Evaluation of smoothing effects of autonomous control of microgrids on line flow fluctuations at the coupling point with the utility grid

Previous studies pointed out that the participation of microgrids in the frequency control enables us to reduce the frequency fluctuation of the power system. This feature of microgrids can help penetration of renewable energy resources without extensive investment in utility grids and to reduce the capacity of thermal power plants for load frequency control (LFC) of the power systems. On the other hand, achieving a matched supply and demand of electricity is obligated to the microgrid as well as energy service providers, called PPS (power producer and supplier) in Japan, while the theoretical grounds are indistinct. Then we executed the simulation about the effect of that the microgrid control on the frequency fluctuation of electric power system. The frequency change that originated by random load change was analyzed using the night time condition of IEEJ(The Institute of Electrical Engineers of Japan) east 30-machine model with assuming 20% of all loads were put into the microgrid. As a result, it was clarified the fluctuation of the system frequency will not increase by introduction of microgrid. Moreover, the variance of frequency fluctuation could be decreased by adopting an appropriate control in the microgrid generator.