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AC/DC hybrid micro grid system (HMGS) is designed with renewable energy sources (RES) and battery energy storage system (BESS) with unique control schemes, interfaced with multi terminal interlinking converters (ILCs). This ILC operates on droop control scheme to guarantee bidirectional power sharing to AC/DC sub grids. The power sources in AC/DC sub grids like PV, Fuel cell, BESS are controlled by advance control methods for maximum power extraction with power quality. A three-level control structure is designed for optimal energy management system (EMS). The first level confirms the power balance in AC/DC sub grid with autonomous bidirectional power transfer via ILC in islanded mode. The second level tracks the batteries state of charge (SoC), based on the minimum and maximum SoC the battery operates for charging and discharging. The third level gives the power redundant capability for critical loads connected in AC/DC sub grid for DC system and single-phase system.

<p>The present trend of integrating renewable energy sources (RES) in AC/DC hybrid micro grid systems (HMGS) has certainly reduced the greenhouse gases and provides the variety of power sources for micro grid (MG). Interlinking converter (ILC) is the main converter for interconnecting AC/DC sub-grids with a variety of features like autonomous bidirectional power sharing, reducing the power conversions in the grid and additionally a featuring aspect for energy management system (EMS). Interlinking converters are desired to maintain stable frequency, constant voltages at buses, reduce the power losses, reduce switching losses and control on circulating currents, most of the control methods could not achieve all. In this paper, the decentralized modified droop control method is presented which is significant in meeting the autonomous bidirectional AC/DC power load demand and in achieving the desired features. A three coordinated model is proposed where AC frequency, ILC power and DC voltage are the corresponding axis. The power sharing through the ILC is dependent on the AC frequency droop and DC voltage droop which occurs due to overloading. This control scheme is compatible for interconnection with multi-port grids. This control schemes provide more reliable, stable and accurate results compare to conventional droop methods.</p>

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