Analysis of the frequency-based control of a master/slave micro-grid

Renewable energy penetration in the low-voltage grid faces several limitations due to the current grid topology. Master/slave micro-grids could help solving these issues, by offering additional services to the grid such as the power management of the distributed power energy sources. In some cases, the power produced by the distributed energy sources exceeds the local consumption of the low-voltage grid. The consequent reverse power flow can be either dangerous (for the medium voltage) or impossible (for a micro-grid with limited storage). The droop characteristic of commercial inverter can be exploited to avoid this behaviour. However, stability problems can arise due to a low phase-locked-loop (PLL) bandwidth. This study investigates the stability of this solution depending on the bandwidth of the PLL of the distributed power generation sources.