变速恒频直驱型风电系统变流器拓扑结构研究

Research on High Power Converters Based on Variable Speed Constant Frequency Direct-Driven Wind Power System

直接驱动型变速恒频风力发电是一种新型的发电技术,它具有无齿轮箱、机械磨损小、整机效率高、运行维护成本低等优点,在风力发电领域中有着很好的应用前景。该系统需要采用全功率变流器,对应的大功率变流器单元可以有不同的拓扑结构,根据每种电路拓扑的特点,整个系统的控制方法都会相应地发生变化。载波相移正弦脉宽调制技术(Carrier Phase Shifted Sinuous Pulse Width Modulation,CPS-SPWM)可以在较低的开关频率下有效地抑制和消除低次谐波,并具有相当大的传输带宽,是一种适于大功率电力电子装置的较佳的开关调制策略。文章首先对直驱型变速恒频风力发电系统基本拓扑结构进行了对比分析,着重介绍了用CPS-SPWM调制方法控制的五电平级联变流器,及其在直驱型风力发电中的应用。直接驱动型风力发电系统几种大功率变流器拓扑结构对比分析,比较了各种拓扑结构的优缺点、技术难点,以及实际应用中存在的问题,并对大功率变流器在风力发电系统应用中的可行性进行了相关分析与探讨,为直驱风力发电系统拓扑结构的选型提供了参考基础。

The Direct-driven variable-speed constant- frequency （DDVSCF） wind energy generation system （WEGS） is a new type wind energy technology. It has many advantages, such as no need to use gearboxes, low mechanical wear, high efficiency, low operation and maintenance cost, therefore it enjoys good application prospect. This system adopts full scale converters with different topologic structures matching along with the corresponding large power converterunit. Baseduponthetopologicfeaturesofeachcircuit, the control method ofthe entire system may be changed accordingly. The Carrier Phase Shifted Sinuous Pulse Width Modulation, （CPS-SPWM） is able to suppress or even eliminate sub-harmonics at the lower switching frequency, thus it has a wide transmission bandwidth and can be used as a better switching regulation strategy applicable to the large power electrical and electronic devices. This paper, first of all, makes a comparative analysis of the basic topologies of the direct-driven variable speed constant frequency wind generation system, laying emphasis on introduction of the converter controlled by CPS-SPWM, and its application in the direct-driven winder power generators. Then more comparative analysis is made among topologic structures of several kinds of large power converters, showing advantages and disadvantages of each structure with its technical difficulties, and highlighting precautions in the actual application. Some feasibility studies are also made for the large power converter to be used in the wind power generation. The study as presented in the paper is of significance to selection of the topologic structure for the direct-driven wind powergeneration system.