Technological Shift: Moving to smart sensors and digital solutions in transmission

The Indian transmission segment is growing at a fast pace to support the country’s decarbonisation goals and connect 500 GW of clean energy (non-fossil fuel based) to the grid. Besides growth in the physical network, the segment is witnessing a technological transformation as utilities take steps to adopt solutions such as flexible AC transmission systems (FACTS) and battery energy storage syste­ms (BESSs), which are necessary to im­pro­ve grid reliability in the wake of increasing integration of highly variable renewable energy generation. There is al­so a shift to­wards smart senso­rs, digital solutions and advanced technologies like IoT, AI and ML to improve the management of the ra­pidly growing transmission network. An account of the key em­erging technologies in transmission…


FACTS devices such as static VAR compensators (SVCs) and static synchronous compensators (STATCOMs) are expected to play a key role in grid operations as greater renewables are integrated into the grid. These power electronic de­vices provide dynamic voltage support, thereby ensuring grid reliability and voltage stability. Powergrid has already installed advan­c­ed STATCOMs in the 400 kV network as well as a thyristor controlled reactor (500 MVAR) in Kuruk­shetra to im­pro­ve the static as well as dynamic voltage profile of the Kuruk­shetra high voltage direct curr­ent (HVDC) stati­on. The utility has commi­s­sioned STATCOMs at 14 substations in the past few years – Solapur, Auranga­bad, Satna and Gwalior in the western region; Lucknow and Nala­garh in the northern region; Ranchi, Ro­urkela, Jaipur and Kishanganj in the eastern region; and Udumalpet, Trichy, Hy­de­ra­­­bad and NP Kunta in the southern re­gion. It has also deployed a STATCOM at its Mahendra­garh substation, which has helped in re­ducing load profile chan­ges as well as auxiliary power consumption. Besi­des STATCOMs, SVC technology, which is being deployed in several sub­sta­tions, en­hances the capacity, security and flexibility of power transmission systems. For instance, two SVCs with 140 MVar inductive capacity each were ins­tall­ed at the Kanpur substation on the Ri­hand-Delhi HVDC line. These SVCs hel­p­ed avert a ca­scade tripping across the network when the grid voltage dipp­ed by 10 per cent on a faulty line.


Energy storage has become crucial for grids aiming for high renewable energy in­tegration. In 2022, the Ministry of Power notified the “Guidelines for procurement and utilisation of BESS as part of generation, transmission and dis­tri­bu­tion assets, along with ancillary services”. The objectives of these guidelines are to facilitate the procurement of BESS, as part of individual renewable po­wer proje­cts or separately, to address va­riability, fi­rm up power supply, increa­se the energy output, extend the time of supply from re­newable energy projects, augment existing renewable power projects, and provide ancillary, grid support and flexibility services for the grid; enable optimum utilisation of the tra­nsmission and distribution network; ensu­re transparency and fairness in the procurement process; provide a framework for an intermediary procurer to act as an aggregator, trading licensee and im­plementing agency for the interstate/intra-state sale and purchase of power; and introduce standardisation and uniformity in processes and a risk sharing fra­me­work between various stakeholders invol­ved in energy storage and storage capacity procurement, the­re­by encouraging competition and enhancing the bankability of projects.

Powergrid is actively planning to invest in BESSs. In 2021, Powergrid’s 500 kW BESS pilot project based on lithium-ion phosphate and lead acid batteries went live in Puducherry. The BESS pilot is aim­ed at demonstrating various possible use cases through enhanced IT-bas­ed controls, ascertaining the feasibility of BESS in the grid, and assessing the eco­nomic value of storage. It will be an important contribution to India’s energy sector. The utility is also implementing a 500 kW energy storage project at Guru­gr­am, Haryana, and a 5 MW BESS in Nagda, Madhya Pradesh.

Reportedly, the government plans to invite bids for setting up around 4 GWh of grid-scale BESSs at the regional load des­patch centres. Last year, NTPC Limit­ed floated a global tender for setting up a 1 GWh grid-scale BESS.

Notably, the Central Electricity Autho­ri­ty’s (CEA) recently released report “Trans­mis­sion System for Integration of over 500 GW RE Capacity by 2030” envisages ne­arly 51.5 GW of BESS capacity in the country over the next decade. A key proposed project is a 12 GWh BESS at Leh, out of which 1 GWh has been planned as a transmission element and the balance 11 GWh will be installed as part of renewable energy generation projects.


HVDC technology enables long distance transmission with minimal losses vis-à-vis high voltage alternating current (HVAC) li­nes. It is set to grow in the coming years especially as India takes steps to rea­lise its offshore wind goals. Though it is an established and known technology in India that has been in existence for over 60 years, there are only a few HVDC links in the country. The CEA’s recent report on RE integration envisages several new HVDC corridors for the evacuation of po­wer from large renewable energy pot­ential zones. These include the ±800 kV Barmer II (Rajas­th­an)-Jabalpur (MP) HVDC line, the ±800 kV Bhadla III-Fatehpur HVDC line, the ±350 kV Pang-Kaithal HVDC line, the ±800 kV Barmer II-Jabalpur HVDC line, and the ±800 kV Khavda-Auranga­bad HVDC line.

Asset management technologies

Transmission utilities are increasingly mo­ving to predictive maintenance stra­te­gies, which call for actions to be taken based on equipment health forecast th­rough the use of data analytics tools for objective decision-making. Some of the key factors considered under the strategy are design and voltage class, past op­erational history, failure trend, service age and health index.

Remote monitoring of transmission as­sets has gathered pace, especially after the Covid-19 pandemic.  Powergrid’s Na­tio­n­al Transmission Asset Monitoring Cen­tre (NTAMC) at Manesar, Haryana, facilitates remote operation of the company’s transmission system and monitoring of various parameters on a real-time basis at regional and national levels. Likewise, regional transmission as­set monitoring centres have been set up at various locations a­c­ross the country. These state-of-the-art centres are ma­n­n­ed round the clock by experts for effective monitoring and management of transmission assets. During financial year 2021-22, two additional ex­tra high voltage substations were integrated with the NTAMC for remote operation, taking the total remotely monitored substations to 264.

Transmission companies are also adopting technological tools such as drones with th­er­movisual scanning, high resolution vide­os and corona cameras for patrolling transmission lines, substations and reactors in real time. Today, utilities can rapidly and ef­fecti­vely identify vulnerabilities of the trans­mission grid with the help of drones. Aerial surveillance as well as remote airborne ins­pection and scanning devices are more effective, less ex­pensive, and quic­ker than traditional line patrolling methods based on monkey pat­rols and on-grou­nd procedures. These imageries can be used to develop intelligent digital twins integrated with AI, which can accurately recreate tra­ns­mission lines and towers to optimise as­set maintenance and records.

Emerging switchgear and substation technologies

The segment has witnessed an increase in the demand for intelligent switchgear, whi­ch has built-in protection and control intelligent electronic devices (IEDs) in their swit­chgear solutions. These new IEDs, co­mbined with the latest information and communication technologies, form a ba­se for enhanced protection, co­n­trol and monitoring. Intelligent swit­chgear can connect with the internet and provide comprehensive monitoring and protection functions, as well as measure all electrical parameters in real time. Intelligent switch­gear can significantly enhance the efficiency and reliability of the grid and help utilities avoid blackouts and equipment failures.

Substation technologies have also evolv­ed considerably to meet the emer­ging requirements of utilities and adapt to the changing grid. New designs and features have been driven by considerations such as space optimisation, lower costs, great­er asset life, enhanced safety and reduc­ed failure rates of equipment. Conventio­na­lly, utilities installed AIS, whi­ch uses air for insulation between va­­ri­ous live parts. A key trend is the growing installation of GIS and hybrid substations in place of co­n­ventional AIS su­b­stations as Indian utilities grapple with right-of-way and land ac­quisition issu­es. In addition, digital sub­stations are ga­i­ning traction across uti­lities as digita­lisation enables utilities to identify, prevent and rectify faults through the use of sensors and IEDs.

Further, the deployment of the IEC 61850 protocol has provided seamless communication and integration between IEDs. In addition, the application of process bus architecture in digital substations helps add flexibility by enabling digital de­vices to co­m­municate directly with each other. Process bus also allows for the replacement of bulky copper wiring with optic fi­bre, making digital substations more co­m­pact and safer than conventional su­b­sta­tions. Further, the pandemic has accelerated the need to automate and digita­lise power systems and equipment. T&D uti­lities have increasingly realised the im­portance of unmanned substations and re­mote operations and maintenance of assets with local/na­tional lockdowns in the past two years. Consequently, substation automation and remote monitoring solutions are gaining traction.


A technological shift in the transmission segment is the need of the hour to facilitate the ongoing energy transition. Utilities need to prepare a technology ro­ad­map to ensure the grid is operated in a smooth and reliable manner.