In summer time, when Delhi often simmers at 42 degrees Celsius till late evening with night temperatures hovering at 28-29 degrees, massive thunderstorms often bring down temperature by as much as 10 degrees.
While the common Delhiites are greatly relieved as the mercury plummets, the power companies used to have a tough time adjusting to the crash in power demand. However, that is a thing of the past with improved weather forecasts by the India Meteorological Department (IMD).
It is but natural that the power demand fluctuates with the changes in weather — temperature and humidity, including heat waves, rainfall / thunderstorms, snowfall, cyclones, solar radiation and wind speed — anything and everything has a bearing on the consumers’ need for power. So, the power suppliers — both generation companies and distribution companies — are constantly on their toes to meet this change in demand.
It is here that as part of the dedicated, customised weather forecast for Power System Operation Corporation Ltd. (POSOCO), the power generation companies are able to plan their schedules better.
For instance, in case of expected thunderstorms as mentioned above, the power generation companies are getting alerts well in advance, starting with 72 hours, coming down to Now Cast service (which gives forecasts for next three hours). When the companies know that the next day the power demand is likely to go down massively for a few hours, they plan their generation accordingly.
The national load dispatch centre (NLDC) and the state load dispatch centre work (SLDC) in tandem with the power generation companies and power distribution companies across India. Power distribution companies plan demand so as to avoid under-drawal as going against demand will not just invite a penalty for them but also runs a risk of disturbing the grind balance, said a power expert.
Helped with IMD alerts, it is not just the power distribution companies but also the power producing companies that can plan their output. “In case of the thunder storm prediction a day ahead, the states surrender their power demand, which helps plan reduced generation at regional levels.
The Earth System Science Organisation, India Meteorological Department (ESSO-IMD), under the Ministry of Earth Sciences, and Power System Operation Corporation Ltd. (POSOCO) had signed a Memorandum of Understanding on May 18, 2015 for optimum use of weather information / forecast in the power sector.
“As part of this deal, the ESSO-IMD provides weather warnings about likely occurrences of thunderstorms, heat waves, cold waves, rainfall, fog, etc., over various states up to the next 72 hours. We provide short and extended range forecasts … We also provide state / region wise monthly / seasonal outlooks of weather conditions,” said R.K. Jenamani, senior scientist at the IMD.
An actual example of how such a forecast helped in Uttar Pradesh was cited in a report prepared by IMD and POSCO together earlier in January 2022. It relates to severe fog conditions in the Indo-Gangetic plains. “It was observed that due to tripping of 765kV Anpara C-Unnao line, line loadings of other 400kV lines, especially 400kV Anpara-Sarnath D/C increased beyond permissible limits (> 700MW per circuit). Operating these lines on such high loading posed a threat to grid security,” it said.
From the inputs of the weather portal regarding spread of fog, Uttar Pradesh SLDC was advised to back down generation in Anpara complex and increase generation in other plants to meet its load, in the interest of grid security. “Low generation in Anpara complex ensured that in the event of tripping of 765kV Anpara C-Unnao line or any other 400kV line in Anpara complex due to fog, the loading of other lines did not exceed operating limits. This provided the operator an increased time window for corrective action,” the example mentioned.
It is not just the regular weather events such as thunderstorms or fog but the extreme weather events when the accurate forecast helps much more to avoid damage. For instance, cyclones cause heavy rains, large storm surges, and strong winds that often damage power elements in the distribution and transmission systems causing widespread interruption of power supply to the affected areas. On the one hand, the affected communities and the disaster managers face distress, on the other hand, the power companies bear losses.
“As increase in the intensity and frequency of extreme weather events poses challenges to secure and reliable power system operations, prior information of weather conditions facilitates power system utilities to advance operation planning, secure system operation and early restoration of the affected area which in turn reduce expenditures also,” power sector expert said.
Enhanced role for IMD forecast as RE usage increases
The Government of India has set a target of 500 GW of non-fossil generation by 2030 as part of the ambitious climate action under Paris Agreement 2015. So, with an increase in share of the renewable energy (RE) resources, which are highly dependent on weather, the challenges for system operators would further increase.
A large part of it is to come from wind and solar power. “If a solar power plant manager knows how much temperature it will reach the next day, whether it would be cloudy or not, then the expected output can be planned. The power generator can also inform the grid operator about the planned lesser generation,” said Solar Energy Society of India (SESI)’s president Prafull Pathak.
“In our power sector, RE is treated as unreliable and therefore, an accurate weather forecast is far more important. Moreover, unlike earlier years, we can now very well rely on IMD forecasts for planning power generation, revised and re-scheduled output etc,” Pathak said.
It is not just the solar sector but the overall RE sector that is highly dependent on weather. And therefore, as the January 2022 report had pointed out, it is not just sufficient to act after weather-related events have taken place to increase the efficiency of the power sector and to make it weather resilient but proactive steps are required to minimise the possible adverse impacts.
(Nivedita Khandekar can be reached at email@example.com )