PITOPS Technology:
PITOPS is basically short form of “Process Identification,
Controller Tuning and Optimization Simulator ”. PITOPS works solely in
time domain and that makes PITOPS different from the other market
simulators which work in Laplace domain. It also has the ability to
identify multivariable process models based on the closed or open-loop
history or live data. It can also simulate the behavior of new vs. old
PID tuning parameters based on the SP change, existing disturbances and
signal noise, valve stiction or some other real-life and frequently seen
process constrains. It does not require new, time consuming and large
plant step-tests. The working of PITOPS is described below:
- A typical PID tuning session begins when a plant operator requests
help from a process control engineer to tackle with an oscillatory or
sluggish response of PID controller to achieve its SP after a
condition change or a load upset.
- Process control engineer will gather past data of closed-loop or
open-loop PID controller from the DCS or a PLC containing just PV and
PID OP.
- Collected data in excel workbook will be imported to PITOPS and based
on the data true process dynamics will be identified. This feature of
PITOPS eliminates the step in which we force PID controller in manual,
producing oscillatory control action or making damaging step-tests for
finding the process dynamics.
- Identification of process dynamics will be done by PITOPS itself in
just 3-5 minutes.
- The next step would be to use identified process dynamics and based on
it to tune the PID controller. In PITOPS the user can choose one of
the following goals for PID tuning:
- PID tuning based on the SP change
- PID tuning based on the PID OP rate of change
- PID tuning based on pulse/step/ramp/sine disturbance
- PID tuning based on the noise
- PID tuning based on the most aggressive but still stable PID tuning
parameters
- PID tuning based on no PV overshoot
- PID tuning based on the sluggish PID tuning parameters
- PID tuning based on the control valves stiction
- PID tuning based on several combined above goals
Once the PID tuning and optimization has been finished, the produced
new PID tuning parameters can be easily tested using robustness
algorithm. Robustness algorithm allows user to test new PID tuning
parameters upon the SP and dynamics change on simulator and see how
process will behave in real. When the process control engineer is
satisfied with new PID tuning parameters he just needs to enter them
back to DCS or a PLC system and they will work properly. The usage of
PITOPS is quite simple and easy to understand. Apart from simplicity,
the time taken in PITOPS for tuning any controller is also less than
using standard methods.