How did India’s power grid survive the country-wide 9 mins blackout on 5th April 2020 ?

The Prime Minister of India appealed to the citizens on 3rd April 2020 to switch off all the lights between 9:00 PM to 9:09 PM on the 5th of April. Obviously, the Union Ministry of Power was quick to act and expressed that this (switching off lights across the big country) may cause instability in the grid and fluctuation in voltage which may harm the electrical appliances.

I guess, right from that moment, the Power System Operation Corp Ltd (POSOCO) - who manages India’s critical electricity load management functions, National Load Dispatch Centre (NLDC) and State Load Dispatch Centers (SLDCs) went sleepless - with a gigantic task of managing the steep ramp down and buildup of electricity load on the national grid. 

Their initial estimate was that the drop would be around 13 Giga Watts (GW) during the 9 minutes; but in reality it dropped 32 GW below the charts yesterday!. Yet, the country’s national grid & home appliances survived. I can’t stop praising the efforts of all the engineers involved. This is how they achieved the feat! 

Summary of electricity grid events:

➤ The total reduction in all India demand recorded during the event was 31089 MW. All India demand started reducing from 20:45 Hrs and minimum demand of 85,799 MW was recorded at 21:10 Hrs. Subsequently, from 21:10 Hrs, the demand started picking up and settled around 114400 MW at 22:10 Hrs.

➤ Grid Frequency during the event remained in the range of 50.26 Hz to 49.70 Hz with maximum and minimum frequency of 50.259 Hz and 49.707 Hz recorded at 21:08 Hrs and 20:49 Hrs respectively.

How did the grid manage the steep swing?

The event was managed smoothly without any untoward incident while power system parameters were maintained within limits. This is how it was made possible. 

➤ Hydro generation was reduced by 17543 MW (from 25559 MW to 8016 MW) between 20:45 Hrs to 21:10 Hrs , matching with demand reduction of 31089 MW during the same period. This hydro generation was again ramped up from 8016 MW to 19012 MW from 21:10 Hrs to 21:27 Hrs to meet the increase in demand after the event.

➤ Likewise, the Thermal, Gas and Coal plants were also simultaneously ramped down and up. Reduction of total 10950 MW generation was achieved through Thermal (6992 MW), Gas (1951 MW) and Wind generation (2007 MW) during 20:45 Hrs to 21:10 Hrs.

➤ Advance actions such as switching off transmission lines, taking reactors in service, changing SVC, STATCOM, HVDC set points etc. were taken prior to the event for keeping voltages and line loadings within permissible limits. 

Real-time graphs reference: POSOCO

Lessons & questions:

1. Managing such a short-time steep swing on the grid load was not an easy task, it required a seamless coordination/co-working between multiple stakeholders across the power sector. Different state grid operators, various sources of power generation companies (such as hydro, gas, thermal, nuclear and some level of wind) run by the centre, states and the private sector all worked together to keep the frequency within the acceptable range of 50.26 Hz to 49.70 Hz.

This once again proves that the India power sector technologies and infrastructure have improved miles ahead, especially when comparing the 2012 blackout incident that left 700 million people across India's 28 states without power for 10-12 hours.

However, the important point to note is that the country’s commercial and industrial power demand has been already at bottom, due to the nationwide lockdown keeping most of the factories, malls, and every big loads shut down. This gave enough buffer capacity for the grid to balance the steep swing.

What would have happened if the situations (peak demands) were normal when all the industries running?. It is never a good idea to play around the grid integrity when it’s running at high capacity supply/demand. It may be mere impossible, or will result as a huge expensive exercise at least.

2. India’s hydro-power stations played a key role as it provided the flexibility of a quick generation ramp up and down as they take the least time to switch on or off. How quick other sources of electricity can react, especially the renewable energy sources ?

3. Last, but not the least: what will happen to the grids when 30% of all India automobile goes electric; and plug-in for charging at the same time (may be in the evening around 6-8pm)?. Will the increasing electric vehicles would destroy power grids & infrastructure? The demand for electricity to power EVs is projected to increase to almost 640 TWh by 2030; which is a huge load to manage, but the real challenge would be the peak hour demands/spikes.

Thus, not only the grid operators, but also the EV charging infrastructures should prepare for grid balanced smart charging, with more intelligent communication & coordination between the electric vehicle, charger and the grid. 

P.S: This article is only for constructive discussions around grid balancing and what to learn from such a big scale rare grid event. So, please keep your political views aside; and share all your technical constructive comments below.

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