India’s distribution sector is at the cusp of a transformational change of driven primarily by the incorporation of cutting-edge technological systems. These technologies can be broadly categorised into innovative hardware, and virtual and software upgrades. Innovative hardware includes smart meters, battery energy storage system (BESS), digital substation, and drone-based surveillance. In contrast, virtual technologies in the distribution segment comprise data analytics such as artificial intelligence (AI)/machine learning (ML) for demand optimisation, blockchain for sustainable energy trading, platform-based smart energy management, etc. Deploying these technologies and systems will aid in reducing aggregate technical and commercial losses, improving efficiency and resilience of discoms and consumers and increasing energy trading, in turn, benefiting the entire ecosystem.
Conductors and cables
New conductors are being deployed for carrying higher currents, while allowing higher temperature ratings. The different types of conductors being used are all-aluminium conductors, all-alloy aluminium conductors, aluminium conductors steel reinforced and aluminium alloy conductors steel reinforced. In addition, high temperature low sag conductors are increasingly being deployed. These are made up of materials such as INVAR steel, aluminium-zirconium alloys, and metal and polymer matrix composites that offer higher temperature resistance and increased ampacity. The aluminium conductor composite core, gap type ZT aluminium conductor steel reinforced and superthermal aluminium clad INVAR reinforced conductors are some of the preferred options for reconductoring lines. Meanwhile, cross-linked polyethylene, high density polyethylene, aerial bunched cables (ABC) and spacer cable systems are the most commonly used covered cables. The use of ABC is widely gaining traction for overhead power distribution networks as it has benefits such as low power loss, negligible current leakage, protection against power theft, low maintenance requirements, lower fault rates and good protection against wind and falling trees.
BESS solutions are the perfect complement for variable renewable energy (VRE) systems such as solar and wind power, given that these systems store excess energy generated by VRE in peak hours so that it can be withdrawn later in off-peak hours. These solutions also have storage capacities of around 5 kWh-100 MWh, making them viable for deployment in a variety of areas within the distribution architecture. For instance, BESS can be deployed in off-grid installations, close to substations, or with third-party aggregators, depending on the size, requirement and budget.
In 2020, the first grid-connected BESS in India was installed by Tata Power in New Delhi and provides a storage capacity of 10 MW. Additionally, the Solar Energy Corporation of India launched a tender for commissioning a 1,000 MWh BESS in Fatehgarh-III substation, Rajasthan.
Distribution transformers (DTs) are stepdown transformers that provide voltage transformation in the electric power distribution system, including the final stepping down of voltage to the level used by customers. Currently, most utilities in the country deploy oil-cooled (mineral oil)-transformers. However, the use of dry-type transformers and K-class (ester) fluid-filled transformers is on the rise, since they are associated with lower failure rates. Also, these transformers offer better protection against fire hazards, have reduced/ no risk of leakage of insulation fluids and entail minimal maintenance.
A digital substation means replacing conventional measuring equipment such as current transformers and voltage transformers with non-conventional instrument transformers using digitalised sensor technology. This, in turn, reduces exposure to high voltage signals. The most important components of digital substations are protection device systems and the substation automation system, which enable optimal deployment of resources in real time via ethernet connections.
In July 2020, Power Grid Corporation of India Limited has commissioned a 400 kV digital substation in Punjab, making it India’s first fully digital commercial substation. The complete digital upgrade of the Malerkotla substation required updating the protection and control systems, including the busbar protection system, for the entire substation. The Malerkotla substation was constructed using insights generated from the pilot digital substation in Bhiwadi.
Distribution utilities are increasingly opting for gas-insulated switchgear (GIS), hybrid switchgear and intelligent switchgear. There has been growing traction in GIS substation deployment, primarily owing to their compact size. The other key features of GIS include high modularisation, high safety index and lower maintenance requirements, and their ability to resist vibration and avoid electromagnetic pollution. Further, as a GIS is housed in a metal enclosure, it offers protection against environmental conditions such as salt deposits in coastal areas, sandstorms and humidity, thereby lowering operations and maintenance costs.
The use of hybrid switchgear is also fast gaining popularity, as it takes advantage of both air-insulated switchgear (AIS) and GIS technologies, striking a balance between the land cost and the facility construction cost. Hybrid switchgear is compact, with the functionality of AIS integrated into a gas-insulated enclosure. With hybrid switchgear, the bay length is reduced as the circuit breaker and the disconnector earth switch functions are integrated into one module. This results in an overall reduction in the area required for the substation. Further, the use of sulphur hexafluoride gas for encapsulation makes the maintenance of hybrid switchgear simple and cost effective. GIS substations take up to 35 per cent less space and have lower maintenance and outage costs than AIS substations. Although GIS substations have greater starting costs than AIS substations, their eventual capital costs are equivalent.
AI and cloud technology
Improved efficiency of data management resulting from cloud computing allows discoms to create evolving digital profiles (digital twins) of physical objects or processes, helping to optimise business performance by detecting physical issues in real time and predicting outcomes more accurately.
On the demand side, integrating cloud-based technologies will also help utilities in predicting short-term demand. Short-term forecasts are used for operations and are obtained based on historical loads and weather forecasts, using different prediction methods such as neural networks. Weather forecasts are also used in predicting the generation and transmission capacity of the grid. AI/ML-based forecasts of grid demand will increasingly acquire more importance, given the rising penetration of VRE systems such as solar and wind power in the electricity mix. Studying the feasibility of integrating renewable energy sources into the distribution network without destabilising grid frequency requires extensive high fidelity simulations under various load, generation and weather conditions.
Increasing cloud computation capacity, in combination with AI/ML, will help discoms in predicting consumer demand, besides aiding in the execution of the time-of-day pricing system. Discoms can also gamify the system and incentivise consumers to use electricity more efficiently, by providing them specific data pertaining to their consumption.
Moreover, blockchain technology, with its emphasis on verifiable transparency, will facilitate the adoption of green energy trading, renewable energy certificates, carbon certificates, etc. The introduction of blockchain technology will help the buyer (the bulk buyer or the discom) directly verify the energy source while purchasing. Additionally, such verification will help convert energy resources into digital assets so that they can be traded on blockchain. In 2021, Tata Power successfully tested blockchain-based solar energy trading among prosumers, demonstrating a way for consumers with rooftop solar to tap into more revenue.
Blockchain will automate the issuance and trading of renewable energy credits/certificates based on the actual energy consumption, while constantly maintaining the energy flow. It will ensure that payments will be executed via smart contracts in a peer-to-peer (P2P) microgrid. Blockchain will coordinate wholesale power trading and eliminate the need for brokers, indexing agencies, specialised energy trading, or risk management software. Electric vehicle (EV) owners can confirm the renewable energy share in charging EVs using blockchain technology and avoid double counting. In a P2P network, homeowners can register their private charging points and earn from the otherwise idle chargers.
The scale and pace of these emerging technologies’ adoption will be driven by the extent of investments made by state discoms, coupled with the amount of support offered by government policies and schemes.