Management of the power supply of a local power transport grid

The system has an energy storing unit (PSD) connected to an energy transporting network (DEN) and configured in a first mode in which the storing unit provides energy to a client device (DCL) or in a second mode (MOD) in which an operator (PSO) provides energy simultaneously to the client device using the storing unit. A control device (GWY) is configured to determine and assign one of the modes to a switching device (COM) based on comparison between an instantaneous level (SEL) of energy stored in the storing unit and a local threshold associated with time periods. Independent claims are also included for the following: (1) a device for controlling a management system (2) a method for management of power supply of a client device connected to a local energy transporting network in a building.