Small-Signal Model Based Frequency Stability Analysis of Multi-Virtual Synchronous Generator Parallel Systems

Unlike the single-machine grid-connected system of virtual synchronous generator (VSG), the multi-machine parallel grid-connected system of VSG has more complex interaction relationships among devices. Therefore, it is difficult to accurately analyze the dynamic performance of the system only by using traditional analysis methods. In order to study the frequency characteristics between VSG and VSG as well as between VSG and the power grid, this paper first derives the general small-signal model of the multi-machine parallel grid-connected system of VSG. Secondly, by combining the motion trajectory of the participation factor of the dominant state variable of the system characteristic root, the influence relationship of factors such as the active power control loop parameters on the low-frequency characteristic root of the system is analyzed in detail, and the influence law of the active power control loop parameters on the frequency between VSG and VSG and between VSG and the power grid is obtained. Finally, the correctness of the frequency stability influence law of the system obtained in this paper is verified by simulation.