Robust Multivariable Model Reference Adaptive State Feedback Output Tracking Control: An Offshore Produced Water Treatment Case Study

With the objective of pursuing eco-friendly and environmentally sustainable extraction in offshore oil and gas production, the Produced Water (PW) treatment is inescapable whether for reinjecting the PW back to the reservoir with the purpose of enhancing oil recovery or discharging it into the ocean. The de-oiling technology based on the hydrocyclones system connected to the three-phase separator is generally employed for the PW treatment. In order to boost the effectiveness of the interconnected de-oiling systems, it is crucial to introduce an advanced coordinated controller for the separators and hydrocyclone systems with regard to the uncertainties and unknown disruptions that occur during dynamic operations. This research suggests a robust Multivariate Model Reference Adaptive Control (MRAC) approach, in order to regulate the Pressure-Drop-Ratio (PDR) of the hydrocyclone and the water level in the separator simultaneously. The suggested control technique is expressed within a framework of state feedback output tracking MRAC by taking adaptive disturbance rejection into account. Furthermore, a control parametrizing obtained from a factorization of the High-Frequency Gain Matrix (HFGM) in the shape of the product of three matrices, i.e. LDS decomposition, is employed in the designing procedure to relax restrictive conditions about the HFGM. Finally, the proposed robust MRAC method is tested on a lab-scaled PW application, and the simulation outcomes explicitly establish the effectiveness and also its remarkable performance of the suggested control strategy.