不平衡电网电压下双馈感应发电机无源控制

本文以抑制电网电压不平衡所带来的定、转子不平衡电流为目标,提出了一种基于无源化方法的双馈感应发电机不平衡控制策略.首先在分析了正转同步旋转坐标系下的双馈感应发电机正序模型及负序模型无源性的基础上,设计了正、负序模型的无源性状态反馈控制器;然后给出了一种期望状态值计算方法,根据不平衡控制目标得到定、转子电流负序分量的指令值,结合定子电压的正序分量和电磁转矩的期望值计算出定、转子电流正序分量的给定值;最后得到电网电压不平衡条件下双馈感应发电机的无源控制器.仿真结果表明:所提出的控制方案有效地抑制了电网电压不平衡故障时定子及转子的不平衡电流,降低了输出电磁转矩的波动,提高了双馈感应发电机系统在电网电压不平衡条件下实现不间断运行的能力.

Passivity-based control of double-fed induction generator under unbalanced grid voltage fault

To inhibit the imbalance current in the stator and the rotor caused by the unbalanced grid voltage, we propose a passivity control strategy for the double-fed induction generator system (DFIG). On the basis of the passivity of the positive and negative sequence models in the positive synchronously rotating frame, a passivity state feedback controller is first designed. Next, a method for calculating expectation values is developed, by which we calculate the command values for the negative sequence components of the stator current and the rotor current based on the unbalanced control objectives. The command values of the positive sequence components of the stator current and the rotor current are calculated on the basis of positive sequence components of the stator voltage and the expectation values of the electromagnetic torque. Thus, a passive controller for DFIG under unbalance grid voltage condition is designed. Simulation results show that the proposed scheme effectively inhibits the imbalance currents in the stator and the rotor, reduces the output torque fluctuation, and enhances the non-interrupt operation ability of DFIG under unbalanced grid voltages.