Complex control loops
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I seek guidance from all the experts here. Our company currently has a materials supervisor who uses a pump to transport materials. And from this main pipe, two branch pipes extend. Each branch pipe is equipped with a flow meter and a control valve, forming a single-loop control system. Now the two valves cannot be set to automatic mode; they interfere with each other, causing the valves to keep flipping back and forth, as after all there are two valves on the same pipe. So I would like to ask the experts here. What are some good control methods that can adapt to such operating conditions? Seek guidance
Is it caused by disturbances in the material supply? If so, it is recommended to add another loop on top of the existing one to form a cascade system
I think a buffer tank or something should be added at the end of one of the pipes, with the flow control valve placed at the outlet of the tank. Otherwise, the interference between the two paths will be too severe
First, it is necessary to clarify how control is implemented – whether one component is turned off or adjusted, or if both are adjusted simultaneously; whether it is caused by the manufacturing process or by a problem in the control circuit. Only after this is determined can steps be considered to resolve the issue
It is estimated that these two pipelines are equally important; otherwise, one could be sacrificed to save the other. Adding a buffer tank to the main pipe and filling it with nitrogen (an appropriate gas) – with two pipelines leading from the buffer tank – should help to resolve or at least alleviate the problem.
This post was last edited by Crazy 丶 on 2017-10-26 at 16:41. The two are adjusted together; the flow control for the two branch pipes shares one main pipe. The material is hydrazine. liquid
This is a multiple-input multiple-output system. There is coupling between the two tube control rooms, and a decoupling algorithm can be used. It has little to do with the manufacturing process; the method mentioned earlier of using a buffer tank is one option, but it requires additional investment and also results in production interruptions.
The poster explained it very clearly: by using automatic mode, interference occurs between the various components, causing the valves to keep opening and closing repeatedly; adjusting the proportional-integral settings of the flow controller will solve this issue
It has been adjusted; the trend of each individual PID circuit shows an ideal pattern. However, when both circuits are set to automatic mode, interference and oscillations occur.
Try slowing things down a bit; take care of each other. It’s common to have multiple branches coming from one pump outlet, but there might be competition for flow rate, which can make it difficult to maintain stability. Make sure the manual valves at the pump outlet don’t get stuck. Hope this helps