双馈风力发电机交流励磁用变频电源拓扑浅析

变速恒频双馈异步风力发电机的控制主要是通过励磁变频器对发电机转子实施功率控制来实现,因而励磁电源的类型、特性对于风电机组的运行性能乃至所并电网的供电质量和运行稳定性至关重要.首先阐述了双馈型风电系统对励磁电源的要求,以此为标准对6种有潜力的频率变换电路分别进行了分析和评价,对如何选用提出了一些可供参考的观点,最后得出了有价值的结论:两电平电压型双脉宽调制(PWM)变换器是目前变速恒频双馈风力发电机交流励磁电源的优选方案,多电平PWM变换器与谐振式软开关变换器相结合是今后交流励磁电源的发展方向.

Analysis on the Frequency Converter Served for the AC Excitation of Wind-power DFIG

Control of variable-speed constant-frequency (VSCF) wind-power doubly-fed induction generator (DFIG) is realized by performing power control of DFIG via AC excitation of frequency converter. Hence, the type and characteristic of the excitation supply is very important for the operational performance of DFIG and, consequently, the electric power quality and operation stability of the grid connected by the DFIG. In this paper, the requirements of DFIG to the AC excitation power supply are described and discussed firstly. Six types of potential frequency converter topology are then analyzed and evaluated according to the aforementioned requirements and, meanwhile, some referable viewpoints for selection of the converter are put foreword. Finally, a valuable conclusion is drawn from the discussions that the two-level voltage-source dual-PWM converter is possibly the optimal design for the AC excitation power supply of the VSCF DFIG at present and the combination of multi-level converter with resonant soft-switching converter is a promising developing direction.