Role of Smart Meters in Smart Grid
The goal this article is to provide the knowledge on the role smart meter technology in the smart grid. The commissioning of smart grid pilot projects for research and supporting them by Government of India shows the interest of future development. Smart meter definitely has a great role in smart grid and is considered as most important for future energy management...
- Dr. Sarat Kumar Sahoo,
The Government of India’s initiatives like 'Make in India' and 'Smart Cities' need the efficient, reliable and continuous power supply. India’s power sector in the present day is facing a lot of problems like AT & C losses, inefficient distribution and transmission system because of age old infrastructure and power theft. The advanced energy management and increased use of renewable energy resources are the foremost areas to concentrate by governments for the development of country. The government cannot take initiatives for complete change of electrical equipment across the country but there is a need for changing the way of operation and control of the electrical equipment. For this Ministry of Power has initiated ISGF (Indian Smart Grid Forum) which works very closely with public, private and research organizations for developing standards and policies so as to deploy the 'Smart Grid' to assure efficient and cost effective power for all stakeholders. The smart meter is very important constituent for smart grid and is expected to provide cost-effective, social and ecological advantages for various stakeholders. The most significant key factors that determines the success of the smart meters is data analysis that deals with data acquisition, communication, processing and elucidation that benefits to consumer, utility company and government.
The idea of smart grid increases the efficiency of power usage by the introduction of bi-directional flow of information from utilities to consumer and vice-versa. This can be possible by the introduction of 'Advanced Metering Infrastructure (AMI)'. The information about electrical consumption of a consumer is recorded in a timely manner and this data is aggregated and analyzed by 'smart meter' installed at consumer premises. The analyzed data is communicated to utilities using AMI. The AMI includes the advanced communication system including home area networks (HAN), neighborhood area networks (NAN) and wide area networks (WAN). Thus, AMI not only communicates the smart meter data to utilities but also transmits information to consumer from utilities about the peak demand, cost of energy consumption enabling the consumer to shift peak loads to some other time. Smart grid using smart metering and AMI technologies establishes the wide area monitoring, protection and control.
Traditional Electricity Meters
In India, mostly electricity utilization of a consumer is recorded by traditional electromechanical meter or an electronic meter (with digital display). The bills are generated by utility personnel just by recording usage for a specific period of time (monthly or bimonthly). This traditional process has no relation with advanced monitoring or control. In general, the traditional meter has following architecture as shown in the figure1.
The smart meter is future for power industry and serves as an interface between consumer and the utility company. The smart meter records the power usage of consumer and communicates this data in a timely manner to utility center. For smart meter, it is very essential to collect precise and appropriate data in a timely manner which includes gathering of data, its communication and storage. The smart meter allows the bi-directional flow of information, as shown in the figure 2, from consumer to utility and vice versa. The systematic analysis from the data acquired will lead to many prospective decisions by utility center that assures the efficiency and reliability of smart grid. This allows the utility center for better monitoring and control. The data communication in real time basis allows the utilities with advantages like real time pricing, outage detection, identification of power theft, avoids meter data tampering and provides better service. With the data received in timely manner utilities shall have a better opportunity to work better with increased stability.
Smart meters can definitely cut the domestic or commercial energy consumption by giving a lot of useful information to the consumer, but this information is useful only if consumer looks into it. Smart meter gives best home energy management solutions for smart homes using wireless technologies like (Zigbee or WiFi). Several sensor and actuators based appliances are commissioned in smart buildings to manage the connection of electrical load remotely based on the consumer choice or utility decisions envisaging the necessity of the smart meter.
Figure1: Traditional Electromechanical Meter Architecture
Figure 2: Smart Meter Architecture
Figure 3: Important tasks carried by smart meter
Smart Meter Functions and Advantages
The smart meter is expected to work in the following way. Data is collected from nodes, establishes the two- way communication, analyze the data and based on analysis it supports the controlling. The important tasks of smart meter is shown in figure 3. The data is collected from the individual appliances and is recorded at regular intervals of time. The data collected is stored in the memory and prioritization of the data is done for communicating to utility center. The command signals can be received from the utility center and the smart meter plans for load scheduling and controlling based on consumer choice. Automatic billing can also be done using smart meter. The figure 4 shows the important functions carried by smart meter.
Advantages of Smart Meters for Utilities
• With the advent of advanced monitoring technology the number of personnel required will be less.
• The increased ability for load management during peak load times.
• Makes more efficient use of grid resources.
• The system offers the latest tariff model for electricity market.
Advantages of Smart Meters for Consumers
• Benefits the consumers in more accurate and timely electrical billing.
• Allows the consumer to schedule the electrical usage in the most optimal manner.
• Allows the user to think about the better plan for using the electrical equipment during the expensive hours.
• Allows the consumer to switch between conventional to renewable resources based on the tariff.
Advantages of Smart Meters for Government
• The encouragement for smart meters will allow utilities to perform better in monitoring and controlling aspects of power systems.
• Encourages the renewable energy resources by consumers.
• An encouragement for environmental conditions with less CO2 emissions.
• Prevents blackout by better monitoring and load forecasting for power grid.
Figure 4: The important function carried by smart meter.
Smart Meter Technologies
Smart meter supports bidirectional flow of information. The smart meter is deployed at the end user premises to collect the information of electrical usage from all the appliances at regular intervals using Local Area Network (LAN). The data from individual smart meter is collected by local data aggregators using NAN and then this information is passed to utility center using WAN. Similarly, utility center also can send some commands or signals or information to the smart meter at end user premises when required. The figure 5 shows a photo picture of Smart meter manufactured by EVB Energie AG in Germany.
The smart meter should communicate the data to utility center in a highly reliable and secured way. The system collects the data from local smart meters and communicates it to utilities using different wired and wireless technologies involving the HAN, NAN and WAN. The data communication in HAN is carried by using power line communication (PLC), radio frequency (RF), Zigbee, WiFi. The data communication in NAN involves, copper or optical fiber, WiFi, general packet radio service (GPRS) and WiMax. The data communication using WAN includes optical fibre, cellular, Satellite.
The smart meter system communication technologies at end user premises are PLC, RF, Zigbee and WiFi. These technologies are employed based on geographical conditions and business needs defined by utility center. Factors of selecting the technology include assessment of existing equipment, influence of new technology to the existing appliances, functionality, should be economic to the end user and should be adaptable for long run based on present and future needs.
Figure 5: Smart meter used by EVB Energie AG in Germany
PLC based Smart Meter Measurements:
The smart gird data communication challenges can be fulfilled by employing the PLC communication by using existing power lines i.e, by using simple electrical conductor lines converting them as hybrid power lines useful for transmission of electricity and bidirectional data communication.
The utility companies have adopted the following two types of PLC standards for smart metering networks. The data communication using narrowband (NB-PLC) using IEEE P1901.2 and ITU-G.9955/9956 can be used for low voltage (LV) electrical networks can be employed in large scale. Broadband-PLC (BB-PLC) defined by the coexistence standards ITU – T G.hn and IEEE-P1901 is actually an extension to HomePlug AV2 specification and is employable for medium voltage (MV) lines based data communication. The G3-PLC is developed for addressing the issues of rural or dense areas. G3-PLC uses OFDM technique in combination with OPSK and BPSK modulations and is adaptable for MV lines data communication. The table shows the technical specifications of NB-PLC, BB-PLC and G3- PLC.
The advantage of PLC include the employment of existing infrastructure like wires and poles make it cost effective for smart meter and AMI. With this PLC can communicate for long distances. The disadvantages include requires more latency (more data transmission time), less data rates and requires high installation cost in the urban areas. The table 1 shows the features of different wired technologies used for smart metering systems.
Figure 6: RF based Mesh network
RF based Smart Meter Measurements
The data is transmitted or received by a wireless radio from source (appliance or smart meter) to destination (Smart meter or local data aggregator) and vice-versa. This data processed and refined then sent to the utility center for different energy management operations and controlling. The smart meters uses RF operates at 915MHz frequency band.
RF based Mesh Technology
The mesh network can be explained in two stages, firstly at home area the individual appliances uses wireless radio to communicate the data to smart meter. All the individual appliances in a home or building form a RF mesh based local area network(LAN) to communicate the data in a timely manner to the local data aggregator (smart meter). Then the smart meters communicate to each other forming a mesh to reach the local data concentrator (distribution transformer) this is called as Neighborhood Area Networks (NAN). This data is processed and is communicated to utility center using Wide Area Networks (WAN). The figure 6 shows the pictorial representation of a RF based mesh network.
The advantages include the acceptable latency requirements and operate at required bandwidth. There is need for research in standardizing this type of network for improving the topography issues and also to improve the long distance issues.
RF based Point to point Technology
Every individual smart meter communicates directly to the local data collector (generally poles near home), the data collector communicates this data to utility center using various NAN and WAN technologies for processing the data. The figure 7 shows diagrammatical representation of RF based point to point network.
The advantages include very little latency, direct communication with two end points, good bandwidth, better throughput. The disadvantages include point to point RF are licensing, faces challenges like line of sight.
Figure 7: RF based point to point network
In addition to the above RF communication the IEEE 802.15.4 based Zigbee is also used for smart metering communication. The amendments like IEEE 802.15.4g and IEEE 802.15.4e are based on the smart grid interoperability standards. This is more advantageous technology for AMI purpose is because of low cost, range and availability of number of channels for data communication are high.
Zigbee operates in the unlicensed frequency bands 868MHz (1 channel), 915MHz (10 channels) and 2.4GHz (16 channels). Operates with the data rates in between 40Kbps to 1Mbps. The maximum range up to 75m can be communicated. It can coexist with other technologies operating under 802.11, 802.15 and 802.16.
The interoperable technology 6LoWPAN also works under IEEE 802.15 and uses Internet protocol (IP) over WPAN (IPv6 over low power wireless personal area networks). The features of 6LoWPAN are almost similar to Zigbee. The main advantage of 6LoWPAN is, it identifies every wireless node by means of an IP address and this increases adaptability and flexibility of the data communication system. The table 2 shows various features of different wireless technologies used for smart metering systems.
Smart Meters in Indian Scenario
The government of India is very keen in the development of industrialization and world is recognizing India as one of the fastest growing economies. For the growth of industrialization, an adequate electricity resource has to be taken care by government keeping in the view of future needs. The Ministry of Power is very keen in taking initiatives for future energy demands and advocating the ideology of smart grid and has unveiled sixteen smart grid pilot projects that employ the combination of smart metering and various technologies for increasing the efficiency and reliability of power systems. ISGF under the Ministry of power is very active in the development of smart grid technologies in the Indian power sector. Some remarkable smart metering pilots are the 'Puducherry Smart Grid Project,' with more than 1400 SMs equipped with different technologies; the 'Bangalore Pilot Project,' which will reach 2,000 residential and commercial customers and the deployment started in 2008 in New Delhi (with 500,000 SMs installed in 2011) where SMs include automated meter reading and a prepaid system utilizing PLC technology. Industry reports estimate that India will install 130 million SMs equipped with both PLC and wireless technologies by 2021. The table 3 shows the smart grid projects commissioned in India whose main functionality is to assess the smart meter data for making important decisions.
The main objective of smart meters is for assuring the systematic energy management with the active participation of end user by coordinating utility companies in making intelligent decisions. The smart grid will enhance the stability and reliability of power systems using AMI technologies. The better outage management increased remote monitoring on power losses and controlling them and accurate billing are most important advantages of smart meters using AMI. The goal of this article was to provide the knowledge on the role of smart meter technology in the smart grid. The commissioning of smart grid pilot projects for research and supporting them by Government of India shows the interest of future development. Smart meter definitely has a great role in smart grid and is considered as most important for future energy management.
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