Abstract: Compared to open-loop control, closed-loop startup control is more adaptive to different generating units, simpler in operation, and easier to implement. Thus it has been extensively developed in recent years. This paper presents a new type of given frequency, namely hyperbolic tangent type that was worked out through our studies on the behaviors of its mathematical functions to meet the dynamic requirements at the startup stage of hydroelectric generating units. We have developed a mathematical model of hydraulic turbine governor system and used it to simulate the startup stage in the Simulink platform. And the scheme of hyperbolic tangent frequencies was compared with the given frequencies of index type and linear type to verify its superiority. Results show that in the condition of limited relay opening time, it can shorten the startup time and reduce the amplitudes of variations in guide vane opening, water hammer pressure, and other hydraulic parameters. In addition, the given frequencies of hyperbolic tangent type can effectively reduce the chance of overspeed, thus ensuring good dynamic characteristics of the startup control.