Figure 6PITOPS process dynamics identification
As it can be seen from Figure 6, identified process model (shown with blue curve ) in PITOPS shows accurate model behavior which perfectly follows the raw reactor temperature data (shown in red ) containing slow dynamics with a dead time of 4.5 minutes, process gain of 2.5 and a process time constant of 25.7 minutes. Considering the slow process dynamics if this process had to be identified using old-fashion methods, it would take much time of process engineer compare to PITOPS.
After process identification, the next step would be to find optimum PID tuning parameters. PITOPS uses precise and accurate algorithm for identifying process model and based on the process needs it tunes PID tuning parameters, as described earlier.
In this example, PID values computed from old-fashion PID tuning methods will be compared with PITOPS for a SP change and PV overshoot. Since this is a temperature controller, it needs to have very tight and stable control action without and oscillations and PV overshoot. To easily compare the PID tuning parameters computed from both methods, trends of both methods will be shown one after another. IMC and Lambda PID tuning standard will produce similar behavior where calculated PID tuning parameters gives very slow and sluggish control action without PV overshoot, as shown in Figure 7. ZN and CC PID tuning standard will produce somehow satisfactory control yet it will be very aggressive, oscillatory and with PV overshoot, as shown in Figure 8. Last shown PID tuning method is PITOPS. In house PID tuning standard will produce tight, stable and fast control action behavior without PV overshoot, as shown in Figure 9.