When ac microgrids (AC-MG) and dc microgrids (DC-MG) are in the vicinity of each other, there is an opportunity to interconnect them via interlinking converters (ICs) and form a hybrid microgrid (HMG). This interconnection, provides the possibility of energy exchange between two grids. Common methods employed in IC control strategy use frequency variation in their structure. These methods require the frequency variation at IC ac-side to be large, leading to poor power quality and stability of AC-MG. In this dissertation, IC control strategies which are independent of frequency variation measurement, are proposed. The ICs are meant to exchange active power between microgrids, however, they can also participate in reactive power sharing of AC-MG. In this dissertation, it is shown that how the reactive power generation method in IC, leads to unstable operation of HMG. Detailed analysis of this instability reveals that it is caused by a phenomenon known as limit cycle. Power sharing and adequate voltage/frequency control are the main functions of AC-MG and DC-MG control systems in standalone mode. When it comes to a HMG, active power sharing throughout the whole system and participation of IC in AC-MG reactive power sharing must also be properly achieved. In this dissertation, a new decentralized control strategy is presented for a HMG which results in better active/reactive power sharing across both microgrids and better voltage regulation. Key Words Distributed energy resources, frequency deviation, hybrid AC-DC microgrids, power sharing, stability
