Two-loop PID control using PSO-RGA algorithm for solar heat pumps

In this paper, a two-loop PID (proportional integral derivative) controller is presented for a class of solar water-source heat pump systems (SWSHPS), which provide warm water with desired temperature for a semiconductor factory. A combination of the well-known particle swarm optimization (PSO) and real-coded genetic algorithm (RGA) is proposed to off-line optimally find the controller parameters of the proposed control law. Through simulations, the two-loop PID control strategy is shown to be effective and robust against parameter variations. By comparing with two existing two-loop PID control strategies, the proposed two-loop PID controller, tuned by the new PSO-RGA algorithm, is shown to give superior transient performance, smaller steady-state errors and better robustness against parameter variations.