BackDust-caked transmission lines cut off northern grid
Dust-caked transmission lines cut off northern grid
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Large parts of north India went without power early Friday for want of helicopters.
The partial blackout was caused by the simultaneous “tripping" of 50 transmission lines in Delhi, Haryana, and western Uttar Pradesh. The tripping—a technical term that means failure to transmit— was caused by heavy fog and pollution. Fog makes power transmission lines moist; atmospheric pollution then sticks to the lines; over time, the lines become caked in dust, resulting in short circuits that trigger tripping. If unchecked, the eventual result could be a collapse of a grid, the network that supplies power to an entire region.
The most efficient way to clean these transmission lines is through helicopters. Power Grid Corp. of India Ltd, or PGCIL, which owns and operates transmission lines in the country, had identified the very lines that tripped Friday for cleaning based on their history of breakdowns.
However, unavailability of helicopters forced PGCIL to postpone this cleaning as reported by Mint on 11 December. Nor did the company go forward with the alternative mechanized cleaning approach where a machine cleans the transmission lines automatically.
Experts say the problem could recur unless the lines are cleaned. With winter over and temperatures on the rise in northern India, demand for power too will increase.
“It was not a grid failure. If the grid had failed it would have taken a few days to restore the links. We have been facing adverse weather conditions and are trying everything to contain the damage. What do you do when the pollution levels have gone up along with a rise in humidity? There have been no rains which would have helped in cleaning the wires. The risks for further tripping still remain. One cannot rule them out," said a senior PGCIL executive who did not wish to be identified.
India’s apex power sector planning agency, the Central Electricity Authority, does not buy this. “There has been a laxity on the part of PGCIL as they have been unable to do the cleaning of the lines efficiently," said a senior official at the agency who did not wish to be identified.
PGCIL is the agency responsible for managing transmission across the country and owns and operates 61,875km of transmission lines.
At present, there are five regional grids in India—northern, southern, eastern, and north-eastern and western—and all of them, except the southern one, are interconnected.
Grid collapse is the worst-case scenario for any transmission utility; if this happens, states that draw power from that particular grid go without power.
The new cleaning system, using helicopters, which is used in many other countries, was to have been tried out for the first time in the country this winter. It was viewed as a preventive measure against major grid disturbance and would have cost PGCIL about Rs8.19 crore. The operation was expected to start in November and the company had planned to clean around 5km of lines an hour.
“Cleaning through helicopters is very much on the agenda. Every year the problem gets aggravated. The permanent solution to this problem is cleaning by helicopters, mechanized cleaning and changing the insulators in a phased manner," the PGCIL official added.
The last time there was a grid collapse in India was in 2001, when the northern grid tripped.
Several incidents of fog related tripping were reported in December, 2005.
The northern region, which comprises Punjab, Haryana, Rajasthan, Delhi, Uttar Pradesh, Uttarakhand, Himachal Pradesh, Jammu and Kashmir and Chandigarh, alone accounts for 33,256.28 MW or 24% of India’s total power generation capacity of 1.40 lakh MW. The region has a present power demand of 8633 MW.
A senior Delhi-based power sector analyst who did not wished to be identified said the utility should have planned better because “line cleaning" was a routine issue and not a “unique" one.
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