Mathematical modeling and analysis of a pressure control system

In this study a pressure control system with a history of performance problems is examined. A mathematical model for the system is developed using a combination of analytical and experimental data. Model responses to inputs are determined and compared to actual system responses to validate the model. Desired system responses are discussed and optimum proportional-integral-derivative controller parameters are determined using a graphical identification approach. Component span adjustment and other system improvements from a hardware standpoint are also proposed. It is found that, even though the pressure control system is not linear, an acceptable model can be developed using Laplace transform techniques that will adequately simulate the system. This model, when used with the optimal controller tuning parameters, produces some improvements in response to both step and disturbance inputs. Improvements in response are also produced as a result of certain component span changes. Hardware modifications can also improve system performance and changes are recommended for the controller, the valves, and the sense lines.