Hierarchical power control strategy on small-scale electric vehicle fast charging station

In order to reduce the environmental hazards from non-renewable energy consumption and promote sustainable social development, renewable electric energy has been developed vigorously in countries around the world as the best strategical choice of cleaner energy development. Especially in transportation sector, large quantities of electric vehicles (EVs) are considered the most promising alternative to alleviate the problems of energy crisis, environment pollution and climate warming. However, with the rapid growth of EVs, much more small-scale fast charging stations (FCSs) have limited distribution capacity to satisfy every charging demand simultaneously and are under big pressure to ensure good service capability. Based on current conditions, this paper proposes a hierarchical power control strategy (HPCS) that considers EVs demand, FCS service capability, and FCS daily load fluctuation as a whole with weighted dynamic priority (WDP) and fluctuation smoothing index (FSI). The assumed system model is based on each EV's unique demand and FCS constraints. The simulation results show that the optimal WDP is sufficiently elastic to satisfy EV's demand urgency and fast charging station operator (FCSO)'s income simultaneously. Moreover, FSI is illustrated concretely to decrease daily load fluctuation and peak load value, which is useful to reduce overall power loss. As a result, the HPCS can be realized on a 32-bit processor platform in a FCS to gain an optimal balance between EVs demands and FCSO's profits.