Design for 765kV high-voltage transmission line likely by year-end
4
LAHORE: Detailed design for laying the country’s first 765kV high-voltage transmission line is expected to be completed by the end of December, paving the way for a bidding process ahead of launching of civil works on the project before June next year.
Owned by the National Transmission and Dispatch Company (NTDC), the project will ensure evacuation of electricity from the Dasu hydropower project for adding it to the national grid and onward supply to consumers through 132kV and 11kV distribution systems of the power distribution companies (Discos).
“The consultants appointed by the company are very busy these days to accomplish the task of designing the project — the country’s first 765kV line — that will ensure evacuation of more than 4,000MW of power, including 2,100MW of the Dasu hydropower project’s stage-1. Hopefully, they will complete it by the end of December, enabling us to move ahead with bidding process and other preparatory works ahead of launching civil works,” a senior NTDC official told Dawn.
Project will ensure evacuation of over 4,000MW of power
The NTDC deals with the affairs of the country’s entire 500kV and 220kV transmission lines and grid stations (except Karachi). The NTDC’s system has a capacity to evacuate over 22,000MW through 500kV and 220kV lines and transmit the same to the Discos’ 132kV distribution system through the national grid. Since the 765kV high-voltage line is the first in the country, the company is also supervising the laying of Matiari- Lahore 660kV high-voltage direct current (HVDC) that is also the first of its kind being executed by a leading Chinese company under the China-Pakistan Economic Corridor (CPEC) to evacuate power from south and transmit it to central and northern parts of the country.
“Actually, the design work had earlier been undertaken by a Korean firm. But later it couldn’t complete, forcing us to reinitiate the process of awarding the remaining design work to someone else eligible under the law. A couple of months ago, we awarded this work to another company that is busy in completing this by December this year,” the official revealed.
He said the 250km-long 756kV line would originate from Dasu project site and end in the west of Islamabad via Mansehra. At the ending point, it will connect to the NTDC’s existing 500kV system.
“A grid station for 765kV/500kV double circuit line would also be constructed,” he added.
Talking about decreasing insulation level of the 500kV double circuit Port Qasim transmission line that is causing tripping and interrupted power supply to the consumers since long, the official said it was due to deposition of pollutants emerging from the sea salt impact and fuel emission from the adjacent K-Electric’s oil-fired power plant.
“The initial stretch (8-9km) of the line, which is situated near the sea and the plant, is very critical, as it needs an immediate rehabilitation to avoid any untoward event in near future,” he explained.
He said the 55km-long Port Qasim transmission line originated from its plant and ends at Hub, connecting Jamshoro-Guddu transmission lines. He said insulators played an important role in transmission lines as whenever there was pollution, the insulation level decreased. It happens when some stick material falls on the insulators as a result of a mixture of emissions and air moisture.
“To deal with this issue, the NTDC is working on a pilot project to replace the normal insulators with RTV (room temperature vulcanising) coated insulators on first 10-km stretch of towers in first phase. The coating actually prevents material from sticking to insulator surface. It is a preferred solution worldwide and reduces the frequency of washing,” the official said.
Published in Dawn, October 29th, 2018
Download the new Dawn mobile app here:
