DC Collection topology and Control for All-DC Offshore Wind Power System Considering Surplus Power Distribution

With the large-scale and far-reaching development of offshore wind farms, the offshore wind power all-DC transmission system has become one of the research hotspots. This article proposes a new series-parallel DC wind farm collection topology for offshore wind power all-DC systems, including series-parallel converter topology design for medium-voltage DC wind turbines to reduce submodule capacitor voltage ripple, which can be applied to medium-voltage large capacity DC wind turbines. Aiming at the problem of "wind abandonment" that is prone to occur in series wind turbines, a power balance converter is proposed to provide a flow path for the surplus power between series wind turbines, so that each wind turbine can achieve maximum power point tracking (MPPT) operation. Then, corresponding control and modulation strategies are designed for the proposed new offshore wind turbine full DC collection topology. Finally, the feasibility of the proposed topology and the effectiveness of the control and modulation strategies are verified through Matlab/Simulink simulation.