基于超级电容储能系统的不对称故障下PMSG控制策略研究

为了提高直驱型永磁同步风力发电机的低电压穿越能力,通过对其在电网电压不对称故障下产生的2倍工频分量机理进行分析,提出了一种基于超级电容储能系统的新型改进控制策略。基于功率平衡的思想,直流侧采用超级电容储能系统,并改用功率外环电流内环的控制策略,以实现不对称故障时堆积在直流侧不平衡功率的平滑控制。同时,在网侧采用双二阶广义积分器锁相环替代传统方法中的单相锁相环,实现不对称故障时正负序基波分量的精确测量。通过Matlab/Simulink仿真表明,该控制策略能有效抑制系统在不对称故障时的网侧有功和直流侧电压二倍频波动,提高系统在不对称故障下的低电压穿越能力,证明了所提出改进控制策略的有效性。

Research on PMSG Control Strategy Under Asymmetric Faults Based on Super Capacitor Energy Storage System

To improve the low voltage ride-through (LVRT) capability of direct-drive permanent magnet synchrono-us wind turbines, a novel improved control strategy based on super capacitor energy storage system is proposed by analyzing the mechanism of double power-frequency component generated under grid voltage asymmetry faults. Based on the idea of power balance, the super capacitor energy storage system is used on the DC-side, and the control strategy of power outer-loop current inner-loop is adopted to achieve the smooth control of unbalanced power accumulated on the DC-side under asymmetric faults. At the same time, the double second-order generalized integrator phase-locked loop(PLL) is used on the grid-side to replace the single-phase PLL in the traditional method, thereby realizing the accurate measurement of positive- and negative-sequence fundamental wave components under asymmetric faults. Simulation results based on Matlab/Simulink show that the proposed control strategy can effectively suppress the grid-side active power and DC-side voltage double power-frequency fluctuations under asymmetric faults and improve the system''s LVRT capability under asymmetric faults, which demonstrates the effectiveness of the proposed improved control strategy.