电网低次谐波电压下双馈风电系统定子谐波电流抑制

Stator Harmonic Current Suppression Strategy for Doubly-fed Wind Power Generation System Influenced by Low-order Harmonic Voltage of Grid

IEEE相关标准对分布式发电系统注入电网的谐波电流作出了严格的限制。通过分析电网低次谐波电压对双馈风力发电系统定子电流总谐波畸变率(THD)的影响发现,传统基于定子电压定向的双馈风力发电系统并网发电矢量控制策略在大容量变流器控制中存在着缺点,即因为控制带宽低而无法有效抑制电网低次谐波电压引起的定子谐波电流,从而在较大工作范围内无法满足相关标准的要求。文中提出了一种基于定子谐波电流闭环控制的矢量控制策略,通过单独添加各次定子谐波电流的控制回路来抑制各次定子谐波电流,以满足THD指标。在30kW双馈风力发电系统实验平台上进行了验证,实验结果表明,通过使用该控制策略,削弱了电网低次谐波电压对双馈风力发电系统的影响,使得定子电流的THD得到了很好的抑制。

IEEE standards have defined the maximum permitted harmonic current injected to the grid by distributed resources.According to the analysis of the stator current total harmonic distortion（THD） influenced by grid harmonic voltage in doubly-fed induction generator（DFIG）,there is a drawback of grid-connected vector control for DFIG in high power converter.Due to the low control bandwidth,this control strategy cannot suppress the harmonica current of stator.So the power quality cannot fulfill the IEEE standards in the full range of operating process.An improved vector control strategy based on the closed loop control of stator harmonic current is presented.It adds a separated control loop for harmonic stator current to fulfill the requirement of the standard.A 30 kW DFIG platform is implemented.Experiment result shows the THD of stator current is reduced by using this improved vector control strategy.