| Digital electro-hydraulic servo control system (DEH) is the key of ensuring steam turbo-generator operating normally. There will never be an end of improving the stability, reliability and precision of DEH. In the condition of small grids, power grid is sensitive of the load fluctuation, and its'frequency fluctuates seriously. Thus, primary frequency regulation of DEH must response fast and have a high stable precision. However, most existing primary frequency regulation of DEH has sampling distortion and computation delay,leading to grids'frequency cannot being control in time, thus decreasing the system's stability. Additionally, actuators of DEH, drive the steam valves. Improving the control quality of servo control loop of actuator is important for the quality of DEH. According to issues mentioned above,this paper have done some theoretical analysis and research.Firstly, a kind of primary frequency regulation fast response loop is designed, its'dynamical response is analyzed and simulated, and its'feasibility is verified.Secondly, a dual redundancy servo control loop of actuator is designed, and models of servo-valve with two parallel inputs and other parts in the control loop is built, and its'dynamical response is analyzed and simulated, and its'feasibility is verified.Finally, a digital electro-hydraulic servo controller of control loop of actuator is designed, using fuzzy PID control algorithm, and its'dynamical response and control precision is analyzed and simulated.The analysis and simulation results show that the control loops and controller designed by this paper have a satisfying dynamical response characteristics and control precision, highly improved the stability and reliability of DEH when running in condition of small grids.
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