Influence of virtual inertia in wind turbines on large scale power grid frequency characteristics

The penetration rate of wind turbines (WTs) has continually increased in large-scale power grid. These WTs, which do not have inertial response, potentially weaken the inertia of power system. To address this problem, researchers have proposed virtual inertia control for WTs. However, only a few studies have investigated the effect of such virtual inertia on improving frequency characteristics of large-scale power grid. In this paper, the power grid frequency characteristics have been investigated from three way: analysis of practical frequency drop incident, typical examples simulation and mathematical model. Based on the investigation results, the influence of inertia support in wind turbines on the frequency drop characteristics in large-scale power grid. Finally, the influence of inertial response on primary frequency modulation in WT was analysed. The result indicated that different virtual inertia control of WTs show variable influences on frequency stability. Moreover, some virtual inertia methods of WTs may contribute to negative damping for frequency characteristics of large-scale power grid.