针对大惯性、大滞后热工过程因负荷、煤种和环境条件的改变以及模型简化等带来的不确定性,设计了一种便于运行人员理解和工程实现的预估滑模控制方案.首先基于标称工况下辨识得到的二阶加纯滞后(SOPDT)模型,构建一个无迟延输出预估模型,用于过程输出值的预测,然后通过合理设计滑模函数和不确定上界自适应估计的滑模控制律,使得具有不确定性的闭环系统能在任何外扰的作用下保持渐进稳定.针对循环流化床锅炉床温对象的仿真实验结果表明:采用该预估滑模控制方案的床温控制系统调节速度快、超调量小且具有很强的抗干扰能力.
To tackle the uncertainties caused by variations of load, coal and environmental conditions as well as by model simplification, a predictive sliding mode control strategy, which is easily understandable and applicable in practice, was proposed for the thermal processes with large inertia or time delay. Firstly, a predictive model without output delay was established to estimate the process output by using a second- order plus dead-time (SOPDT) model obtained in nominal case. Secondly, a reasonable sliding function and a sliding mode control law with adaptively estimated uncertain upper bound were designed to asymptot- ically stabilize the closed-loop system with uncertainties and disturbances. On the basis above, numerical simulations were conducted on bed temperature of a circulating fluidized bed (CFB) boiler. Results show that the control strategy proposed is fast in bed temperature regulation with small overshoot and strong an- ti-disturbance capability.