Analysis of an integrated offshore wind farm and seashore wave farm fed to a power grid through a variable frequency transformer

This paper presents the analyzed results of an integrated offshore wind farm (OWF) and seashore wave farm (WAF) connected to an onshore large power grid through a variable frequency transformer (VFT) to simultaneously achieve power-fluctuation mitigation and stability enhancement. The performance of the studied OWF is simulated by an equivalent aggregated 80-MW doubly-fed induction generator (DFIG) while the characteristics of the studied WAF are simulated by an equivalent aggregated 40-MW squirrel-cage induction generator (SCIG). Steady-state operating conditions of the studied system under various values of wind speed and axial speed are performed. A time-domain scheme based on a nonlinear system model subject to a disturbance condition is also carried out. It can be concluded from the simulation results that the proposed VFT can effectively stabilize the studied hybrid OWF and WAF under various disturbance conditions. The inherent fluctuations of the power injected to the power grid can also be effectively smoothed by the proposed VFT.