Decentralized PID control with inverted decoupling and superheating reference generation for efficient operation: Application to the Benchmark PID 2018

This paper deals with the control problem of a refrigeration vapor compression system proposed as a benchmark for the IFAC Conference on Advances in PID Controllers (PID’18). This refrigeration system is a multivariable nonlinear process that shows interactions and is subjected to input constraints. In this work, a decentralized PID control with inverted decoupling is proposed as control structure. The inverted decoupling is designed from an approximated multivariable linear model. Then, the PID controllers are tuned by genetic algorithms to minimize a performance index. In addition, a superheat reference generation is developed to achieve stationary operation points with maximum coefficient of performance which is a widespread efficiency measurement in these systems. Simulations considered in the benchmark show that the proposed design achieves better performance than the reference case.