Greetings everyone! Our homogenizing oven is equipped with three zones, each with 2 burners - one soak (smaller) and one main (large). During the ramp-up to the air temperature setpoint, the main burner primarily heats the oven. Once the set temperature is reached and the load temperature reaches the soak level, the smaller burner takes over to maintain the temperature. Unfortunately, the company that handled our ControlLogix migration did not do a thorough job, resulting in the oven not performing as efficiently as it could be. I am interested in utilizing the PIDE in ControlLogix and considering if a cascaded PIDE could improve the performance of our two-burner, one-zone thermocouple setup. Any insights on this matter would be greatly appreciated. Thank you for your input!
Which measurement controls are you looking to cascade? Temperature is the primary process variable (PV) for the first loop, but what is the PV for the second cascade Proportional-Integral-Derivative (PID) loop?
Thank you for your input, Dr. BitBoy. Initially, I assumed it was just a temporary issue, but upon further examination over the last 90 minutes, I believe it could be related to both air temperature and load temperature. Alternatively, the air temperature could be the primary factor with the secondary being the main burner output. This is because any changes in the main burner output would likely occur before any changes in air temperature, allowing the smaller burner to adjust accordingly and prevent a significant temperature drop during the transition. Can you confirm if my understanding is on the right track?
The concept being discussed here is more closely related to "split range" rather than "cascade" control. Split range control involves utilizing multiple systems to regulate the Process Variable (PV) through a single feedback control loop, such as a PID controller. The output of the Controlled Variable (CV) from the loop adjusts the output of each system within different ranges. An example of split range control is when one system provides heating while another offers cooling, allowing for flexibility in controlling a process. In contrast, cascade control involves using the measured temperature as the PV and setting a target setpoint (SP) for the primary PID controller. The output of the primary PID is then connected to a secondary PID to regulate a different variable, such as fuel flow. To simplify the process, it may be easier to implement a two-mode approach. In the startup mode, the main burner operates at full capacity until the temperature approaches the desired setpoint. Once this is achieved, the system switches to PID control using the soak burner. This approach eliminates the need to consider the relative gains of the two burners during system tuning. Ultimately, the goal is to efficiently reach the soak temperature by initially using the main burner at maximum capacity. The transition from startup to soak mode is crucial in order to avoid unnecessary time delays or temperature overshoot. By understanding the differences between split range and cascade control, you can optimize the control system for better performance and efficiency. Experimenting with different approaches will help determine the most effective method for your specific application.
I completely agree with the insights shared by drbitboy@jrhpuuk123. It would be greatly beneficial if you could provide a process diagram illustrating the relative positions of the zones and their intended purposes. Additionally, could you elaborate on the necessity of having two heaters instead of just one with power control? Furthermore, a clarification on the concept of "cascade control" would be greatly appreciated. The ultimate question to address is: What is the end goal of this system? What needs to be achieved, and what are the current system's shortcomings? It's important to note that a loop-loop cascade system tends to be significantly less reliable compared to a single-loop system.
User jrhpuuk123 expressed dissatisfaction with the controllogix migration performed by a company, noting a decrease in oven performance. It is crucial to consider how the oven operated before the conversion to Logix. Was it manually operated or did it use an analog PID controller? By consulting with operators and identifying any system quirks, a more effective programming approach for the Logix PLC can be determined to optimize oven performance.
Hi there, it sounds like you're dealing with a tricky situation. Implementing a cascaded PIDE system could indeed improve the control over your process. This setup has been handy in managing multi-stage systems precisely. However, to optimize it, you have to fine-tune the PID parameters for both primary (main burner) and secondary (soak burner) loop. You might also need to consider the dead time, which can often affect the process control. It's always best to work with a specialist who can configure your ControlLogix properly and ensure an efficient setup. Good luck!
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Answer: - PIDE control is a control algorithm that combines proportional, integral, derivative, and enhanced features to regulate a process. In the context of an oven with multiple burners, utilizing PIDE control in ControlLogix can help optimize efficiency by providing more precise temperature control and better response to changing load conditions.
Answer: - Cascaded PIDE control involves using multiple PIDE loops in a hierarchical manner, where the output of one loop controls the setpoint of another. In the case of a homogenizing oven with soak and main burners, cascaded PIDE control can help improve temperature control by allowing the smaller burner to take over once the set temperature is reached, leading to more efficient operation.
Answer: - Implementing cascaded PIDE control in a setup like the one described can result in improved temperature regulation, reduced energy consumption, and better overall performance of the oven. By allowing the smaller burner to maintain the temperature once the setpoint is reached, the system can operate more efficiently and effectively.
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