Abstract: An active disturbance rejection control method based on an improved state error feedback law is developed for a hydraulic turbine regulating system with a nonlinear dead zone and mechanical time delay. First, we develop a mathematical model for such systems considering the gap characteristics in the transmission process of its electro-hydraulic servo system, and transform the state space equation with the dead zone and time delay characteristics into a controllable standardized mathematical model through coordinate transformation. Then, a proportional integral derivative (PID) link is introduced to design a new active disturbance rejection controller that can eliminate the chatter in error signals processed by the state error feedback control law. Finally, we analyze the system error equation based on the Lyapunov stability theorem, and prove the convergence of the extended state observer. The simulation results show that this new controller has a better control effect than the PID control or the traditional active disturbance rejection control under various operating conditions, verifying its effectiveness, superiority and practical significance.

Key words: nonlinear dead zone, mechanical time delay, active disturbance rejection control, hydraulic turbine regulating system, stability