中文摘要：

为了提高效率,直驱永磁同步风力发电系统采用三电平双PWM变流器.分析了永磁同步发电机（PMSG）和网侧变流器的数学模型,PMSG采用转子磁场定向的矢量控制策略,网侧变流器采用电网电压定向的矢量控制策略.还详细分析了背靠背系统的中点电压数字模型,由此模型得到通过注入零序电压来平衡中点电压的方法.最后通过风力发电模拟实验,实现了系统单位功率因数发电并网,验证了系统控制策略的有效性;实验结果表明,所采用的中点电位平衡方法具有较好的动稳态平衡能力,能够实现中点电位平衡.

英文摘要：

In order to improve efficiency, three-level dual-PWM converter was used in direct-drive permanent magnetsynchronous wind power generation systems. The mathematical models of the permanent magnet synchronous generator（PMSG） and grid-side converter were analyzed, then rotor field oriented vector control strategy was adopted in PMSG andgrid voltage oriented vector control strategy was applied to the grid-side converter. The neutral point voltage model of back-to-back system was analyzed in detail, according to which a neutral point voltage balancing method based on zero-se-quence voltage injection was obtained. Finally, the systems爷unity power factor generation was achieved and the effective-ness of system control strategy was verified by doing wind power simulation experiment. The experimental results show thatthe neutral point voltage balance method has good steady state and dynamic balance ability, and can implement the bal-anced of neutral point voltage.