Modeling and criterion for voltage stability of grid connected droop controlled inverter

Increased penetration of distributed generators (DGs) in the grid can cause instability in the system. One such problem is voltage rise. In transmission system, where lines are highly inductive real power depends mainly on angle difference between buses and reactive power exchange depends upon voltage magnitude of buses. Such an assumption might not be valid for distribution system or small scale system. Hence it is important to consider R/X ratio of line while modeling a system for stability studies. This paper models a single inverter system connected to stiff grid. Further the factors that may led to voltage instability of a single inverter system were studied and criterion for system's stability was established.