Coordinated Control Scheme for Electric Vehicles Connected to Droop-Controlled MicroGrids

This paper proposes a coordinated control scheme for electric vehicles (EVs)connected to droop-controlled AC microgrids that consist of energy storage systems (ESSs)and EVs. The control scheme consists of two control levels: primary control and secondary control. The primary control is implemented on the local controllers of the microgrid (MG)units and is based only on local measurements. The EVs connected to the MG are used as controlled units, they contribute to the frequency and voltage control, their charging power is variable, and they can also support the MG with reactive power. The secondary controller is implemented in a microgrid central controller (MGCC)and the communication between the MGCC and the MG units is based on a low bandwidth communication link. The secondary control restores the amplitude and the frequency of the load bus voltage to their nominal values and consists of frequency and a voltage controller. The restoration signals are sent to all units of the MG, they are used to coordinate between all the MG units and control their active and reactive power. The control scheme is implemented in Matlab/Simulink environment and is validated through dynamic simulations.