摘要
由于在加氢裂化过程中闪蒸罐压力控制存在非线性、大滞后等问题,运用常规比例-积分-微分(Proportion-IntegralDerivative,PID)控制效果较差,虽然传统遗传算法可以优化PID参数,提高控制精度,但是收敛速度慢,整定时间长,限制了其在闪蒸罐压力控制中的应用。针对以上问题,提出了一种通过改进遗传算法优化PID参数的新型方法,该方法以传统遗传算法为基础,通过对适应度值的自适应缩放、交叉率和变异率分别按Sigmoid函数和高斯分布函数自适应调整等策略来提高遗传算法的全局搜索能力和收敛速度,从而实现对PID控制参数的优化。仿真结果表明,用改进遗传算法优化后的闪蒸罐压力PID控制具有更好的自适应性和鲁棒性,使系统调节时间减少到86 s,超调量减少到0. 141 8%,有效地改善了系统的动、静态特性。
Because of the non-linearity and large hysteresis in the flash tank pressure control during the hydrocracking process,the conventional Proportion-Integral-Derivative( PID) control is less effective. Although the traditional genetic algorithm can optimize the PID parameters and improve the control accuracy,it has a slow convergence speed and a long dynamic response time,which limit its application in flash tank pressure control. Aiming at these problems,a new method for optimizing PID parameters by improving genetic algorithm was proposed. Based on the traditional genetic algorithm,the global searching capability and convergence speed of genetic algorithm are improved by adaptively scaling fitness values,the crossover rate and mutation rate are adjusted adaptively according to Sigmoid function and Gaussian distribution function,In order to achieve the optimal PID control parameters setting. The simulation results show that the flash tank pressure PID control with improved genetic algorithm has better self-adaptability and robustness,accommodation time and overshoot separetely descrease to 86 s and 0. 141 8 %,and improve the dynamic performance and static performance of the system.
引文
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