海上直流风电场内网中串联直流风机的变速控制

Variable Speed Control of Series-Connected DC Wind Turbines in the Internal Grid of Offshore DC Wind Farm

直流风电场内网中直流风机的串联被证明是一种有潜力的大规模海上风能汇聚方案。然而,直流风机电压限幅期间的弃风现象是制约直流串联型风场商业化的主要因素。描述了海上直流风场内网中串联直流风机的耦合特性。为减少弃风,提出了电压限幅下串联直流风机的变速控制策略。为实现风场级研究中的所有控制,建立了含机电暂态特性的直流风机平均值模型。仿真算例结果,验证了所提策略的有效性。

It is proved that the series-connected DC wind turbine （DCWT） in internal grid of DC wind farm is a potential scheme for large-scale offshore wind energy collection. However, the wind energy curtailment during the period of wind turbine voltage limitation is a main factor that constrains the industrial development of this DC wind farm scheme. The interaction characteristics of series-connected DC wind turbines are described in detail. To decreasing wind energy curtailment, a variable speed control strategy under voltage limitation of series-connected DC wind turbines is proposed. To implement all control function researched in the scale of wind farm, a generalized average model of DCWT, in which the electromechanical transients and all control functions are included, is established. The effectiveness of the proposed control strategy, by which the output performance of the series-connected DC wind turbine can be improved significantly, is validated by PSCAD/EMTDC based simulation results.