Comparison of Linear Controllers for Nonlinear, Open-loop Unstable Reactor
Journal article, Peer reviewed
Published version
Permanent lenke
http://hdl.handle.net/11250/2584140Utgivelsesdato
2018Metadata
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Originalversjon
Linköping Electronic Conference Proceedings. 2018, (153), 185-192. 10.3384/ecp18153185Sammendrag
Many industrially important reactors are operated over a regime where they exhibit nonlinear behavior. Exothermal reactors are often open-loop unstable. For such reactors, safe operation with good performance requires good control. We have considered linear controllers and tested these on a simple chemical engineering non-linear, open loop unstable model and an extension of the model in order to do a basic test of model uncertainty. Specifically, a PI controller has been tuned and tested, the operation of an Extended Kalman Filter (EKF, KF) has been tuned and tested. Based on feedback from estimated states in the EKF, a linear quadratic controller with integral action (LQG+I) has been tuned and tested; the study has been carried out using MATLAB for KF and LQG+I tuning; the remaining study has been carried out in a Jupyter Notebook using Python in tandem with Modelica. The PI controller lead to negative cooling water temperature upon a step change in temperature reference. When constraining the input to liquid water with anti-windup, PI control gives considerable undesirable overshoot in the reactor temperature. The LQG+I controller performs much better wrt. temperature overshoot. Overall, the reported work has demonstrated how a modern simulation set-up (OpenModelica + Python) can be used for model based control analysis and design. Comparison of Linear Controllers for Nonlinear, Open-loop Unstable Reactor