Recently, smart grid has become a crucial issue and many studies have been conducted by various organizations and research institutions. The Korean government also developed smart grid roadmap and has invested for several years. Jeju is the largest island in Korea with high wind penetration and quality. In the coming years, there are plans to reduce thermal units and increase renewable energy such as WT & PV in Jeju Island. Moreover, The Korean government selected Jeju as one of the sites for electric vehicle propagation. In particular, Jeju has been operating the Smart Grid Test-bed for the next-generation energy systems. Therefore, effects of the smart grid elements and their combination could be checked by simulations of these elements implemented onto the Jeju power system. In this paper, the stability of the Jeju power system is investigated considering the various changes owing to the smart grid elements such as renewable sources, EV and HVDC.