The Maharashtra Transmission Committee (MTC) recently approved a proposal of upgrading the existing 220kV Mahalakshmi substation to 400kV level with a view to providing a robust 400kV system to south Mumbai.
The project, estimated to cost Rs.1,295 crore, will have an implementation timeframe of FY31 (by March 2031). The scheme, following approval by MTC, has been forwarded to Maharashtra’s Grid Coordination Committee (GCC) for final consent.
Tata Power, the owner of the existing 220kV Mahalakshmi substation, will implement the project under the regulated tariff mechanism (cost-plus) mode. MTC ruled out the tariff-based competitive bidding (TBCB) option as the project involves upgrade of a pre-owned transmission asset. Practical delineation of assets, as would be needed if the TBCB mode were deployed, would be infeasible in this case, MTC said.
Rationale
South Mumbai currently operates at 220kV level resulting in operational constraints and overloading of the network. Growing urban demand, electricity load growth due to massive redevelopment and expansion of metro rail network are just some of the factors that have warranted the need for a strong 400kV corridor towards south Mumbai.
This project aims to emulate the benefit that the under-development 400kV Vikhroli scheme would provide to eastern Mumbai, and the newly-commissioned Aarey-Kudus HVDC link, to north Mumbai.
Peak demand in Mumbai
Mumbai’s peak demand is projected to grow from the current 4,300 MW to nearly 6,000 MW over the next ten years, even considering a conservative 4 per cent annual growth rate. Massive redevelopment projects such as Bhendi Bazar, Dharavi, Worli BDD Chawl, Kamathipura and Mumbai Port Authority, are expected to significantly increase power demand in south Mumbai.
Project details
The project will involve laying of 400kV EHV cable from Dharavi substation to Mahalakshmi substation. At Mahalakshmi, 17 GIS bays – seven of 400kV and ten of 220kV – will be put up, apart from 2×500 MVA, 400/220/33kV interconnecting transformers and two 125 MVA, three-phase, 420kV reactors. At Dharavi, similar reactors will be installed in addition to two GIS bays of 220kV.
Tata Power – Transmission Division, known as TPC-T, has confirmed availability of space at the Mahalakshmi substation (better known as Mahalakshmi receiving substation or Mahalakshmi RSS) for the upgrade works. TPC-T also owns the Dharavi RSS.
The HVDC link
While the project under discussion is currently planned by using a single 400kV cable from Dharavi RSS to Mahalakshmi RSS, the full operational benefits of the project can be derived only when the Dolvi-Sewri HVDC link is commissioned. The commissioning date of the Mahalakshmi RSS upgrade project, envisaged as end-FY31, is aligned to the aforementioned HVDC link.
The HVDC link, running from Dolvi (Ratnagiri, Maharashtra) to Sewri (Mumbai) is an important element of an overarching project that aims to boost Maharashtra’s intrastate supply from the interstate transmission system (ISTS) network.
According to information available with tndndia.com, this interconnection project was deliberated at the 38th Consultation Meeting for Evolving Transmission Schemes in Western Region (CMETS-WR) in August 2025.
The pivotal element of the project is a new 6×1500 MVA, 765/400kV substation at Dolvi to be commissioned by FY30. This substation will act as the interconnection point between Maharashtra’s intrastate grid and the ISTS network.
The Dolvi-Sewri HVDC link, based on VSC technology, will operate at ±320kV and will have transfer capacity of 1,500 MW. The overall project also envisages, among several other elements, a similar HVDC link between Dolvi and Trombay in eastern Mumbai.
Editor’s Note: The Sewri RSS and the Mahalakshmi RSS will be connected by a 400kV EHV cable link, implying that the Sewri RSS, currently 220kV, will also be upgraded to 400kV. This project element, according to information available with tndindia.com, would fall under a separate project.
Featured photograph (source: Godrej Enterprises Group) showing a GIS substation in Mumbai is for representation only