Using PSO-Smith cascade control algorithm for water source heat pump systems.

Heat pump systems are suitable for most factory and commercial air-conditioning applications. This paper presents Cascaded smith control plus PWM Algorithm in Compressor speed and Refrigerant flow rate Control for water source Heat Pump Systems. The controller’s parameters are off-line optimally selected by particle swarm optimization (PSO) algorithm. This proposed presents control structure retains the best merits of cascade PID control structures for compressor speed adjust and the refrigerant flow rate regulate of WSH PS. The control strategy is shown effective for such a system. The performance of the control is compared to that of a conventional pure PID control strategy (Ziegler-Nichols method) and the results reveal that the control strategy gives superior performance, reduced transient performance and smaller temperature overshoots. Cascaded smith control structure retains the best merits of both smith predict and cascade control structures. Through implement, the Cascaded smith control plus PWM strategy is shown effective, and shown robust against parameter variations. The performance of proposed is compared to existing PID control strategies, and the results reveal that the proposed PID controller tuned by the proposed PSO-Smith plus PWM Algorithm gives superior performance , reduced transient performance and better steady-state errors.