Opinion The line that snapped
Penalise overdrawing and stop rewarding underdrawals to prevent grid collapse
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Penalise overdrawing and stop rewarding underdrawals to prevent grid collapse
Two successive grid collapses served as a rude wake-up call on what is arguably Indias biggest infrastructure bottleneck the electricity generation and transmission systems. But weeks after the collapses,under-frequency load shedding relays in nearly all major states continue to remain disconnected. Simply because states find these relays,programmed to reduce load in the wake of a sudden drop in frequency that could set off a potential grid collapse,an inconvenience. They just do not want their load to be cut off at any time,choosing instead to switch off these relays the first line of defence that could have salvaged the grid in the wee hours of July 30,had they been in working order.
To most,it is difficult to imagine that the fate of a grid could boil down to the load-bearing capacity of just a single line. As the findings of a preliminary report by the grid operator suggest,the biggest lesson from the events that unfolded over 48 hours is that,even if the grid frequency stays healthy,crucial parts of a large,interconnected grid can get critically overloaded due to complementary underdrawal and overdrawal among constituents. This is what happened in the collapse. The system frequency was normal on the first day,even though western states were underdrawing from the grid while northern states were complementing this by overdrawing. This resulted in excessive line loading on the Agra-Gwalior-Bina transmission link,which connects the northern region with the west. The line snapped,setting off cascade tripping.
In India,under the current grid frequency-linked penalty scheme,called the UI (unscheduled interchange) regime,constituents underdrawing from the grid stand to get paid in time. In the UK,in contrast,underdrawal is also treated as grid indiscipline,and those drawing power below what they have declared beforehand to the grid manager are not rewarded in any form. After the grid collapse,there is a need to revamp the UI regime to disincentivise all deviations from schedule. So while UP,Punjab and Haryana deserve to come under fire for overdrawing,Maharashtra and Gujarat should not be rewarded for underdrawing.
Apart from keeping a tab on grid frequency,there is a need to monitor the loading of critical links,especially inter-regional lines. As for the under frequency relays (UFRs),there is a need to activate them quickly and ensure they are not disconnected on the whims and fancies of states. For that,the oversight mechanism needs to be overhauled. Currently,the regional power committees (RPCs),manned by state government representatives with state electricity board chiefs at the helm,are responsible for ensuring the deployment of these relays. A good 15 days after the two consecutive grid collapses,no emergency meeting of the RPCs had taken place ample testimony to how seriously states view the lapse. The only way to fix this is to have these committees are headed by neutral observers,such as representatives from the Central Electricity Authority,so that there is accountability.
Operation of the grid infrastructure is crucial,especially the need to double-check the reliability margins of inter-regional links,because the tripping of inter-regional links can have a severe cascading effect,putting their whole grid in jeopardy. Strengthening crucial links by keeping more margins is warranted. Protection audits to prevent malfunction of relays under conditions of stress also makes sense,considering the reluctance among states to keep them in working condition.
Besides,there is a pressing need to expedite the implementation of smart grid equipment,such as phasor monitoring units. Such equipment increases the visibility of the grid to the operator and is an integral part of the grid systems of China,Russia and the US. It should also be examined why some of the northern states,especially the perennial offenders,were overdrawing on the days the grid collapsed. Haryana and UP have extremely bad excuses to offer. In Haryana,the CLP-owned Jhajjar plant was shut down till recently. Currently,even though one unit has become operational,the transmission system is inadequate to evacuate the generated power. The state is also not able to fully absorb power from Adanis Mundra power project,again due to transmission constraints,while the Yamunanagar plant is shut down due to equipment trouble. In UP,two major projects,Lancos Anpara-C and Reliance Powers Rosa plant,are running at about 50 per cent capacity,on account of payment delays and coal shortages. If these units were running at full capacity,UP probably wouldnt have needed to overdraw from the grid.
Ultimately,the solution could lie in making overdrawal prohibitively expensive while ensuring that underdrawal does not get rewarded. This could be the only way to ensure that states move away from the UI market to the power exchanges to sell much of their real-time surplus and deficit power. For this to work,one option could be to facilitate online electricity trading round the clock to ensure that buyers and sellers transact power on the designated market platform. Suitable action on getting states to activate the UFRs would also help. Else,Indias wildly overstretched electricity sector could collapse again if basic grid discipline is repeatedly found wanting.
anil.sasi@expressindia.com
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