额定风速以下风力发电系统的双频环优化控制器设计

Design of Two-Frequency-Loop Optimal Controller for Wind Power Generation System Below Rated Wind Speed

分别针对低频风速和高频风速建立风力发电系统的双频环基本非线性模型,在此基础上设计双频环优化控制器。该控制器由低频On-Off控制部分和高频H∞动态输出反馈部分组成。仿真实验表明,在额定风速以下时,该控制器低频On-Off部分可以使风力发电系统的叶尖速比λ快速跟踪其最优值λopt,实现最大风能捕获;高频H∞动态输出反馈部分可以抑制过大的电磁转矩振荡,尽量使发电机机械振荡最小,相对于单纯的On-Off控制具有更高的控制精度和更好的鲁棒性能;并且风力发电系统的多个控制目标之间需要进行折衷处理。

For low-frequency wind speed and high-frequency wind speed, two-frequency nonlinear model of wind power generation system was established, and then two-frequency-loop optimal controller was designed. The controller is composed of an On-Off optimal controller and an H∞ dynamic output feedback robust controller. Theoretical analysis and simulations show that,with the On-Off controller,the tip speed ratio can quickly track the optimal value,and the system can effectively implement maximizing the efficiency of captured wind energy below rated wind speed; and that with the robust controller, the mechanical oscillation is reduced to keep the wind power generation system reliable. The proposed controller has much better control accuracy and robustness than simple On-Off control. Moreover, a trade-off is needed between multicontrol objectives of wind power generation system.