India’s power sector is experiencing a paradigm shift, driven primarily by a strong demand growth, and the government’s target to achieve 40 per cent non-fossil fuel-based generation capacity as per its intended nationally determined contributions. The country’s abundant renewable energy potential is also helping its inclusion in the mainstream power sector. With 175 GW of installed capacity by 2022, renewables’ penetration is expected to reach 32.7 per cent, significantly up from 20 per cent in 2018. The peak demand is expected to grow from 159 GW in 2017 to 225 GW in 2022, and further to 682 GW in 2036, as per the Central Electricity Authority’s National Electricity Plan.
However, there are significant issues in integrating renewable-based power into the existing grid. From a grid planning point of view, these challenges pertain to the short gestation period of renewable energy plants, the fault level at the point of interconnection, the diversity of resources (hybridisation/dispersion), the quantum of renewable energy generation, and reactive power management. Moreover, there are operational issues that emerge as a result of the variability and intermittency associated with renewable energy. This leads to challenges in maintaining load generation balance, and reducing system inertia, among other things.
The central transmission utility, Power Grid Corporation of India Limited (Powergrid), has been working towards the expansion and strengthening of the grid network, to ensure transmission availability and robustness of the grid for better integration of renewable energy into the network. Powerline takes a look at Powergrid’s plans and initiatives in this regard.
The Green Energy Corridors (GEC) Phase I programme involves the development of transmission infrastructure to facilitate the flow of 33 GW of renewable energy in eight renewable energy resource-rich states. The interstate transmission system (ISTS) expansion and strengthening is being undertaken by Powergrid, while the intra-state transmission systems are being developed by the respective state transmission utilities. As part of Powergrid’s mandate for this phase, 3,200 ckt. km of new transmission lines have been envisaged, along with six substations with a total capacity of 17,000 MVA. Long-term access applications for an estimated 11,000-12,000 MW for GECs have been received by Powergrid in this phase. Part of the transmission capacity in this phase has been commissioned progressively since December 2017.
Forecasting and scheduling are among the most critical solutions to mitigate the variability of renewable energy. Renewable energy management centres (REMCs) are equipped with systems that can forecast renewable energy generation on different time scales at different levels. They also undertake real-time tracking of generation from renewable energy sources, and have web-based scheduling solutions. REMCs work in close coordination with the respective load despatch centres for renewable energy generation and control for smooth grid operations.
Powergrid is developing 11 REMCs across the country. Of these, one is a national-level REMC, three are regional centres, and seven are located in the renewable energy-rich states of Andhra Pradesh, Gujarat, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan and Tamil Nadu. These centres are funded by the Ministry of Power and will begin progressive commissioning from March 2019.
Phase II of the GEC programme caters primarily to the transmission system for the evacuation of power from ultra mega solar power parks (UMSPPs). Across 21 states, 34 UMSPPs have been planned. The implementation of the ISTS by Powergrid for seven UMSPPs, with a cumulative capacity of 6,450 MW in five states, is currently in progress. The ISTS has achieved completion of three solar parks. At the NP Kunta UMSPP, with a total capacity of 1,500 MW located at Anantapur, Andhra Pradesh, 650 MW of generation capacity has been commissioned while the entire transmission system has been commissioned by Powergrid. Similarly, for the Pavagada Solar Park, with a total capacity of 2,000 MW located in Karnataka, the transmission system has been commissioned by Powergrid. For the Rewa Solar Park in Madhya Pradesh, while only 430 MW of generation capacity has been commissioned out of the total planned capacity of 750 MW, the transmission system has been commissioned by Powergrid. In addition, transmission systems for four more UMSPPs are currently under implementation– the Pavagada Phase II, Bhadla Phases III and IV, Essel Solar Park, and Radhanesda (Banaskantha).
With inputs from the Ministry of New and Renewable Energy and the Solar Energy Corporation of India, Powergrid has identified the transmission scheme for 66.5 GW of renewable energy zones with high potential in resource-rich states. For wind power, 16.5 GW of potential has been identified at various locations in five states. These are Gujarat, where two phases of 3,000 MW each are earmarked in Bhuj, another 2,000 MW in the Lakadla area and 2,000 MW in Dwarka. In Maharashtra, Osmanabad has been identified as a site with 2,000 MW of potential wind capacity. Similarly, Koppal in Karnataka and Kurnool in Andhra Pradesh have been identified with 2,500 MW and 3,000 MW of potential capacity respectively. In Tamil Nadu, Karur and Tirunelveli, with 2,500 MW of wind power capacity each, have been identified as potential sites. Meanwhile, 50 GW of potential solar power has been earmarked by Powergrid across 15 sites in six states. The highest potential of 20 GW is in Rajasthan, including 8 GW at Jaisalmer and 5 GW at Barmer. Gujarat follows with a potential of 10 GW, wherein the Kutch area has 5 GW, and Banaskantha and Jamnagar have 2.5 GW each. Madhya Pradesh, Maharashtra, Karnataka and Andhra Pradesh have been estimated to have a potential of 5 GW each.
The cost of developing GEC III has been estimated at Rs 433 billion. About 28 GW of the renewable energy zone scheme has been prioritised, with a total expense of Rs 168 billion. Transmission plans, envisaging a cost of about Rs 95 billion, for evacuating 12.5 GW are already under way. The balance 15.5 GW under the scheme, costing Rs 73 billion, will be taken up for construction with the receipt of long-term access applications. Meanwhile, Powergrid has envisaged REMCs in other renewable energy resource-rich states.
Powergrid has also undertaken initiatives to provide transmission systems for new projects, which include renewable energy generation in special economic zones (SEZs). For instance, Powergrid has proposed the development of a transmission network with an installed capacity of 8.9 MW for an SEZ located in Rajasthan. The plan requires the inclusion of the SEZ in the GEC transmission network. Two SEZ substations at Bhadla II (2.5 GW) and Fatehgarh II (2.3 GW) have been identified.
Meanwhile, the SEZ will be connected to GEC substations located at Bikaner (1.85 GW), Ajmer and Chittorgarh. Built at a cost of Rs 63.8 billion, this transmission network will enable the mainstreaming of renewable energy from the SEZ. Another transmission network has been planned for the evacuation of power from a prioritised wind energy zone with a capacity of 3.5 GW in Gujarat. This transmission network is being built at a total cost of Rs 37.8 billion.
The way forward
Powergrid’s initiatives are focused on establishing a robust transmission path across the country, through advance transmission planning. In view of the 175 GW targeted renewable energy capacity expected to come online by 2022, it is important to achieve flexibility and controllability of the grid for smooth grid integration and evacuation of this renewable energy. To this end, Powergrid believes that strict compliance with regulations and adherence to standards are of utmost importance. It is also important to include important emerging elements of energy storage systems, and dynamic reactive support, to mitigate the variability of renewable energy. Powergrid’s role, therefore, in developing strong transmission networks is highly significant as India strives to achieve its long-term target of renewable energy-based power generation.
Based on a presentation by Kashish Bhambhani, Deputy General Manager, Smart Grid, Power Grid Corporation of India Limited