A new interstate transmission system (ISTS) scheme has been proposed to relieve overloading on the 765kV Vindhyachal-Varanasi line.
In its latest meeting, National Committee on Transmission (NCT) has proposed to develop this scheme under the tariff-based competitive bidding (TBCB) mechanism, and has nominated PFC Consulting Ltd (PFCCL) as the bid process coordinator.
This ISTS-TBCB scheme, with an estimated cost of Rs.2,368 crore and gestation period of 24 months, has been recommended to the Union power ministry for final approval.
Rationale
Interregional transfer from the Western Region to the Northern Region (WR-NR) is traditionally very high. In fact, WR-NR transfer is the biggest component of the overall interregional exchange between the five regional grids.
When there is high demand in Uttar Pradesh, the 765kV Vindhyachal-Varanasi double-circuit line that transfers power from WR (Madhya Pradesh) to NR (Uttar Pradesh) gets overloaded. This results in violation of the WR-NR ATC (available transfer capacity) in real time.
NCT has said that such violations of WR-NR ATC would result in a situation where NR states would not be able to draw further power from WR. This, in turn, could potentially result in a situation of over-drawl or load shedding in NR, if internal generation in NR is not available.
The scheme aims to create a new source for WR-NR transfer, thereby relieving overloading on the Vindhyachal-Varanasi line, as described ahead.
Project Elements
The key element of this scheme would be the new 765kV Prayagraj AIS substation (near Prayagraj in Uttar Pradesh) equipped with 2×330 MVAr 765kV bus reactors. This substation would be linked to the Vindhyachal Pool through a 765kV double-circuit line running around 220 km. This line will have a 330MVAr switchable line reactor at Prayagraj end on each of the two circuits of the aforementioned line. Besides, the upcoming Prayagraj substation will be LILOed to the existing 765kV Fatehpur-Varanasi single-circuit line and the 765kV Fatehpur-Sasaram single-circuit line.
Both circuits of the existing 765kV Sasan-Vindhyachal Pool (2xsingle-circuit) line will be bypassed at Vindhyachal Pool, and connected to the proposed 765kV Vindhyachal Pool-Prayagraj double-circuit line, thus forming the 765kV Sasan-Prayagraj double-circuit line.
Thus, the emerging 765kV Sasan-Prayagraj double-circuit line will be a new source for WR-NR transfer.
Interregional transfer
According to latest statistics released by Grid Controller of India Ltd (GRID-INDIA), the total electricity transfer from WR to NR during the first ten months (April to January) of FY25 was 80,380 MU, which was 37 per cent of the total interregional transfer of 217,102 MU between the five regional grids. Of the total WR-NR transfer in the given period, the PGCIL-owned 765kV Vindhyachal-Varanasi line alone accounted for nearly 20 per cent. Further, there was no reverse transfer (from NR to WR) from the Vindhyachal-Varanasi line.
Featured photograph is for representation only
