Assessment of achievable PI control performance for linear processes with dead time

A numerical scheme is outlined for the estimation of achievable PI control performance measured by output variance in linear processes with dead time when stochastic load disturbances are affecting the process. For this numerical scheme, an approximate stochastic realization is employed for disturbance model identification, and this realized model is then used for the achievable performance prediction. The approximate stochastic disturbance model realization is performed based on the feedback invariant closed-loop impulse response coefficients so that the impulse response coefficients of the realized disturbance model are approximately equal to a given feedback invariant impulse response sequence. A computer simulation is carried out for the estimation of achievable PI control performance, and the result is compared to the true PI control performance bound.