Formation of the cost of electricity in the local power generating systems of Microgrid should be based on dynamic models that properly take into account the fundamental nature of the dynamic power control system, and enable for flexible changes in economic parameters of the generating system. An urgent task is to create a dynamic mathematical model of the "producer - consumer" system of electricity, which should combine, on the one hand, the energy performance of the generating system, and on the other - economic indicators of macroeconomic closed system. The article describes an example of an isolated system consisting of a diesel generator and the consumer. The resulting model allows to investigate the impact of macro-economic parameters of an isolated system to change the value indicators of the economic system when changing the power level, given the presence of transients in the generator.