Establishment and focus: To calculate the capacity of an energy storage device efficiently, it is necessary to realistically consider wind power generation and the size of the connected load. When considering wind power generation, since the utilization rate differs for each season, it is necessary to thoroughly examine the magnitude of the load and the utilization rate of the installation for each time unit. In the case of a separated island system, the sum of the amount of fossil power generation and the total amount of the HVDC link may exceed the entire load. Therefore, taking into account the capacity of connected HVDC, it is very important to examine the acceptable capacity of wind power generation, so it is necessary to review in advance the operating capacity limit of the energy system and establish an optimal distribution target for wind power.

This paper has attempted to calculate the capacity of the energy storage device based on the expected excess power in the high wind penetration system. Based on realistic HVDC connections of ROK, ESS storage estimates were progressed. Practical wind and power system conditions are utilized in simulation to reflect possible critical situation. The main case studies focus on the feasibility of ESS operation with applied capacity and control method.