The honorable Prime minster of India has requested the people to switch of the lights for 9 minutes on 5th April 2020 at 9:00 PM in support of the fight against Covid-19. In this article we will analyze the demand reduction in those 9 minutes (April 5th 9:00 PM – 9:09 PM) and what it holds for the future electricity system management.
The sudden variations in both electricity supply and demand side is expected to be regular in future and we need effective solutions in managing these eventualities in the future electricity systems.
Status of electricity demand
Figure 1 presents the All India electricity demand met by the utilities on 5th April between 20:30 and 21:30 hours in time step of 5 minutes. The all India demand was 117.80 MW at 20:30 hrs and it has reduced to 85.80 MW at 21:10 hrs and it again increased to 108.81 GW at 21:30 hours. Between 20:30 and 21:10 the electricity demand was reduced by 32 GW i.e. a reduction of around 27%.
Table 1 presents the electricity demand met by the utilities before and after the event. As we can observe from the table that, the highest reduction in demand was experienced by the Northern region (NR) with 10.37 GW followed by Western region (WR), Eastern region (ER), Southern region (SR) and North eastern region (NER) with 9.11 GW, 6.64 GW, 4.97 GW and 0.88 GW respectively. In terms of percentage, highest reduction is experienced in NER with 47%. During this time period, the percentage demand reduction was lowest in SR with 15%.
Actions taken by the utilities to meet the fluctuations in demand
The utilities maximized the hydro generation by 20:45 hrs and when demand had decreased from 20:45 hrs to 21:10 hrs the generation from hydro was reduced from 25.6 GW to 8 GW. Further to meet the increase in demand post 21:10 hrs, hydro generation was ramped up to meet the increased demand from 8 GW to 19 GW by 21:27 hrs. Also, during this time there was a substantial reduction in electricity generation from coal, gas and wind power plants to match the reduction in demand (Source: POSOCO).
The reason is, hydro power plants need very short start up time. The moment you switch on the hydro power plant you can start generating electricity, where it is not the case with other power plants. Hydro power plants just take a minute to bring the unit from cold start-up to full load. This is much shorter start up time when compared to gas turbines or steam plants. Also, with hydro power, generation can be reduced rapidly when there is a surplus.
Lessons for the future
This 9 PM 9 minutes was a demand side event where utilities experienced sudden drop in demand. Further, huge variations in electricity generation is also possible in the supply side due to the installation of more renewable energy into the electricity system. The present installed electricity generation capacity of India is 370 GW and in that renewable energy constitutes nearly 87 GW i.e. close to 24%. The installed capacity of renewable energy includes Wind energy (37,694 MW), Solar energy (34,628 MW) followed by Biopower (10,023 MW) and Small hydro (4,683 MW). The electricity generation from solar and wind power are highly variable owing to the fluctuation of generation sources as solar can generate electricity only when there is sun and wind power is only possible when there is wind. With India plans to add 175 GW of renewable installed capacity by 2022 the variability in the electricity generation is expected to increase
Since this 9 PM 9 minutes was a planned event the utilities were able to manage it without any mishap. In the future electricity systems with more variable resources, the sudden variations in the electricity supply are expected to be regular. So, in addition to variability in demand, there will be variations in electricity supply too. Managing variability both in supply and demand sides is not going to be easy and we need effective solutions for the proper functioning of the electricity system. Though we have required conventional electricity system capacity to meet the demand, it cannot be used all the time as India’s pledge to generate more electricity from renewable sources will be violated. At present, we have close to 46 GW of hydro power installed in the electricity system. With around 175 GW of renewable energy, this hydro capacity is not enough to meet the fluctuations. So, most of the times conventional coal power plants are used as backup to these renewable power plants. However, there is a huge cost and technical difficulties associated with frequent ramping up and ramp down of conventional coal power pants. Options like demand side management, needs to be pursued aggressively, else in future grid blackout will be a regular thing in the Indian electricity system.
Article by – Mr. Balasubramanian Sambasivam
Balasubramanian Sambasivam is a researcher in the Department of Management Studies, Indian Institute of Science (IISc), Bengaluru. He holds a PhD in Electricity Transitions & Demand Response from IISc Bengaluru. Balasubramanian obtained a Masters in Renewable energy technology from Technical University of Berlin, Germany. His main interests are at renewable energy transitions, electricity demand-supply management and implementing demand response in electricity systems.