Worst blackouts in a decade

The government is still clueless about what caused the massive grid failures – first on 30 July and then again the next day – plunging half of the country’s population into darkness. It has initiated several investigations, including one by the Intelligence Bureau and another by the National Technical Research Organisation, to look into the possibilities of sabotage or cyber attacks. The blackouts were the worst in a decade.

On 6 August, union power minister Veerappa Moily, who assumed charge on 31 July, called a high-level meeting and ordered an independent inquiry into the loopholes in the power transmission grids. As a precautionary measure, he asked state power departments to prepare islanding schemes for specific regions and critical infrastructure like hospitals and the railways. The scheme would allow the region or infrastructure to isolate in the event of a grid failure. 

Soon after the northern, eastern and northeastern grids failed, the Central Electricity Regulatory Commission [CERC] initiated a probe into the issue of overdrawal of electricity by member states. 

But going by a quarterly report of the Power System Operations Corporation [POSOCO] that manages the national grid, the problem seems deeper. 

The Operational Feedback on Tranmission Constraints, circulated on 27 July, suggests that poor infrastructure of the northern grid is largely responsible for the outage. The grid supplies power to seven states – Delhi, Haryana, Himachal Pradesh, Rajasthan, Uttar Pradesh, Punjab and Jammu and Kashmir. Unbalanced load on transmission lines and overdrawal of electricity by member states tripped it on 30 July. This had a cascading effect, and led to failure of the interconnected eastern and northeastern grids the next day.

Most of the nodes [electricity distribution points] in this region have faults and the grid witnessed 14 power outages between April and June [see map]. To take care of this, the report suggests introducing split busbars or separate busbars at stations. 

A busbar determines the maximum amount of current that can be safely transmitted, and split busbars protects groups of cicuits and helps stop outages. Many stations in the northern grid, however, operate on single busbar; several substations do not even have the busbar protection, notes the report.

Yet another reason for an outage is the lack of low-voltage substations. A low-voltage substation transforms voltage from high to low and makes it suitable for distribution to consumers. Thus every high-voltage station in the upstream has a set of low-voltage substations. Ten high-voltage stations of northern grid do not have low-voltage substations. This is when only four high-voltage stations in the rest of the country lack in low-voltage substations. This places the load of high-voltage transmission on a handful of substations, resulting in power outage.

The report also cites that in June, the Northern Region Load Dispatch Centre [NRLDC] of the Power Grid Corporation issued messages of caution to Haryana [114 times], Punjab [98 times], Uttar Pradesh [110 times], Uttarakhand [58 times] and Jammu and Kashmir [40 times] against overdrawal of electricity. In the following month, it issued show-cause notice to the states for violating the Indian electricity grid code. But the warnings were ignored.

No doubt some northern Indian states need surplus power, says N Shreekumar, member of the energy group in Prayas, a non-profit in Pune. 

Since most substations are under state government’s control, they keep overdrawing despite repeated warnings. States need to be transparent about consumption of electricity. That way the grids can balance the demand and supply of power with planned load shedding and avoid such an outage, he suggests.

On arrangement with Down to Earth magazine