Supply and demand control of distributed generators in a microgrid

Abstract

Distributed generators (DGs) that use renewable energy sources have an unstable output and this can negatively affect existing electric power systems. To reduce this impact, we developed an energy control system for controlling the output from individual DGs that were installed in a microgrid. Controlling the DGs’ outputs enabled the power fluctuation at the point where the microgrid was connected to the existing power grid to be reduced. The microgrid was installed and operated in two separate locations for a total of 672 days. The actual DGs were photovoltaic power generation (PV) systems, fuel cells, and a NaS battery. We demonstrated that 99% of the power imbalance between the supply and demand over 10-, 15-, and 30-minute periods was within a range of ±3% under normal operating conditions when using our power control system. Furthermore, we demonstrated that, by using our power control system, the power flow fluctuation of the PV systems output at the grid connection point was smoothed.