Role of dual active bridge isolated bidirectional DC-DC converter in a DC  microgrid

In the present scenario of “sustainable energy for all,” the requirement of DC microgrid has become a necessity. Electricity at cheap cost, without causing pollution or health hazards, and affordable at the same time is the need of the hour. DC microgrid plays a pertinent role in achieving the abovementioned goals and abiding the economic and environmental constraints. DC microgrid is basically a power system designed for the integration of renewable energy sources with storage elements and works at the distribution network. Various control strategies broadly categorized into three categories: centralized, decentralized, and distributed. Master-slave control is the most common strategy used in centralized control strategy in which one of the distributed generator (DG) acts as the master and rest of the DGs acts as slaves. In this approach the master DG acts as a voltage source and carries on the voltage regulation. For secondary and tertiary control of DC microgrid, distributed control strategy is used. On the basis of consensus protocol, several algorithms are developed for improving power share and DC voltage regulation. In decentralized control strategy the communication is totally ignored. As the microgrid consists of nonconventional sources of energy and energy storing elements, requirement of a power electronics interface becomes unavoidable. The importance of power electronics-based energy conversion system that facilitates energy transfer in both the directions (forward as well as backward) owning high efficiency has increased manifolds in DC microgrids. As the power electronics-based energy conversion system finds its application in DC microgrid, it has to be light in weight, has high power density and reduced switching losses. Applications utilized in industries based upon power electronics (electric vehicle, transformers working on solid-state devices) are finding isolated bidirectional DC-DC converters very useful and are incorporating these in their central power unit. In the present chapter the role of dual-active bridge (DAB) converter acting as a power electronics interface in DC microgrids is presented. The working of DAB as a power electronics interface for facilitating bidirectional power in DC microgrid is discussed. The single-phase shift control strategy of converter operation along with simulation results is presented.