Offline Converter Undisturbed Grid-connected Strategy Based on Virtual Synchronous Generator Control

When recovering from faults in medium and low voltage DC distribution, offline converters need to be connected to the grid. If an effective grid-connected control strategy is not adopted, it will cause disturbances to the system and induce secondary faults Aiming at this problem, this paper proposes a non-disturbed grid-connected strategy for offline converters based on Virtual Synchronous Generator (VSG). First of all, this article briefly introduces the grid-connected mode of the converter, and analyzes the operating principle of the virtual synchronous generator based on the operating characteristics of the converter; Then, the control strategies for converters using rectification and inverter grid-connected modes are respectively given; Finally, a two-terminal DC distribution network simulation model was built in Matlab/Simulink to verify the effectiveness of the proposed strategies under the two grid-connection methods.