基于非线性内模控制的直流炉机组协调控制系统设计

Design of the once-through boiler-turbine coordinated control system based on nonlinear internal model control

直流炉机组三输入三输出强耦合、非线性的对象结构使其协调系统的抗干扰性和负荷适应能力受到影响。为提出机组全工况优化运行的控制方案,首先通过合理的简化,建立起具有一定精度且利于控制器设计的直流炉机组模型。应用状态反馈精确线性化求出其逆系统,通过反馈控制律的作用实现了系统模型的线性化与输入、输出的完全解耦。并结合对建模误差与外扰有较强鲁棒性的多变量内模控制结构,对反馈线性化后的伪线性系统进行控制设计。最后在不同的稳态工作点下进行状态扰动与设定值扰动的仿真试验,结果表明应用非线性内模控制方法设计的协调系统在较大的工况范围内具有较好的稳定性与动态性能。

The structural features of the once-through boiler-turbine unit are nonlinear,strong coupling and multivariable,which affect the disturbance rejection property and load adaptability of its coordinated system. In order to propose the control scheme of optimal operation of the unit under the condition of variable load operation,this paper firstly gives a simplified non-linear model of the once-through boiler-turbine unit which has certain accuracy and is fit for the controller design for coordinated control system. Then the method of exact linearization via state feedback is applied to calculate the inverse system of the non-linear model. Through the feedback control law,the linearization of the unit model and complete decoupling between the input and output are realized. And the multivariable IMC structure which has strong robustness of modeling error and external disturbance is introduced to control the feedback linearized pseudo-linear system. Finally,simulation tests of the state,set point perturbation in different static operating conditions are carried out. Simulation results show that good stability and dynamic performance is achieved and the strategy is effective in a large range of operating conditions.