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Grid frequency norms add to power woes

According to reports, tightening of grid frequency norms by the Central Electricity Regulatory Commission (CERC) has increased power deficit in the state by 20% since September 17.

Struggling with the problem of a drastic fall in wind power generation, the Tamil Nadu Electricity Board (TNEB) has increased unscheduled load shedding. On September 19, wind energy generation almost stopped. Windmills had been contributing 2,800-3,200MW for more than three months. Chennai, already facing a one-hour power cut, has been spared the additional burden as it houses vital installations like the state secretariat, high court and foreign consulates.

The rest of the state is not that lucky. Sources in the TNEB said power cuts in many rural areas now extend up to 12 hours, instead of the scheduled three hours.

It all started with the CERC in April this year reducing the grid frequency bandwidth by 0.2hz for ensuring better grid discipline and stability. The bandwidth, for operating the grid, which used to be 49.5hz to 50.2hz, was reduced to 49.7hz to 50.2hz. The commission also tightened the rules governing issue of warning messages — from the grid to the state utilities — for overdrawing power at low frequency.

Though the TNEB obtained a stay on implementation of the CERC order pointing out that the commission was trying to upset a well-functioning grid, the court dismissed the case on September 14 and the new rules came into effect on September 17. Since then, loadshedding has increased as the board is maintaining the frequency above 49.8hz. Though up to 49.7hz is permissible under the new norms, gird discipline violation messages start pouring in the moment frequency falls below 49.8hz.

“Before the court order, southern grid managers even disconnected four supply lines to Tamil Nadu — at Salem, Hosur, Udumalpet and Chennai — when the state continued to draw extra power at 49.7 hz,” said a TNEB official. Power managers feel the new CERC rules may help only private power generating companies and traders. “Before the amendment of grid bandwidth, one unit (1,000 watts) of power from the grid at 49.7hz cost Rs 3.87. Today, one unit at the same frequency costs Rs 5.91. The increase is 53%,” said another official.

Apart from wide variations in wind energy generation, poor output in hydro stations owing to the failed south west monsoon and fall in generation in Central power-generating stations like Talcher, Ramagundam, Kaiga and Kalpakkam have increased the burden on Tamil Nadu, officials said.

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