Why is it necessary to tune a controller with a delay in HYSYS?
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In HYSYS, if a delay is added to a controller, why is it usually necessary to tune the controller?
Please describe the problem in more detail or attach the file, thank you.
There are no documents; it’s just done in one of Luyben’s books. For ordinary controllers, it’s sufficient to simply enter the PID parameters. As for controllers that have a delay module, they use the autotuning tool built into the software to carry out autotuning, thereby determining a set of PID parameters.
I guess, just a guess~~ Since the signal transmission of controllers in the HYSYS system is delay-free, whereas in real DCS systems there are issues such as signal transmission delays, the PID parameters of controllers that work well in HYSYS generally do not apply in practical situations. I guess, just a guess, the reason why the author you mentioned added a delay is to better simulate real-world DCS; as a result, it’s necessary to re-tune the PID parameters. For example, in the case of a flow controller, without a delay module, the PID parameters set in HYSYS have a Kc value of only 0.03 and a Ti value of only 0.05; such values are not appropriate in real DCS systems, so it is necessary to reset these parameters. By the way, could you send me the article you mentioned? My email: scbnmao@yahoo.com.cn
It’s the book titled Plantwide Dynamic Simulators in Chemical Processing and Control by William L. Luyben; no electronic version of it seems to exist, and I read it from a library book. I searched on Google, and only some chapters are available; you can search for them yourself. I asked someone in our company who specializes in control systems about this issue, and he said that controlling flow rate and pressure is relatively simple; it’s usually sufficient to rely on experience when setting the parameters. However, for controlling temperature and concentration, there is often a delay, so it’s not possible to rely on experience alone, as such approaches are often unreliable and require adjustment.
Can you scan this book into an electronic version? For the benefit of all marine enthusiasts.