Dividend Transmission Method for V2G Aggregators to Participate
in Market Transactions
Li Tao
1, 2
, Xin Du
1, 2*
, Pengfei Zhao
3
, Lin Zhang
1, 2
, Ke Zhao
3
and Zhiqiang Zhao
3
1
State Grid Electric Power Research Institute Co., Ltd., Nanjing, 211106, China
2
Beijing Kedong Electric Power Control System Co., Ltd., Beijing, 100194, China
3
State Grid Shanghai Electric Power Company, Shanghai, 200122, China
4
State Grid Chongqing Electric Power Company, Chongqing, 400014, China
Keywords:
Vehicle to Grid, Dividend Transmission.
Abstract: Driven by the current goal of "carbon peak, carbon neutral", the penetration rate of electric vehicles will
accelerate, and electric vehicles will become an important energy storage support for the development of
renewable energy. By the end of 2020, the number of new energy vehicles in China will reach 4.92 million,
of which 4 million are pure electric vehicles, accounting for 81.32% of the total number of new energy
vehicles. The increment of new energy vehicles has exceeded 1 million for three consecutive years, showing
a sustained high-speed growth trend. With the continuous progress of power electronics technology, the
electric vehicle as a new type of energy storage facilities, through the V2G mode (vehicle to grid) to realize
the two-way flow of electric energy with the grid, can become an important way to improve the power grid
regulation ability and power supply reliability. This paper combs the services provided by V2G for power
system, and based on the current electricity trading market and the cost of power battery, puts forward a
method of electric vehicle V2G aggregator dividend transmission, which will help to encourage electric
vehicle owners to participate in grid interaction more fully.
1 INTRODUCTION
Electric vehicle V2G technology (Liu, 2012) refers
to the technology of electric vehicle power
transmission to the grid, and its core idea is to use a
large number of electric vehicle energy storage as
the buffer of grid and renewable energy. When the
electric vehicle is not in use, the power of the on-
board battery is sold to the grid system. If the
vehicle battery needs to be charged, the current
flows from the grid to the vehicle. Because most of
the vehicles are stopped 95% of the time, the vehicle
battery can be used as a distributed energy storage
unit. Electric vehicles (EV) have the property of
energy storage, which can quickly adjust the power
in a short time (
Sarker, 2016)
. Through V2G, the
problems of low grid efficiency and renewable
energy fluctuations can not only be alleviated to a
great extent, but also can create benefits for electric
vehicle users.
The schedulable capacity of a single EV is
limited. A large number of EV in the charging
station can be aggregated, and the aggregator
manager can participate in the market and schedule
as an agent, so as to improve the overall responsive
capacity of the EV cluster (
Renewable and
unstainable Energy Reviews, 2016)
. However, on
the one hand, the uncertainty of EV's charging
demand and charging behaviour makes it difficult to
evaluate the reserve capacity and response ability of
EV participating in the power market (Xing, 2020);
on the other hand, the charging power optimization
for power response and the compensation
mechanism for EV users are also lack of mature
operation framework.
In terms of charging cost and transaction income
settlement, the price mechanism can encourage
users to respond to the system demand. From the
perspective of day ahead, the more EV charging, the
greater the adjustment margin; from the perspective
of real-time scheduling, EVs can also support each
other in a short time. Therefore, we can establish a
cost / benefit settlement framework for EV
aggregators from the perspective of cooperative
game (Ma, 2020). From the perspective of Sharpley
value generation (Zhao, 2013), we can evaluate the
Tao, L., Du, X., Zhao, P., Zhang, L., Zhao, K. and Zhao, Z.
Dividend Transmission Method for V2G Aggregators to Participate in Market Transactions.
DOI: 10.5220/0011735400003607
In Proceedings of the 1st International Conference on Public Management, Digital Economy and Internet Technology (ICPDI 2022), pages 307-310
ISBN: 978-989-758-620-0
Copyright
c
2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)
307
marginal cost and marginal benefit of EV access, so
as to reasonably allocate charging cost and
transaction revenue.
2 SERVICES PROVIDED BY V2G
FOR POWER SYSTEM
2.1 Peak Shaving
Through V2G, the idle energy of electric vehicles is
sent back to the grid during peak load period, which
can reduce the demand of the grid for peak load
regulation resources and increase the income of
electric vehicle users. In foreign mature power
markets such as the United States and Europe, the
role of peak shaving is realized through the price
mechanism in the spot market of electric energy.
Peak shaving is a unique auxiliary service in China.
From the perspective of power grid companies, peak
shaving through V2G mode requires additional
investment to upgrade the power grid. From the
perspective of electric vehicle users, the shortening
of battery life caused by the new charge discharge
cycle due to peak shaving is also an important factor
affecting users' willingness to participate.
2.2 Frequency Modulation
The power battery of electric vehicle can be used as
shunt active power filter through V2G to improve
the power quality of distributed renewable energy
grid connected generation. Reactive power
regulation is often needed during the operation of
power system, and the reactive power is usually
provided by capacitor banks or other reactive
compensators. If there is an electric vehicle charging
station in the distribution network, it can be used as
the source of reactive power in the power system.
2.3 Standby
In order to deal with potential accidents, the grid has
prepared a lot of standby units to deal with
emergency. Although the power of these standby
units is not large, the cost is high due to the harsh
response time requirements (less than 1 minute). It
is a potential application for electric vehicles to
provide rotating reserve capacity. As long as the
charger is connected and the battery has the
remaining power, the electric vehicle can provide
the standby capacity to the grid. The number of
times that the rotating spare capacity is actually
called by the grid is relatively small, about 20 times
in a year, so that the electric vehicle can only obtain
the profit through the spare capacity cost in most of
the parking time of the year.
In V2G mode, electric vehicles can adjust
charging time and charging power according to the
needs of the grid, and discharge through V2G
terminals when the vehicle is stopped. The
interaction between electric vehicles and the grid is
shown below.
3 COST AND BENEFIT
ANALYSIS OF V2G
The total energy cost for aggregators to participate
in electricity trading is C
E,i
𝐶
,
= 𝜋
,
𝑃
,
𝑡
,
(1)
Among them, π
,
represents energy market
price, P
,
represents energy market power, t
,
represents energy market time.
EV group
V2G Aggregator
Charge and discharge
inspirit
Electric energy
market
Auxiliary services
market
Capacity market
Guarantee the safety of
power supply
Improve the quality of
power supply
Mitigate grid congestion
Delay investment in
electricity
Eliminate renewable energy
Improve system efficiency
Figure 1: The interactive diagram of electric vehicles and the grid.
ICPDI 2022 - International Conference on Public Management, Digital Economy and Internet Technology
308
For EV with charging record, its charging cost in
period i can be recorded as c
i, j
,
𝐶
,
=
∑
𝑐
,
(2)
Through the "peak cutting and valley filling"
mode, the electric vehicle aggregator can directly
trade electric energy, and can choose to purchase
electricity from the power grid when the price is
low; when the price of electricity is high, the
electricity is sold to the power grid, thus obtaining
certain benefits. The income from electric vehicles
is deducted from the income allocated to the
aggregators.
𝑌
,
= 𝜋
,
𝑄
,
(3)
1 −𝛼
𝑌
,
=
∑
𝑌
,,
(4)
In the power market environment, electric
vehicles participate in demand response, and make
comprehensive planning of the resources on the
power supply side and demand side, which can
improve the security, reliability and power quality
of the system.
𝑌
,
= 𝜋
,
𝑄
,
𝐾
(5)
Among them, K
is the peak adjustment
contribution rate.
1 −𝛼
𝑌
,
=
∑
𝑌
,,
(6)
When participating in adjusting the frequency,
the aggregator shall report its standby capacity in
different periods before the day, and the power that
the aggregator can up / down regulate in each period
will not exceed the capacity. R
,
and R
,
are
the uplink and downlink Reserve reported to the
reserve market, η
and M
represents the accuracy
and mileage in the process of real-time response
adjustment signal.
𝑌
,
= 𝜋
,
𝑅
,
+ 𝜋
,
𝑅
,
(7)
𝑌
,
= 𝜋
,
𝜂
𝑀
(8)
For EV with charging record, the regulation
frequency gain can be recorded as y
i,j
1 −𝛼
𝑌
,
+ 𝑌
,
=
∑
𝑌
,,
+
∑
𝑌
,,
(9)
4 COST AND INCOME
DISTRIBUTION OF V2G
AGGREGATORS
As a manager, EV aggregators need to distribute the
total cost and total revenue fairly to each EV and
calculate c
i,j
and y
i,j
. Within the aggregator, from the
perspective of a single EV, because it only accepts
the charging power allocated by the EV aggregator,
there is no explicit boundary between the reference
power for planned charging and the power for peak
shaving and frequency modulation. Therefore,
within the aggregator, the settlement of each eV by
the aggregator should be treated as a cooperative
game problem. Based on the Shapley value theory,
the energy resource occupation of EV should be
considered in the energy cost allocation, and the
contribution of EV should be considered in the
transaction income, so as to distribute the energy
cost and transaction income fairly. The basic
equation of Shapley value of energy cost and benefit
of the j-th EV is given by equation (10), where Xi is
the set of all Xi EV, Γ represents one of all
nonempty subsets of X
i
that does not contain the j-th
ev. v(Γ) is the utility function of the independent
variable set as Γ. Then the essence of equation (10)
is to calculate the marginal cost or marginal benefit
of the EV, that is, the difference between the cost or
benefit generated when the EV is charged and not
charged.
𝜑
𝑣
=
∑
||!
||
!
!
⊆
\
𝑣
𝛤⋃
𝑗
−
𝑣
𝛤
(10)
After the Shapley value is obtained, the total cost
or total income is allocated according to the
proportion.
𝑐
,
=
,,
∑
,,
𝐶
(11)
𝑦
,
=
,,
∑
,,
1 −𝛼
𝑌
(12)
φ
,,
represents the Shapley value of charging
cost of the j-th EV in period i. φ
,,
represents the
Shapley value of benefit of the j-th EV in period i.
Equation (10) expresses the general situation in
the allocation of cooperative games, that is, the
marginal effects of the participants may be coupled
with each other and do not have monotonic
additivity, so it is necessary to traverse all subsets Γ
without J. The final Shapley value can be obtained
by calculating the marginal effect. For the
aggregator which involves scheduling problem and
contains a large number of EVs, the calculation of
traversing all EV combinations to derive Shapley
value is too large, so this paper will give the
calculation method combined with EV
characteristics.
• Distribution of charging cost
Since the charging of each EV does not interfere
with each other, the charging demand of different
EV is monotonous and additive. Therefore, equation
Dividend Transmission Method for V2G Aggregators to Participate in Market Transactions
309
(10) can be reduced. The charging cost of each EV
can be allocated proportionally according to their
marginal cost:
𝑐
,
=
,
∑
,
𝐶
(13)
• EV revenue distribution of electric vehicles
The essence of the marginal effect of a single
EV on revenue: when the EV participates in power
trading, it shares the change of the power margin of
the rest of the EV by changing its own power
margin. The physical meaning of power margin is:
compared with the minimum power to meet the
user's demand, the EV has more spare power.
Demand response income distribution:
𝑦
,,
=
∑
∆
,
∑
∆
,
𝑌
,,∈
(14)
Income distribution of peak cutting and valley
filling:
𝑦
,,
=
∑
∆
,
∑
∆
,
𝑌
,,∈
(15)
Adjusting the income distribution of frequency
assisted services:
In the real-time phase, the more EV charging,
the more available capacity. Therefore, this part of
revenue can be directly based on the allocation of
EV capacity and charging time in this period.
𝑦
,
=
,
∑
,
𝑌
,
(16)
𝑦
,,
=
∑
∆
,
∑
∆
,
𝑌
,,∈
(17)
5 CONCLUSION
As a highly flexible distributed energy storage
method, V2G can participate in peak regulation,
frequency modulation, standby and other services
through bidirectional power flow between electric
vehicle and power grid during non driving period,
and support safe and stable operation of power grid.
With the increasing of the total number of electric
vehicles in the whole society, large-scale electric
vehicle V2G is a potential resource for grid
flexibility regulation.
This paper analyzes the cost and benefit of EV
aggregators participating in grid services, and
proposes the internal cost and benefit allocation
method of EV aggregators. The revenue of V2G
service providers is closely related to the electricity
price policy and whether there is a mature electricity
spot market and supporting service market. From
the actual situation of our country, the spot market
and auxiliary service market are still in the stage of
construction and trial operation, which is far from
mature operation.
In the current market environment, we can
consider appropriately relaxing the flexibility of
V2G, adjusting the access threshold of resources to
participate in the spot market of electric energy and
auxiliary service market, improving the
competitiveness of electric vehicle V2G, and
improving the enthusiasm of market players to use
V2G. Worldwide, although V2G is still in its
infancy, the large-scale development and application
of electric vehicles has made the V2G applications
widely available.
ACKNOWLEDGMENTS
This work was supported by State Grid Company
Science and Technology Project-Research on the
key technologies and market model design of the
Internet of Vehicles market trading to promote the
green energy consumption(5100-202040443A-0-0-
00).
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