# V2G Strategies to Flatten the Daily Load Curve in Seoul, South Korea
## 1 Introduction  
Efforts to promote electric vehicles (EVs) and fuel cell vehicles (FCEVs) are increasing worldwide as part of the fight against air pollution caused by CO2 from automobile exhaust fumes. Therefore, it is expected that the number of EVs and FCEVs connected to the distribution system will increase rapidly in the future. This expansion is expected to ultimately place a strain on utilities. Most electric power companies and governments are cooperating with each other to predict electricity demand that occurs during charging and discharging of electric vehicle batteries, support related technical standards and trade regulations, and prepare for the global spread of electric vehicles. In addition, various studies are being conducted on whether the power grid can meet the growing power demand of EVs. To prepare for such a situation, various studies and demonstrations are being conducted on whether the power grid can meet the increasing power demand of electric vehicles using V2G technologies. V2G technology is a system technology that trades power in both directions between an electric vehicle and the power system. It not only transmits power from the power system to charge the electric vehicle but also transmits power back according to the auxiliary service market or demand response signal in the power market during power peaks. It can be expected to increase the efficiency of power production and consumption. When analyzing the trends in overseas technology in this regard, in the case of the US, a PJM-led mid-Atlantic grid-interactive car consortium and smart car consortium are proving and evaluating V2G technology, and in Korea, there is Jeju Smart Grid Demonstration Complex Smart Transportation. In the presentation business, V2G tests and demonstrations are being carried out on how to send EV (electric vehicle) batteries back to the power system. However, in order for V2G technology to achieve its final goal, it is necessary to secure large-capacity, high-output, long-life and low-cost batteries, develop communication with the vehicle's main controller and custom service to determine battery charge/discharge time, link AMI interface technology and V2G technology, and overcome V2G technology issues such as permitting and stabilizing systems for bi-directional power flow between operational vehicles and grid-connected infrastructure. Among these various problems, grid stabilization measures using V2G strategic technology are very important, but most studies are focused on evaluating the impact of electric vehicle charging and discharging on the grid, and studies that reflect V2G strategic measures for grid stabilization are currently insufficient [1; 2]. Various studies on EV energy consumption (EV battery charging load) suggest that the large-scale deployment of electric vehicles can have a significant impact on the national power grid and residential distribution system. Below, we offer an analysis of previous studies on this issue. For the distribution system in residential areas, uncoordinated charging and coordinated charging according to EV penetration were reviewed and optimization methods were presented, but charging and discharging were not considered at the same time [3]. A method for simulating electric vehicle impact on the distribution system was presented, but it was limited to charging, and no specific case review was presented [4]. Probabilistic modeling of the distribution of electric vehicles (EVs) in the power system was proposed and the resulting clustering characteristics were analyzed to predict the EV charging demand for each bus line of the distribution system, but there was no review of grid peak reduction due to electric vehicle V2G [5].