A daily consumption irregularity of residential and public buildings determines the topicality of leveling the daily schedule of these consumers. An energy storage device is required for this task. A simulation model of a synchronous machine has been developed and a simplified algorithm for controlling its active power has been presented in the SimInTech simulation environment. The simulation model of a synchronous machine considered in this research is part of a simulation model of a reversible energy converter with a flywheel energy storage device. One of the tasks of this electrical engineering complex is the leveling of daily load schedule of transformer substations of residential and public buildings. The mathematical model is based on the Park-Gorev system of equations. The synchronous generator MC375-1000 was selected as a synchronous machine. The missing parameters and resistances are determined by calculation. The simulation considers the variable-frequency start of a synchronous machine, the charge of a flywheel storage and the discharge of a flywheel storage. The simulation is performed in relative units in dq-coordinates. To control the charge and discharge mode of the flywheel storage, a PI controller with feedback on the error in setting the current iq of the synchronous machine was selected. The flywheel energy storage is taken into account by the moment of inertia on the shaft of the synchronous machine.