Power coordinated strategy of vehicle-to-microgrid integrated hybrid AC/DC microgrids considering electric vehicles as flexible energy storage

Abstract

Increasing adoption of electric vehicles (EVs) entrance to hybrid ac/dc microgrids (HMGs) would provide flexible energy storage sources (FESSs) to perform vehicle-to-microgrid (V2MG) operation. However, especially in islanded mode, the state of charge (SOC) of traditional energy storage unit (ESU) approaching the critical value of charge/discharge would inevitably lead to unreliable power supply. To solve this problem, a power coordinated strategy of V2MG integrated HMGs considering EVs as FESSs is proposed in this paper. First, a joint energy storage sources (JESSs) dynamic grouping method is presented for traditional ESU and scaled electric vehicle groups (EVGs) within HMGs containing multiple subgrids, which divides ESU and EVGs into panels and sets at the same time scale. Then, the operation modes and conditions of HMGs are classified according to the power surplus/deficient state of each subgrid. Further, this paper designs response priority based on real-time grouping of JESSs to balance the SOC of ESU and formulates power coordination control strategies for abnormal SOC of ESU and subgrid power overlimit, among which the FESSs provide auxiliary service for system power regulation. Finally, the results of the simulation analysis show that the proposed strategy can achieve coordinated regulation of traditional ESU and EV as FESSs in islanded microgrids, reducing the system's dependence on traditional ESU and improving the power supply reliability of microgrid systems.