International telecommunication union

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9 Sample Implementation of Smart Grid Applications

9.1 ITU-T G.9970 Home Network Transport and Application Layer Architecture

ITU-T G.9970 [5] addresses the home network architecture for both the transport layer and the application layer. The physical configuration depicted in Figure 14 shows home networks consisting of multiple networks technologies, including IP-based and non IP-based terminals, and gateway to the IP-based carrier networks. It shows the protocol mapping and how they are interconnected. It also includes the following features:

– The primary terminal contains both the IP terminal function and the Application Layer Device Function (ALDF), while the secondary terminal contains both the non-IP terminal function and the ALDF. The AGW (Access Gateway), which is the aggregated type in this example, contains NT, AGTF (Access Gateway Transport layer Function) and AGAF (Access Gateway Application layer Function).

– The AGW terminates the public IP address and interacts with the IP terminal function by a local IP address, while the IP terminal function interacts with the non-IP terminal function by non-IP (L3) protocol. Both the IP terminal function and the non-IP terminal function lie within the transport layer in the home network.

– On the other hand, the ALDF in the primary terminal interacts with functions in the application layer of the carrier's network via the AGAF in the AGW. It also interacts with ALDF in the secondary terminal at the application level.

– The primary domain is provided over an IP home network, while the secondary domain is provided over a non-IP home network.

Figure 14: One Physical Configuration of Generic Home Network Architectures

Figure 15 from ITU-T G.9971 [6] illustrates the functional architecture of the AGW. Note that although management and security functions are related to transport layers 1, 2, and 3 as well as the functions above layer 4, G.9971 handles only layers 2 and 3 aspects. Among functions shown in Figure 15, transport related functions are specified as follows:

– Layer 1 Termination (L1T): Termination functions of physical layer, such as Ethernet PHY.

– Layer 2 Termination (L2T): Termination functions of Ethernet port, such as MAC address assignment.

– Layer 2 Forwarding (L2F): Ethernet bridging functions using MAC forwarding table as well as L2 QoS processing, such as L2/L2 QoS mapping. Note that L2F of Ethernet bridges also contains L2/L2 mapping function between Ethernet and wireless within LAN.

– Layer 3 Termination (L3T): Termination functions of IP port, such as IP address assignment.

– Layer 3 Forwarding (L3F): IP routing functions using IP routing table as well as L3 QoS processing, such as L3/L3 and L3/L2 QoS mappings.

Figure 15: Functional Architecture of Separate Type AGW

9.2 Architecture with the HAN and Relevant External Interactions

Figure 16 presents a functional model of Smart Metering and home energy management in a graphical format in which both communication and power flows are depicted. Functions similar to the End-User Functions shown in Figure 4 are presented in the right four columns of Figure 16. These include:

Energy Service Interface (ESI), which provides an interface for energy management and advanced energy services that enable secure interactions between relevant home area network devices and electric power companies or IP based energy service providers.
Energy man-machine interface (MMI) devices, which are to provide a customer with home electrical energy service interaction; display, control, selection, management, verification, and so forth.
Energy devices, which are end devices that consume the electrical energy, control electrical energy usage, monitor energy usage, store electrical power, and recover and supply the electrical energy.
Advanced energy services, which are to provide new emerging energy services based on IP based home area network to home energy customer.

The Application Functions and Network Functions are shown on the left side of Figure 16. This conveys similar functional structure with more implementation details.

Figure 16: Another Functional Model of Smart Metering and HAN

Components inside the functional model shown in Figure 16 correspond to the relevant functions specified in Figure 4, which represents for the Smart Metering and Load Control, and in Figures 5 and 6 representing for the Energy Distribution and Management. To be specific, the Advanced Energy Service and the Energy MMI devices depicted in Figure 16 are closely related to the Power Grid Monitoring and Control in Figure 5, and the Energy Usage and Distribution Management in Figure 6, those of which are two major application areas in the Energy Distribution and Management application.

The next sub-section of 9.3 addresses another example of the necessity of further functional considerations in the functional architecture model in order to deal with more implementation details.

9.3 Architecture Focusing on Interface between HGW and PEV

Figure 17 considers another different configuration model of HAN. Similar to the previous example shown in Figure 16, the End-User Functions shown in Figure 4 will be presented.

There are PEV and home area networks with HGW, which controls whole electricity inside customer premises. In addition to PV, PEV, and HGW, there are components such as a power conditioning system, a femto base-station (BS), a storage battery, home appliance / household equipment, and a power meter/a sensor/a monitor as depicted in Figure 17.

Some of the functionalities related to HGW are listed and explained in the followings:

Detection of the PEV coming to (or out of) the garage. The HGW authenticates and authorizes the PEV. The PEV sends information such as charge level, miles driven, and driving patterns to the HGW.

Monitoring power generation of PV and electricity consumption of home appliances/ household equipment, the HGW decides whether to charge or discharge the PEV.
Information received during processes relevant to the above functionalities is accumulated in the HGW. The HGW analyses the information and learns electricity usage / generation patterns. Based on learned information, the HGW renews its policy for charging / discharging the PEV.

Similar to the previous example described in the sub-section 9.2, the model here explains the detail of the Energy Distribution and Management Application that are specified in 7.2.2. The functionality explained above would be additionally required for the functional model in Figure 6 if more implementation details are considered for this type of application.

Figure 17: Another Functional Model of HAN

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