Fault Current Calculation of Virtual Synchronous Generator Based on Adaptive Virtual Impedance

The grid-following control distributed power system with "low inertia", "low damping", and "weak voltage support" characteristics cannot meet the requirements for high-proportion integration of renewable energy in new distribution system. As a type of grid-forming control, Virtual synchronous generator (VSG) can support high proportion integration of renewable energy, its control strategy has been widely researched. Recent research has focused on improving control strategies and analyzing control stability, but the research on fault current analysis and calculation is not comprehensive. Based on an adaptive virtual impedance fault ride through control strategy and virtual impedance equation, this paper proposes a VSG steady-state fault current calculation formula through theoretical derivation, which quantitatively describes the fault output characteristics of VSG. By comparing theory and simulation result, the accuracy of the steady-state fault current calculation formula was verified. This paper also provides a theoretical basis for the fault characteristic analysis of VSG.