Abstract: Disclosed herein is a modular power supply system and method for controlling the same. In one embodiment, a modular power supply is disclosed comprising a housing comprising an equipment enclosure conforming to the requirements of an ISO container; a plurality of power generation modules housed at respective ends of the housing, a respective power generation module including a variable speed diesel engine coupled to a generator, a pair of rectifiers coupled to the generator, a pair of inverters coupled to the rectifiers, an LCL filter coupled to each inverter, a breaker coupled to each LCL filter, the breakers connected to a central AC power bus; and a plurality of energy storage subsystems housed at respective ends of the housing, a respective energy storage subsystem comprising one or more batteries connected to a pre-charge circuit, a DC/DC boost converter connected to the pre-charge circuit, and a DC power bus connected to the input of the inverters.