# V2G Strategies to Flatten the Daily Load Curve in Seoul, South Korea
## 3 Conclusions  
According to the estimation of the shares of electric vehicles in Seoul in 2030 and 2040, the amounts of electric vehicle charge and discharge for the corresponding years were calculated. More specifically, considering whether or not the charging and discharging rate system was reflected, the daily load curve for charging and discharging electric vehicles for each year was calculated by dividing the scenarios into an uncontrolled mode, control mode 1, and control mode 2.  
Figure 16: Daily load curve in Seoul in 2040 (controlled mode 2).  
Figure 15: Daily load curve in Seoul in 2040 (controlled mode 1).  
When calculating daily load curves for the uncontrolled mode, control mode 1, and control mode 2 in 2030 and 2040 for Seoul, compared to the uncontrolled mode considering only vehicle operation, the current charge and discharge rates applied by KEPCO [23] were reflected. It was found that control mode 1 flattened the daily load curve more, and control mode 2 (to which the more adjusted charge/discharge rate was applied) flattened the daily load curve the most. Putting these together, the following conclusions can be derived.  
First, when the EV share is 10% (in 2030), neither the controlled mode nor the uncontrolled mode show high charge and discharge loads at home or in the workplace. Concerning the uncontrolled mode, the total load increases by 1-2% from late at night to 10:00 a.m. (off-peak time). Between 11 a.m. and 5 p.m. (peak time), it decreases by 1-4% for control mode 1 and control mode 2. Therefore, applying the TOU and SMP tariffs can increase the morning load and decrease the load in the afternoon.  
Second, when the EV share is 30% (2040), control mode 1 and control mode 2 show high charge and discharge loads at home and in the workplace. In the case of control mode 1, the total load increases by 2-3% from late at night to 10 a.m. (off-peak time) and decreases by 3-9% between 11 a.m. and 5 p.m. (peak time). In the case of control mode 2, it increases by 3-5% from late at night to 10 a.m. (off-peak time) and decreases by 6-15% between 11 a.m. and 5 p.m. (peak time).  
To conclude, the TOU and SMP tariffs could significantly increase the morning load and decrease the load in the afternoon. Control mode 2 can flatten the load curve most effectively compared with the other modes.  
The results of this paper also provide an accurate picture of how much the V2G strategy contributes to daily load flattening via the charge and discharge loads of electric vehicles at workplaces and homes in Seoul. In other words, this paper proposes a strategy for establishing an SMP rate and a TOU rate management plan in order to flatten the daily load curve of the Seoul power system and prevent overload through a V2G strategy. However, research to establish a V2G strategy that simultaneously considers EVs and FCEVs will be conducted in the future, factoring in the influence of other external factors such as seasonal demand changes and energy supply and demand.  
Conceptualization, S.C.; Validation, B.S.; Formal analysis, C.K. All authors have read and agreed to the published version of the manuscript. This research was funded by the Korea Institute of Energy Technology Evaluation and Planning (Grant No. 20192010107050). Not applicable. Not applicable. Not applicable. Not applicable. Data Availability Statement: Data are not publicly available due to privacy or ethical restrictions. The authors declare no conflict of interest.