纸浆间歇蒸煮过程的分数阶建模及内模控制

纸浆间歇蒸煮是在高温高压密封的蒸煮锅中进行,是一个复杂的黑箱过程.针对间歇蒸煮过程的非线性和系统参数不确定性问题,在机理建模的基础上,通过函数拟合及数值逼近对模型的非线性部分进行数学近似,建立了间歇蒸煮过程的分数阶模型.针对分数阶系统,采用内模控制原理设计分数阶PID控制器,以简化分数阶控制器的可调参数,并基于最大灵敏度及稳定裕度整定控制器参数,使系统在保证期望的动态性能条件下,获得较好的鲁棒性.仿真结果表明,间歇蒸煮过程的分数阶内模控制在超调、响应速度和鲁棒性方面优于整数阶控制.

Fractional-order Modeling and Internal Model Control for Pulp Batch Cooking Process

The pulp batch cooking process, a complicated black box process, is carried out in a sealed digester of high temperature and pressure. Based on the analysis of the batch cooking process mechanism, the nonlinear part of the mechanism model is mathematically approximated by function fitting and numerical approximation. A novel fractional-order model is proposed for solving the problem of model imprecision and system parameters uncertainties in batch cooking process. For the fractional-order system, a fractional-order PID controller is designed, and the internal model control is adopted to simplify the adjustable parameters of the fractional-order controller. Then the controller parameters are tuned by maximum sensitivity and stability margin so that a good robust performance can be achieved under a good dynamic response condition. The simulation results show that the fractional-order internal model control of the batch cooking process is superior to the integer-order control in terms of overshoot, response speed, and robustness.