Research on multisite collaborative control method and frequency stability improvement of grid‑connected energy storage based on VSG

With the large-scale integration of new energy and the expansion of power grid construction, the stability problems such as uneven distribution of inertia and frequency fluctuation of power system are becoming increasingly prominent. With the advantages of voltage source characteristics, black start ability and active frequency and voltage regulation, grid-structured energy storage has become a key technology to solve the stability problem of weak grid and island scenarios. In view of the limitation that the current distributed grid-connected energy storage mostly adopts independent control and the inertia support ability is difficult to adjust adaptively, this paper studies the principle of grid-connected energy storage and the multi-site cooperative control method. Firstly, the core differences between grid-connected energy storage and grid-connected energy storage are compared, and the control mode of grid-connected energy storage and the application mechanism of power grid are analyzed. Furthermore, a multi-energy storage cooperative control method based on virtual synchronous generator (VSG) is proposed. By introducing the inertia center theory and cooperative control instructions, the dynamic adaptive adjustment of inertia support is realized. Finally, an example simulation is carried out based on the actual photovoltaic and load data in G area. The results show that the proposed cooperative control method can effectively suppress the fluctuation of photovoltaic output and improve the inertia support capability of the system. In the scenario where the maximum frequency change rate is allowed to be ≥ 0.35Hz/s, it canstably provide about 2.30MW. h of accumulated output to suppress fluctuations, significantly reduce the risk of system instability, and provide technical support for the efficient application of grid-connected energy storage.