PID setpoint,
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At our facility, the temperature of one of the towers is currently controlled manually. I would like to switch to automatic control, but the temperature fluctuates too much. I was wondering if anyone knows what values should be set for the PID parameters. Our heat transfer medium is heat transfer oil, at around 170 degrees Celsius. The mixture of hydrocarbons that needs to be heated is at approximately -32 degrees Celsius. We want to raise the temperature of this mixture to 50 degrees Celsius, but every time we switch to automatic control, the temperature fluctuates significantly. The opening degree of the manual valve is usually around 10%. It seems that the size of the control valve chosen is a bit too large. So, what values should be set for the PID parameters of this control valve? Thank you in advance here
It depends on the regulation characteristics of this system
This control valve has always been adjusted manually; the size chosen for it was a bit too large. I now plan to switch it to automatic mode, but after trying for several days I still don’t know how to do it. Do you think it’s possible that the valve was selected with an oversized size, which is why it can’t be set to automatic mode? Is that a possibility?
The opening degree of the control valve is too low; generally, a range of 30%-70% is more suitable for proper operation.
Yeah, it’s just a bit too small. I’ve been working on it for several days now with no idea what to do, so I came here to ask for help from fellow users, to see if we can solve this problem
The tuning of PID parameters should be carried out gradually, based on the actual fluctuation curve. If the amplitude is high and the integral effect is too strong, it is possible to reduce the influence of the PI component; conversely, if the integral effect is insufficient, the influence of PI can be increased. As a starting point, the derivative component should be removed first, and once the PI settings have been adjusted, a small amount of derivative action can be added to see how it works.
I just try different approaches one by one; when even the proportional control function doesn’t work, significant fluctuations occur. Moreover, the opening degree of the control valve can be reduced to 0, and there’s nothing else that can be done. I’m turning to everyone here for help – what value should it be in this situation? Generally, our control valves have an opening degree of around 10
If the valve size is too large, it is difficult to switch to automatic mode at low opening degrees, and there is no room for adjustment
Do you mean it’s set to automatic difficulty? I think if the PID tuning is done properly, there shouldn’t be any problems; it’s probably just difficult to find the right setting
Adjust the proportional gain individually; keep reducing it until valve position fluctuations similar to a sine wave can be achieved, and then add integration. If you choose a value that’s too large, the ratio, that is, K, will need to be very small
I adjusted it to 0.1, but it still doesn’t work; the opening degree of this control valve still ranges from 0 to 100. What should I do in this situation? Are there any other good solutions?