Aiming at the problem that the DC bus voltage fluctuation will be caused by the power change of new energy equipment

and the active power may produce power oscillation under the weak power network environment with large frequency fluctuation of the power grid

thus worsening the transient performance of the grid-type optical storage system

based on the virtual synchronous generator technology

a novel terminal complementary sliding mode control(NTCSMC)strategy based on the reduced-order high gain observer(RHGO)is proposed.Firstly

a high gain coefficient is introduced into the observer to suppress transient oscillations

and the structure of the observer is simplified by a reduced-order design.Secondly

the control coefficient is introduced on the terminal complementary sliding mode surface to enhance the stability of the controlled system

and the superhelical switching law is designed to suppress buffeting.Then

the stability of RHGO and NTCSMC is proved theoretically.Finally

proportional integral(PI)control

traditional extended state observer-sliding mode control(ESO-SMC)

and improved ESO-SMC control methods are simulated and verified by experiments on MATLAB simulation and experiment platform. The results show that the proposed control method has a good effect on the transient performance of grid-connected photovoltaic energy storage systems.