The technology landscape in the power sector is evolving at a fast pace driven by the changing energy mix and increasing electricity supply. As renewable capacity continues to grow, technology adoption becomes imperative to maintain grid stability and store energy. In addition, with a change in power demand-supply dynamics in recent years, electric vehicles (EVs) are expected to come up in a big way and the requirement for adequate charging infrastructure will increase. In the transmission and distribution (T&D) segments, the growth of smart grid technologies to monitor and control the grid, ensure energy accounting, and provide quality power are making headway.
The intermittency and variability of renewable energy necessitates energy storage solutions to meet peak demand and grid balancing requirements. To this end, the Central Electricity Regulatory Commission released a draft paper on energy storage in January 2017. Although pumped storage plants are the most common form of energy storage in the country, their uptake has never really picked up in the power sector with a share of just about 2 per cent in the total installed capacity of over 330 GW. This calls for the development of unconventional energy storage solutions (ESS) such as electrochemical battery cells, flywheels and compressed air energy storage. Even though currently no pilot project is under way to test/deploy these unconventional ESS, a few thermal and battery-based storage systems (BESS) are being developed. In 2016, 45-50 MW of BESS was announced/contracted. The market opportunity is expected to double to 100 MW in 2017. The Solar Energy Corporation of India is inviting bids for BESS projects aggregating 15 MW associated with large concentrating solar power plants such as the 100 MW Kadapa Solar Park in Andhra Pradesh and the 200 MW Pavagada Solar Park in Karnataka.
Given that coal would continue to provide baseload power, it is crucial to deploy technologies that require less coal consumption per kWh of energy and lead to lower carbon dioxide emissions. Ultra-supercritical and advanced ultra-supercritical (A-USC) are two such technologies. Ultra-supercritical power plants operate at a temperature of 600 ºCelsius and a pressure of 32 megapascal to achieve efficiencies over 40 per cent as compared to 37 per cent and 32 per cent offered by supercritical and subcritical plants respectively. India’s first ultra supercritical plant is under development by NTPC Limited in Madhya Pradesh the (1,320 MW Khargone power plant). Meanwhile, A-USC technology which requires a temperature of 710 ºCelsius and a pressure of 310 bar is still under development. Bharat Heavy Electricals Limited, NTPC and the Indira Gandhi Centre for Atomic Research are jointly undertaking a research and development (R&D) project for the development of an 800 MW A-USC plant at an investment of Rs 15.54 billion. A-USC technology has the potential to offer 20 per cent reduction in carbon dioxide emissions compared to a subcritical plant.
In addition, development activities are underway for the commercialisation of other clean coal technologies such as integrated gasification combined cycle, methods for bulk ash utilisation, and solutions for the optimisation of water consumption in thermal power plants (TPPs). Besides, power plant operators are increasingly opting for IT solutions to monitor and control various plant parameters centrally and plan preventive maintenance. The performance, analysis, diagnostics and optimisation (PADO) software is one such solution.
With the growing need for environmental protection, there is also increased policy emphasis on curtailing emissions from TPPs. Compliance with the norms by December 2017 would require significant equipment upgrades and a large number of emission control systems such as retrofitting of flue gas desulphurisation (FGD) systems, boiler modifications and retrofitting of electrostatic precipitators along with the commercialisation of selective catalytic reduction/selective non-catalytic reduction technologies.
Another key technology trend in the generation segment is flexibilisation. In view of substantial growth of renewable energy, flexible operations have become inevitable for TPPs. While flexibility can be achieved through a number of means including energy storage and demand-side management, the flexibilisation of existing conventional generation plants through a combination of capital retrofits and operational modifications is being seen as the optimum solution in the short term.
Technology adoption in the T&D segments has been primarily driven by the need to reduce right-of-way requirement, deploy higher voltages, lower network losses, monitor and control the grid in real time, and reduce the maintenance requirements. In this backdrop, compact transmission line support using fibre-reinforced polymer is gaining importance and new conductors are being deployed for carrying higher currents while allowing higher temperature ratings. High temperature low sag, gas-insulated lines and high performance superconductors are some of the advanced variants of conductors.
Transformer technology has also evolved considerably over the years from conventional oil-filled transformers to dry-type transformers and further to advanced smart transformers. The next generation of transformer technology including smart transformers comes with remote monitoring of a wide range of grid parameters as well as transformer parameters. Further, with the growth of high voltage direct current (HVDC) lines, the demand for converter transformers to enable efficient electricity transfer over long distances has increased in recent years.
Digital substation is another emerging trend. Digital substations are simpler, more compact and safer than conventional substations. Digital substations comprise smart primary devices and intelligent electronic devices to achieve information sharing and interoperability based on the International Electrotechnical Commission (IEC) 61850 protocol. Power Grid Corporation of India Limited (Powergrid) launched a pilot project to set up a digital substation in line with IEC 61850 protocol-based process bus architecture, which was successfully commissioned during 2014-15 at the 400 kV Bhiwadi substation.
In the case of switchgear, developments are under way to replace sulphur hexafluoride (SF6) with an alternative medium in gas-insulated switchgear due to environmental concerns associated with the former. Instead, a mixture of fluorinated nitrile with a balanced percentage of carbon dioxide can be used to replace SF6 in power systems/grid applications, as it is more environment-friendly. Another emerging trend in the switchgear segment is the use of intelligent switchgear, which allows real-time flow of information.
In addition, transmission utilities are deploying flexible alternating current transmission systems (FACTS) to enhance the control and power transfer ability of the grid through power electronics and other static controllers. Powergrid has been a pioneer in this regard and has carried out a power system study through real-time digital simulator (RTDS) for HVDC. RTDS has a specialised system designed to achieve real-time simulation of power systems with HVDC, FACTS and protective relays. Powergrid is also implementing a phasor measurement unit-based unified real-time dynamic state measurement project and a wide area measurement system, which involves the integration of all state and central grids.
In the distribution segment, utilities are focusing on technologies to reduce aggregate technical and commercial losses as well as ensure proper energy accounting. Cross-linked polyethylene conductors and aerial bunched cables are increasingly being used at the distribution level.
On the smart grid front, pilot projects are under way in different states with advanced metering infrastructure as the core technology. In 2012, the Ministry of Power (MoP) launched 14 smart grid pilot projects, of which 10 are currently under way (four were cancelled). Further, four smart grid projects are under way in Chandigarh, Maharashtra and Kanpur as a part of the National Smart Grid Mission. Various private utilities including Tata Power and CESC Limited are also in the process of implementing pilot projects. Besides, a smart city pilot is being implemented at IIT Kanpur and a smart grid knowledge centre is being set up by Powergrid in Manesar.
These projects involve the installation of smart meters to aid energy accounting and track consumption. Also, under the Ujwal Discom Assurance Yojana, the MoP has announced that all the participating states and utilities would adopt smart metering for consumers with energy consumption beyond a certain threshold limit.
As the adoption of EVs is expected to grow in the coming years, the demand for charging infrastructure will increase. Most utilities are currently setting up charging stations as a part of pilot projects to understand the way technology works and how it can be integrated with the discom’s grid with limited constraints. Tata Power Delhi Distribution Limited has set up five EV charging stations and plans to install about 1,000 such stations in Delhi over the next four years. NTPC has also commissioned two charging stations at Delhi and Noida and plans to add 20 more.
In addition, utilities are going digital in a big way through multiple bill payment options, the latest one being QR-code-based payments. This method has been recently adopted by Tata Power, Mumbai; Eastern Power Distribution Company of Andhra Pradesh; Southern Power Distribution Corporation of Andhra Pradesh and more discoms are expected to follow suit. Besides, in line with the objective of improving transparency in terms of information dissemination, a number of new mobile applications have been launched by the MoP (GARV, UJALA, VidyutPravah, URJA, etc.) in the past one year or so.
The way forward
Going forward, R&D is required to introduce technologies that can help improve capacity utilisation of renewable energy plants as well as reduce the cost of emission control technologies for TPPs. Some of the advanced IT technologies such as internet of things, big data analytics and cloud computing are also expected to witness greater adoption by T&D utilities. Overall, technology penetration and digitalisation is expected to increase significantly in the power sector in the coming years.