Is it a PID issue?
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The pure water flow meter used in our company’s resin tower originally had a range of 25 m3/h; it was unable to be automatically controlled during backwashing, and the flow rate fluctuated significantly. Adjusting the PID settings didn’t help either. We suspect that the flow meter had an insufficient capacity, so we replaced it with one with a range of 40 m3/h. However, the fluctuations remain large during backwashing. Could it be a problem with the PID settings? (The current backwash flow rate is 15.8 m3/h, P: 100, i: 0.6)
Look for reasons related to the processing process; could it be that something happens during backwashing that causes a significant change in pressure? It doesn’t seem to have much to do with the range
There shouldn’t be any issues with the process; it works fine when the flow rate is 14.5 m3/h, but fluctuations occur once this value is exceeded. Could it be due to low pressure of the pure water? This post was last edited by Ai Zhi Yuan on 2009-4-5 12:20.]
It seems that the integration time is set too low; the integrating effect is too strong, which can easily lead to oscillations. In the PID parameter settings for the control loops in our factory, the integration time is generally above 20 seconds.
After I increased the time for integration, the flow became divergent; should I reduce the integration value? In manual mode, the flow rate can reach 25 m3/h
If the manual mode can be kept stable, it may be due to an improperly tuned PID or a problem with the positioner. Also, what is the unit for your score time of 0.6? Is it minutes or seconds? Setting the integration time to a large value should prevent divergence; the larger the integration time, the weaker the integrating effect, and when set to its maximum value, it’s as if there is no integration at all.
First, set the regulator to manual mode at 25 M3/H and check whether the system is stable; if it is not stable, the issue lies with the valve or the transmitter； If it is stable, then it is a PID issue. However, I suggest adjusting the PID parameters first: P to 0.4, and I to 10s.
You should use your P:50 I； 15 I think it’s just that your parameters aren’t set properly
The traffic is stable, so I’ll give it a try with the PI you mentioned