Charging and Discharging Strategy of Electric Vehicles Within a Hierarchical Energy Management Framework

As the number of EVs is increasing modern methods are required to understand their impact to the power grid (operators and users). In order to reduce/manage fluctuations on voltage stability and angle stability there is a need for a management control strategy. This paper presents an energy management concept of Charging Station System (CSS) to charge or discharge power of EVs in different situations while retaining system integrity. A suitable objective function is formulated of frequency deviation and voltage deviation on the optimal operation of the charging station are evaluated by formulating and solving the optimisation problem using mixed integer linear programming. The results show that EVs act as a regulator of the microgrid which can control their participation role by discharging active or reactive power in mitigating frequency deviation and/or voltage deviation. The optimisation algorithm is evaluated by formulating and solving the optimisation problem using mixed integer linear programming. Case studies are used to show the viability of the proposed energy management concept.