Data Exchange

A reliable communication system key to successful operation of smart meters

Smart metering and smart grid technologies require the exchange of large volumes of data and thus, communication networks play an important role in their implementation. A key requirement of a smart grid is two-way data communication. Technologies such as power line communication (PLC), radio frequency (RF) mesh and cellular networks are potential options for this. To help utilities choose the right technology for their smart meter implementation plans, the Central Electricity Authority (CEA) has notified the Guidelines for Communication System of Smart Meters in 2018. Power Line presents an overview of the key communication technologies…

PLC

PLC is a mature and reliable communication medium that uses electrical wiring to transmit both data and electric power without any interference as both are at different frequencies. PLC has been effectively deployed in telecommunication, teleprotection and telemonitoring between electrical substations through extra high voltage power lines. PLC can be deployed for smart metering in areas where the system is robust and data can be collected at a central server, depending upon the network strength and site feasibility. Some of the commonly used protocols for large-scale PLC communication on the electrical grid are IPV6, G3-PLC and PRIME.

However, PLC comes with certain limitations such as slower data transfer, interruption on operation of switches, disconnections in the electrical system and distortion of signals while passing through power transformers, inductors, etc.

RF communication

RF, typically used in radio communications, is a type of wireless communication technology, which has a frequency range from 20 kHz to 300 GHz. The higher the frequency band, the lower is the bandwidth available for the RF communication range. As the allocation of special spectrum for distribution utilities for smart metering applications is a time- and cost- intensive process, utilities should consider the use of the licence-free ISM (industrial, scientific and medical) band for RF communication.

Some of the key benefits of RF technology are negligible running cost and the ability to increase data transmission range by simply hopping off the signal over the modem. The key cost associated with RF technology is the one-time canopy installation cost, which is typically recovered within a few years of operation. RF can be deployed for smart metering applications with proper management of the RF canopy communication backbone in any confined area like townships. Since RF does not require large investments, it is ideal for distribution utilities and consumers as it will not impact tariffs significantly.

The main challenge in the usage of RF is the reduction in range when line of sight of modem/radio is not clear as the signals do not penetrate through concrete structures. However, this issue can be mitigated through the installation of repeaters and high gain antennas. Additionally, there are interoperability issues as the smart meter is generally designed based on the network interface card (NIC)/RF card of only one company, which provides the communication medium from smart meters to the meter data management system. This issue can be solved by the use of smart meters with a plug-and-play type configuration wherein the NIC of one company can be removed and another can be inserted in case of a change of the communication service provider.

Cellular network

Over the years, cellular technology has evolved from general packet radio services to 3G and 4G, with an ability to handle voice and data on the same network with good speed. Globally, many countries have used 3G technology in smart metering for transferring data to utility servers. The key advantages of cellular technologies is fast speed at affordable rates, owing to the growing competition between network providers/mobile operators. As per the CEA, cellular technologies are best suited for handling data, given the widespread mobile operators’ network in the country. The deployment of these technologies for smart metering augurs well for distribution utilities as they would only be required to pay monthly rentals/ data charges as network maintenance (and related charges) will be under the ambit of mobile operators.

However, there will be an operating cost for each meter, which will lead to serious cost implications for large-scale smart meter installations. Also, there is a risk of data delay/loss in the remote areas where the network strength is poor. In addition, there is an issue of technology obsolescence as cellular technology further evolves from 4G to 5G and 6G and so on.

Conclusion

A robust and reliable communication system is essential for the successful operation of smart meters. Since all communication technologies come with their own set of advantages and disadvantages, utilities need to use a mix of technologies, depending on the geographical and network conditions after finalising their smart meter installation roadmap.

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