2010 International Conference on Power System Technology
Convergence of Sensor Networks/Internet of Things and Power Grid Information Network at Aggregation Layer Dahai Han, Jie Zhang, Yongjun Zhang and Wanyi Gu, Fellow, IEEE
Abstract-The Sensor Networks and ''Internet of Things" (lOT
II. INTRODUCTION
for short) have been regarded as the trend of information technology. At the same time, Intelligent Power Grid is also becoming the key part of national energy program. As the collection of power engineering and ICT, the key technologies of lOT and ICT applied in Power Grid System are being highly concerned with manufacturers and government. In this paper, the natural bottleneck between mass sensor information and Electric Power Communication Transmission Network is proposed and put forward the concept of information aggregation layer under the background of heterogeneous network convergence. Power Grid Information Network and Sensor information processing and data fusion in Aggregation Layer will be taken on the embedded smart gateway and provide front-end processing and analysis of sensor information, which can be used to implement in varied Intelligent Power Grids scenario with a unified data aware, access, transmission and data fusion. At the end, the article describes a number of Intelligent Power Grids application of innovation based on the aggregation layer embedded smart gateway device and looking forward to a vision of fully perception and integrated next-generation Power Grids.
Index
Terms-Aggregation Layer, Data Fusion, Intelligent
Power Grids, Internet of Things, Smart Gateway, Sensor Net works, Power Grid Information Network Information Network
I. NOMENCLATURE lOT: Internet of Things for short, a critique of ambient technology and the all-seeing network of RFID. Aggregation: Several things grouped together or considered as a whole, in information technology, it is several information flow or traffic grouped together into a storage device or a node. ICT: Refers to activities or studies involving computers and other electronic technology. ICT is an abbreviation for Information and Communications Technology. Fusion: A fusion of different qualities, ideas, or things is something new that is created by joining them together, in ICT, fusion is the process in which information packet combine and produce a large amount of new information, such as data fusion means information interchange and combination. This work has been supported in part by 973 program (20IOCB328204), 863 program (2009AAOIZ255), NSFC project (60772022), PCSIRT program (IRT0609) and III Project (B07005) of China and BUPT Excellent Ph.D. Students Foundation. Dahai Han is with Key Laboratory of Information Photonics and Optical Communications, Ministry of Education, P.O. Box 128, #10 Xitucheng Road, Haidian District, Beijing 100876 (e-mail:
[email protected]). Jie Zhang is with the same affiliation (e-mail:Igr24@bupt. edu.cn). Yongjun Zhang is with the same affiliation (e-mail:yjzhang@bupt. edu.cn) Wanyi Gu is with the same affiliation (e-mail:
[email protected]). 978-1-4244-5940-7/1O/$26.00©201O IEEE
HE proposal of lOT and its application have attracted
T great attention from Government, which actively pro
motes its development. A new round of information technol ogy innovation will facilitate the community into a nothing not-known communication age of the "Internet of things". Along with the gradual deployment of the network, we will manage our production and life in a more sophisticated and dynamic way, to achieve the state of "wisdom", enhancing resource utilization and quality of life and improving the relationship between human beings and the nature. The explo ration and application of "Internet of Things" at this stage is in line with the development of national information technology strategy. At present, the application situation of sensor networks includes environmental awareness, logistics surveillance, the region monitoring, smart home, building energy conservation, the future of education, the future of shopping and so on. The industrial applications being explored and implemented include precision agriculture, water quality nutrient testing, aquaculture, intelligent parking lot, triggering scenes tour, anti-intrusion scenario, sports and leisure, logistics surveil lance, video surveillance, military, safe home, electrochemical sensing, and mobile phone payments and so on. All areas involving production and life will gradually form an extremely heterogeneous network. As for the Intelligent Power Grids, the critical part of sensor networks development is the application mining based on data fusion. The application includes the following area and the related research would compel the convergent development of lOT, Power Grid Information Net work and Intelligent Power Grids. Includes: Transmission line online surveillance system; Protection of Power Facilities and electrical safety protection; Intelligent Patrolling System for power transmission, distribution, and transformation; Power system on-site monitoring system; Power plant automatic climate probe system; Intelligent customer and electric energy data acquire system; Condition Online Monitoring System for Electrical Equipments. Thus, with the rapid development of sensor networks in Intelligent Power Grids, the number of the sensors increases in the form of a geometric progression, the number of sensor types and interface types will be more complicated, and form ing the large-scale distributed sensor networks. As a subset of next generation Internet or Internet of Things, sensor networks will bring a certain degree of difficulty for the aggregation
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and transmission of sensor information data, forming the natural bottleneck between massive sensor information and the existing Power Grid Information Network. Therefore, the evolution trend of sensor networks is information aggregation and system reaction and ubiquitous fusion. For a large number of multi-type sensor devices and large scale sensor networks there need for a unified layer of data perception and accessing to complete the front-end aggregation of data for uplink trans mission. The following part mainly discusses the positioning of the aggregation layer in the sensor networks and data fusion of a mass of sensing information in the gateway of sensor networks, which is a common problem about network and data fusion, especially in the newly boomed Intelligent Power Grids. III. THE DEFINITION AND CRITICAL POSITION OF AGGREGATION LAYER IN INTE L LIGENT POWER GRIDS At present, the research of the access and aggregation of sensor information is a hot spot at home and abroad, and also an important element in the standardization work of Sensor networks. The international organization is conducting interface and network standards, a present team is drawing up the relevant standards of the physical interface and the sensor model.
B. Aggregation layer and gateway
Sensors in intelligent power grids, the basis for networking constructs, are object that install information devices in the power apparatus, achieving intelligent networking through the interface. But such information is varied types and large quantities, widely distributed, and needs aggregation before entering the data transport network. The basic framework of the general sensor networks can be described as the Application layer - Network layer - Perceptual layer [1]. If the deployment and application of the aggregation layer is introduced, it will described as the Application layer Network layer - Aggregation layer - Perceptual layer, or the "aggregation services" of Information aggregation - System Sensing - Ubiquitous fusion. Simply, the application layer is mainly used for central office computing interaction, and network layer is used for constructing the transmission channel between the information center, and aggregation layer is used for sensor data pre-processing, docking with the network layer after unifying transmission format. The perception layer shall be inexpensive, reliable and easy- to - deployment. Fig. 1. shows the typical sensor networks architecture with aggregation layer.
_______ •
Application Layer
A. lOT architecture
Fresh network architecture will be proposed that different with OSI seven-layer architecture and Internet four -layer architecture. The new architecture integrates network resource, service and customer as a whole and suitable for the idea of Unified Network and Universal Service of sensor networks. The aim of Sensor networks is establishing a credible integra tion network platform and provide varied information access ing and multi-granularity transmission. The convergence with IPv6fIPv4 and mobile network is another critical character of integration accessing, transmission and service carrying Sensor networks architecture. In the architecture, the trade is exploring the common platforms and the technical line of a subset of applications for a further step, and the new proposals of collaborative informa tion processing, such as data formats, exchange methods and standards between and inside the layers in the collaborative information processing. In the network layering and network protocols, the aggregation layer of the information that being studied is a critical part, it is the key role of linking and the network bridge between the mature transmission network and widely deployed sensor networks. From the application point of view, there must be a distinct aggregation layer (as the gateway device) between the sensor networks and the transmission network, whose objective is classification, storage and pre-treatment of the sensing signal, to reduce the pressure to the back-end network, and it is likely to adopt Ethernet signal as the unified signal format suitable for IPv6 from the aggregation layer to the transmission layer. And also, the Sensor networks Gateway has been researched in the recent standard conference, which is the typical aggregation device in Sensor networks.
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Network Transport Layer
}
Aggregation Layer
Sensor Access Layer
Fig. 1.
Network architecture of Sensor networks
The task of aggregation layer in intelligent power grids is coordination of wireless access, mobile access and fixed line (maybe power line) access, to achieve the integration of sensor networks and transmission networks. And transmit the great amount of information to multiple nodes by gateway in aggregation layer, and expanding the scope of information transmission to achieve a variety of perceptual access and substantial fusion of the power grid information core network. The Gateway in aggregation layer (between newly deployed varied sensor and Power Grid Information Network) is also a critical part for Intelligent Power Grids. The typical character of Intelligent Power Grids is the convergence of power flow, information flow as well as the convergence of sensor networks and control network. The power grid data network will need both local information interchange and wide area information
interchange. The distributed sensors and controllers must have network edge gateway at the aggregation layer to collect varied infor mation from the sensors, which is the basic infrastructure for Intelligent Power Grids. IV. SENSOR INFORMATION PROCESSING AND DATA FUSION IN AGGREGATION LAYER The increasingly large-scale sensor networks will generate great amount of multi-type datum, front-end information pro cessing technology will contribute to the effective carrying of the power grid data transmission network, depressurize for the background computing platform and control system, and improve the effective delivery of information in sensor networks. The sensor information front-end processing here is also a requirement of data fusion. There are energy constraints for sensor networks, and reducing the number of transmission channels can effectively save energy. Therefore in the process of collecting data from various sensor nodes, we can take advantage of the node's local computing and storage capacity to handle data, to do basic data fusion and remove redundant information, so as to achieve the purpose of saving energy. Sensor networks information and data fusion in aggregation layer can be described as Fig. 2. Aggregation Layer Data Fusion External Distributed
Information
Situation
Alarm
Object
Assessment
Assessment
Assessment
Assessment
Processing
Processing
Processing
Processing
Local Broadband Uplink Interface! Up·layer Application
Sensor Information
divide the system functions of sensor networks into three modules, namely the perception module, aggregation module and transmission module. Among them, perception module obtains information any time and anywhere by various sensors that deployed in power generation system. Aggregation module mainly does the front end processing and analysis of sensor data, realizing data fusion and the unity of transmission formats. This module is mainly to address two key issues, that is, the interface protocol adaptation and varied information formats processing based on embedded processing chip. Pre-processing module, as the front-end perception, allows various types of data input and data communication of multiple types of interfaces. The transmission part, talked about with combination of strategy and industrial development. Transmission module is the object that transmits information accurately in time, guarantee the data collected through different types of network interface going into the power grid information communication net works, or wide area network. With the mature transmission technologies and their associated communication protocols to support, we can complete the "highway" of sensor networks and the construction of power grid information backbone transmission networks through cross and relay among power line (optional) transmission "pipelines" [4]. The kernel part is the information processing mentioned above. The typical information processing hierarchy in a distributed power generation system is as below Fig. 3. It is a typical application of the data fusion mode as we divide the system functions of sensor networks into three modules, namely the perception module, aggregation module and trans mission module.
Local Load
Database System
Fig. 2.
Support
Fusion
Database
Database
Distributed
Electricity
power source
transformation
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Data fusion in aggregation layer in sensor networks
DGeonlrol
Layered data fusion and information processing module provide the basic component, and then take the assessment processing with information, situation and other state, the original data becomes the specific characteristic data and policy-making data [2]. Three-layered information processing model is clear here with Signal processing layer, Feature fusion layer and Decision layer [3]. Collaborative mechanism can be applied in all these different layers. And also, collaborative information processing can be applied in various entities in sensor networks we divide the system functions of sensor networks into three modules, namely the perception module, aggregation module and transmission module. Collaborative mechanism can be applied in all these dif ferent layers. And also, collaborative information processing can be applied in various entities in sensor networks we
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Typical information processing hierarchy in distributed power
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Sensing information aggregation and data fusion are the ba sic technologies of Sensor networks application in intelligent power grids, and also a key aspect of seamless access of sensor networks and existing power grid information transmission network. The technology will address the data in the way
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of integrating multiple signal traces into one single uplink data; provide convenient and rapid technical support for the deployment of Sensor networks in intelligent power grids. V. THE EMBEDDED SMART GATE WAY IN INTE L LIGENT POWER GRIDS A. Data fusion and standard gateway
The function of data fusion is neither suited to be embedded into the sensor itself, nor suitable for integrating into the transmission unit. So introduce the function into an appropriate aggregation layer device can meet the current sensor networks application development. The data fusion at aggregation layer can bear more processing target than the backend Server, there shall exist much more information processing capability for storage, alarm and threshold judge. The sensor networks gateway device with intelligent infor mation management and control platform, coordinating with the applications based on large-scale database. Such kind of device makes the distributed data-aware, multi-interface access, multi-protocol aggregation and multiple means of transmission functions into one set, it can integrate various types of management and control of the end-points of large scale sensors, provide basic means of the controlling and manageable functions of the sensor networks. The sensing aggregation devices are the hardware carriers used to achieve the functions. Relying on the control of "smart gateway" to achieve data fusion has been expressed in the IEEE1888 [5], which have got the recognition of industry. And it shall achieve: 1) : To receive varied types of front-end sensing data and to achieve a unified management. As a front-end sensing module, it allows the data entry of varied types, allowing multiple types of interfaces for data communication. It not only accepts digital input, but also allows the collection of analog, and can automatically identify and standardize the processing. 2) : To realize intelligent process and feedback control. Achieve multi-sensor information storage, management and control. Provide the basic function for information, such as database management, fault management, performance man agement, security management, voice and video management on the back-end computing platform. Achieve the judgment management of feedback control signals. Make intelligent analysis and processing according to the received data, and judge the front-end actual situation in accordance with ap plication requirements and send the correspondent control feedback signal to form the mechanisms of automatic, linkage, interaction [6]. B. Standard smart gateway interface and module
The technology mentioned above are the critical character of Sensor networks Gateway, the Gateway device is the ob jective carrier of aggregation layer, and also the most standard component of future sensor networks. It is obviously that, the Smart Gateway will play a critical role in the convergence of lOT and intelligent power grids, and will be the kernel edge node in Power Grid Information Network. The embedded smart gateway will be deployed at the aggregation layer in
varied innovation application in such as Power Transmission Line online monitoring and intelligent inspection, electrical device online monitoring, green machine room intelligent management. The standard gateway of power grid is the basic media center between sensor networks and public network (or power line) in Fig. 4. A critical character for Smart Gateway is multiple interface and universal accessing. It also has the capability of accepting the new sensor access and a wide range of application. Reserve a number of front-end exploration interfaces to be an access of new sensing devices, to make the whole system have powerful scalability, which is convenient to enhance the application functions. According to different application scenarios and technology development requirement, the front-end sensors can be removed or added at any time. At the same time, a distributed sensor networks suitable for intelligent power grids can be built. The reserved front-end detection interface can also be connected to many sensors of the same type, to meet the need of distributed arrangement and detection of sensors [7]. In the particular application scenarios, it can complete a specific task of information collection. The smart gateway in intelligent power gird is the communication door of sensor networks and higher-layer network, which bearing the mass information from complex surroundings. So, the gateway shall have an embedded unit and powerful processor. Another character of smart gateway is high-efficiency and high-reliability in power gird. ADC analog interface AlD converter Audio sampling GPIO RS232 RS485/RS422
ARM9 Linux Database
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Ethernet: RJ45 MAC TO-SCDMA WCDMNCDMA2000 IMFi GEPON/GPON xDSL
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Fig. 4.
Standard smart gateway interface and module
At the same time, data fusion in smart gateway will promote a comprehensive network aggregation of the sensor networks and the existing power grid information network. With appli cation development of a variety of transmission technologies in sensor networks is taken into account, determine the optimal transmission strategy according to the specific applications and cost requirements, and then deploy the transmission "pipe" flexibly according to the choice of different transmission technologies and communication protocols to obtain the most reliable transmission and the best price-performance ratio in specific scenarios [8]. Based on the above consideration, the smart gateway in power grid information network requires lying different transmission channel interfaces at the interface of the perception module and transmission module when building the application system of power grid sensor networks, which is easy for the collected information to complete the transmission task relying on a variety of techniques.
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C. Innovation application based on Smart Gateway in Power
Grid Information Network
The smart gateway device that with intelligent information management and control platform used in Power Grids, coordi nating with the applications based on large-scale database that already exist in Power Grid Information Networks. Such kind of device makes the distributed data-aware, multi-interface ac cess, multi-protocol aggregation and multiple means of trans mission functions into one set, it can integrate various types of power generation management and online/onsite control of the end-points of large-scale sensors, provide basic means of the controlling and manageable functions of the Power Grids. The sensing aggregation devices are the hardware carriers used to achieve the functions. Relying on the control of "smart gateway" to achieve data fusion has got the recognition of power industry. Innovation application in Power Grid Information Network contains a great number of field as we mentioned and the power industry focus on: Transmission line online surveil lance system; Protection of Power Facilities and electrical safety protection; Intelligent Patrolling System for power transmission, distribution, and transformation; Power system on-site monitoring system; Power plant automatic climate probe system; Intelligent customer and electric energy data acquire system; Condition Online Monitoring System for Electrical Equipments. The critical component is the smart gateway and its deployment. Recently, the gateway device and intelligent software has been implement in some field as: Power Transmission Line online monitoring and intelligent inspection, electrical device online monitoring, green machine room intelligent management.
technology is used in order to meet the needs of network convergence. Intelligent Power Grid does not mean all that the sensor networks, which shall be intelligent or smart. The key point is that after connecting all information nodes to the data center, make new value to the Power Grids and the cost is less than the value it generates. AC K NOWLEDGMENT
This work has been supported in part by 973 program (201OCB328204), 863 program (2009AAOIZ255), NSFC project (60772022), PCSIRT program (IRT0609) and III Project (B07005) of China and BUPT Excellent Ph.D. Stu dents Foundation. The authors gratefully acknowledge the contributions of Jie Zhang, Yongjun Zhang and Wanyi Gu for their work on the original version of this document. REFERENCES [I] Y Fangchun, "Internet of Things should be more concerned the devel opment of industrial applications", Things networking technology and industrial development Forum, 2009. [2] D. L. Hall and J. L1inas, "Handbook of Multi-sensor Data Fusion", CRC Press, 200 l. [3] Barabasi A L and Albert R, "Emergence of scaling in random net works",Science. 286(5439) pp.509-512, 1999. [4] L Wei, "China Mobile to develop networking standards for materials", Wireless technology in the world cum Things Forum, 2009. [5] Z Jun, "IEEE1888 standard language of things", Wireless technology in the world cum Things Forum, 2009. [6] Lymberopoulos D and Savvides A, "XYZ: a motion-enabled, power aware sensor node platform for distributed sensor networks applications", in
Conf of Information Processing in Sensor networks, IEEE,
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454,2005. [7] Bianconi G and Barabasi A L, "Competition and multi-scaling in evolving networks",
Euro-physics Letters.
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[8] Newman M E J, "The structure and function of complex networks", Review,vol 45, pp.167-256.
SIAM
VI. SUMMARY The definition and function of aggregation layer in lOT is a basic idea of next generation network architecture, the same to Power Grid Information Networks, it contains the idea of network convergence. The standard aggregation services shall be in a state of Information aggregation, then System Sensing, and then ubiquitous fusion. Smart Gateway shall be a critical component in the conver gence of lOT and Electric Power Communication Transmis sion Network. It takes the function of data fusion, which is neither suited to be embedded into the sensor itself, nor suit able for integrating into the transmission unit. The embedded gateway with more powerful CPU and more types of interface will carry more information at aggregation layer and meet the fast-developed sensor network application development. Sensor networkslIOT will be the extension and expansion of present network, eventually becoming part of the next gen eration Internet to achieve global interoperability. Sensor net workslIOT should be integrated into Power Grid Information Network and as a typical infrastructure of Intelligent Power Grids. Sensor networkslIOT have their own technologies and standards. If there are no universal and suitable information aggregation technologies and data fusion technologies, you can only deal with a particular situation, which has some limitations. The scalability and openness of aggregation layer
Dahai Han
was born in Inner Mongolia Province,
China, in 1979. He received the B.E. degree in electronic science and technology from Chang Chun University of Posts and Telecommunications, Chang Chun, China, in 2002. He won the qualification of direct candidate for the Ph.D. degree in electromagnetic field and mi crowave technology from Beijing University of Posts and Telecommunications in 2004. He is currently a lecturer at BUPT. He works in Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education since he graduate from the laboratory. His work includes optical networks and Sensor NetworkslIOT. Research field includes: Internet of Things; Wireless Sensor Network; lOT gateway with broadband network; lOT related research experience includes: Participate in BUPT youth science research innovation
project
"lOT
platform in BUPT", in charge of "Embedded intelligent lOT and WSN gateway device development". Participate in China ICT project (State Grid), in charge of "Intelligent and Green Grid". Authenticated member for WGSN (Standardization Working Group on Sensor Network) in PG9-Sensor Network Gateway.
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Jie Zhang
was born in Henan Province, China, in
1972. He received the B.S. degree in communication engineering and Ph.D. degree in electromagnetic field and microwave technology from Beijing Uni versity of Posts and Telecommunications (BUPT), respectively in 1993 and in 1998. He is currently a professor at BUPT. He has published 6 books and more than 100 articles. Also 11 patents has been obtained or applied. His research focuses on GMPLS, Automatic Switching Optical Networks (ASON) and adaptive optical networks.
Yongjun Zhang was born in Heilongjiang Province, China, in 1969. He received the B.S. degree in com munication engineering. He received Ph.D. degree in electromagnetic field and microwave technology from Germany UNIY STUT T GART in 2003. He is currently a professor at Beijing University of Posts and Telecommunications (BUPT). He has published 3 books and more than 40 articles. Also 10 patents has been obtained or applied. His research focuses on T MPLS, Automatic Switching Optical Networks (ASON) and adaptive optical networks.
Wanyi Gu received the B.S. degree in physics from Peking University, Beijing, China, in 1970, and the M.S. degree in electromagnetic field and microwave technology from Beijing University of Posts and Telecommunications, Beijing, China, in 1982. She is currently a Professor and at the College of Telecommunication Engineering, Beijing Univer sity of Posts and Telecommunications. Her research interests include high-speed optical communication systems, broad-band sub-carrier multiplexed light wave systems, and WDM optical networks. She has authored more than 100 papers in the field of optical fiber communications. Prof. Gu was awarded the Science and Technology Progress Prize by the Chinese former Ministry of Posts and Telecommunications.
