Strategic charging of electric vehicles in public parking areas: Optimized charging strategies of electric vehicles from a parking area operator perspective
Typ
Examensarbete för masterexamen
Program
Publicerad
2022
Författare
Björklund, Filip
Ekström, Jonathan
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
As part of current climate change, with focus on the reduction of green house gas
emissions, the automotive industry is shifting from internal combustion engines
(ICEs) to electric motors. As of 2021, in Sweden, around 45% of all newly registered
vehicles are electric vehicles and it is expected that this share will increase
in the future [1]. The electrification that society faces also creates challenges to the
current electricity systems in place as new loads are introduced. This will not only
mean there is a need to expand the current electricity generation and grid, but also
that electricity has to be used smarter.
This master’s thesis investigates possible advantages with implementing smart charging
strategies in parking areas. A linear programming model was developed to evaluate
the aggregated EV charging load in a parking garage located in central Malmö,
Sweden. Real parking data on incoming and outgoing vehicles, i.e. over 8000 registered
parking events in September 2021, is used as a case study allowing for one
month of parking need to be analyzed. There are four cases that are compared,
each with a distinct objective. The first case is a reference case in which charging
is undertaken as quickly as possible, i.e. restoring the state of charge (SOC) as
soon as possible directly upon arrival. Remaining cases optimizes economical aspects,
where the second case minimizes the cost of grid connection capacity and the
third case minimizes the cost of electricity given the spot prices on the electricity
market for the investigated period. The fourth and final case is a combination of
cases two and three with the purpose of minimizing the total cost. These cases were
also subjected to different scenarios; a base scenario that reflect the parking garage
today, a scenario with an assumed integrated solar PV system, and a scenario with
Vehicle-to-Grid (V2G) implemented. Finally, a scenario investigating the impact
from electricity prices in terms of grid connection capacity and value of solar PV.
Results show that smart charging may reduce the peak capacity of this parking
garage by just over 70%, given a suitable governing algorithm. Given the assumptions
on entrance and target SOC levels the parking area should be able to be
operated in an off-grid mode without grid power supply, i.e. all charging is made
from incoming EVs that have higher entrance SOC than target SOC. Avoided grid
costs could in such case be used to reimburse vehicle owners for discharging some
electricity to other vehicles and get free parking or even make money from parking.
Case 4, minimizing the total cost, resulted in a large transferable capacity. The
large capacity was used to turn a profit from arbitrage transactions and the selling
of excess electricity stored in EVs entering the parking garage. A PV system can
be introduced to reduce the cost of purchased electricity and peak demand, with
greatest effect on the cost of purchased electricity. In current economical pricing
model there are larger potential savings in using electricity in-house than selling it
to the grid, which means that the savings found in this study should be larger with
increasing electricity prices.
Beskrivning
Ämne/nyckelord
Electric Vehicles , Charging Strategy , V2G , PV , Smart Charging , Peak Shaving , Aggregated Charging