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This work presents an extensive review of hierarchical control strategies that provide effective and robust control for a DC microgrid. DC microgrid is an efficient, scalable and reliable solution for electrification in remote areas and needs a reliable control scheme such as hierarchical control. The hierarchical control strategy is divided into three layers namely primary, secondary and tertiary based on their functionality. In this study, different methods of primary control for current and voltage regulation, secondary control for error-correction in voltage and current, power sharing in a microgrid and microgrid clusters and tertiary control for power and energy management with a primary focus on minimal power loss and operational cost in a DC microgrid system are reviewed in-depth. Along with this, the advantages and limitations of various control structures like centralised, decentralised, distributed are discussed in this study. After a comparative study of all control strategies, the optimum control schemes from the author's point of view are also presented.

In this paper, closed-loop control of isolated bidirectional dual-active bridge (DAB) DC-DC converter is proposed for dual-phase-shift (DPS) scheme using fixed frequency pulse-width-modulation (PWM) plus transmitted command power. DPS is a well-known control scheme to reduce backflow power, current stress, and losses, it also provides better power transfer flexibility under high frequency. However, the conventional DPS scheme has limited performance in light load conditions. The discussed control technique overcomes the instant variation of inner phase shift ratio (D 1 ) w.r.t outer phase shift ratio (D 2 ) during light load conditions. The theoretical concepts of the transmitted power in different modes of operation are presented in this paper along with a detailed analysis of MATLAB simulation results in dynamic conditions and both directions of power flow. The implemented control scheme leverages most of the improved features of the DPS scheme to transfer power from one end to another end.