East North Interconnection Company Limited (ENICL) is a first-of-its-kind mega independent power transmission project awarded in India through competitive bidding. The aim of the project is to evacuate power from the eastern and the north-eastern states. ENICL’s two 400 kV Double Circuit transmission lines (with a total line length of 450 km) traverse through difficult terrains in Bihar, West Bengal and Assam.
During commissioning, the project witnessed challenges like floods and earthquakes, and the crossing of large rivers such as the Ganga, Teesta and Kosi, and socio-political obstacles like riots in Kokrajhar and ‘Right of Way’ hurdles. ENICL will operate and maintain these transmission lines for a minimum of 25 years.
The project has been identified as one of highest priority by Power System Operation Corporation Limited (POSOCO), the national system operator, as it provides critical connectivity for the transfer of power from generation plants in the north-eastern region. Also, this project will end power shortfall during non-monsoon months, thereby bringing relief to the people of Assam.
On March 19, 2013, POSOCO communicated to the Central Electricity Authority a list (known as POSOCO List) of Inter State Transmission Systems that are critical and need to be prioritized to relieve congestion in the system. ENICL is part of this POSOCO List since it is expected to relieve loading of the Farakka-Malda transmission line and improve eastern region-northern region Total Transfer Capability (TTC) during the winters.
Also, this project will end power shortfall during non-monsoon months, thereby bringing relief to the people of Assam.
ENICL comprises of the following:
- 400 kV D/C Quad line from Purnea to Biharsharif of nearly 233 km
- 400 kV D/C line with Quad conductor from Bongaigaon to Siliguri of nearly 221 km
Bongaigaon substation in the north-eastern region is the main inter-linking substation with the eastern region and Biharsharif is the main power landing point in the eastern region for further dispersal of power towards the northern region.
For the transmission between Siliguri and Purnea, two 400 kV D/C lines already exist that are being currently being upgraded by PGCIL.
River Crossing : Transmission lines of Sterlite Grid traverse through some of the most difficult Indian terrains including challenging streams of rivers Ganga, Kosi and Narmada. The vivacious Ganga during peak monsoon posed as a major hurdle for the commissioning of ENICL. Through its experience in operating in any type of adversity, Sterlite Grid’s team overcame the challenges thrown by ferocious Uttarakhand floods in 2014. Barges of 1,000 metric tonne capacity were anchored in the middle of the river to erect the tower amid Ganga’s high swings. Barge mounted telescopic cranes with 90-meter hydraulic boom enabled the erection of a 100-meter high tower from the foundation level with project inputs transported through mechanized country boats.