IEEE Electrification - September 2021 - 36

TABLE 1. The infrastructure solution evaluation at 100 EV/day.
EVSEs
Swaps
102
102
30
102
EVSE Level
Level 1
Level 2
Level 2
Level 2
Unctrl: uncontrolled; CM: cost minimization.
Algorithm
Unctrl
Unctrl
Unctrl
ASA-CM
Capacity (kW)
200
680
200
200
(Number/Month)
1,103.5
Demand
Met (%)
75.4
99.9
99.6
99.8
Cost
(US$/kWh)
0.278
0.351
0.256
0.234
TABLE 2. The infrastructure solution evaluation at 200 EV/day.
EVSEs
Swaps
102
102
30
102
201
EVSE Level
Level 1
Level 2
Level 2
Level 2
Level 2
Algorithm
Unctrl
Unctrl
Unctrl
ASA-CM
ASA-CM
Capacity (kW)
200
680
200
200
200
680- kW transformer and the associated service upgrade
would be cost prohibitive for most sites, and installing
only 30 level 2 EVSEs requires more than 1,100 swaps per
month, leading to lost productivity and poor user experience.
In this case, we see that ASA with the objective of
cost minimization (CM) results in reduced capital costs,
higher user satisfaction, and lower operating expenses.
The benefits of smart charging are amplified as EV
adoption grows, and charging infrastructure must
scale accordingly. In this scenario, we consider how the
system will rise to 200 charging sessions per day. The
results are shown in Table 2. Intuitively, the systems
designed for 100 EVs per day require far more swaps
with increased demand, and, similarly, the percentage
of demand met decreases. This is also true for the
smart charging (ASA-CM) case.
However, while scaling the number of EVSEs in traditional
uncontrolled charging systems would require a
corresponding scaling of the transformer capacity to
ensure safety, smart charging enables us to add new
EVSEs without increasing the transformer capacity. This
allows us to meet more than 99.8% of energy demands,
require zero swaps, and maintain low operating costs.
Conclusion
Smart charging will be key to enabling safe and cost-effective
EV charging at scale. However, new research and development
will be needed to bring the promises of smart
charging to the marketplace. The ACN Research Portal provides
researchers the data and tools they need to develop
these new technologies and deploy them quickly.
36
IEEE Electrification Magazine / SEPTEMBER 2021
(Number/Month)
1,174.5
1,081.5
2,973.9
1,441.9
Demand
Met (%)
73.2
99.8
91.6
87.1
98.4
Cost
(US$/kWh)
0.244
0.327
0.233
0.223
0.227
For Further Reading
Z. J. Lee et al., " Adaptive charging networks: A framework for
smart electric vehicle charging, " IEEE Trans. Smart Grid, early
access, 2021. doi: 10.1109/TSG.2021.3074437.
Z. J. Lee, S. Sharma, D. Johansson, and S. H. Low, " ACN-sim:
An open-source simulator for data-driven electric vehicle
charging research, " IEEE Trans. Smart Grid, early access, 2021.
doi: 10.1109/TSG.2021.3103156.
Z. J. Lee, J. Z. Pang, and S. H. Low, " Pricing EV charging service
with demand charge, " Electric Power Syst. Res., vol. 189,
p. 106,694, Dec. 2020. doi: 10.1016/j.epsr.2020.106694.
Z. J. Lee, T. Li, and S. H. Low, " ACN-data: Analysis and applications
of an open EV charging dataset, " in Proc. 10th ACM Int. Conf. Future
Energy Syst., 2019, pp. 139-149. doi: 10.1145/3307772.3328313.
Z. J. Lee and S. Sharma, " ACN portal, " GitHub, 2021. https://
github.com/zach401/acnportal
Z. J. Lee and S. Sharma, " ACN research portal examples, "
GitHub, 2021. https://github.com/caltech-netlab/acnportalexperiment
Biographies
Zachary
J. Lee (zlee@caltech.edu) is with the Department
of Electrical Engineering, California Institute of Technology,
Pasadena, California, 91125, USA, and PowerFlex Systems,
Los Altos, California, 94022, USA.
Sunash Sharma (sbsharma@caltech.edu) is with the Department
of Computing and Mathematical Sciences, California
Institute of Technology, Pasadena, California, 91125, USA.
Steven H. Low (slow@caltech.edu) is with the Departments
of Electrical Engineering and Computing and Mathematical
Sciences, California Institute of Technology,
Pasadena, California, 91125, USA.
http://www.github.com/zach401/acnportal http://www.github.com/zach401/acnportal https://github.com/caltech-netlab/acnportal-experiments https://github.com/caltech-netlab/acnportal-experiments
IEEE Electrification - September 2021

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