Smith-fuzzy PID compound control strategy for variable volume water system

Aiming at the characteristics of chilled water system in central air conditioning, such as nonlinear, large hysteretic nature and strong time-varying, proposes a Smith-fuzzy PID compound control strategy. Develops a mathematical model of chilled water system in the central air conditioning system. Presents the principles of fuzzy PID and Smith predictive compensation respectively. Combining advantages of two methods, proposes a compound control strategy which adding Smith predictive compensation to fuzzy PID control according to the system state. Simulation results show that the system can quickly reach the set value by this control strategy, with better dynamic performance and anti-interference ability. Even though the parameters vary, the system is still of good adaptability. Applies the control strategy to an experimental platform, and the experimental data shows that compared with traditional PID control, Smith-fuzzy PID compound control strategy is more energy efficient.