Curve selection in PID control
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I study *technology, and I’m particularly interested in learning about PID tuning. I’ve been struggling with one concept in * lately and would like to ask for some guidance. The book explains that in single-loop PID tuning, the setpoint curve, the process variable curve, and the PID output curve are selected; in the diagrams, it refers to this as the T-out curve. I temporarily consider the first two curves to be the SP setpoint curve and the PV value curve. So, which curve is the last one? Is it the OP value curve representing the valve opening degree? It seems a bit different from what was explained earlier. I’d like to ask everyone. Thank you so much.
SP is the setpoint, PV is the process value, OP represents the valve opening trend (it can also be expressed using other symbols such as Y), and M refers to the manual opening degree~
To learn PID tuning, one first needs to know how to identify trends, display them, and analyze them. The notation used varies slightly across different DCS systems, but the basics remain similar; the exception is ABB’s system, where WAY is used for SP, XAY for PV, and YAY for OP. Being able to read trends means understanding the relationship between these three values. You can refer to the posts I’ve shared regarding tuning for more details.