含无刷DFIG的风电系统低电压穿越极限控制能力分析

Analysis of Low Voltage Ride Through Control Limit of Wind Energy Conversion System Based on Brushless DFIG

无刷双馈感应发电机(BDFIG)由于其良好的维护特性,在风力发电中具有良好的应用前景。作为大功率并网发电装置,基于BDFIG的风电系统需要满足电网的低电压穿越(LVRT)并网导则。双馈型风电系统机侧变流器的极限控制能力决定了系统LVRT的控制方案与控制成本,具有重要的实际意义。文中详细分析了BDFIG在电网故障时的瞬态模型,通过引入庞特里亚金极小值算法分析基于BDFIG的风电系统的机侧变流器控制端电压最优值,得到整个系统LVRT极限控制范围,并进一步与普通双馈感应发电机进行了比较。结果表明,BDFIG具有更加优异的LVRT能力。

Because of the excellent maintenance features of the brushless doubly-fed induction generator（BDFIG）,it has good prospects for application in wind power generation.As a high power grid connected system,wind energy conversion system based on BDFIG needs to meet the grid code of low voltage ride through（LVRT）.The control limit to the generator side converter is of great research value in determining the LVRT control strategy and control costs.This paper analyzes the transient model of BDFIG during grid fault.The Pontryagin＇s minimum algorithm is employed to analyze the optimum value of the control voltage of BDFIG at the motor side.Compared with the doubly-fed induction generator（DFIG）system,it is shown that the BDFIG has even more remarkable LVRT capability.