The Hindu Business Line : National grid plan may get derailed

Power play
With onset of summer, the northern grid States have only increased overdrawal.
Violation of grid frequency limits raises questions over effectiveness of existing norms.

New Delhi , May 14

States of the northern region that have been rampantly overdrawing power from the regional grid could be playing spoilsport in the Government's national grid project.

According to the Government's latest grid frequency profile data, the northern grid's average frequency fell below the stipulated limits into the crisis zone — a whopping 27 per cent of the total time between April and January 2005-06. In comparison, the other four regional power transmission grids — Western, Southern, Eastern and North East — have flouted the prescribed grid frequency limits less than four per cent of the total time during the period.

Any deviation in the grid frequency position beyond prescribed levels magnifies the chances of a grid collapse, with the northern grid narrowly averting blackouts in the region on at least two occasions during the last six months.

Ineffective norms

With five distinct grid systems in the country at present, flouting of grid frequency norms by States threatens only a particular region. But as the Government progressively enhances inter-regional grid linkages to form the national grid, lack of discipline among the northern grid constituents could plunge the entire country into a blackout. Rampant violations of the grid frequency limits by northern States also raise question marks on the effectiveness of the existing norms in subverting grid indiscipline.

According to the data, the northern grid has witnessed rampant overdrawal by States such as Uttar Pradesh, Rajasthan and Haryana, with the situation worsening in December (when grid frequency was lower than limits 58.51 per cent of the time during the month) and January (54.87 per cent of the time).

With the onset of summer, the northern grid States, led by UP, Rajasthan, Jammu & Kashmir and Haryana, have only increased overdrawal from the grid to tide over peaking shortages and the region continues to be on the brink on a daily basis, officials said.

According to Power Ministry data, UP overdrew 1,844 million units beyond its allocation during the whole of last fiscal, Haryana 1,348 MUs and Rajasthan drew 420 MUs over its allocated capacity.

What causes collapse

The grid frequency is a real-time measure of how well the member States are adhering to their respective allocations for drawing power from generating stations within the region. The grid frequency should be between 49.0 hertz and 50.5 hertz at all times, but if some of the constituents draw electricity beyond their quota, grid frequency could dip below 49 hertz and lead to a collapse. Also, if constituents are drawing power below their allocations, grid frequency could shoot up beyond the upper limit of 50.5 hertz and threaten grid stability.

However, since it is inevitable that some States draw more than their schedule in real-time operations, the Central Electricity Regulatory Commission has put in place a tariff regime under which penalties are levied in the form of unscheduled interchange charges. However, with nearly all constituents of the northern region overdrawing at the same time during the last few months, leading to grid frequency dipping regularly below the lower limit of 49 hertz, it seems the unscheduled interchange mechanism is not proving to be much of a deterrent.