In the year 2012, two large-scale power blackouts occurred in India. The blackouts which occurred on 30th July and 31st July respectively are termed as the ‘ worst power crisis ever ‘ in the history of mankind and affected 21 out of 28 Indian States.
As the global media started covering the issue, key players Indian Power Sector started playing the infamous blame game. In-spite of all this, let’s dig in deep to understand what really happened that affected 350 million people in the first outage and a whooping 670 million people in the second outage.
Key highlights of the blog are:-
- The Traditional Electricity Grid Of India
- The Modern Electricity Grid Of India : Formation, Functions And It’s Management
- What Happened? – Prevailing Conditions Prior To Outage, Incident of First Outage, Incident of Second Outage
- Restoration Of Power Supply
- Causes Of The Outages
- The Way Ahead
- The Bottom Line
The Traditional Electricity Grid Of India
- The electrical network in India is divided into 5 main regions namely Northern, Eastern, North-Eastern, Western and Southern regional grid.
- About two-thirds of the electricity generated in India, comes from Coal- Fired Thermal Power Plants which are concentrated in the Eastern region because of their close proximity to the major coal mines. Hydro-generation which accounts for one-tenth of power generation in India, is located in the Eastern and North-Eastern regions. While these are the major generation of power in India, North-Western and Southern regions are known as major power draining loads of the country.
- To fuel the needs of the growing economy, a heavy traffic of power flows across thousand of miles. The distribution of power within each regional grid is managed independently by each state by its power utility.
The Modern Electricity Grid Of India : Formation, Functions And It’s Management
As a result of the reforms in India in early 1990s, the plan for connecting the regional grids to form a nationalized grid was conceptualized following which all the regional grids (except the Southern Grid) was inter connected. This was called the North-East- West (NEW) Grid whose main purpose was to ease the power exchanges across different geographic regions and manage the power generation to meet the surplus and deficit effectively. This corridor which is made up of high capacity lines which connected Agra and Gwalior in the West, Sasaram in the East aimed primarily to flow the power from thermal power stations to the load centers in West and North.
For Coordinating the power exchanges across regions, a National Load Dispatch Centre (NLDC) was set up in Delhi, in addition to existing Regional Load Dispatch Centers (RLDCs). These Load Dispatch Centers (LDCs) are autonomous subsidiaries of the Power Grid Corporation of India.
Keeping in mind the needs of the growing economy, The Indian Electrical System is expected to operate at a frequency of 50 Hertz always. However, whenever the demand in the regional grid extends the supply, the frequency tends to fall. As a result, to compensate this the generators in the region and all over the NEW Grid start pumping more power which is then transmitted over the transmission lines. However, this leads to thermal stress in the transmission lines and can lead to protective shut down when the safety limits are reached. This partial shutdown of some grid may then increase subsequent pressure in the other transmission lines leading to shut down of the generators and ultimately a blackout.
What Happened ?
The outage in the month of July, 2012 was a result of sequence of events and is resembled as classic “spiral breakdown effect” of the Indian Power System.
To understand the intensity of the situation and how it all happened, we must take a look at:-
Prevailing Conditions In The Network Prior To Outage
As the reports say, the NEW Grid was already operating under a lot of stress throughout the month of the July. In addition to that, the failure of South-West Monsoon rains in the year 2012 made an extraordinary increase in the power demand for agriculture in the Northern region. Adding to the woes, there was a power surplus in the Western region which resulted in higher outflows of power to the Northern region. Amidst all this, another factor which needs to be remarked is that the Northern-Western inter-connection was operating only with 2 out of 4 high capacity inter-connections.
Incident Of First Outage : 30th July, 2012
While one of the two unavailable lines was placed under planned outage the other one went into a forced outage as a result of equipment failure the very next day. On July 29, nearly about 3 p.m., the Agra-Gwalior power line collapsed. Even then, no significant steps were taken to meet the demand of the Northern region or to curtail the surplus power generation of the Western region, which was the major reason of the outage caused on 30th July 2012. Approximately, at 2:30 a.m. there was disturbance in the NEW Grid which disconnected the Northern region from the rest. As a result, 8 out of 28 Indian States plunged into darkness, affecting approximately 350 million people.
Incident Of Second Outage : 31st July, 2012
The second outage happened within a span of two days. Just 36 hours after the first outage occurred, the second outage followed and the reason yet the same. There was another disturbance in the NEW Grid, originating again in the critical North-West regional interface. While the power restoration process was still on, the high power vortex condition in the Northern and surplus power conditions in the Western region still prevailed.
However, due to power restoration process 3 out 4, NR-WR links were made operational. When two of them failed to operate in overloaded condition at 1 p.m. on 31st July, 2012, a very similar cascade of shut downs of other NR-WR links followed.
Also, the grid was considerably weak due to the last outage. Several ER-WR links were still down and the whole system was running in a compromised state, such that it was even difficult to meet the load. As a result 38 links between Northern, Eastern and Western grids disconnected due to overloading within a span of one minute. Along with this, most of the generation protection system were shut down in the Eastern region and thus a huge chunk was taken away from net generation pool. The Northern, Eastern and North-Eastern were disconnected from the NEW Grid and thus faced an outage while the Western region which was having surplus power production was also disconnected from the NEW Grid and thus was saved from an outage.
Restoration Of Power Supply
While the process of restoration of power supply started soon after the incident, it took long to restore due to a variety of reasons.
- Due to the intensity of the incident, it took long for the systems to come online as the generators in various stages needed to be put online. Moreover, these generators could be only put online when they are sufficient enough to serve the load and the supply meets the demand at different stages.
- Due to delay in the onset of Monsoon, the generation of hydro-power was almost negligible in the Northern region. This meant that the loads mostly relied on thermal power generated by burning coal in the Eastern region. However, as a matter of fact, thermal power stations do not respond such shortly and incidents like tripping and overload require the plants to cool down before beginning the production again.
- Due to all these issues, the restoration of power took approximately 8-10 hours after the outage. And, in some areas the power supply was restored after 16-20 hours of the actual grid failure. However, the critical loads of railway traction power were among the first ones to be restored after the incident.
Causes Of The Outages
The outages in the year 2012, was a result of spiral down effect of several factors that led to increased stress on the network. However, a close observation reveals the following factors responsible for the blackouts in the year 2012:-
- Heavy Requirement Of Power By Northern States And Over Supply By The Western States
Despite the directives given by NLDC, the northern states continued to draw power from the grid in the order of 2000 MW. While, western states over production was 2700 MW. This would have been alright if NR-WR links were in place, but since one of the lines were under planned outage and the remaining were under forced outage, it became difficult to look after the supply-demand skew.
- Self Interest Ahead Of Grid Security
The operation of UFRs (Under Frequency Relays) to curtail the part of the load on the system could have minimized the impact or perhaps avoided it completely. But, the socio-political pressure and huge negative balances of the state utilities do not leave them with much steps to express their concerns and take necessary actions on grid safety. As a result of continued negligence in taking measures to curtail the load by several states at the same time, led to the disturbance in the system which ultimately led to large scale blackouts.
- Sick Mentality Of Generators
To cope up with the issues of unexpected regional grid imbalances ABT ( Availability Based Tariffs) has been put in place since 2002. ABT is a tariff scheme which acts as a motivator for the power suppliers to stay committed to their scheduled power generation plans. According to this, generators and loads declare 24 hours in advance the amount of power they are going to draw or add into the network to enable the LDC to plan the physical outflows in the network a day ahead.
However, if the loads continue to draw more power than stated, it leads to fall in the frequency of the network. As a result, the cost of making each unit escalates making it more expensive for loads to buy and more profitable for suppliers to supply than agreed. At such a time, if a buyer reduces his consumption, he/she is rewarded by paying a special premium known as Unscheduled Interchange (UI) rate. The same UI is charged from generators as a compensation who fail to stick to their commitment.
However, with passing time the rise in the cost of fuel have led to an increase in the cost of generation of electricity making the per unit generation cost higher than the UI. Thus, in a situation of heavy demand, power suppliers prefer to pay the penalty rather than generating enough electricity. When this economic choice is made by large section of generators, the supply-demand gaps worsens leading to blackouts.
- Improper Grid Management And Inadequate Monitoring Of The Network
The visibility and situational awareness of the LDCs was severely compromised at that time which led to outage and delay in power restoration. The unavailability of the real-time data from the network made it very hard for them to issue directives keeping in mind the health of the entire grid.
The Way Ahead
Undoubtedly, both of these incidents were an eye opener not only for the authorities in-charge but also for the general public. While we need bolder laws, stricter adherence to grid discipline, modernization of the network and increased coordination between the state utilities and the LDCs on one hand to avoid such incidents in the future, we also need to shift and look for a cleaner and renewable sources of energy in the meantime. Certainly, the incident in July,2012 highlighted the prime reason behind why we need to shift from coal and look for a green, clean and renewable source of energy not only for the survival of the planet, but also for our survival.
The Bottom Line
Wrapping it up, all I would say is while this two day incident was strange and unique for most of us, some of the people may not have even noticed it as a huge supply disruption. Undoubtedly, it is not the fault of their mentality, having an uninterrupted 24×7 power supply is still a dream for a large section of the population in the country.