中文摘要：

传统交流组网风电场系统存在多次电能转换、成本高的问题。针对这个问题,设计了一种大容量直驱风电机组级联直流组网海上风电场系统,其直接将每台机组的直流输出级联形成高压直流进行传输,而无需额外的海上升压站平台。风电机组采用了永磁直驱风力发电机及其变流器,其中变流器包括了AC/DC单元和DC/DC单元,并设计了控制策略,即通过DC/DC单元的占空比调节来实现电流的持续输出和最大功率跟踪。陆基逆变电站采用晶闸管型逆变器,设计了工作模式和控制策略,其主要功能是实现高压直流链路的电压电流调节。最后,基于PSCAD/EMTDC仿真平台,搭建了容量为150 MW的风电场系统进行了仿真计算,计算结果验证了该系统具有较高的鲁棒性和对风速变化的适应性,同时每个机组都能独立的实现最大风能捕获。

英文摘要：

The traditional AC network wind farm system has some problems, such as repeated electrical energy conversion, high cost. Aiming at it, A large capacity direct drive wind power unit cascaded DC grid system was designed. The network allowed series interconnection of wind turbines to distributed high-voltage DC （HVDC） power transmission without the AC transformer and the offshore platform. The direct drive permanent magnet power generator （PMSG） and the converter were used in the wind turbine. The converter including the AC/DC unit and the DC/DC unit, and the control strategy has been designed, that was allowed the current to flow at all times in the DC link while simultaneously regulating generator torque by adjusting the duty of the DC/DC unit. The working mode and the control strategy of the land-based thyristor-based inverter power plant had also been developed to realizing the voltage and current regulation of the HVDC link. At last, a complete 150 MW wind farm simulation based on PSCAD/EMTDC was built, and some calculations had been done. The simulation results indicated that the stable operation of the proposed configuration where each turbine was able to independently perform peak power tracking and the robustness and adaptability to the change of wind speed was also good at the same time.