Decentralized voltage regulation in islanded DC microgrids in the presence of dispatchable and non-dispatchable DC sources

Voltage control in islanded DC Microgrids (MGs) is essential in the presence of various types of DC Distributed Generation (DG) units. This paper proposes a control system to accurately share loads among dispatchable DG units in a decentralized way, while the DC network voltage is regulated. The non-dispatchable DG units can operate independently interfacing a voltage-regulated network. To this aim and for providing decentralized load sharing, the conventional droop control is modified by defining a voltage compensation term. The proposed control system utilizes a superimposed AC voltage to adjust the voltage compensation term. This term shifts the terminal voltage of DG units proportional to the frequency of the AC voltage component. The importance of synchronization for the superimposed AC voltage in the dispatchable and non-dispatchable DG units is discussed in this paper. Also, the performance of the proposed control system is validated by a set of simulation studies using PLECS.