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Wthdrawal of overdrawal

Since the mega power blackouts of July, overdrawal of power by states has fallen sharply. Ironically, there is more evidence to suggest that the fault doesn’t lie wholly with them

When the grid collapsed twice over two days at the end of July, plunging India into its worst power crisis in over a decade, the focus of the blame was on a bunch of northern states such as Punjab and Uttar Pradesh. These states were accused of drawing much more power from the grid than they should have, thus overloading key components which failed. Following the public outcry, UP chief minister Akhilesh Yadav went so far as to sack the head of UP power Corporation, Avanish Awasthi.

But even at that time, the ‘overdrawal’ theory was weak. Data about grid conditions at the time didn’t quite support it. An enquiry report did talk about overdrawal but it pointed to other factors which were also important. Now further evidence has emerged which complicates the ‘overdrawal’ story.

But ironically, given the outcry about the supposed irresponsibility of the northern states, their behaviour since the grid collapse has changed for the better. “After the grid disturbance, the deviations from schedule have come down sharply,” says a senior official of Power System Operation Co (POSOCO), the main operator responsible for co-ordinating the different players in India’s national grid, and ultimately, the safety of the grid itself. POSOCO runs the regional and national load dispatch centres, which coordinate power flows in each of the regional grids, as well as the national grid.

Better Safe than Sorry

Following the outcry over the supposed role of some northern states in ‘overdrawing’ power, POSOCO clamped down heavily. They effectively banned any overdrawing whatsoever, even though grid regulations do allow for it under certain conditions. “The northern region load dispatch centre [which manages northern grid], has become extremely strict about overdrawing of power,” says an official of the Haryana State Load Dispatch Centre (SLDC), which is under the jurisdiction of the state government. During the blackouts, it was the SLDCs, which acts as a conduit to move power from the national grid to the state-level grids, which came in for a lot of flak for not doing enough to limit the amount of power they draw, and for overburdening the grid. In the past, the relationship between the regional load centres, under the jurisdiction of POSOCO, a central government company, and the SLDCs, has been strained because of such over-drawls.

But how was this achieved?

States can match their demand for power with the available supply in four ways — ramp up their own generation, buy power in the short-term electricity market, draw more than they had scheduled (now frowned upon), or simply turn off the lights and leave their consumers in the dark — in other words, resort to load shedding.

Consumers bearing the brunt?

Given the improvement in the monsoon after July, and the resultant fall in demand for power especially from agricultural consumers, the power deficit would have become more manageable anyway. But there is some evidence that buying power from short-term electricity markets, and load shedding, have been more resorted to.

According to the market monitoring cell of the Central Electricity Regulatory Commission (CERC), states like Haryana and J&K are now resorting less to overdrawing power from the grid to meet demand. Instead they are buying power in the short-term electricity markets to make up any shortfall. Buying power in the short-term market this way, rather than simply drawing more power in ‘real time’ makes planning power flows easier.

What about load shedding?

In August 2012, peak demand was actually lower than a month earlier. Despite this, supply of power to meet that demand fell short by about 8.9% in August, compared with 5.39% in July. A large chunk of that shortfall would have been made up through load shedding. “States have resorted to increasing load shedding in the past few months, following the restrictions on over-drawl,” says Puneet Chitkara, director of AF-Mercados EMI, a power consultancy firm.

Improving Discipline

So tight have the restrictions become, on overdrawing power from the grid that Punjab’s power utility has asked the northern region power committee for a rethink on the issue, pointing out that even grid regulations allowed for overdrawal under certain conditions. “Continuous underdrawal has serious financial implications. Punjab State Power Corp (PSPCL) has purchased power at high rates from the market. Any underdrawl of this power and simultaneously imposition of cuts is financially not prudent,” it said in its submission to the committee.

“As long as the grid is not being put in danger, we should not be too hard on overdrawing of power,” says Bhanu Bhushan, former member of the CERC.

Bhushan was one of the architects of the so-called unscheduled interchange system or UI. Under grid rules, utilities and generating plants are supposed to declare a day in advance, how much power they will draw from, or supply to, the grid. Under situations of shortage, any overdrawal of power is priced at a penal rate (called the ‘UI’ rate). But the UI rate also acts as an incentive — utilities who draw less than the full amount of power they have scheduled at a time of shortage, are actually paid this UI rate since they are in effect, freeing up extra power. Generation companies too, can get paid the UI rate for the extra power they generate, above what they are supposed to.

The UI system was intended to act as a carrot-and-stick to ensure that imbalances in the system smoothened themselves out. Following the grid collapse, the grid manager POSOCO filed a petition with the CERC asking that it restrict the use of the UI system to only inadvertent drawals. What POSOCO argued, as did other critics, was that while the UI system was developed to handle short-term and unforeseen departures from schedule, in effect, it had become a way for states to regularly draw more than they were supposed to. UI rates are currently lower than short term rates for traded power, and for cash-strapped power utilities, that made it attractive. But it was this very attractiveness that made planning power flows difficult, hence the clampdown.

The end-result has been an improvement in ‘grid discipline’. But bearing the brunt of it is the end-consumer, who has to face the burden of increased load shedding. Ironically, even as supposedly erring states were forced to behave, evidence emerged which complicates the picture of what lead to the July blackouts.

More Light on Blackout

Days before the first blackout, a key component of the grid — a transmission line from Agra to Gwalior was partially shut down for planned upgradation work by Power Grid Corporation, the central PSU which builds and maintains a large chunk of the inter-state transmission lines in the country (incidentally POSOCO is a subsidiary of Power Grid). The Agra-Gwalior line has two circuits, both of which play a crucial part in moving power from the western grid, which generates more power than it needs, to the power hungry northern grid, where the opposite is true. One of these circuits was being upgraded to a higher capacity, as a result of which a large chunk of the power flow between the two grids was on this circuit alone on the July 30, overburdening it. The enquiry committee on the grid failures, stated that “effectively, 400 kV Bina-Gwalior-Agra (one circuit) was the only main AC circuit available between WR-NR [western and northern regions] interface prior to the grid disturbance”. The failure of this line due to the heavy burden on it caused it to trip. This meant power from the western to the northern grid had to be transported through the eastern grid, causing lines to overload there, putting in chain the sequence of events which lead to the first and the second blackouts.

In mid-August, officials at a meeting of the Northern Regional Power Committee (NRPC), which coordinates planning and maintenance for the northern grid, asked Power Grid representatives why the committee hadn’t been informed about the upgradation work as regulations required. The availability of important transmission lines is a crucial factor in determining the actual ability of the grid to move power from one point to the other — if a line is not available, this means that limits have to be imposed on how much power can be transferred. Further, the ‘planned outage’ of different parts of the network has to be coordinated with each other to ensure that too many lines aren’t out of commission at the same time. At the same time as the Agra-Gwalior line was down, another important line between the northern and western grids — the Kankrauli Zerda line was also out. In the absence of up-to-date information on what lines were down, the grid managers were allowing far more power to be moved than they should have.

Crossed Wires

On July 28, two days before first blackout, Power Grid starts upgradation work on one circuit of critical Agra-Gwalior line which transports power from western to northern grid another line connecting the two grids – Kankrauli-Zerda was also out. So were other important lines in the region.

The northern region power committee, which oversees maintenance of northern grid, criticised Power Grid for not informing it of upgradation of Agra-Gwalior line questions a couple of weeks later, Power Grid told the committee that the Agra-Gwalior line was the responsibility of the western region, which was doing the upgrade work. Thus, said Power Grid, it was the western region which was handling the issue. The committee checked this with its counterpart in the western grid, and discovered that no approval had been taken from the committee in that region either. And as NRPC pointed out, both committees should have been informed anyway.

The grid enquiry report didn’t mention Power Grid’s failure to keep an important set of planners in the loop about its upgradation work. Questions emailed to Power Grid’s chairman and managing director RN Nayak remained unanswered as of the time of going to press.

Days after the second grid collapse on July 31, the national load dispatch centre, which coordinates the entire grid, revised capacity of important parts of the grid down to reflect reality. But by then it was too late.

Whether or not overdrawal, or non-communication, or a combination of these factors was responsible for the blackouts of July, grid managers have achieved what they set out to do, which was to cut the level of overdrawal.
At least for now.


The result of the clampdown has been a sharp decline in the extent of overdrawal by different states
  • Uttar Pradesh for instance, which drew around 29 million units more power per day than it was supposed to, in the month of July, actually drew about a million units less per day than it was supposed to, in August, after the blackout.
  • Punjab, which drew about 6 million units a day more than it was supposed to in July, reduced that to about a million.
  • Haryana drew exactly as much power in August as it was supposed to, whereas in July it went over budget by about 13 million units of power a day.
  • In August, the grid frequency remained within its officially approved limit about 90% of the time, compared with 74% of the time in July.
  • The grid frequency is a measure of the extent to which demand and supply are in balance across the grid. Power demand is seasonal, so this data cannot be compared across months beyond a point, but it does showcase the extent of the decline.

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