并联背靠背PWM变流器在直驱型风力发电系统的应用

Application of Parallel Back-to-back PWM Converter on the Direct-drive Wind Power System

直驱型风力发电系统需要全功率变流器,在现有器件功率水平以及开关频率等诸多因素制约下,变流器直接并联的方式具备结构简单、模块化设计、易扩展的优点。文中通过有效的控制,使并联运行达到了大电流输入的要求,并将基于载波相移技术的背靠背脉宽调制(PWM)变流器应用在直驱型风力发电系统中,开关频率仅为1 kHz。实验表明,在提高等效开关频率、改善输出电流波形的同时不会带来环流问题,这在风电系统的全功率变流器中具有重要意义。

Direct-drive wind power system needs full-scale power converters. To overcome the limits in the capacity and switching frequency, converters are connected in parallel which is simple, modular designed and easy to extend. The paper presents an effective control method to enable the parallel operation meet the demand of large current input. The carrier phase shift technique based parallel back-to-back PWM converter is used on the direct-drive wind power system, with a switching frequency as low as 1 kHz. Experimental results demonstrate the method achieve an equivalent high switching frequency, improve the waveforms of output currents while avoid internal circular currents. This is very important for full-scale power converters used in the wind power system.