load is first performed s 501 then processing of the economical load distribution 207 for determining economical output distribution from the fuel consumption characteristics of the degs determined by the power supply activating and stopping plan 206 is performed s 502 processing of the facility characteristics identification for sequentially updating the contents of the data from the operation data about the microgrid is performed s 503 subsequently simulation processing for effecting various operation simulations and displaying the results on input output means is performed s 504 details of the steps described in connection with fig5 are described using the functional blocks of fig4 about the microgrid control system the system is composed of the blocks of the power supply activating and stopping plan 206 economical load distribution 207 facility characteristics identification 208 and operation simulation 209 the blocks have the following functional configurations the blocks correspond to the various programs stored in the storage device 205 described in connection with fig2 the block of the power supply activating and stopping plan 206 consists of a demand and solar photovoltaic output forecasting portion 401 a demand and solar photovoltaic output predictive error forecasting portion 402 for forecasting generation of errors of forecasting of the demand made by the load facilities and errors of forecasting of the output from the solar power generators a probabilistic optimum power supply activation amount determining portion 403 for determining the amount of activation of the degs for causing the microgrid to perform an interconnected operation parallel operation and the amount of the operation of the solar power generation facilities interconnected to the microgrid this amount of activation of.