Model Predictive Control for pressure regulation and surge prevention in centrifugal compressors

This paper proposes a multivariable model predictive control scheme for discharge pressure regulation in centrifugal compressors. The main novelty of the proposed approach is that three control inputs are considered: the rotational speed of the compressor, an anti-surge valve for gas recycle and the inlet guide vane, whose variations allow one to significantly enlarge the operating region of the compressor and hence to enhance the authority of the control system. Surge prevention is achieved by including in the model an output variable accounting for the distance of the operating point from the surge limit. Such distance is defined on a compressor performance map which is invariant to changes in the inlet conditions, and thus its computation requires only standard pressure measurements available from the plant. Numerical simulations show that the proposed control system is able to meet the desired specifications, in the presence of different types of disturbances occurring along the pipeline.