PITOPS - PID Tuning Simulation, Optimization, Closed-Loop System Identification and APC Design (Advanced Process Control).

Figure 1 shows a transfer function identification between steam flow and distillation column temperature. The red trend with up-and-down steps is the steam flow setpoint. The noisy red trend is the temperature and the blue trend is the transfer function model prediction for temperature.

Notice that almost all dynamics identification work can be done simply and easily from this single main Pitops-TFI screen. Since Pitops-TFI works wholly in the time domain, no conversion is needed to go from Z (discrete domain) or S (Laplace domain) to the time domain. Also, there is no need to know or understand complicated terms like ARMA, Noise Models, poles or zeros and other complicated academic control jargon. There is also no need to understand cross-correlation and auto-correlation theory. Everything is so simple and straightforward for anyone to understand and start using quickly.

The software also allows you to easily conduct “what-if” simulation studies by specifying guessed values of transfer function parameters and to even compare predicted models with other data sets not used in the dynamic estimation. This feature allows you to quickly and easily check the model accuracy.

Pitops TFI can identify Control Valve Stiction using plant data. The stiction identification location is shown in Figure 3.

Dynamics identification in other competitor products is far more complex, dealing with discrete (Z) transforms. Pitops-TFI makes dynamics identification delightfully simple even for a new engineer or technician. Pitops-TFI is the only product required for all possible primary and Advanced Process Control (APC) dynamics identification in any type of chemical or refining operation.

Click on Schedule a Demo below to download and examine a full-blown demo of Pitops-TFI.

• Single/Slave PID simulation and tuning optimization
• Cascade/multiple cascade simulation and tuning optimization
• Override constraint control schemes
• Random (white) noise, to precisely match the actual noise level seen on DCS
• Slow process drift representative of slow and medium-fast disturbances actually seen in DCS
• Internal model control (IMC) simulation
• Deadtime compensated (DTC) controller implementation and optimization
• Feedforward simulation and optimization
• Model-based control using regressed and/or rigorous model
• Production rate maximizer design and parameter optimization
• Millisecond surge control tuning and optimization
• Integrating transfer function tuning and optimization
• First-order, second-order with dead time simulations
• Open-loop unstable process dynamics simulation and characterization
• Simulation and optimization of nonlinear processes
• Control valve characterization
• Optimizing PID parameters to deal with Control valve stiction or deadband
• Gap action control simulation

The optimal tuning of critical loops must take into account the nature of the process, how fast the control valve can be allowed to move, the nature of known and unknown disturbances and other customs issues unique to the loop. Pitops-PID allows you to configure a custom simulation quickly and easily.

Figure 2 shows a simulation comprising of superimposed disturbances like those seen in the real process. After configuring the disturbances, Pitops-PID optimizes the tuning parameters based on the custom simulation, taking into account the control needs of the loop, which include the following:

1. Typical setpoint changes
2. Typical disturbances
3. Output rate of change consideration
4. Any other custom needs specific to the PID loop
5. Optimize PID tuning to handle control valve stiction or deadband

Most other products optimize tuning based on heuristics and error criteria; in contrast, Pitops-PID optimizes based on the precise (custom) process characteristics and control objectives.

Pitops-PID provides cascade PID simulation and sequential optimization capability to optimize both slave and cascade controllers – see Figure 3. A single, easy-to-use master screen allows you to specify most parameters.

You can specify slow loops, GC analyzer sample time delay and special transforms like natural logarithms, square and square root to linearize commonly known non-linear processes. These transformations are used for constraint control for distillation column delta pressure to infer column flooding limits and also for tighter control of tall superfractionators where the distillation purities behave non-linearly.

Pitops-PID provides calculation procedures and commissioning guidelines to design and implement feedforward controllers.

Most other competitor software products run in the discrete (Z) domain. In contrast, Pitops-PID runs completely in the time domain which is easier to understand by people of all skills and experience levels.

Pitops provides powerful, easy to use feedforward simulation module. Many skilled control engineers have admitted that they began to truly appreciate some important aspects of feedforward control design only after being exposed to Pitops-PID. Pitops-PID automatically optimizes controller parameters for a closed-loop simulation for a real-plant case configured with a disturbance and feedforward model precisely matching the process dynamics. The feedforward trends in Pitops-PID are shown in Figure 4.

Powerful model-based control schemes can be built in the DCS using Pitops-PID suite of model-based controller design, see Figure 5 for an illustration.

Using regressed, empirical, semi-empirical or rigorous chemical engineering models, effective model-based dynamic controllers can be easily implemented. The procedures show how to build controllers at a fractional cost and effort compared to other options.

Pitops-PID is the only tool that any control engineer will ever need in the control room. All simulations can be built very easily in a matter of minutes. This ease of use is unmatched by any other competitor software. Both new and skilled engineers and also DCS technicians/operators have successfully used Pitops-PID with ease and confidence.

Pitops optimizes PID tuning parameters to improve control action amidts control valve problems such as stiction and deadband. For control valves with stiction or deadband, Pitops will move the controller settings in the direction of increased proportional and derivative action and reduced integral action.