The transmission network is a crucial link in renewable energy integration. With the growing share of renewables in the energy mix, states are facing multiple challenges, in terms of renewable penetration and transmission, owing to their limited evacuation capacity. This has also led to the curtailment of renewable energy plants, which have a must-run status. In order to overcome the intermittency and variability issues associated with renewable generation, the grid network has to be strengthened significantly. In this regard, a comprehensive plan for transmission network expansion and renewable energy management was identified as part of the Green Energy Corridors (GEC) programme. This programme covers strengthening of intra-state and interstate transmission system (ISTS) infrastructure, and the establishment of renewable energy management centres (REMCs) at the national, state and regional levels. Power Line takes a look at the status of these renewable energy integration initiatives, key challenges faced in their implementation and the way forward…
GEC I and II
The GEC programme is being carried out in three phases. GEC I involves the development of the transmission infrastructure to facilitate the flow of 33 GW of renewable energy in eight renewable energy resource-rich states in India. ISTS expansion and strengthening is being undertaken by Power Grid Corporation of India Limited (Powergrid), while intra-state transmission systems are being developed by the respective state transmission utilities. Meanwhile, GEC II involves the development of a transmission system for the evacuation of power from ultra mega solar power projects (UMSPPs). About 34 UMSPPs have been planned across 21 states in the country.
As part of Powergrid’s mandate for GEC-I, 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 11,000 MW-12,000 MW of capacity have been received by Powergrid in this phase. Part of the transmission capacity in this phase has been commissioned progressively since December 2017.
So far, intra-state transmission capacity of 24 GW has been awarded under GEC I and is to be commissioned by March 2020. ISTS capacity of 6 GW each is being set up by Powergrid under GEC I and GEC II.
It is estimated that the country would need an additional 66.5 GW of ISTS network for renewable energy zones. The transmission infrastructure is expected to be set up in Rajasthan, Gujarat, Madhya Pradesh, Maharashtra, Karnataka, Tamil Nadu, Andhra Pradesh and Telangana. Of the total evacuation capacity to be added, 50 GW (20 GW for Phase I by 2020-21 and 30 GW for Phase II by 2021-22) and 16.5 GW (9 GW for Phase I by 2020-21 and 7.5 GW for Phase II by 2021-22) has been earmarked for solar and wind projects respectively. Powergrid, Power Finance Corporation and the Rural Electrification Corporation (REC) Limited have invited tenders for projects worth 12 GW. The Ministry of New and Renewable Energy (MNRE) is planning to set up the remaining 17 GW of capacity and is confident that by March 2021, 29 GW of ISTS network for solar and wind projects will be set up.
Under GEC II, 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 in Anantapur, Andhra Pradesh, 650 MW of generation capacity has been commissioned by Powergrid. For the 2,000 MW Pavagada Solar Park in Karnataka, too, 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 Radha Nesda (Banaskantha).
Further, about 22 GW of ISTS under GEC II is on the cards, which will be partially funded by KfW. The proposals for these projects have been received by nine states: Tamil Nadu, Andhra Pradesh, Kerala, Gujarat, Odisha, Uttar Pradesh, Maharashtra, Himachal Pradesh and Karnataka. Two more states will join this list when they are cleared by the Central Electricity Authority of India. These projects will be developed at an estimated cost of Rs 150 billion. The technical scrutiny of these projects has already been undertaken. On the whole, the MNRE has planned about 199.5 GW of transmission infrastructure.
GEC III
With inputs from the MNRE and the Solar Energy Corporation of India, Powergrid has identified a transmission scheme for 66.5 GW of renewable energy zones with a high potential in renewable resource-rich states. For wind power, 16.5 GW of potential has been identified at various locations in five states. In Gujarat, 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 at 15 sites across 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, of which 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 for evacuating 12.5 GW envisaging a cost of about Rs 95 billion are already under way. The balance 15.5 GW under the scheme, entailing an estimated cost of 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.
REMCs
Forecasting and scheduling are among the most critical solutions to mitigate the variability of renewable energy. REMCs will be 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 commissioning progressively from March 2019.
With the purpose of collecting and monitoring real-time data for forecasting and scheduling of renewable energy projects, the government has planned to set up 11 REMCs between April 2019 and March 2020. These centres will coordinate with the grid operation teams at the load despatch centres for safe, secure and optimal grid operations. Developers will benefit a lot from the generation of accurate data, as they will be able to manage their assets better. These centres will be built at an estimated cost of about Rs 4.09 billion.
Conclusion
To summarise, significant transmission capacity is planned and is also under implementation at both interstate and intra-state levels. However, given that the gestation period of renewable energy projects is relatively small vis-à-vis conventional power projects, transcos need to speed up project execution to prevent renewable energy developers from facing the risk of stranded power.