Integrating ultra‐fast charging stations within the power grids of smart cities: a review

Abstract

Plug-In Electric Vehicles (PEV) have become a key factor driving towards smart cities, which allow for higher energy efficiency and lower environmental impact across urban sectors. Industry vision for future PEV includes the ability to recharge a vehicle at a speed comparable to traditional gas refueling, i.e., less than 3 minutes per vehicle. Such a technology, referred to as Ultra-Fast Charging (UFC), has drawn much interest from research and industry. The large power density, impulsive, and stochastic loading characteristics of UFC, however, pose unprecedented challenges to existing electricity supply infrastructure. Planning the locations and electric capacities of these UFC stations is critical to preventing detrimental impacts, including grid asset depreciation, grid instabilities, and deteriorated power quality. In this paper, we first review planning methods for conventional charging stations and then discuss outlooks for UFC planning solutions by drawing an analogy with renewable energy source planning, which presents similar power density and stochastic characteristics as UFC. While this paper mainly focuses on UFC planning from the power grid perspective, other urban aspects, including traffic flow and end-user behavior, are examined for feasible UFC integration within smart cities.

Location Planning of Fast Charging Station Considering its Impact on the Power Grid Assets

“…4b and 5b shows the evolution of probability vectorv t , which converges to a binary vector corresponding to the optimal solution. Therefore, the optimal locations to place FCS for N F CS = 5 and N F CS = 10 are X = [8,9,13,20,22] and X = [3,4,7,8,9,12,13,20,22,23], respectively.…”

“…As an unconventional type of electric load, PEV consumes a large amount of power in a fast and discrete manner, which far exceeds the peak power demand for an average household in the U.S [2]. In continuing towards the goal of resembling traditional refueling stations, multiple charge ports per station are built, bringing total power capacity in a Fast Charging Station (FCS) to Megawatt level [3]. Prior works have shown that the impulsive characteristics of PEV charging load, especially when aggregated at the FCS, will result in negative impacts on the power grid, including disruptively varying voltage profiles along the feeder and lifetime depreciation of critical grid assets [4].…”

Cooperative Optimization of Electric Vehicles and Renewable Energy Resources in a Regional Multi-Microgrid System

“…Therefore, minimizing the total operation cost of the whole system is regarded as the objective function. The total cost can be described by equations (4)- (7). Since there are many EVs in each microgrid, it is not impractical to optimize the charging and discharging powers of every EV, nor is it necessary.…”

“…Most research has discussed the issue from the aspect of economic dispatching. The majority of the studies elaborated the optimal charging management of EVs [6,7]. However, as a kind of storage units, EVs can also discharge to the main grid or microgrid, providing a vehicle-to-grid (V2G) service to participate into the operation of the power systems [8,9].…”

In-Life Range Modularity for Electric Vehicles: The Environmental Impact of a Range-Extender Trailer System

“…Although this option creates a lesser burden for the EV user in terms of charging time, the challenge remains to limit the impact of charging rates >50 kW have on the cycle-life of the respective battery packs. Moreover, fast-chargers put a substantial strain on the available power grid [42,43] , if they are not coupled to a local storage system, consisting of second-life batteries or supercapacitors that are charged when power demand is low. For these reasons, a concept of in-life modularity is proposed in this paper, consisting of a range-extender trailer that can be connected to an EV.…”