基于预测虚拟转矩控制的DFIG并网逆变方法

针对双馈风力发电机组(DFIG)高性能并网控制问题,提出一种DFIG并网逆变系统预测虚拟转矩控制方法。虚拟转矩的概念衍生于直接转矩控制中的电磁转矩,是由DFIG的转子磁链和电网虚拟磁链合成产生的。在建立DFIG并网逆变系统数学模型的基础上,分析了不同扇区中电压矢量对系统虚拟转矩、转子磁链的影响趋势,选取一个包含两个有效电压矢量和一个零电压矢量的三矢量序列,并给出功率无差拍跟踪时的矢量作用时间求取方法。最后,基于55 kW双馈风力发电实验样机对所提预测虚拟转矩方法进行性能验证。实验结果表明,该方法可实现DFIG系统平滑、无冲击并网,保证了并网接入点的动、稳态电能品质。

The predictive virtual torque control method for distributed DFIG grid connected inverter system

To solve the high performance control grid-connected control problem of doubly fed induction generator(DFIG), we propose a predictive virtual torque control method for distributed DFIG grid connected inverter system. Virtual torque is derived from the concept of direct torque control in motor driven system. It is synthesized from the rotor flux of DFIG and the virtual flux of grid. On the basis of establishing the mathematical model of the DFIG grid-connected inverter system. The effects of voltage vectors in different sectors on virtual torque and rotor flux are analyzed. Sequence of three vectors containing two effective voltage vectors and a zero voltage vector are selected, and it also give a method to calculate the vector action time to make the power tracking. Finally, the performance of the proposed method is verified based on the 55 kW DFIG experimental prototype. The experimental results show that this method can achieve the DFIG system smooth and shock free grid-connection, and guarantee the dynamic and steady power quality of the grid-connection point.