一种三自由度串级控制的仿真研究

Research on Simulation for Three Degree of Freedom Cascade Control

关于优化控制系统性能问题,由于控制系统中存在非线性滞后各种干扰因素,严重影响响应和稳定性。为实现在线独立调节副回路设定响应与扰动抑制响应,增强主回路的抗干扰能力,改善系统性能,提出一种新的三自由度串级控制方法。在副回路中采用两自由度内模控制,主回路采用单位反馈控制结构,并根据闭环最优灵敏度函数方法确定主控制器,从而保证系统的整体性能。对各个控制器的解析建模设计,对每个控制器都可以进行单参数调节和优化,并对主回路和副回路存在的乘性不确定性进行仿真。仿真结果表明,新的控制方法具有较好的设定值跟踪性能和抗干扰能力,提高了系统的鲁棒稳定性。

Response performance and stability are affected because of some nolinear time delays and disturbs in control system when optimizing the system performance. In order to improve the anti-disturbance capability of the major loop and separate the setpoint response and the load disturbance response, a new cascade control scheme of three degree of freedom was proposed for industrial cascade processes. Two three-degree-of-freedom internal mode controlers were proposed in the minor loop. The structure of unity feedback was used in the major loop, and the major controller was derived according to the closed-loop sensitivity function, which guaranteed a good system performance. Simple and effective analytical method is adopted to devise the controllers, each controllers can be adjusted and optimized by a single parameter. The control system robust stability is analyzed in the presence of the process multiplicatire uncertainty in the major loop and in the minor loop. Simulation example demonstrates the excellent performance of setpoint tracking and better anti-disturbance capability.