Smart grids represent an evolution from conventional power distribution systems. They are dependent on robust communication infrastructure for effective functioning.
Smart grids employ two-way communication, digital technologies, advanced sensing and computing infrastructure and software to provide improved monitoring, protection and optimisation of all grid components. Various communication technologies such as ZigBee, RFR mesh, WiMAX, power line communication (PLC) and cellular communication are currently being utilised in smart grid deployments. Notably, industry experience suggests that most successful advanced metering infrastructure projects operate either on RF mesh technology or PLC technology for last mile connectivity.
Notably, Intellismart Infrastructure Private Limited and Adani Energy Solutions Limited have partnered with Airtel Business for powering up to 20 million smart meters. Airtel’s IoT proposition includes its proprietary platform “Airtel IoT Hub”, which will help the utility track and monitor these smart meters with advanced analytics while maintaining extremely high reliability augmented with telco grade security.
Communication infrastructure
The communication infrastructure of smart grid comprises three key networks – the home area network (HAN), the neighbourhood area network (NAN) and the wide area network (WAN) – each serving distinct purposes across varying geographical scales.
The HAN operates within small areas like homes and offices, enabling communication among smart home devices and meters using technologies such as ZigBee or Ethernet. With transmission rates typically in the range of hundreds of bits per second, HAN facilitates efficient energy management by allowing devices to share data and coordinate energy usage, transmitting information such as energy consumption to smart meters.
The NAN extends coverage to urban clusters, connecting multiple HANs and aggregating data on energy consumption from various households. Using technologies such as PLC, Wi-Fi and cellular connections, NANs transmit this aggregated data to local data centres (LDCs) for storage and analysis, facilitating consumer billing and energy demand pattern recognition.
The WAN serves as the backbone of the smart grid communication infrastructure, operating across vast geographical areas and connecting multiple NANs and LDCs. With high speed transmission capabilities reaching up to several gigabits per second, WAN enables real-time monitoring and control of energy generation, transmission and distribution. Technologies such as Ethernet networks, WiMAX, 3G/LTE and microwave transmission are employed in WAN implementation, ensuring robust connectivity and data exchange across the entire smart grid ecosystem.
Non-cellular communication technologies
PLC enables data exchange over existing power line installations, eliminating the need for dedicated cables and providing a cost-effective solution. However, it faces challenges such as attenuation on certain frequencies due to random switching of electrical equipment, strong noise interference from devices like switched mode power supplies, and variations in signal voltages due to load impedance changes. PLC often needs to be complemented with other technologies for optimal performance.
In smart grid applications, PLC is utilised in NAN communication, connecting smart meters to LDCs, while WAN communication between LDCs and other grid components takes place via cellular networks. Despite advantages such as widespread infrastructure reducing installation costs, PLC is hindered by the presence of higher harmonics in power lines interfering with communication signals and limiting communication frequency.
Another communication technology, the RF mesh facilitates wireless communication and plays a central role in automatic meter reading (AMR) systems. Integrated into meters, it enables the measurement of power consumption and data collection from energy consumers. This technology is cost-effective, energy-efficient and easily embeddable into existing meters. However, it performs optimally in limited ranges with high concentrations of RF modules. Combining RF mesh PLC can enhance accuracy and coverage, leveraging the strengths of both technologies.
ZigBee technology offers a versatile solution for building mesh networks connecting smart meters and data concentrators, catering to machine-to-machine (M2M), wireless and IoT-based applications. While cost-effective and flexible, ZigBee faces challenges such as high interference from applications sharing the same bandwidth and limited support capacity of up to 65,000 devices. It is suited for lighter applications like home automation or smart lighting compared to RF mesh, which is more reliable for industrial settings. ZigBee offers advantages like low cost and small size. However, operating in unlicensed frequencies may lead to interference with other signals like Wi-Fi and Bluetooth.
Fibre optic communication, while pricier than other options, is particularly well suited for control, monitoring and backbone communication within WANs. Its advantages include long-range transmission, high bandwidth and rapid data transfer rates, coupled with immunity to electromagnetic interference. However, fibre optic communication is constrained by the number of access points available. Typically, fibre optics are employed to establish connections between substations and utility company control centres.
Cellular communication technologies
Cellular networks, widely deployed across several countries, have robust infrastructure and support high speed data communications, reaching up to 100 Mbps. Consequently, they serve as viable communication channels, facilitating connectivity among various components and devices within the smart grid framework.
LoRa, derived from chirp spread spectrum technology, offers a long-range, low-power wireless platform. LoRa devices and networks like LoRaWAN support smart IoT applications for diverse purposes such as pollution control, infrastructure efficiency, disaster prevention and smart metering communication. Despite their utility, LoRa technologies have limited cellular connectivity capabilities.
NB-IoT offers extensive cellular connectivity through several partner networks at a lower cost compared to other M2M technologies, ensuring global network coverage with high reliability. It seamlessly integrates with existing PLC/RF mesh infrastructure, expanding smart metering reach and eliminating the need for manual reading in remote areas. NB-IoT does not require concentrators or gateway devices and provides unified data visualisation through dashboards.
General packet radio service (GPRS)-based AMR systems provide secure, low-cost solutions for calculating and transmitting electrical energy consumption data to main servers using GSM networks. These systems consist of digital meters, transmission facilities and billing servers, enabling remote reading and enhancing billing accuracy with near real-time consumption data.
Conclusion
To conclude, selecting the most suitable end-to-end communication technology requires careful consideration of factors such as network strength, cost and throughput requirements. Backward compatibility and a technically knowledgeable workforce are also critical requirements.
India’s ambitious smart metering plan underscores the importance of efficient communication technology in achieving success. By selecting and implementing the right technology, discoms can reduce expenses, increase revenues and improve their overall financial health. Moreover, efficient technology deployment will contribute to the advancement of the power sector in India, paving the way for a more sustainable and reliable energy infrastructure.
Aastha Sharma