Research on coordinated charging for electric vehicles

At present, the battery management system (BMS) of lots of electric vehicles (EV) with different types cannot communicate normally with AC charging piles in residential quarter. The paper proposed a coordinated charging strategy for EV aggregator in residential quarter without collecting the state of charge (SOC) of EVs. The method obtains the constant charging time of EVs by certainty analysis, then seeks for the period of the lowest total loads in the power system and arranges the charging starting time by reverse recursive principle, thus meets customer charging requirements making full use of the valley period. The arrival time of EV users is simulated by Monte Carlo method, and the load condition of distribution transformer under three charging modes, namely the uncoordinated charging, the charging in the minimum load period and the charging in the reverse recursive period, are simulated and analyzed. Research results show that the charging at the reverse recursive period can reduce peak-valley ratio signally and cannot cause new peak load, thus it is suitable for practical application.