Modelling and Transient Stability Analysis of Interconnected Autonomous Hybrid Microgrids

Stand-alone microgrids comprising diesel generators and inverter-based renewables can be interconnected to increase the cost efficiency and security of supply. Investigation of the transient stability of such hybrid microgrids is crucial in the planning phase. To analyse the dynamic behaviour of hybrid microgrids in island and cluster modes, two exemplary microgrids were modelled. Firstly, different droop-control strategies were compared and the best strategy for the microgrids was selected. According to the results of the short circuit analysis, clustering of the studied hybrid microgrids reduces the critical fault clearing time as against in the island mode. Diesel generators tend to loose synchronism mainly due to the intentional active power reduction in renewables during fault-on period. Further, the system voltage recovery in the post-fault period is strongly influenced by the 100 % provision of reactive power by renewables.