低短路比下双馈风力发电机组电压主动支撑的优化控制策略

Optimal Control Strategy of Voltage Active Support for Doubly Fed Induction Generator With Low Short Circuit Ratio

随着风力发电机的大规模并网发电,并网点的短路比不断降低。风电机组并网功率增大使得线路阻抗上的压降上升,并网点电压也随之降低,进而导致风力发电机的输出功率受到限制。为改善风机并网在低短路比下电压降低致使输出功率受限的问题,以双馈风力发电机为研究对象,提出了一种基于电压主动支撑的闭环优化控制策略。该方法在实现对并网点电压的支撑的基础上,提高了双馈风电机组在低短路比下的功率传输能力,同时解决了常规电压闭环控制中由功率耦合引发的系统稳定性问题。在优化控制策略下,系统的主导极点阻尼比更大,使得系统更加稳定。最后,在11 kW的双馈电机实验平台上验证了优化控制策略下双馈电机的阶跃响应稳定性更高。

With the large-scale grid connection of wind turbines, the short circuit ratio of point of common coupling(PCC)is decreasing. As the positive power of wind turbines increasing, the voltage on the line impedance increases, and the voltage of PCC also decreases at the same time, which results in the limitation of the output power of wind turbines. In order to improve the output power limitation caused by voltage reduction under low short circuit ratio, a closed-loop optimal control strategy based on active voltage support was proposed for doubly fed induction generator. On the basis of supporting the voltage of PCC, the active power of the doubly-fed wind turbine under low short-circuit ratio is improved,and the system stability problem caused by power coupling in conventional voltage closed-loop control is solved. Under the optimal control strategy, the damping ratio of the dominant pole is larger, which improves the stability of the system.Finally, the step response stability of doubly fed induction generator under the optimized control strategy is verified on the 11 kW doubly fed induction generator experimental platform.