This document discusses vehicle-to-grid (V2G) technology which allows electric vehicles to provide power to the electric grid during periods when they are parked and connected to the grid. V2G technology integrates electric vehicles into the smart grid and allows them to provide services like frequency regulation. It describes how V2G works by establishing communication between vehicles and charging stations that can then form a "virtual storage network" to provide balancing services to the electric grid. V2G provides benefits like improving power quality and reducing electric bills but requires standards and legislation to fully integrate electric vehicles into grid operations.
1. Titolo presentazione
sottotitolo
Milano, XX mese 20XX
Vehicle-to-Grid future technology
assesment
Review of V2G technology prospetive and potential
interaction with RES-E volatile production as well as
integration in the ancillary service market for dispatching
service
2. Marco Tognoli 842586, Dept. Of Energy Engineering
Vehicle to grid or dual energy flow EV process is a concept recently introduced and currently
under testing.
This concept involves strictly three vehicle powertrain technologies:
□ Plug-in hybrid car
□ Fuel-cell hydrogen car
□ Electric-vehicle powered by Li-ion batteries (EV)
Due to technological flexibility of EV we will always refer to V2G technique as strictly related to
EVs.
Following a 2001 US research, cars are daily driven for nearly 63 min/day. This means that a car
stay parked for most of the time in a year. The V2G approach helps into exploiting this wasted
time for delivering a grid service. The conflict in place regards the functioning of this service
which is technically different from the EV construction architecture.
Vehicle-to-Grid technology
4. Marco Tognoli 842586, Dept. Of Energy Engineering
Purpose of the project:
□ Integrate the existing smart grid
□ Create a new service
□ Improve QoS especially at DSO side
□ Prosumers’ smartening
□ Displacement of traditional balancing reserves with beneficial
economic effect on the electric bill
Vehicle-to-Grid technology
5. Marco Tognoli 842586, Dept. Of Energy Engineering
Basic functioning operations:
□ As the EV is physically connected to a
charging station the company responsible
of the station establish an identification and
control processes on the system installed
on board by a powerline medium
communication.
□ The pole station inform the company
central system (Station Company Operator)
in real time of the operation performing at
the station itself (Grid-to-Vehicle or V2G)
communicating the power allocated and
the battery residual capacity.
□ The central system at SCO, as central post
communication with all the charging
stations, create a virtual unique balancing
reserve or “virtual storage network” that
can directly participate by placing bids in
the Ancillary Service Market.
Vehicle-to-Grid technology
8. Marco Tognoli 842586, Dept. Of Energy Engineering
The EV’s owner requires special needs separated from network situation. The owner may
requires a charging operation or more strictly a fast charging mode.
Consequently the system is arranged in three main working possibilities:
□ Not in place, no control on the charging process. This possibility is not going to be in place
on the long run due to the expected EV share in the transportation field, this is going to
cause unpredictable congestion situations at specific hours (this is not a pragmatic solution).
□ Smart charging or demand dispatch, the vehicle-to-grid architecture is in place but not
under use. The SCO collects congestion situation of the network close to the charging station
and sent dispatch information to the station requesting rump-down of power allocated for
charging process. The command could even request the abort of charging process, charging
is postponed in time.
□ Ancillary grid service, online negotiation between car and SCO is established so that
reverse power flow is allowed. The EV’s owner receive income from frequency regulation
service and this could represent a faster way to return on EV initial investment.
Vehicle-to-Grid technology
9. Marco Tognoli 842586, Dept. Of Energy Engineering
□ The device needs to rely on the daily car schedule and particularly on some special events.
Apparatus must be very smart so that they need to integrate a “machine learning” algorithm.
□ This schedule is integrated, and improved in time, inside the vehicle so that the charging
station download these data every time the car is grid connected.
□ Some basic charging choices can be directly done at the charging pole side or by a remote
platform like a web page or a simple mobile application so that the owner is informed in real
time and he/she is allowed to receive notifications at status change.
□ To terminate the grid connection the owner have to perform a remote billing operation. To
interrupt the energy flow the system requires an authorization by means of an univocal card
which communicate with the charging station by means of an RFID or NFC communication.
The TSO or DSO provide the monetary value of service exploited and finally the system
aggregator perform the billing process which will be globally accounted at the end of the
control period.
Terms of innovation
11. Marco Tognoli 842586, Dept. Of Energy Engineering
The leading goal of the V2G integration is the regulation service provided.
□ This statement suffers from lack of actual legislation nor for complexity of its integration in the
existing network framework.
□ A possibility is represented by merging together the SCO or system aggregator with the
existing DSO or TSO management. Even though currently the engagement rules for ancillary
service participation allows connections just on the TSO side.
□ A reform on ancillary service requirements is expected in the future and it will introduce a
more strict partnership and open access policy between TSO and DSO.
□ As a consequence other services away from V2G could enter the regulation services like:
home storage systems, RES-E programmable/non-programmable or high efficiency CHP
plant, demand response (user’s self curtailment).
A new service on the market
12. Marco Tognoli 842586, Dept. Of Energy Engineering
□ V2G can answer to system regulation that occurs at every hours of the day. The dispatch
order of rump up power injection or proceed with charging operation to reduce over
frequency can be made with little time delay. The system inertia of a V2G device is negligible
and just limited by the power electronic.
□ It is observed that dispatched amount does not last for very long time, in general it involves
just some minutes and much less than contracted amount.
□ This consideration result in quite constant battery residual capacity with very little discharge-
charge. This result is in favour of battery wear which does not entail deep battery discharge
and recharge cycle.
□ The V2G process involves much more deep power injected or exploited rather than an
energy intensive mechanism.
□ EVs are mostly connected to LV lines and at some public charging station at MV lines. Their
contribute is an homogeneously dispersed type which could provide beneficial effects on
constrained DSO network portions.
A new service on the market
14. Marco Tognoli 842586, Dept. Of Energy Engineering
□ Even though, a reserve connected to high power line (i.e. MV) is much more valuable than a
standard LV single phase connection.
□ Managing such service with a battery EV represent some sort of constrain. Every dispatch
order must match the power capacity of the line and the charge level of the battery. The
operator can no longer ask for down regulation beyond battery full charge as well as no
further injection into the grid beyond battery dead level.
□ Two hypothesis can be performed on the contract type accounted for the service:
1. Long term contract, a minimum number of hours per day in service is the key part of the
contract. Billing process is then performed on the stipulated hours. Possible integration with
capacity mechanism.
2. Join as-you-go, dynamic contract at which the TSO (or DSO) accounts for every regulating
session. Constrain free solution but still much more challenging under management point.
A new service on the market
15. Marco Tognoli 842586, Dept. Of Energy Engineering
□ Regulation service could represent a consistent voice of income and its magnitude depend
linearly with: time spent to serve the system, power allowed by the charging station, smart
logic control of charging/discharging device. Average income value over 10 years is 10.000$.
□ It has been demonstrated that V2G service is responsible for just 5% over battery
degradation over the control period. This effect is not going to represent any issue in case of
battery leasing contract which is a quite common situation.
□ Future improvements are expected, particularly regarding the Vehicle-to-home strategy to
energize the household in case of local network loss of main. Improved security systems
must be present to avoid any local islanding away from house grid portion in order to
maintain a feasible security level.
□ V2G technology requires full-optional smart grid infrastructure particularly at LV and MV side.
Moreover a widespread EVs presence over the system requires network physical
improvement as contractual power of many users is going to increase and become
bidirectional. This reflects also on network apparatus like power transformer and security
devices.
□ The other improvement side is on interoperability issue of aggregator services and feel-like-
home policies abroad. Each nation has to provide sufficient legislation and access to V2G
technology even coming up with an unique and interoperable standard.
A new service on the market
17. Marco Tognoli 842586, Dept. Of Energy Engineering
• http://www.mobilitaverde.it/wp-content/uploads/2016/05/nissan-enel.jpg
• http://www.automotive-fleet.com/news/story/2016/09/commercial-vehicle-to-grid-hub-
installed-in-denmark.aspx
• http://www.nuvve.com/gtm-can-nuvve-make-v2g-work-in-the-real-world/
• US Patent 8509976 B2 by Willett Kempton “Electric vehicle equipment for grid-integrated
vehicles”
• “A Test of Vehicle-to-Grid (V2G) for Energy Storage and Frequency Regulation in the PJM
System” Willett Kempton, Victor Udo, Ken Huber, Kevin Komara, Steve Letendre, Scott
Baker, Doug Brunner, & Nat Pearre
• https://www.youtube.com/watch?v=QqfMwEQ2pbc
Reference
