Modeling and Calculation of Grid Frequency Support Effect and Transient Energy Demand of a Virtual Synchronous Generator

Virtual synchronous generator (VSG) is a promising control strategy of an inverter-interfaced distributed generator, owing to its ability to provide inertia support and primary frequency regulation after a grid disturbance. These new features, however, require extra transient energy, which is generally released/absorbed by energy storage (ES). To optimize the design of the ES of a VSG, it is necessary to establish a modeling and calculation method of the transient energy demand (TED) of a VSG and the corresponding maximum grid frequency deviation (MGFD) under a given grid disturbance condition. This method should take the dynamic models of both the grid and the VSG into consideration, including nonlinearity such as droop deadband. Hence, a systematical modeling method and calculation algorithm for the TED and MGFD is presented in this paper. The numerical results obtained by the proposed algorithm are well verified by simulation results from PSCAD/EMTDC. Based on this algorithm, we investigate the influence of VSG parameters on TED and MGFD, and will propose a VSG parameter optimization method to minimize the TED with a given MGFD constraint in our future work.