India electricity grid operators on Sunday managed the unprecedented ramp down and build up of electricity load within a nine-minute window, a feat that had not been tried anywhere in the world on such a scale and one that experts have hailed as a ‘miracle’.
At 9pm on Sunday, the load dropped sharply and continued to fall, as people even switched off appliances, despite Prime Minister Narendra Modi’s call for switching off only lights. The estimated electricity load reduction at 32 gigawatts (GW) was enough to meet the estimated power demand of Pakistan.
“The anticipated reduction in all-India demand during this period of 9 minutes was 12,000–14,000 MW, considering that only lights would be switched off," said a preliminary report prepared by the government.
“However, the demand went down from 117,300 megawatts (MW) at 8.49pm to 85,300MW till 9.09pm. That is a reduction of 32,000MW. Then it started increasing. The frequency was maintained within a band of 49.7 to 50. 26 Hz, which means the voltage was kept stable," said power minister Raj Kumar Singh.
India’s grid code calls for grid frequency of 49.5- 50.2 Hz. Any sudden change in demand pattern impacts grid frequency and engineers were worried as India’s massive power transmission failures in July 2012, which left around 700 million people without electricity.
India’s hydropower stations played a key role as they provided the flexibility of a quick generation ramp up and down as they take the least time to switch on or off.
“Hydro generation across the country was maximized by 20:45 hrs and generation reduction of 17,543MW from 25,559MW to 8,016MW between 20:45 hrs to 21:10 hrs matching demand reduction of 31,089MW during the period was achieved with these resources. This hydro generation was again ramped up from 8,016MW to 19,012MW from 21:10 hrs to 21:27 hrs to meet the increase in demand after the event," the report said.
“A reduction of a total of 10,950MW generation was achieved through thermal (6,992MW), gas (1,951MW) and wind generation (2,007MW) from 20:45 hrs to 21:10 hrs," it said.
The expertise of India’s grid engineers is good news for the country’ ambitious green energy plans as it aims to add 175GW) of renewable capacity in solar and wind energy. Given the national grid interconnection with India’s neighbours, it also adds heft to the ambitious global electricity grid plan pitched by Modi to leverage solar power generated in one geography to feed the electricity demands of other nations.
“Kudos to Power System Operation Corp. Ltd (Posoco) and the load despatch centres for pulling off this spectacular event within the technical range of system frequency," said Debasish Mishra, partner, Deloitte India.
Posoco manages these complex functions through the national load despatch centre (NLDC), the regional load despatch centres (RLDCs), and the state load despatch (SLDCs) centres. The country has 33 SLDCs and five RLDCs, and one NLDC.
“Our engineers managed it brilliantly. Full credit goes to our system operators—NLDC, RLDCs, SLDCs, and generators," said Reji Kumar Pillai, president, India Smart Grid Forum, and chairman, Global Smart Grid Federation. “You can call it quite an experience," quipped a government official closely involved in the gargantuan exercise asking not to be named.