm and seashore wave farm fed to a power grid using an HVDC link

This paper presents the analyzed results of an integration of an offshore wind farm (OWF) and a seashore wave farm (SWF) connected to an onshore large power grid through a high-voltage direct-current (HVDC) link to simultaneously achieve power-fluctuation mitigation and dynamic-stability enhancement. The performance of the studied OWF is simulated by three equivalent aggregated doubly-fed induction generators (DFIGs) driven by three equivalent aggregated wind turbines through three gearboxes. The characteristics of the studied SWF are simulated by three equivalent aggregated squirrel-cage induction generator (SCIG) driven by three equivalent aggregated Wells turbines through three gearboxes. A frequency-domain approach based on a linearized system model using eigenvalue analysis and a time-domain scheme based on a nonlinear system model subject to a torque disturbance are systematically carried out. It can be concluded from the simulation results that the proposed HVDC can effectively stabilize the studied integrated OWF and SWF under various disturbance conditions. The inherent power fluctuations injected to the power grid can also be effectively mitigated by the proposed control scheme.