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Tuesday, 7 August 2012

Calcutta’s ‘splendid’ isolation


http://www.telegraphindia.com/1120802/jsp/frontpage/story_15803877.jsp#.UBqTmKBmm9s

Calcutta's 'splendid' isolation

MEGHDEEP BHATTACHARYYA
Calcutta, Aug. 1: If minimal exposure to global markets saved India from the Southeast Asian economic crisis in 1997, a somewhat similar situation helped Calcutta stand out like a beacon on Blackout Tuesday.
Not being fully synchronised with the eastern grid — staying connected to the grid at one point instead of four —appears to have played a crucial role in the success of CESC in sparing its 26 lakh consumers the trauma without break that the rest of Bengal and many other states underwent yesterday.
At the time of the collapse, at 1.01pm yesterday, CESC was connected with the eastern grid, which collapsed along with the northern and northeastern grids.
But the connection was at just one point — through its receiving station at Garden Reach (known as Southern) with the Howrah substation of the state-run distribution utility and then with the eastern grid. The distributor is the West Bengal State Electricity Distribution Company Limited (WBSEDCL).
At the three other substations of the distributor at Kasba, Liluah and Titagarh, CESC was connected to the network of the WBSEDCL but not with the eastern grid.
"As CESC is also not fully synchronised, which helps in maintaining a free flow of power, with the eastern grid, it is easy for the utility to snap ties during such crises to prevent a cascading impact," said a senior power department official.
According to him, the one-point connection with the grid and the absence of full synchronisation allowed CESC to isolate itself from the eastern grid in a split second when the collapse took place yesterday.
The isolation allowed CESC to serve the 567sqkm spanning Calcutta and Howrah. "Whichever utility faced a blackout yesterday was only because it was fully synchronised and thoroughly connected with the regional grid," said the official.
In contrast to CESC, which was connected at one point, the distributor was linked at 103 points in Bengal.
"It's really easy to isolate yourself when you're connected with the grid through just one point. The isolation technology available with CESC is basic and commonly used in India and elsewhere in the world," the power department official said.
The situation was more or less similar to that in India during the Southeast Asian economic crisis of 1997. Fifteen years ago, India's scant exposure to the global markets in the early days of liberalisation spared it the domino-like ramifications of the crisis.
However, CESC did succeed in spotting the problem on time — one of the most crucial and difficult tasks in transmission management. For some reason, others did not. (Raj Rao, an American electric company executive, told The New York Times that "my hunch is, somebody fell asleep and they did not cut off" the excess load.)
The power department official clarified that he was not grudging the achievement of CESC, which displayed remarkable alertness and came up with a rapid response, but putting matters in perspective.
When the collapse took place, the isolators at the circuits of CESC's Garden Reach-based Southern receiving station kicked in, detaching CESC from the eastern grid in less than a second.
Till 1.01pm, CESC was successfully meeting demand of around 1,460MW with its own generation of around 1,200MW and imports from the WBSEDCL. After the collapse, CESC was forced to resort to loadshedding because imports were not possible and it had to supply over 150MW to the state-run utility to help keep some essential services alive. That was the reason for phased power cuts in parts of the city, though there was never a blackout in Calcutta yesterday.
"We are not trying to take credit, but everyone's seen what happened yesterday. We were the only utility that functioned and we worked on a war footing to minimise inconvenience to our consumers," said CESC managing director Sumantra Banerjee this afternoon.
"We owe our performance on days like yesterday to large volumes of investment in technology and infrastructure over a decade and a half. We have an excellent team handling system operation. This cannot be achieved in a short time," he added.
Other sources in the power department pointed out that not being fully synchronised is "a bad idea", except on rare days like yesterday.
Some power distribution veterans said cascading failures in grids are rare phenomena whereas other glitches —which require support from the grid — take place at frequent intervals.
"If you are not fully synchronised, not connected at all four points, you cannot be rescued by the grid on days when you need support. There are at least six to seven such days every year," said an expert. "Days like yesterday are very rare. Investments in infrastructure should be made to connect fully with the grid to better protect yourselves from crises in areas you serve," he added.