Proportional-integral-plus (PIP) control of the ALSTOM gasifier problem

Although it is able to exploit the full power of optimal state variable fee dback within a non-minimum state-space (NMSS) setting, the proportional-int egral-plus (PIP) controller is simple to implement and provides a logical e xtension of conventional proportional-integral and proportional-integral-de rivative (PI/PID) controllers, with additional dynamic feedback and input c ompensators introduced automatically by the NMSS formulation of the problem when the process is of greater than first order or has appreciable pure ti me delays. The present paper applies the PIP methodology to the ALSTOM benc hmark challenge, which takes the form of a highly coupled multi-variable li near model, representing the gasifier system of an integrated gasification combined cycle (IGCC) power plant. In particular, a straightforwardly tuned discrete-time PIP control system based on a reduced-order backward-shift m odel of the gasifier is found to yield good control of the benchmark, meeti ng most of the specified performance requirements at three different operat ing points.