MIMO model predictive control for integral gas engines under switching disturbances

The ambition of NO_x emission reduction on legacy gas engines for compressor stations leads to focusing not only on improvement of mechanical components but also on enhancing the control. The engine shows a strong coupling and furthermore the compressor clearances are switching fast during transients. Due to the engine inertia the switching is filtered, hence the nonlinear jump parameter system is approximated by linear dynamics. A MIMO linear explicit model predictive controller (MPC) with the objective of keeping the fuel/air ratio and the engine speed constant was applied and compared to the standard SISO PID controls. The steady state comparison showed less misfires by MPC while approaching the lean combustion limit and the tracking of the fuel/air ratio during the transients was improved up to 80%.