Decoupling control of series-connected DC wind turbines with energy storage system for offshore DC wind farm

DC wind farm (DCWF) with series-connected DC wind turbines (DCWT) is proved to be a potential solution of offshore wind power collection. The coupling behavior of series-connected DCWTs is described in detail. Possible wind energy curtailment during the period of wind turbine voltage limitation and its key impact factors are firstly quantitatively derived. A decoupling control strategy is proposed under voltage limiting condition of the DCWT with energy storage system (ESS) to improve its wind energy capture. This control algorithm can be implemented in the local DCWT controller without the communication. Dynamic simulation cases under different operation conditions have been conducted to evaluate the effectiveness of the proposed control strategy. It is found that the proposed control strategy might be a solution for wind energy curtailment, which will significantly improve the performance of the series-connected DC wind turbines between the time scale above seconds and below minutes.