Charging-Cost Minimization of Electric Vehicles and its Impact on the Distribution Network

Widespread deployment of electric vehicles (EVs) could have adverse effects on the operation of power systems, especially at the distribution level. To prevent network overloads caused by the simultaneous recharge of several vehicle batteries, there is a need for coordinated charging schemes that can optimally schedule the EV charging loads. The scheduling algorithm determines the optimal time and power at which individual EVs should be recharged to achieve certain technical or financial objectives. Technical objectives, such as peak shaving, loss minimization, or voltage enhancement seek to improve the operational aspects of the distribution system. Financial objectives, such as minimization of generation cost or charging cost aim to improve the economics of power distribution. In this paper, the impact of financially-motivated charge scheduling on the operation of a distribution network is examined. The scheduling algorithm seeks to minimize the total charging cost incurred by vehicle owners using convex optimization. The impact of optimized EV charging on the system demand and voltage profile of the test system is analyzed here. The simulated algorithm is able to reduce charging cost and peak load by 30% and 41% while improving the load factor and minimum voltage by 76% and 18%, respectively.