A Virtual Synchronous Generator Based Hierarchical Control Scheme of Distributed Generation Systems

International audienceSustainable energy-based generation systems, such as photovoltaic and wind turbinegeneration systems, normally adopt inverters to connect to the grid. These power electronic interfacespossess the characteristics of small inertia and small output impedance, which create difficultiesto stabilize the voltage and frequency of a distributed power source. To deal with this problem, aVirtual Synchronous Generator (VSG)-based inverter control method is presented in this paper byintroducing virtual inertia and damping coefficient into the control loop to emulate the dynamicbehavior of a traditional synchronous generator. Based on this VSG control method, a three-layerhierarchical control scheme is further proposed to increase the control accuracy of the voltage andfrequency in a VSG-based distributed generation system with parallel inverters. The principle ofthe VSG control method, the system stability analysis, the design process of the hierarchical controlstructure, and the frequency/voltage secondary regulation processes are all specified in this paper.Finally, some numerical simulations are carried out and the effectiveness of proposed control schemeis verified by the simulation results analysis