As recently the demand on electric power has been increasing, the requirement of power supply reliability has been increased. Accordingly, the number of HVDC transmission systems in the world has been steadily increased, which have been installed in the power system to transmit a large capacity power to the long distant and interconnect between power transmission grids of different countries. etc. #1HVDC Transmission System was installed between Haenam and Jeju island in 1998, which is the first HVDC system furnished in korea. and has been operated until now. Before #1HVDC Transmission System being installed, the power system of the Jeju Island is a isolated power system from that of Korea mainland. After the construction of #1HVDC the system has made the Jeju power system more reliable and also been able to supply the mainland power, which was cheaper than that of Jeju island, to Jeju island. The construction of additional HVDC transmission system between mainland and the Jeju Island has been currently underway to cope with recent changes of the power market of the Jeju island, for examples the increase of power demand and the capacity of wind power generation. etc.
#2HVDC Transmission System is under construction now and the construction will be completed in 2012. #3HVDC Transmission System will be also installed in 2016 according to the plan.
If all goes as planned, the Jeju power system will be operated with Multi-Infeed HVDC system connected to mainland power system. So the additional studies are needed in order to maintain the stability of the Jeju power system and get the efficiency of the Multi-Infeed HVDC system.
Therefore, in this paper, the optimal operation strategies of the Multi-Infeed HVDC system between the mainland of Korea and the Jeju are suggested to ensure the stability of the power system in Jeju Island when the Multi-Infeed HVDC system is operated between two power system.