解耦二自由度控制策略在过热汽温串级控制中的应用

在串级控制中,由于内环的抗干扰控制器和外环的跟踪设定点控制器存在着耦合关系,因此在设计过程中不能对它们进行单独地设计,在工程应用中,常常会因为一个控制器的设计不当,而导致系统的重复设计。本文针对这一问题,采用了一种基于内模控制原理的二自由度的控制结构,该设计方案可以将控制系统的设定点响应与内环的抗干扰作用解耦。结合H2范数的性能指标设计了与控制方案结构相对应的设定点跟踪控制器和内环抗干扰控制器,每个控制器都可以单独地进行参数调整。火电厂中过热汽温系统是一类大滞后、大惯性的控制问题,在实践中大都采用串级的控制方式。在本文中将解耦二自由度串级控制策略应用到过热汽温控制中。从仿真结果来看,无论是系统跟踪设定点能力还是系统的抗干扰能力都得到了很大的改善。

Application of Decoupling Two-Degree-Freedom Control Strategy in the Superheated Steam Temperature Cascade Control

The inner loop rejection and the outer loop tracking setpoint controllers are coupled with each other in the cascade control,so they can't be respectively regulated in the process of the design,which will result in redesigning the system in the application of engineering,since either is inappropriate.For this problem,this paper adopts a control structure of two-degree-freedom based on the Internal Model Control,which can deal with the decoupling between the nominal setpoint response and the rejecting function.According to the H_2 optimal performance index,this paper designs the setpoint tracking and the inner rejecting controllers on the basis of the control trajectory structure proposed,the parameters of the both can be regulated respectively.The superheated steam temperature sytem is a kind of large lag and inertia control problem in the thermal power plant,which usually adopts cascde control manner in practice.The decoupling two-degree-freedom cascade control strategy is used to the superheated steam temperature control.From the simulation results,the application in the superheated steam temperature improves the ability of tracking setpoint response and rejecting disturbance.