Abstract: In order to improve the grid-connected stability of the energy storage converter and the controllability of the energy storage power station participating in the frequency regulation of the power grid. This paper proposed a third-order synchronous machine model based active support control strategy for battery storage power plant. This control strategy can make the energy convertor equal to a quasi-synchronous voltage source with the excitation system and speed control system, which provides the necessary inertia and damping characteristics for low-inertia, weakly damped renewable power systems. Through designing the difference coefficient of the energy storage power plant, the forward static frequency characteristics adapting to different frequency regulation depth requirements of power system were described. The inertia reaction and primary frequency response characteristic of the energy storage power plant with different control parameters was analyzed. At the same time, the ratio of the frequency adjustment output of the energy storage power plant to the traditional units was defined as the contribution factor of the energy storage power plant participating in the grid frequency adjustment, which was used to characterize the contribution of the steady-state frequency deviation of the energy storage power plant. Through the reasonable and flexible allocation of storage plants, a stable and friendly frequency environment can be built for the high-penetration renewable power system.