To avoid a blackout such as the one that affected several states on 31 July and 1 August 2012, and caused an estimated $2 billion (around Rs. 11,960 crore today) in losses, the Central Electricity Regulatory Commission (CERC) plans to further narrow the frequency band for the country's national grid.
Grid frequency is a critical aspect of power system operations and a function of demand and supply (when demand exceeds supply, frequency falls and vice versa). Global standards require that grid frequency be kept close to 50 hertz (Hz), but power-short India has had a history of the frequency fluctuating from below 48Hz to above 52Hz. A low or high frequency could result in the grid collapsing.
In a discussion paper, the country's apex power sector regulator has suggested a grid frequency band of 49.95Hz to 50.05Hz. The current band is between 49.7Hz and 50.2Hz.
"The discussion paper inviting comments has been floated. Grid frequency reflects the discipline in the system and the stress in the system. We expect it to become a reality by September post the inputs and the hearing. This tight band will put the states to test," said a senior CERC official, speaking on condition of anonymity.
India regulates grid frequency by making states pay more for power when they draw it at low frequencies, but several states have continued to do this, and then not pay the extra amount on time they are supposed to.
Such indiscipline by the states was the cause of India's worst blackout that left nearly 620 million people across 19 states and three Union territories without electricity for hours together last July and August when the northern grid collapsed on 31 July and, in a wider blackout, the northern, eastern and northeastern grids, too, broke down on 1 August.
"Last year's grid failure was primarily due to lack of grid discipline. A lot of work has since been done. We have been cutting down overdrawing (of power) by cutting supplies. With the narrowing of frequency band, the load management will be strengthened and become stricter," said R.N. Nayak, chairman and managing director of Power Grid Corp. of India Ltd (PGCIL), which runs and maintains the grids.
Load management functions are overseen by the state-owned PGCIL and carried out by its subsidiary Power System Operation Corp. Ltd (Posoco). Regional load despatch centres (RLDCs) are responsible for maintaining grid discipline and supervising optimum scheduling and delivery of electricity in their regions, and function under Posoco.
The country has 33 state load despatch centres, five RLDCs—for the five regional grids—and one national load despatch centre.
CERC had earlier narrowed the frequency range to enforce grid discipline. In May 2010, the range was reduced from 49.2-50.3Hz to 49.5-50.2Hz. It was then further lowered to the present range of 49.7-50.2Hz from 17 September.
A grid collapse is the worst-case scenario for any transmission utility. When this happens, states that draw power from a particular network go without electricity.
India has five regional grids—the northern, southern, eastern, northeastern and western grids. All except the southern one are connected.
"The tolerance has been drastically reduced to bring system discipline. Both the distribution utility and generator will have to strictly adhere to the schedule given by them," said Debasish Mishra, senior director at Deloitte Touche Tohmatsu India Pvt. Ltd, an audit and consultancy firm. "Given that there is no flexibility in the supply side, the only way out to meet these strict parameters is to back down load."
India has a power generation capacity of 225,133.10 megawatts (MW). While India's overall energy deficit and peak electricity shortage narrowed to 8.7% and 9%, respectively, the country is reeling under a chronic fuel shortage, which, in turn, has affected power generation.
"When you are talking about narrowing frequency bands, you are talking about system stability. We are seeing a lot of technical fixes. It is a difficult one to balance but from the system operations point of view, when you have supply issues, you have to balance out by curtailing load," said James Ooi, director, gas and power, IHS CERA—an energy research firm. "It is necessary until the power sector can acquire more fuel and improve interconnection transmission capacity so that a swing in one region can be absorbed by another."
Power producers have been battling a fund crunch, delays in securing government approvals and shortages of coal and gas in the past couple of years, contributing to a slowdown in economic growth. India's economy is estimated to have grown at 5% in the year ended 31 March, the slowest in a decade.
The report of a committee headed by A.S. Bakshi, chairman of the Central Electricity Authority (CEA), India's top power sector planning body, blamed last year's outage on a dangerous imbalance—too much power being drawn by northern states such as Uttar Pradesh, Punjab and Haryana and too little of it by those in the west. It also recommended tightening the frequency band closer to 50Hz.