高阶时滞系统辨识方法

Identification Method for High Order Time Delay Systems

工业生产中高阶系统较为复杂,为了改善系统辨识效果和模型预测控制,在二阶加时滞系统基础上进行改进。运用频域方法,对高阶时滞系统进行研究。在系统低频和中频段找出合适的采样区间。对系统划分子区间长度,对输出信号进行拟合,使系统进行数次迭代,求出临界频率,确定高阶系统的重要频率段,得出辨识系统在频率段的特性响应矩阵。通过幅值和相位关系,采用最小二乘法拟合二阶加滞后模型参数。利用MATLAB对模型进行验证,得出系统的Nyquist曲线和单位阶跃响应曲线。仿真实验表明,辨识的系统结构简单,有利于系统的整体控制和控制器参数整定,整个系统辨识效果提高了31.65%,达到了对系统降阶的目的。

In industrial production,higher-order systems are more complicated.In order to improve system identification effects and model predictive control,improvements are made on the basis of second-order time-delay systems.In this paper,the frequency domain method is used to study high-order time-delay systems.This study finds suitable sampling intervals in the low-frequency and mid-frequency bands of the system,divides the sub-interval length of the system,fits the output signal,makes the system iterate several times,finds the critical frequency,and determines the important frequency band of the higher-order system.The characteristic response matrix of the identification system in the frequency band is obtained.Through the relationship between amplitude and phase,the least square method is used to fit the parameters of the second-order plus lag model.By using MATLAB to verify the model,the system Nyquist curve and unit step response curve are obtained.Simulation experiments show that the identification system has a simple structure,which is conducive to the overall control of the system and the setting of controller parameters.The identification effect of the entire system is improved,and the purpose of order reduction is achieved.