This thesis is concerned with the improvement of reactive power sharing and dynamic stability of islanded microgrids (MGs). A well-known method adopted to achieve reactive power sharing in decentralized control strategy is using Q-V droop characteristic. Using such a characteristic normally fails to provide adequate reactive power sharing as voltage is not usually the same at different microsource (MS) buses due to different line impedances and loading pattern variations. Most of proposed methods in the literature are limited to specific MG structures or need extensive information of grid. In this thesis, three methods are proposed to improve reactive power sharing in islanded microgrids with converter-based MSs while using decentral ized control strategy. These methods are adding a small series converter which is added to MSs output terminals, modifying Q-V droop characteristic using a combined characteristic and modifying Q-V droop characteristic based on harmonic signal injection. The dynamic stability of system using the proposed methods is also studied in details. To verify the validity of proposed methods, two different case studies are presented and will be used. Key Words Microgrid, Power sharing, Stability, Series Compensator, Characteristic Modification, Signal injection
