Stability Analysis and Control Strategy for Multi-Machine Parallel System with Grid-Forming Inverters

Virtual synchronous control technology can enable new energy generation to possess similar characteristics to synchronous generators, such as rotational inertia and frequency and voltage regulation. It is currently widely used as a network control strategy for new energy generation integration. In this paper, research is conducted on the power oscillation problem in a grid-forming multi-inverter system that uses virtual synchronous control technology. By establishing a state-space model for the grid-forming multi-inverter system, the dominant mode of power oscillation caused by load disturbance is calculated. The impact of the matching relationship between virtual inertia and line impedance on system stability is analyzed, and virtual damping adaptive control and virtual impedance adaptive compensation methods are proposed. The results show that compared to the virtual damping adaptive control method, the virtual impedance adaptive compensation method can ensure optimal dynamic performance of the system while improving system stability and significantly reducing the risk of power oscillation caused by load disturbances in the grid-forming multi-inverter system.