交流励磁变速恒频风力发电系统的运行与控制

Operation and Control of AC-Exited Variable-Speed Constant-Frequency Wind Power Generation System

合理的励磁控制是确保变速恒频风力发电机可靠、高效运行的关键。分析了旋转坐标系下双馈型异步发电机(DFIG)的数学模型,采用定子磁链定向方式推导了DFIG矢量控制策略,并通过DFIG功率控制实现最大风能追踪。采用双PWM变换器作为DFIG的励磁电源,其中网侧变换器通过电网电压定向矢量控制实现交流侧功率因数和直流母线电压控制。在10kW机组上进行了包括发电机稳、动态变速恒频运行,最大风能追踪以及网侧变换器控制等内容的实验研究,实现了DFIG功率解耦、最大风能追踪以及相应的变换器工作状态的切换,验证了控制策略的正确性。

Reasonable excitation control is crucial for variable-speed constant-frequency （VSCF） wind power generator to operate efficiently and reliably. The mathematic model of doubly-fed induction generator （DFIG） is firstly analyzed in the rotational reference frame. Based on stator flux orientation, vector control strategy of DFIG is investigated, by which the maximum wind power can be traced. Back-to-back PWM converters are constructed as the excitation source of DFIG, and the AC power factor and DC bus voltage of grid-side converter are regulated by grid voltage orientation vector control. Experimental research, which includes static ＆ dynamic VSCF operation, the maximum wind power tracing, grid-side converter control and etc., is conducted on a 10 kW experimental rig. The decoupled control of DFIG active power and reactive power output, the tracing of maximum wind power and the corresponding switch of converters operation status are achieved. Experimental results confirm the correctness of control strategy proposed by this paper.