Distributed Global Economical Load Sharing for a Cluster of DC Microgrids

Control Strategies of DC Microgrids Cluster: A Comprehensive Review

“…Where the better accuracy of current distribution and the larger voltage deviations occur, the higher the droop coefficient, and vice versa, which implies the droop coefficient value selects the controller's intrinsic trade-off [36]. This control method is mostly used in coordinating DGs in each DCMG within a cluster, as shown in [27,60,78,80,87,88]. In each microgrid within a cluster, a virtual resistance loop that embodies droop control is constructed on the outer loop of the local control layer, which allows various sources to be connected in parallel, hence sharing load current among units in the system.…”

“…Noteworthy advancements were achieved in evolving distributed controllers for interconnected DC MGs, which can work in either off-grid or on-grid configurations. To achieve the key objectives, non-pinning distributed secondary controllers must be capable of achieving both effective voltage adjustment and proportionate load sharing across the local DGs while remaining resilient to communication connection unpredictability as well as cyberattacks and other threats [87]. In this technique, the non-pinning distributed protocol at each agent can be expressed in Equations ( 3) and ( 4) as follows:…”

“…The tertiary control layer is the third level of a hierarchy control strategy that is accountable for managing the flow of power between the MGs and an exterior power grid, which could be the grid or another MG, which can be implemented based on the secondary voltage control [87]. This level is the most complex level of the control hierarchy structure.…”

“…This approach has been used in many articles in the literature because of the abovementioned features. For example, a fully distributed control approach with local and global layers is suggested in [87] to ensure appropriate power-sharing for DC clustered MGs with various DG types. To avoid the complexity of central controllers, each DG can intercommunicate exclusively with its two neighbors over a two-layer communication system.…”

“…It can be noticed that the protocols in [8,87] are continuous, which is incompatible with real-world applications. To resolve this inconsistency, a discrete-time control approach is necessary [77].…”