Network strengthening and expansion are among the top priorities for transmission and distribution (T&D) utilities in the country to provide quality and reliable power supply. Utilities are increasingly adopting state-of-the-art technologies and digital solutions to upgrade and optimise their operations. The increasing share of renewable energy sources in the grid is driving the expansion of the transmission network, ensuring adequate evacuation infrastructure for the upcoming renewable energy plants. Besides, distribution utilities are adopting advanced metering infrastructure solutions to modernise their metering infrastructure and improve their operational and financial performance. The utilities are ramping up investments in new technologies to make the grid more reliable, secure and smart. Digital substations and battery energy storage systems are being adopted along with digital solutions like IoT, AI and ML to improve grid reliability and take advantage of new capabilities to support grid operations.
Power Line takes a look at the key trends in the T&D space…
Increasing renewable energy integration: One of the key growth drivers for the expansion of the transmission network is the need to provide evacuation infrastructure for growing renewable energy sources. Adequate evacuation infrastructure is essential to provide connectivity to the upcoming renewable energy and meet the green energy goals of the country. India has set the target to install 500 GW of non-fossil-based capacity by 2030 and meet 50 per cent of the energy requirement from renewables by 2030. For increasing the renewable energy capacity, areas with high solar and wind energy potential need to be connected to the interstate transmission system (ISTS) to evacuate power to the load centres.
Recently, the Central Electricity Authority (CEA) released a report, “Transmission System for Integration of over 500 GW of Renewable Energy Capacity by 2030”, which provides a detailed plan for the evacuation of planned renewable energy capacity by 2030. It identifies the major upcoming non-fossil-based generation centres in the country. These include Fatehgarh, Bhadla and Bikaner in Rajasthan; Khavda in Gujarat; the Anantapur and Kurnool renewable energy zones in Andhra Pradesh; offshore wind sites in Tamil Nadu and Gujarat; and an upcoming renewable energy park in Ladakh. The plan projects the addition of 8,120 ckt. km of high voltage direct current (HVDC) transmission corridors (+800 kV and +350 kV); 25,960 ckt. km of 765 kV AC lines, 15,758 ckt. km of 400 kV lines and 1,052 ckt. km of 220 kV cable at an estimated cost of Rs 2.44 trillion. With the planned transmission system, the interregional capacity will increase to about 150,000 MW by 2030 from 112,000 MW at present.
Managing RoW: A key challenge for power utilities in expanding their T&D network is right of way (RoW). To optimise RoW utilisation in congested urban and semi-urban areas and difficult terrain, utilities are adopting higher voltage systems, multicircuit towers for stringing circuits, and new-age technologies such as HVDC systems and gas-insulated switchgear (GIS). They are also adopting series capacitors, FACTS devices and phase-shifting transformers in existing and new transmission systems to increase power transfer capability; upgrading the existing AC transmission lines to higher voltage using the same RoW; and reconductoring existing AC transmission lines with higher ampacity conductors. In addition, the use of multivoltage level and multicircuit transmission lines, narrow base towers, and pole-type towers, HVDC transmission (both conventional and voltage source convertor based), and GIS/hybrid switchgear (for urban, coastal, space-constrained and polluted areas, etc.) is growing.
Shift to higher voltages: Transmission of power at higher voltages improves the efficiency of power transfer, thus reducing losses in long distance transmission. Besides, power transmission at higher voltages requires less bulky and lightweight conductors, and the transmission towers required to support the cables must also be engineered appropriately. The use of HVDC technology is growing for long distance bulk power transfer as it results in lower transmission losses and requires a lower footprint. Typically, HVDC systems report 50 per cent lower losses compared to HVAC technology.
In a key development, Powergrid commissioned the first VSC-based HVDC system in the country, the ± 320 kV, 2,000 MW, Pugalur-Trichur system. VSC technology significantly reduces land use compared to conventional HVDC systems and is ideal for areas with limited land. It combines overhead lines and underground cables to overcome limited transmission corridors.
Smart metering: Revamping the metering infrastructure with the adoption of smart meters has been one of the key focus areas of distribution utilities. Smart meters can improve the operational and financial performance of discoms by automatically generating bills, preventing delayed payments through the remote disconnections feature, and reducing aggregate technical and commercial losses, among other things. The government’s Revamped Distribution Sector Scheme aims to achieve 100 per cent smart prepaid metering at all levels. The scheme envisages the installation of 250 million prepaid smart meters. Along with prepaid smart metering for consumers, system metering at the feeder and DT levels with a communication feature and associated advanced metering infrastructure would be implemented in totex mode under the scheme.
Advance cables, conductors, and substations technologies: XLPE cables are increasingly being deployed by utilities. XLPE-insulated cables have better resistance to thermal deformation due to their higher thermal tolerance, resulting in a higher current-carrying capacity higher than conventional cables. These cables also offer greater tensile strength, elongation and impact resistance. Advanced conductor technologies such as HTLS conductors, high surge impedance loading lines, HVDC cables and underground cables are gaining traction among utilities. Substation technologies have also evolved considerably over the years to meet the changing requirements of utilities such as remote monitoring and control, space optimisation, lower cost, longer asset life, enhanced safety, and reduced failure rates. Transformer technologies have progressed and made way for advanced solutions such as HVDC converter transformers, phase-shifting, coupling and mobile transformers. An emerging trend in India is the replacement of conventional AIS substations with GIS substations to address RoW issues. Equipment manufacturers have also developed new environment-friendly insulation mixtures to allay the environmental concerns related to the use of SF6 in GIS. In addition, digital substations are gaining traction across utilities as digitalisation helps to improve the availability and reliability of power supply through the use of sophisticated sensors and intelligent electronic devices.
Increased deployment of AI, ML and IoT: Digital solutions such as AI, ML and IoT are gaining popularity for efficiently managing networks, quickly restoring outages and managing distributed energy generating sources in the most effective and affordable manner. Utilities are increasingly integrating AI-based solutions for granular visibility at the appliance level and ML for distilling actionable patterns from aggregated data. Utilities are increasingly adopting these technologies to optimise processes, predict issues and optimise O&M.
BESS for firm power supply: Battery energy storage systems (BESSs) are an emerging technology that can help the power sector store electricity generated by renewable energy sources, reducing intermittency issues. Load support BESS, installed on the distribution side, helps balance the load and improve reliability and quality. In April 2022, the SECI awarded the tender for setting up 500 MW/ 1,000 MWh of standalone BESSs to JSW Energy. The project will provide discoms with storage facilities to be used on an “on-demand” basis. The two projects of 500 MWh capacity each will be installed near the Fatehgarh-III grid substation in the ISTS network on Rajasthan.
Remote monitoring and advance asset management solutions: With advanced technological solutions, network operators have improved their network monitoring and asset management. Remote monitoring and automation tools are modernising inspection, survey, and O&M of the network. IoT enables real-time monitoring of asset health and performance, which improves network availability and reduces outages. To effectively monitor the performance of their assets, utilities are increasingly adopting helicopter-based and drone-based patrolling in addition to ground patrolling. Drone patrolling provides detailed information about the line and tower top portions such as condition of insulators, earth peak and earth wire, and allows the utilities to effectively manage and maintain assets.
Backed by data analytics and predictive modelling, utilities are moving from reactive asset management towards preventive and predictive asset management as well as condition-based and reliability-centred maintenance. This has led to an increase in equipment uptime and decrease in outages. Notably, Powergrid has established a National Transmission Asset Management Centre at Manesar, Haryana, for centralised and remote monitoring of its substations across the country. As of December 2022, 270 extra high voltage substations are being controlled and monitored from control centres.
To conclude, driven by technological advancements and changing utility requirements, the T&D segment is witnessing rapid uptake of digital and advanced technology solutions. This trend is expected to continue in the future. Further, utilities will undertake significant investments in cybersecurity initiatives as their operations become more digital and connected. Besides, increasing consumer awareness, training and upscaling of the workforce and change management will support the seamless adoption of newer technologies in the industry.