The Communication Technologies for Smart Grid

Abstract
Smart Grid is next generation power transmission system with advanced communication technologies. This article will make a review of some possible communication technologies for the smart grid. The applications and limitations of these technologies will be introduced and discussed.

1. Introduction
Smart grid is next generation of the power transmission system and is a revolution of the old electrical power grid which has been used for about one hundred years. Now there is still not a clear definition of smart grid but some main aims and features of expected smart grid are: observable, controllable, efficient (energy and economy), incorporating renewable and distributed generation, enable demand side operation and the ability of automated.
The technologies support the future smart grid can be divided into three parts:
1. Information and Communication Technologies (ICT)
2. Sensing, Measurement, Control and Automation Technologies
3. Power electronics and energy storage Technologies
This article will only introduce the current information and communication technologies for the smart grid because of the length restriction. The reliable and stable communication system is a key factor for the power delivery system. Therefore, a communication system that meets the requirements is the foundation to the successful implementation of Smart Grid in the future.

2. Information and Communication Technology (ICT) for Smart Grid
The application of the ICT in the Smart Grid is to establish a high-speed, bi-directional communication network between every components in the grid to realize a dynamic and real time data collecting and exchanging power system.
2.1 Smart Grid Communication Architecture
The establishment of an integrated communication system requires several kinds of network topologies:
Local Area Networks (LAN): a basic shared access technology
Home Area Networks (HAN), Building Area Networks (BAN) and Industrial Area Networks (IAN): confined and combined LANs
Neighbourhood Area Networks (NAN): HAN, BAN and IAN will form a NAN
According to NIST in [3], the smart grid architecture should include these domains: Markets, Operations, Service Providers, Customers, Distribution, Transmission and Bulk Generation. Smart Grid Architecture is shown in Figure1. Figure1: Smart Grid Architecture[7]
2.2 Smart Grid Communication Technologies:
1) IEEE 802 series: It is a family of standards support the LANs
(i) Wireless LAN (WLAN)/IEEE 802.11:
It supports high speed P2P (point to point) and P2M (point to multipoint) communication. WLAN can be used for monitoring and controlling the remote distribution energy resources because the characteristics of point-to-point communication. The disadvantage of WLAN is that the interference such as High Voltage and Radio will limit the availability.
(ii) ZigBee / IEEE 802.15:
ZigBee technology is low cost, power effective and low complexity and can achieve a high reliability. According to NIST in [4], ZigBee is most suitable technology for HAN to control home smart applications. For example, it can be used for remote smart meter reading, remote load control, real time monitoring and home automation. However, the power supply, small size and low data rate limit the ZigBee only in residential system (HAN).
(iii) Worldwide Interoperability for Microwave Access (WiMax) /IEEE 802.16:
WiMAX technology formed in 2001 the main advantage is supporting worldwide microwave access. It also provides connectivity for both mobile and fixed device by Orthogonal Frequency Division Multiple Access (OFDMA) technology. MiWAX can provide coverage about 50km and data rate about 70Mbps. According a release of IEEE 802.16m(2010), the data rate is expected to reach 200Mbps to 300Mbps and it can maintain connection with moving station up to 350km/h[1]. WiMAX is very suitable for remote meter reading, remote monitoring and real time pricing because of the large coverage area. WiMAX is one of the best choices for future smart grid communication network but the main drawback is high cost of the WiMAX tower.
2) Cellular Networks
The cellular network communication technologies such as 2G, 3G, 4G (WiMAX) have developed for years and are relatively mature. For the smart grid, abundant existing communication infrastructures will make the data communications cost effective and cover a large geographic area. These advantages make cellular communication one of the leading technologies in the market. The main concern on the cellular communication is that the shared network maybe has impact on the service of smart grid.
3) Power Line Transmission
Power line transmission (PLC) technology uses the exciting power lines to transmit data.
Broadband over Power Lines (BPL) /IEEE P1901 (2005):
BPL is a special case of PLC and this technology can be described as a power line transmission with Internet access. BPL can provide direct bi-directional and real time communications between utilities. BPL technology applied in Smart Grid is that provide in Medium Voltage side connectivity between substations (P2P) and in Low Voltage side between transformers and meters (P2M). The main disadvantage of PLC is that noise caused by high voltage will make the channel hard to be modelled.
4) Other potential technologies:
(i) Bluetooth / IEEE 802.15:
Bluetooth is a Wireless LAN technology with low power and short distance radio transmission. The drawback is very obvious which has very low level of security.
(ii) Mobile Broadband Wireless Access (MBWA) or Mobile Fi/IEEE 802.20[5]:
MBWA can provide large bandwidth and mobility and can be used in Smart Grid for monitoring and data collecting. It is a new technology so that the infrastructures are not reliable and costly.

Table1: Communication Technologies for Smart Grid[6] 3. Conclusion and Discussion:
Future smart grid should be a dynamic, visible and controllable power system. To achieve this goal, a communication system with heterogeneous modern information and communication technologies needs to be established to realize these expected functions of smart grid. These technologies allow all devices, substation and energy generation in the grid to communicate with each other in a high speed and bi-directional way. As a conclusion, every mentioned technology, both wired and wireless, has been tableted in Table1 with their possible application and limitation in the Smart Grid. Each technology has its own advantages and limitations and is suitable for different situations. For the situations such as home area automation or long distance control, one or more technologies are used to meet different requirement. Therefore, the integrated communication system will be very complicated so the interoperability is a challenge because many different communication technologies and standard coexist in one system. Besides, smart grid is the next generation of power system so that it will support millions of users in the future. The stability of such a huge communication system is another challenge and it will affect the quality of service. Similarly, multi technologies and millions of users will also cause the concerns on the security.
Finally, all exciting and new developed technologies aim to establish a bi-directional, high speed, reliable and safe communication system for the Smart Grid.

Reference:

[1]Cudak, M. (ed.), 2010, IEEE 802.16m System Requirements, IEEE 802.16 Task Group M, January 2010, Available at: http://ieee802.org/16/tgm/docs/80216m-07_002r10.pdf (Accessed on 28 Nov 2014). 

[2] Janaka Ekanayake, 2012, Smart Grid: Technology and Applications. 1 Edition. Wiley.
[3]NIST, 2010, NIST framework and roadmap for Smart Grid interoperability standards, Release 1.0 Available at: http://www.nist.gov/public_affairs/releases/upload/smartgrid_interoperability_final.pdf. (Accessed on 28 Nov 2014)

[4]Y. Peizhong, A. Iwayemi, C.Zhou, 2011, Developing ZigBee Deployment Guideline Under WiFi Interference for Smart Grid Applications, Available at: http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5672592&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F5165411%2F5446437%2F05672592.pdf%3Farnumber%3D5672592 
(Accessed on 28 Nov 2014)
[5]IEEE, 2008, Std.802.20, IEEE Standard for Local and Metropolitan Area 
Networks
[6]Parikh, P.P.,Kanabar, M.G. , Sidhu, T.S.. 2010. Opportunities and Challenges of Wireless Communication Technologies for Smart Grid Applications. Available at: http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5589988&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5589988. [Accessed 28 November 14].