Algorithm for bottom charge based on load-duration curve of plug-in hybrid electric vehicles

In the transport sector, Plug-in Hybrid Electric Vehicle (PHEV) is being developed as an environmentally friendly vehicle. PHEV is a kind of hybrid electric vehicle, which can be charged from power grid. Therefore, when analyzing reduction effect of CO₂ emission by PHEVs, we need to count the emission from the power sector. In addition, the emission from the power sector is greatly influenced by charge pattern, i.e. timing of charge. For example, we can realize the load leveling by bottom charge, which charges late at night. If nuclear power plants were introduced by load leveling, we could expect substantial CO₂ reduction. This study proposes an algorithm for bottom charge based on load-duration curve of charging. By adjusting the amplitude of charging power, we can bring the shape of curve close to that of ideal bottom charge. We evaluated the algorithm by using optimal generation planning model. The evaluation index is a difference between Target case, in which PHEVs ideally charge to raise the bottom demand, and Proposal case, in which PHEVs charge using the proposed algorithm. Annual CO₂ emissions of Target case and Proposal case are 20.0% and 17.5% less than that of Reference case. Percentage of the reduction effect of Proposal case to that of Target case results in 87.5%. These results show that the proposed algorithm is effective in bottom-up of daily load curve.