The National Committee on Transmission (NCT) has recommended the regulated tariff mechanism (RTM) route for the proposed HVDC link to feed electricity to the Andaman & Nicobar Islands (ANI) from India’s eastern coast.
While the tariff-based competitive bidding (TBCB) would have otherwise been a logical choice, the RTM route was preferred as the proposed link is construed as being of strategic importance. Accordingly, a yet undecided government agency will be nominated as the implementing agency for the project.
A subsea link to meet growing electricity requirements of ANI has been in the discussion stage since June 2024. NCT had then directed Central Transmission Utility of India Ltd (CTUIL) to conduct a techno-commercial feasibility study of a subsea HVDC link. Read T&D India’s story dated August 6, 2024.
It may be mentioned that ANI today relies almost entirely on diesel generation sets and this HVDC link is seen as a means to supply cleaner, reliable and perhaps cheaper power to the islands.
CTUIL has now established that from its sixth year of operation, the HVDC link can provide electricity at a rate cheaper than diesel-based electricity. Based on long-term trends in crude oil prices, CTUIL has projected that cost of electricity from diesel generation to be Rs.62.50 per unit (kwh) by the year 2031, which is when the HVDC link would be commissioned.
Further, the study has suggested that the HVDC link could be feasible from the second or third year of operation itself, if financial assistance like low-interest loan, waiver of taxes and duties, viability gap funding (VGF), etc were to be provided.
Project cost
NCT has estimated that HVDC link would cost Rs.37,981 crore, including Rs.7,457 crore for supporting power T&D infrastructure development at the Andaman & Nicobar Islands. However, it is currently assumed that these T&D works, largely 66kV lines at Andaman and Nicobar, will be undertaken by Andaman & Nicobar Electricity Department.
Project outline
The HVDC system will include the following seven broad components:
- New ±320kV, 250 MW VSC-based symmetric monopole HVDC station at Paradeep in Odisha
- New ±320kV, 250 MW VSC-based symmetric monopole HVDC station at Andaman Island
- New ±320kV, 250 MW VSC-based symmetric monopole HVDC station at Nicobar Island
- Extension at upcoming 765/400kV Paradeep GIS substation in Odisha (See endnote)
- 400kV double-circuit (twin moose) line connecting #4 and #1 [12 km]
- 320kV, 500 MW HVDC undersea cable connecting #1 and #2 [1,150 km]
- 320kV, 250 MW HVDC undersea cable connecting #2 and #3 [550 km]
Selection of voltage
Several alternatives for the HVDC voltage, such as ±220kV, ±320kV and ±525kV, were examined. However, ±320kV was selected as ±220kV would have resulted in higher losses. Similarly, ±525kV would entail larger land requirements and would be too high a voltage considering the anticipated quantum of power transfer.
It may be observed that while the cable from Paradeep to Andaman will have 500 MW capacity (#6 in the list above), that from Andaman to Nicobar will be rated at 250 MW. Space provision will be made at the Paradeep HVDC station for upgrade of the terminal by 250 MW, which will take effect when the total demand towards A&N Islands exceeds 250 MW.
National Component
NCT has expressed the view that the proposed Paradeep-Andaman-Nicobar HVDC link may be taken up under the “Green Energy Corridor-III” (GEC-III) scheme so as to avail fiscal benefits— mainly Central government grant. GEC-III is currently in the planning stage and is likely to be formalized this year.
NCT also felt that the HVDC link under discussion may be considered as a “National Component” so as to reduce the tariff burden on A&N Islands. This would be on the lines of the ±800kV Biswanath Chariali-Alipurduar-Agra HVDC link, owned by Power Grid Corporation of India Ltd (PGCIL) and in operation since 2016.
Note: The 765/400kV Paradeep GIS substation in Odisha is coming up through an independent ISTS-TBCB project. Featured photograph (source: prysmian.com) is for representation only.
