Study of fuzzy PID controller for industrial steam turbine governing system

In order to satisfy the higher control performance requirement of the industrial steam turbine governing system, the electro-hydraulic servo system and turbine governor based on fuzzy PID control are researched. Since the electric and the heat load models of the turbine always have uncertain dynamics and cross coupling influencing factors, the simple linear or nonlinear differential equations can not sufficiently represent corresponding practical system. And many conventional control methods based on mathematical models are limited in their abilities to improve the tracking performance. This study presents a nonlinear self-adaptive fuzzy PID controller adopting fuzzy rule and inference to adjust PID parameters on-line, which greatly improves the robustness, the dynamic and static properties of the system. Additionally, the idea of variable universe is employed to improve the disadvantage that the membership functions and the control rules can never be modified once they are defined. The proposed fuzzy controller shows excellent robustness against variations of system parameters and external disturbances by comparison with the commonly used classical PID controller or the fixed fuzzy controller via simulations and experiments, which is useful for the future theory research and practice in hydraulic turbine regulation.