The role of electric vehicles for frequency regulation during grid restoration

摘要

Power system restoration after a blackout involves generation restart, energization of buses/power lines and sequential load pickup. During this process, it is of paramount importance to maintain system frequency stable to prevent system collapse or cascading events. As a fast response energy resources in smart grid with bidirectional power flow capability, Electric Vehicle (EV) can be used to compensate for load-generation imbalance in the system which stabilizes frequency and accelerate the load pick up process. In this paper, an optimization problem is formulated which utilizes EVs to provide for frequency regulation over the restoration time horizon. At the end of restoration the EVs are also returned to their initial State of Charge (SOC). The problem is solved as a finite time optimal control problem which determines the global optimal charging/discharging trajectories of the EV batteries which regulates system frequency and also returns the SOC of the batteries to the original state at the end of restoration. Simulations are carried out to illustrate the analytical results.