With the continuous change of power grid system load, the frequency of power grid system will change continuously. The main task of hydraulic turbine governor is to maintain the rated speed of hydraulic turbine generator unit by adjusting the output power of hydraulic turbine generator unit. The process that the turbine changes the guide vane opening (or needle valve stroke) accordingly with the change of unit load to restore and maintain the unit speed to the rated value or a predetermined value is called turbine regulation.