Double Closed-Loop Speed Control Method for Variable Frequency Papermaking Machines Based on PLC

To improve the control accuracy, dynamic response, and operational stability of frequency-controlled paper machines, this paper proposes a dual-loop speed control method based on programmable logic controllers (PLC). Initially, the motor of the frequency-controlled paper machine is modeled and analyzed to establish a foundation for precise speed regulation. Subsequently, a PLC-based control system is designed, in which the ideal speed ratio of the paper machine is calculated, and the deviation between the actual and desired speed is determined. The proportional-integral (PI) control strategy is applied to regulate both current and speed within the dual-loop system. Furthermore, the grey wolf optimization algorithm is employed to automatically tune the PI control parameters, using an objective function tailored to minimize speed deviation and improve system robustness. Experimental results demonstrate that the proposed approach effectively enhances the control performance, maintaining stable and accurate operation even under external disturbances and varying load conditions. The method provides a practical solution for optimizing the speed control of frequency-controlled paper machines in industrial environments.