Economic evaluation of charging/discharging control of electric vehicles as system flexibility considering control participation rate.

In Japan, installed capacity of variable renewable generation (VRG) is rapidly increasing. Through the efforts to make VRG into one of main power resource, vehicle‐to‐grid (V2G) is considered as an effective source of flexibility, which is concerned to lack under large amount of VRG. In this study, we analyze the cost reduction effect of using V2G as system flexibility through calculation of day‐ahead unit commitment (UC) in Kyushu area. To consider uncertainty of day‐ahead UC, we calculate UC simulation with operation reserve requirement considering day‐ahead forecast error of photovoltaic generation, followed by economic dispatch simulation using actual photovoltaic generation. V2G as LFC reduces operation cost especially when demand is low, even with 180 000 electric vehicles (EVs). Cost reduction per EV is about 20‐80 JPY/day with 180 000 EVs, which saturates if more EV participates in the control. V2G as operation reserve reduces discharge from EV for about 0.5‐1.5 kWh/day/EV, which results in reducing degradation of EV battery. [ABSTRACT FROM AUTHOR]