Internal Model Control for Multivariable Coupling System with Time Delays and Optimization Research

In view of multivariable strong coupling system with multiple time delays, a new multivariable decoupling internal model control method is proposed in this paper. Based on the model of the plant, a pre-compensator is designed to decouple the system into open-loop diagonal dominant system. The compensated diagonal elements are used as internal model to design a multi-loop internal model controller, and the diagonal filter is designed with improved Luus-Jaakola optimization algorithm. Then the internal model controller is converted into PID controller which can be used in DCS applications. Finally, this new method is applied in a reheat gas temperature control system of steam-steam heat exchanger in a 200 MW unit, and the control results show that the control structure can be tuned easily and achieved good trade-off between performance and robustness.