Central Transmission Utility of India Ltd (CTUIL) has very recently approved several interstate transmission system (ISTS) projects to be implemented under the regulated tariff mechanism (RTM) framework.
CTUIL has approved a total of five such ISTS-RTM projects with an aggregate project cost of Rs.211.49 crore, and covering three regional grids – northern, southern and northeastern. In almost all cases, Power Grid Corporation of India Ltd (PGCIL) is the implementing agency.
It may be mentioned that CTUIL is empowered to approve ISTS projects with an estimated cost of up to Rs.100 crore autonomously. This approval entails the mode of implementation – whether tariff-based competitive bidding (TBCB) or RTM. However, since projects costing Rs.100 crore or less are usually augmentation schemes, as opposed to new-build ones, the mode of implementation is invariably RTM.
Northern region
In the northern region grid, PGCIL has been assigned a project costing Rs.63.44 crore to augment its 400/220kV Sonepat substation in Haryana by putting up a new 400/220kV, 1×500 MVA interconnecting transformer (ICT), which would be fourth at the substation. This project, which also involves installing additional ICT bays, is scheduled for completion in 30 months.
CTUIL has also approved a project to implement dynamic line rating (DLR) system with respect to five existing transmission lines, of 400kV and 765kV, in the NR grid. With a total outlay of Rs.66.73 crore, the project involves commissioning of 159 DLR sensors on these five lines having a running length of 756 km. While four of these five DLR projects have been assigned to PGCIL or its TBCB subsidiaries, one will have RAPP Transmission Company Ltd, a subsidiary of IndiGrid, as its implementing agency. Each of the five projects has an implementation period of eight months.
Southern region
In the SR grid, PGCIL has been assigned an RTM project to implement two 400kV line bays at the 400/230kV Tirunelveli substation for termination of the 400kV double-circuit Tirunelveli-Edamon line (presently charged at 220kV) to 400kV level. With an envisaged outlay of Rs.32.36 crore, the project is expected to commission by June 7, 2029, which is in a matching timeframe of that of the Edamon substation upgrade from 220kV to 400kV level.
PGCIL has also been allocated a Rs.13.10-crore project to put up an additional 400kV line bay at its own 765/400/220kV Kurnool-IV pooling station in Andhra Pradesh. This line bay will help integrate generation from the RE project of Reliance NU Suntech Pvt Ltd, a subsidiary of Ani Ambani-controlled Reliance Power Ltd. (See related story)
Northeastern region
In the NER grid, CTUIL has allocated eight projects with a total cost of Rs.35.86 crore. These include reconductoring with HTLS conductor of four transmission lines with a total length of around 63 ckm, and extension works at four substations.
Cost escalation
The project costs indicated are those estimated by CTUIL. As finalized in a meeting of National Committee on Transmission (NCT) in January 2025, if the project cost assessed by the transmission service provider (TPS) concerned, based on the detailed project report (DPR), is found to be higher by 10 per cent or more than the CTUIL cost, the TSP needs to intimate the same to CTUIL within 30 days of the scheme allocation.
Featured photograph (source: MPPTCL) is for representation only