Introduction

This project involved the implementation of a comprehensive automation system for a paper mill utilizing Siemens S7-1200 PLCs as the core control units. The system was designed to precisely control the paper-making process, ensuring optimal product quality and efficiency.

System Architecture

The automation system consisted of three primary components:

• Siemens S7-1200 PLCs: These PLCs served as the brains of the operation, handling all control logic and data processing.
• Advantech Industrial PCs: Equipped with WINCC SCADA software, these PCs provided a user-friendly interface for monitoring and controlling the process.
• DELL Server: The server was used for data storage, backup, and networking.

Process Control Challenges

One of the most significant challenges in this project was achieving precise control of paper tension. Fluctuations in tension can lead to paper breaks or poor quality. To address this challenge, a PID control loop was implemented to regulate the speed of the paper-making process.

PID Control for Tension Management

By employing a PID control loop, the system could automatically adjust the speed of the variable frequency drives (VFDs) to maintain a constant paper tension. This ensured that the paper was neither stretched too tightly nor allowed to sag.

Additional Considerations

To further enhance the precision of the control system, the following measures were taken:

• PROFINET Communication: The PLCs and VFDs were connected using PROFINET, a high-performance industrial Ethernet protocol, to ensure fast and reliable communication.
• Tension Control for Each Section: Individual tension control for each section of the paper-making process allowed for fine-tuning of the overall system.
• SMART Series HMI: Although the SMART series HMI could not directly communicate with the S7-1200 PLC, a third-party router was employed to bridge the communication gap.

Conclusion

The successful implementation of this automation project demonstrates the power and flexibility of Siemens S7-1200 PLCs in addressing complex industrial automation challenges. By carefully considering factors such as PID control, communication protocols, and HMI selection, we were able to deliver a solution that met the customer's specific requirements and exceeded their expectations.

Unique Insights

• PID Control: The use of PID control for tension management is a common practice in the paper industry, but the specific tuning of the PID parameters can significantly impact the performance of the system.
• PROFINET: The selection of PROFINET as the communication protocol was crucial for ensuring high-speed and deterministic communication between the PLCs and VFDs.
• HMI Selection: The choice of the HMI and the use of a third-party router to enable communication highlights the importance of considering the specific needs of the application when selecting automation components.

Additional Considerations for Future Projects

• Predictive Maintenance: Implementing predictive maintenance strategies can help to reduce downtime and improve overall system reliability.
• Cybersecurity: As industrial control systems become increasingly connected, it is essential to implement robust cybersecurity measures to protect against cyberattacks.
• Cloud Integration: Integrating the automation system with cloud-based platforms can enable remote monitoring, data analytics, and machine learning applications.