A DC-microgrid control strategy using DC- bus signaling

DC Microgrids (DC MGs) gain popularity as they present attractive features such as: high system efficiency, high power quality, reduced cost, reduced power conversions and less complex control. This paper presents a local control strategy of a DC MG consisting of a fuel cell and a composite energy storage system that includes super capacitors and a battery bank. The control strategy is based on the local measurement of the common DC bus voltage. The different levels of the DC bus voltage serve as an information carrier and dictate the different operation modes of the microsources (DC bus signaling). The proposed control strategy also takes under consideration the appropriate load management, which involves load shedding based on predefined load priority levels, that may be necessary during abnormal or island conditions. The control is tested via simulation studies under islanded, interconnected mode and under transitions proving satisfying response.