CHAPTER 2: BACKGROUND AND RELATED WORKS

2.1. Introduction to Smart Grid / Advanced Metering InfrastructureGrowing the need for the Smart Grid (SG)A smart grid [1] delivers electricity from suppliers to consumers using two-way digital communication technology. Smart grid allows controlling appliances at consumer’s homes to save energy, and reduce cost. The operation status of the smart grids can be monitored in real time, so the smart grids are more reliable. Many governments are promoting such a modernized electricity network as a way of addressing energy independence, global warming and emergency resilience issues.Utilities can archive energy efficiency and maintain the competitive of services by taking advantages of the smart grid and its market benefits. The smart grid solutions that utilize the information technology for data collection, monitoring and control, data analysis and information communication infrastructure, will cost-effectively protect revenues today, while laying the foundations for future services.

Advanced Metering Infrastructure (AMI)Advanced Metering Infrastructure (AMI) [2] that is as part of larger Smart Grid initiatives, is implemented by government agencies and utilities to meet the above challenges. Extending from the current Automatic Meter Reading (AMR) technology, AMI provides two way meter communications, and allows commands to be sent toward the home for multi purposes, including Time-of-Use pricing information, demand-response actions, or remote service disconnects.The Department of Energy estimates that over 280 Giga-watts of new generating capacity will be needed by 2025 [5]. It results in new power plants would be built in the future. The energy industry is facing the critical issues such as the need for new plants, maintaining overburdened infrastructure, coping with an aging workforce, complying with regulations, and environmental concerns. For a long time, the energy industry has rightfully focused on the supply side of this challenge. But now, the demand side of the equation can be significantly impacted by the existing of the wireless mesh networking [3]. Wireless mesh networking can use as the backbone of the AMI solutions to enable two-way intelligent networked communications with smart meters. With the AMI, the value added services such as demand response and demand side management would be enabled, besides meter reading. AMI solutions allows interoperable networks and systems across the entire power structure aid in the management and control of energy consumption, improve operations management, conserve the environment, and adhere to evolving regulations.

2.2. Introduction to Wireless Mesh Network (WMN)What is WMN?A WMN [3,4] is a communications network made up of radio nodes organized in a mesh topology. Wireless mesh networks often consist of mesh clients, mesh routers and gateways. The mesh clients are often laptops, cell phones and other wireless devices while the mesh routers forward traffic to and from the gateways which may but need not connect to the Internet. A mesh network is reliable and offers redundancy. When one node can no longer operate, the rest of the nodes can still communicate with each other, directly or through one or more intermediate nodes. Wireless mesh networks can be implemented with various wireless technology including

802.11 [12], 802.15 [13], 802.16 [14], cellular technologies or combinations of more than one type.

WMN is as wireless infrastructure solution for AMIWhen the WMN technology is applied in AMI solutions, it can bring new components to the electrical grids, such as self-managing and self-healing mesh networking, intelligent meters, and bridging to Home Area Networks (HAN) [2] for connectivity with energy consuming appliances. The real time communication between the smart meters and the utility’s data center provides detailed usage data while also receives and display Time-of-Use (TOU) pricing information, and offers other on-demand abilities such as remote connect or disconnect, unrestricted monitoring and control, etc. Customers are able to access the usage data for tailoring consumption and minimizing energy expenses while helping balance overall network demand.When WMNs are used in the AMI, they can provide the following features [5]:

Low cost of management and maintenance - WMNs are self-organizing and require no manual address/route/channel assignments. It is simple to manage thousands or millions of devices resulting in the lowest total cost of ownership.

Increased reliability – The WMN routing mechanisms provide the redundant paths between the sender and receiver of the wireless connection. Communication reliability is significantly increased because of the eliminations of single point failures and potential bottleneck links. Network robustness against potential problems, e.g., node failures and path failures due to RF interferences or obstacles, can also be ensured by the existence of multiple possible alternative routes.

Scalability, flexibility and lower costs - WMNs are self-organizing and allow true scalability. Nodes and Gateways are easily added at a very low cost with:

o No limitation on number of hops o No network address configuration o No managed hierarchical architecture o No hard limitation on number of Nodes per Gateway

Robust security – WMNs have the security standards that allows all communications in AMI are protected by mutual device authentication and derived per-session keys using high bit rate AES encryption. This hardened security approach allows for authentication as well as confidentiality and integrity protection in each communication exchange between every pair of network devices – Smart meters, Relays, or Wireless Gateways.

2.3. Related Works2.3.1. Colorado Springs Utilities AMI Network InfrastructureA brief introductionThe AMI wireless network infrastructure used the Point-to-Multi Point topology. The current meter data reading interval is five minutes for electric, fifteen minutes for gas and water meters.

2.3.2. SkyPilot’s Synchronous Mesh Network SolutionA brief introductionMetroFi (www.metrofi.com) has deployed a mesh network in the Silicon Valley – California. The installed wireless mesh metropolitan area network can provide the Internet access service to the resident user in a geographical area that covers about 250,000 households. The SkyPilot’s Synchronous Mesh Network solution was employed to build this mesh network. The SkyPilot’s mesh network solution combines standard-based WiFi access with a high performance wireless mesh backhaul network using SkyGate nodes to interface with the Internet, SkyExtender DualBand nodes that integrate WiFi access and mesh backhaul.

The mesh network MetroFi is a success deployment of the WMN onto the large geographical area. However, in the AMI meter data collection application, there is a different in the network traffic pattern compared to the regular Web applications. The Web applications usually need the connection with low bandwidth uplink, and high bandwidth downlink. In contrast, the AMI meter data reporting process requires the high bandwidth uplink connections to send the data from smart meters to data center. We can make an assumption that we intend to use the MetroFi network for the AMI communication infrastructure solution. Then, there is a research opprtunity about the MetroFi or WMN performance – Whether the WMN is suitable for the AMI network infrastructure, especially for the real-time meter data reporting application?

2.3.3. EkaNet™ Smart Network - Wireless mesh network solution for the Smart grid/AMIA brief introductionThe wireless mesh infrastructure includes the smart meter nodes, ranger extension nodes, and gateway nodes. The smart meter nodes are networking together to form the wireless mesh network. It means that, the communication between a smart meter node and the gateway will replay on a number of other smart meters. The range extension nodes are used to help connect the out of coverage nodes. The gateway nodes provide the interface to the Internet network.

The EkaNet has been deployed in some world wide areas such as Guayaquil - Ecuador, St. Petersburg – Russia. In Guayaquil – Ecuador, the utility has installed 3,614 wireless meter nodes, 314 repeaters, and 47 gateways. Meter data collection interval period is fifteen minutes.Advantages

- Wireless mesh network provides a low cost, easy deployment and management, scalable, flexible

Disadvantages- The number of relay hops will increases with the increasing number of the the smart

meters. As a result, the network performance will go down fastly, especially in the service place where the smart meter density is high, i.e. hundreds of smart meters in the area 100 meters by 100 meters. In the high resident density area, the mesh topology will not be a good choice for the network performance goal. Instead, the point-to-multipoint topology such as WiFi infrastructure mode would provide a better network performance.

2.4. Research OpportunitiesThis thesis discusses about the evaluation of performance of the WMN when it is employed as the wireless infrastructure solution of the AMI real-time meter data collection application.The related works have proved that the WMN can be used in the networking solutions that requires the deployment onto a large geographical area, such as the AMR/AMI meter data collection application. However, the WMN infrastructure needs a high bandwidth for transmitting the meter data from the smart meters to the data center in real-time. The conducted researches has shown that the WMN network bandwidth is effected by the hop number. The more hop number is the WMN routing path, the less performance is the WMN […].

2.5. ConclusionIn general, the wireless mesh network infrastructure can provides a cheap solution, compared to the wire network, connectting the smart meters to the utility data center. However, to answer the challenge question, whether the wireless mesh infrastructure is suitable for the real-time meter data reporting process, this thesis will go into more detail in the analysis of the performance property of the wireless network infrastructure solution. We will develop new tools and techniques to assist the planning and design phase. We will also use the network simulation method to evaluate the network performance.