IEEE Electrification - June 2019 - 50

Standard, fixed-price
electricity rates do
little to encourage EV
adoption or optimize
charging times.

and with a high degree of flexibility,
are quick-response units with the
potential to offer bidirectional power
flow, known as a vehicle-to-grid (V2G)
function. Studies have estimated that
EVs could provide active and reactive
power support as well as renewable
energy integration support. Through
active power support roles, EVs can
help manage congestion, reduce
power losses, shift loads, shave peaks, fill valleys, and control voltages (voltage control through active power management is more relevant for distribution grids with lower
nominal voltages due to the higher line reactance/line
resistance ratios of distribution lines.) Reactive power support comes in the form of reactive power compensation
(injection or absorption) to regulate voltage profiles and/or
minimize reactive power losses. Renewable energy support is typically in the form of capacity firming to compensate for the intermittent nature of wind and solar
power generation. As experimentally validated in a field
trial at the Los Angeles Air Force Base, V2G could also provide ancillary services, which are becoming more important as synchronous generators are replaced with
inverter-based generation on bulk electric systems.
Although these value streams are typically for larger
customers (workplaces and parking lots, for example),
they might also be accessible to residential customers via
aggregators. Some prototypical projects to enlarge the
type of services provided by EVs already exist. In the case
of ancillary services, the field trial project at the Los
Angeles Air Force Base found a theoretical profit of
US$70/month/vehicle. However, in practice, the project
recorded net losses due to additional fees from participating in the market. The ancillary service market is a
small fraction of the energy market. Therefore, it is

exposed to saturation effects. In 2018,
eMotorWerks, a company selling connected EV chargers, mobilized 6,000
chargers corresponding to 30 and
70 MWh virtual batteries to participate in the California Independent
System Operator's demand-response
market. Both of these examples represent services provided at the transmission level. As of today, there are
few demonstration projects and field tests to coordinate
EVs for the provision of distribution grid services. Two
examples are the EcoGrid EU project, funded by the European Union, and the Nikola project, funded by the Danish ForskEL R&D program. The Technical University of
Denmark is involved in both demonstrations.
While some utilities and states (especially California)
invest in programs to ease the transition to an electrified
transportation sector, this is not necessarily the case
across the United States and among smaller utilities. A
recent survey of 486 utilities (Smart Electric Power Alliance, 2018) states that nearly 75% of the utilities were in
the early stages of planning for EV market growth. Furthermore, regulatory uncertainties make replicating EV
programs between states and utility territories difficult.
Therefore, collaboration will be essential for widespread
deployment of EVs.

Methodology for Impact Analysis
and Case Study
This study evaluates the impact of large EV penetration on
distribution grids from the PG&E service area in a future
scenario where each household has one EV. Typically, for
residential feeders, 4,000-8,000 EVs were added according
to the total number of households on each feeder (Figure 2).
The scenario assumes that 50% of the vehicles have access

Number of EVs

32
6k

25
4k

11
9
4

5
2

15
12
14
13
8
3

34
33

24
22
17
16

27
23

20
10

0
0

6k
8k
10 k
Feeder Peak Demand (kW)

12 k

14 k

Figure 2. A graph showing the number of EVs added per feeder as a function of the feeder's peak demand. Each feeder is represented by a blue
dot. The dashed red line indicates where y = x.

I E E E E l e c t r i f i cati o n M agaz ine / J UN E 2019

IEEE Electrification - June 2019

Table of Contents for the Digital Edition of IEEE Electrification - June 2019