Communication Networking Schemes for Wide Area Electric Vehicle Energy Service Network

doi:10.4236/epe.2013.54B268

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Energy and Power Engineering, 2013, 5, 1415-1420

doi:10.4236/epe.2013.54B268 Published Online July 2013 (http://www.scirp.org/journal/epe)

Communication Networking Schemes for Wide Area

Electric Vehicle Energy Service Network

Dequan Gao1,2, Jinping Cao3, Yiying Zhang1, 2 , Xiuli Wang4

1Beijing University of Posts and Telecommunications, Beijing 100876, China

2State Grid Information & Telecommunication Company Ltd., Beijing 100761, China

3China Electric Power Research Institute, Beijing 100192, China

4Information Communication Branch of Beijing Electric Power Company, Beijing 100031, China

Email: [email protected]

Received March, 2013

ABSTRACT

Electric vehicles (EVs) are an emerging type of mobile intelligent power consumption devices in Smart Grid as new

green transport tools. In order to provide a powerful automation and intelligence support for wide area electric vehicles

energy service network, we analyze the network infrastructure and communications demands of various terminals,

devices and monitoring systems distributed in wide area electric vehicle energy service network. According to

interactive user services scenarios and en ergy operations intelligent monitoring, we propose multimode communication

integration architecture for wide area electric vehicle energy service network by means of the fusion of the Internet of

Things (IoT) technology. Then, we design different networking schemes in access networks and backbone transmission

networks meeting multi-scene and multi-operation interaction requirements. The networking schemes will provide

efficient technical support to implement intelligent, cross-regional, interactive energy services for electric vehicle users.

Keywords: Electric Vehicle; Wide-area Energy Service Network; Communication Networking; Internet of Things

1. Introduction

Many developed countries and megacities are undertak-

ing serious environmental pollution and great oil short-

age challenges. So world automobile industries are turn-

ing to develop clean energy vehicles with huge invest-

ment. Now, many people have realized that future trends

of automobile industry are green, energy-saving and in-

telligent. Electric vehicles (EVs) are seen as one of the

most promising means to improve the near-term sustain-

ability of the tran sportation and stationary energ y sectors

[1]. Electric vehicles have improved their performance

and made suitable for commercial and domestic use dur-

ing the last decades [2]. Electric vehicles will be promi-

nently taken as the mobile infrastructures of electrified

transportation mode. Electric vehicles development has

been as one of new energy national strategies in China.

More importantly, electric vehicle is an emerging type of

mobile intelligent power consumption device and energy

storage terminal for Smart Grid. With the large-scale

population of electric vehicles, electric vehicles can be

conventionally charged to play the role of the valley

filling in the power grid while its load is low. Thu s, they

will improve the comprehensive utilization efficiency of

power generation equipment, and achieve the effect of

energy saving and emission reduction. Inevitably, to

construct wide-area energy service network for electric

vehicles is the core premise of their large promotion.

According to the 12th Five-Year special plan on electric

vehicle technology development in China, a networked

power supply system, which includes 400,000 charging

piles and 2000 charging-swap stations, will be built in

above 20 demonstration cities and their surrounding

areas to meet the energy supply requirements of large-

scale commercial demonstration of electric vehicles until

about 2015.

The domain of electric vehicles opens new business per-

spectives and opportunities [3]. Electric vehicle energy

services businesses mainly cover battery charging, battery

swap, battery discharging, battery distribution, electric

energy metering and billing, fund settlement, scheduling

monitoring, etc. the basic operations functions are devices

running IntelliSense, real-time monitoring and warning

of battery status, vehicle status information acquisition,

charging-swap path intelligent navigation, battery life-

cycle management, centralized monitoring of equipment,

optimal allocation of resources, etc. The distributed smart

charging-swap information in energy service network

should be measured, interacted, shared and controlled,

which necessarily relies on rapid and reliable information

communication system.

D. Q. GAO ET AL.

1416

Next generation electric vehicles will radically change

the design paradigms in the automotive network domain

[4]. Ho wever, information communications network sup-

porting wide-area electric vehicle information acquisition

and key charging-swap service operations and monitoring,

has not met the practical, interactive requirements. These

problems have made intelligent interaction more difficult

between the power gr id and users, an d led to be unable to

provide conveniently, efficient and safe services for

electric vehicles users. Therefore, reliable information

communication technology (ICT) should be developed to

support information perception, aggregation, interaction,

and highly automated, in telligen t charging -swap services.

This paper focuses on the objectives of providing

efficient and interactive electric vehicles smart energy

services. Some exploratory researches involve wide-area

electric vehicles energy services network communica-

tions networking architecture. In this paper, we synthetically

apply the Internet of Things (IoT) technology and power

communication to improve intelligent perception of electric

vehicles energy information and services integration level

between electric vehicles and power grid.

2. EV Energy Service Network Facilities

Electric vehicle energy service network is indispensable

infrastructure for large-scale commercialization of elec-

tric vehicles. Many Chinese cities have released prefer-

ential policies and invested massive funds to promote the

construction of electric vehicle energy service facilities.

Generally, electric vehicle energy service network facili-

ties are composed of centralized charging stations, bat-

tery swap stations, battery distribution stations, AC

charging pile, operation monitoring center, etc. They will

guarantee reliable energy supply for electric vehicles in a

wide area.

Centralized charging stations can provide electric ve-

hicle battery charging and battery distribution stations.

Typically, a centralized charging station has the capabili-

ties of charging, discharging, maintenance and detection

of large amount of standardized battery packs.

Battery swap stations are power battery supply spots

by exchanging batteries for electric vehicle users. In a

battery swap station; there are power supply area, charg-

ing area, battery replacement area, battery inspection and

maintenance area, control room, parking lot, etc. Battery

distribution stations provide battery replacement and

logistics services for battery packs distribution without

charging function. AC charging piles are slow charging

devices for electric vehicles. The functions of a charging

pile involve timing, power energy measurement, costing

calculation. Operation service centers are responsible for

monitoring and management of regional electric vehicle

energy ser v i ce network o p erators.

3. Communication System Architecture of

Wide Area EV Energy Service Network

Shifting bulk l oads and dem a nd response programs require

communication between consumers and producers of

energy and will be more widely enabled with the expansion

of grid communication networks across the country [5].

The communication system of electric vehicle energy

service network will achieve the interconnection and

interoperability of all kinds of terminal, electric vehicle

and operations management system. The communication

system can support orderly, seamless cross-regional com-

munication services in the cities, provin ces, inter-city and

inter-provincial areas.

3.1. Communication System Demands

The characteristics of the communication system are

flexible networking, multi-mode access, and massive

access points. We analyze its demands from the view of

security, real-time and bandwidth. As an important part

of intelligent distribution and utilization networks, it is

linked with the power grid enterprise businesses such as

energy metering, tariff settlement, electricity manage-

ment. So po w er gr id mu s t be sa f e and s t ab le wh en a large

number of wide-area distributed charge-swap devices are

linked into it. Therefore, security requirements of wide-

area communication network are rather higher for opera-

tion service center.

All business surveillance, operations monitoring , video

monitoring, battery monitoring, power supply monitoring,

logistics distribution information of centralized charging

stations, battery-swap stations, battery distribution station,

and service management center must be real-time up-

loaded, so the real-time requirements of communication

performance are highly efficient. Moreover, electric ve-

hicles (including logistics vehicles) will upload vehicle

conditions, battery status information and receive value-

added services and scheduling information, relatively,

their real-time communication requirements are also

higher.

Electric power information acquisition system, opera-

tion management system, station-level monitoring sys-

tem need be deployed in centralized charging stations

and battery swap stations. Their communication band-

width is expected to reach MB level. The communication

bandwidth of charge piles and electric vehicles is

approximate 30 kbps.

3.2. Communication System Architecture

At present, there are some technical problems restricting

the large-scale commercial development of electric vehi-

cles in China. For example, the existing communication

networks cannot cover both urban and rural areas, cross

area to support complex electric vehicles services. Thus,

D. Q. GAO ET AL.

1417

we must integrate power communication network, the

public network (GPRS/3G/4G), cable network, wireless

sensor networks (WSN), and other communications

technology to establish top-level communication system

architecture of the electric vehicle energy services net-

work. The communication system will smart, effective

interaction between electric vehicles, battery packs,

charging-swap facilities and power grid, and seamless

mobile information services.

According to the above demand analysis of electric

vehicle energy network communication system, we

propose three-layer communication network architecture

supporting dynamic access and switch, as shown in

Figure 1. The network architecture will establish cross-

regional information transmission covering headquarters

operation service center, provincial operation service

centers, municipal operation service centers and station

monitoring center.

First-level network is the backbon e telecommunication

network linking operation service headquarters and sub-

ordinate operation service centers. First-level network

adopts power communication private network. However,

for the construction of power communication private

network relies on power transmission line path, it actually

hasn’t covered some expressways, provincial highways.

Power companies have built current communications

network involving optical fiber cable, microwave, Power

Line Carrier (PLC), satellite, which have fully covered

headquarters, provincial and municipal companies. There-

fore, the communication system of electric vehicle en-

ergy service network can further extend current enterprise

network to solve the wide-area coverage problem.

Second-level network is the transmission network

linking subordinate operation service centers and station

level facilities. Second-level network mainly adopts

provincial power communication private network. If the

private network isn’t available, the public communi-

cation network can be rented. Here, Access networks can

apply WSN, Optical Fiber Composite Low-voltage Cable

(OPLC), 3G/GPRS/4G/TD_LTE to implement infor-

mation exchange between charging-swap devices, vehicle

automatic identification equipment and monitoring equip-

ment, and information interaction between inner equip-

ment inside charging-swap stations, electric vehicles and

battery packs, and information access of geographically

distributed charging piles. On the whole, the communi-

cation network coverage is small for low-voltage side

distribution network. We can adopt wired communica-

tions (optical fiber communications, etc.), IoT com-

munication technologies and public wireless communi-

cations (GPRS/3G/4G) for different scenarios to ag-

gregate a variety of perception information, for example,

battery status information, identity information, electric

vehicle status information, location information, the

smart electric card identity information, charging-swap

environment information. The aggregated information

will be uploaded to the Second-level network layer

through the IoT aggregation gateway. Meanwhile,

charging-swap devices and various intelligent terminals

also receive control instructions.

Figure 1. Three-layer communication network architecture.

D. Q. GAO ET AL.

1418

4. Networking Schemes of Access Networks

Now the backbone telecommunication transmission net-

works and data communication network built by power

grid companies can basically meet communication business

demands of the First-level and Second-level network in

the energy service network architecture. Here, we will

mainly focus on designing networking schemes of access

network layer and take low-voltage power communica-

tion network as main basic of access network. We will

use self-built fiber network, electricity wireless broad-

band network, IoT technology together with renting public

network to solve heterogeneous interconnection and

collaborative communication problems for power wireless

broadband network, mobile communication network, and

WSN applied in different application scenarios. a particular

IoT service can be applied in order to optimize appli-

cation development and speed up application implementa-

tion [6]. Monitoring and automation applications will be

central for IoT and rely on eventing and group com-

munication [7]. These networking schemes will realize

seamless network coverage for centralized charging

stations, battery swap station , battery distribution stations,

charging pile and electric vehicles, and network access

within station sites.

4.1. Networking Scheme of Centralized Charging

Stations

The communication network within a centralized charging

station will connect with access network through the

access gateway nodes. The operations, power utilization

and monitoring information on the station LAN will be

transmitted to provincial service center, and share data

with electric vehicle operation management system. The

networking structure inside a centralized charging station

is shown in Figure 2. The following is networking

description.

1) Switches will be core nodes interconnection of

equipment inside centralized charging stations to suppo rt

station-level operations. A workstation connects core

switches via Ethernet interfaces.

Figure 2. Networking scheme inside centralized charging

station.

2) Charging devices access IoT communication gate-

way via industrial Ethernet or CAN bus, by which they

upload battery information and charger information to

the monitoring system, and also receive command in-

structions.

3) A power supply monitoring unit accesses IoT

communications gateway via RS232 interface. A collec-

tor uses RS485 interface to communicate with electric

energy meters and collect real-time consumption infor-

mation.

4) Video terminals send surveillance data to station

operation monitoring system via video cables.

5) Logistics vehicles can use micro-power wireless

network to automatically communicate with vehicle

identification readers inside a station.

In order to ensure station-level information network

security, local centralized charging station business

systems are logically isolated via Virtual LAN (VLAN)

technology.

4.2. Networking Scheme of Battery Swap

Stations

According to the practical communication requirements

in a battery swap station, the swap devices usually use

wireless communication technologies to link station- level

monitoring system, for example, WIFI, ZigBee. The

operations, power consumption and monitoring informa-

tion of a battery swap station will be sent to regional

operation management system via uplink network by

renting special public communication network.

In urban areas, a battery swap station will connect the

nearest 10kV switching substation, 35/110/220 kV

substation with fiber optic cable resources. While in

intercity highways or highway service areas, a battery

swap station will connect the nearest 35/110/220 kV

substation with fiber optic cable resources. The uplink

communications network fiber optic cable can be laid

along wit h power lines.

4.3. Networking Scheme of Charging Piles

Charging piles usually have CAN bus, PLC and RS485

communication interfaces, by which charging status

information can be sent to centralized monitoring system.

Charging piles can Real-time communicate with battery

management system (BMS) to get battery type, single

voltage, State-of-Charge (SOC), temperature and warning

information.

The uplink networks of charge piles have two access

ways: self-built power private networks and rented public

networks.

The operations information, power consumption infor-

mation and monitoring information can be uploaded via

LAN deployed in10kV distribution room, switching

D. Q. GAO ET AL. 1419

cabinet, box-type substation. Also, they can use embed-

ded wireless communication modules to connect public

network.

4.4. Networking Scheme between Charging-swap

Facilities and Operation Service Centers

The key communication requirements between charging-

swap facilities and the operation service centers of

energy network are wide communication range, rich data

semantic content and various bandwidth applications, so

we must flexibly use multiple communication tech-

nologies for different application scenarios. Power optical

fiber, PLC, GPRS and other communication technologies

can be mixedly used to communicate with operation

service centers fo r charging- swap stations an d distributed

charging piles. For power fiber cables only rely on

electric power communication systems resources, they

can avoid technical conflict on frequ ency resources, routing

coordination and electromagnetic compatibility with

other users. PLC technology is unique communication

way for power industry. The PLC scheme doesn’t need

to newly build communications infrastructure for it uses

power line as communication media for data transmis-

sion and information exchange. Station-level manage-

ment systems can real-time interact with electric vehicles

energy service management system in operation service

center, electric energy data acquire system and 95598

call center through power fiber-optic net work.

4.5. Networking Scheme of Electric Vehicles

The main external interaction objects of electric vehicle

are operation service centers, charging-swap stations and

charging devices. For mobility of electric vehicles, their

driving range, spatial location and speed are random.

Obviously, different communicatio n technologies will be

applied inside electric vehicles or while they are moving

in urban areas or on inter-city highways. The networking

schemes of electric vehicles are described in Figure 3.

Interactive services of electric vehicles in different

scenarios will adopt different communication modes.

Careful monitoring and control of energy flows allows

for minimum investment with respect to cost, weight and

Figure 3. Networking scheme of electric vehicles.

volume [8]. Users can get real-time battery status data

via vehicle CAN bus interface interacting with BMS

while driving. The application of bus technology with

CAN as the representative in vehicles not only reduces

the har-ness of the car but also in creases the reliability of

the car [9]. IoT based smart interactive terminals can be

embedded into electric vehicles to realize perception

information transmission among different interior parts.

Smart interac tive terminals integrate battery energy sensor,

temperature sensor, identification chip, communication

unit, GPS module, navigation software to realize battery

packs identification, power information collection, speech

warning and map navigation, etc.

Electric vehicles can use WIFI, micro-power wireless

network to interact with smart terminals via Iot gateways

set in charging-swap stations. Furthermore, they generally

interact with charging devices via CAN interface.

Users often adopt renting public wireless communi-

cation network to interact with service centers v ia GPRS/

3G/4G outside charging-swap stations. In the future, the

new generation power wireless broadband private network

and White Space (WS) technology-based low-frequency

wireless communication can be used to achieve region-

scale coverage data transmission. In general, wireless

mobile communication network can be used as the primary

networking means, the roadside big WiFi AP networks

and TD-LTE based new power wireless broadband com-

munications serve effective supplement means.

4.6. Communication Protocols and Interfaces

Security

The main communication interfaces of electric vehicles

energy service Network are data communication interface

of charging-swap devices, information interoperation

interface of operation monitoring center and BMS inter-

face of electric vehicles. In order to establish universal

communication protocol, we must find out the common

characteristics of electric vehicle charging demands and

charging-swap device functions from too many manu-

facturers. However, the communication protocol for

electric vehicles hasn’t been already unified for the BMS

interfaces from different manufacturers are special. To

actually ensure real-time data upload of monitor electrical

equipment operating condition, switch status and fault

alarm in charging-swap facilities, the modified IEC

60870-5 - 1 0 4 p ro tocol can be wi d el y used.

In order to ensure wired communications security

inside charging-swap stations, the monitoring systems of

charging-swap and power supply management must only

access the internal information network through com-

munication front-end processor. Station-level security

and protection subsystems ac cess upw ard s the n etwor k to

implement data transmission of video stream. Moreover,

the devices inside a station must firstly be requested to

D. Q. GAO ET AL.

1420

traverse firewalls for ensuring network security if they

will access to the internal information network. Under

some special conditions, public wireless networks may

be used in charging-swap stations if there are no wired

power network links. In the above case, the com-

munication front-end processor must be equipped with a

radio signal transceiver and a SIM card. Meanwhile, The

SIM card should have a static IP address. Thus, the

equipment in a station will access the internal infor-

mation network via public wireless communication

network according to the APN (Access Point Name)

special line of a station system

5. Conclusions

The reliable information collection, transmission, control

and management of electric vehicles and charging-swap

facilities are some important links to effectively super-

vise energy service proc edure. In order to adap t mobility,

diversity and universality requirements of electric vehicle

energy services, we make deep demand analysis on the

networking infrastructure and communications demands

of diverse terminals, devices and monitoring systems

distributed in wide area electric vehicle energy service

network. According to energy service scenarios for

electric vehicle and systematic requirements of intelli-

gent operation monitoring, we propose multimode com-

munication architecture for supporting wide area electric

vehicle energy service network with the fusion of IoT

technology. The architecture involves hybrid networking

mode widely covering expressways, national highways,

provincial highways, charging-swap facilities to imple-

ment seamless coverage and dynamic access of energy

service information. We integrate Multimode communi-

cation technologies to design interactive networking

schemes for EVs multi-business energy services. The

networking schemes will partly solve some basic

problems of perception data aggregation and information

communication support for cross-regional energy ser-

vices, and provide some technical means for friendly

information interaction.

Electric vehicle energy service infrastructures will

have rapid development in next decades in China. In fu-

ture, it is urgently necessary to innovatively use IoT

technology to build a demonstration platform of data

acquisition and information management for electric ve-

hicles energy service network. Moreover, the research on

information interaction methods between electric vehicle

and charging-swap networks should be further done.

Wireless smart sensors, perception tags, GPS and other

IntelliSense technologies need be integrated to fully

collect data in physical world for reliably solving the

problem of the electric vehicle performance assessment,

fault diagnosis, safety pre-warning and error risks

analysis.

6. Acknowledgements

This work is supported by National High-tech R&D

Program of China (863 Program) (No. 2011AA05A116,

2012AA050804) and National Program on Key Basic

Research Project of China (973 Program) (No.

2011CB302900).

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