A year after India's biggest power blackout Why it happened and the lessons learnt

413 views

Published on

A year after India's biggest power blackout Why it happened and the lessons learnt

Published in: Technology, Business
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
413
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
Downloads
31
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

A year after India's biggest power blackout Why it happened and the lessons learnt

  1. 1. A year after India's biggest power blackout: Why it happened & the lessons learnt (This article is by Avinash Celestine, published in Economic Times) One year after India's biggest power blackout, what have we learnt from a series of technical failures which plunged large parts of the north, east and west into darkness? Immediately after the incident, the blame fell on northern states such as Haryana and Uttar Pradesh for drawing more than their quota of power from the national grid, thereby weakening it, and ostensibly bringing about the failure. Uttar Pradesh chief minister Akhilesh Yadav even proceeded to transfer the head of the UP Power Corporation for the incident. A year later, the picture looks far more complex. Northern states, being chronic offenders, can hardly avoid part of the blame for what happened that evening. Following the blackout, the Central Electricity Regulatory Commission (CERC) initiated a case to look into the events of July 30 and 31, 2012 (quite apart from the official inquiry into the incident). While the CERC's final ruling in the case is yet to come, it has become clear that other states, including some in the western region that were drawing less power than they had 'scheduled', also bear an important part of the blame. "Messages were sent to these states to resolve the problem at that time, but for commercial reasons they did not do so," says an official responsible for managing the western grid. In the days and hours leading up to the blackout, engineers responsible for the overall operation of the grid had repeatedly sent messages to offending states warning them about potential problems, but these were ignored, according to records of CERC proceedings. "Our biggest learning from the failure was the need for much tighter regulation, and the stronger enforcement of those regulations," points out a senior official responsible for the safety of the grid. Demand & Supply In the initial days after the blackout, when officials looked at the data about the state of the grid at the time, they noticed a seemingly odd fact: the 'frequency' of the grid, which in India is supposed to be around 50 Hz (that's also the level at which all electrical devices from television sets to washing machines operate), was only slightly below normal. An indicator that should have been flashing red at the time, to flag any serious imbalance in the system between the demand for power and the supply of it, was actually indicating that conditions in the system were close to normal. The demand for power fluctuates sharply —
  2. 2. across months and even over the course of a single day. It typically shoots up early in the morning as consumers wake up and switch on the lights or washing machines or geysers. Demand drops over the course of the day but shoots up again in the evenings. In northern states, the summer months are times of high demand due to the operation of air conditioners and coolers. In winters, heaters suck up a large chunk of power from the grid as well. Since power in the grid cannot be stored (at least not on any large scale), it has to be generated as people demand it. Power stations tend to work overtime during peak demand. But as demand drops, power stations too have to slow down. If they don't, the frequency of the grid could move sharply away from 50 Hz, seriously damaging both large-scale power equipment, as well as the appliances we use at home. And if the system moves the other way, and more power is being 'demanded' from the system than available, the same problem arises. On the evening of July 30 last year, despite the allegedly large amounts of power being demanded by the northern states well beyond their quota, a key health indicator of the system was actually saying that things were close to normal. Frequency Factor Unlike in the West, the frequency of India's grid for long has fluctuated well beyond its 'ideal' limit of 50 Hertz. The incentives facing power stations and state power utilities has meant that stations would often continue generating power well beyond the point at which there was demand for it. For their part, utilities continued to draw large amounts of power from the system more than it was prudent to do so. The result? Sharp spikes and drops in frequency and a resulting damage to power equipment. To fix the problem, grid operators evolved a mechanism of carrot and stick. Those drawing more power than allotted, at a time when supplies of power were already tight (when the frequency was below 50 Hz), had to pay more for the privilege. Conversely, power stations willing to supply more power to the system at this time were rewarded with higher tariffs. The opposite was true when the frequency was above 50 Hz indicating excess supply of power. Power producers were penalised with lower tariffs, but those willing to buy more at the time were rewarded. For a time this worked well and, over the years, the sharp spikes and drops in frequency gradually evened out, though they never actually disappeared. Soon the frequency of the system took on the role of key indicator of the health of the overall grid.
  3. 3. Deviations from it would lead to the grid operator, under the control of the central government, sending frantic messages to state electricity boards (SEBs) to draw less power. SEBs, under political pressure of their own from their respective state governments to maintain supplies of power to important constituencies such as farmers, would often ignore those messages. At about 2.30 am on July 30, 2012, just a few minutes before the entire northern grid went down for the first time, the net over-drawal by northern states (the extent to which they were drawing more power from the system than they officially committed to) was around 500 MW. A bulk of this power was being drawn by northern states from western India, and flowing over just two key transmission lines — the Agra-Gwalior-Bina line and the Zerda-Kankrauli line. And what added to the problem was that these were weak links, partially shutdown for upgradation and repairs. So large amounts of power were flowing across the grid at a time when key parts of
  4. 4. the network were weak. In retrospect it was an accident waiting to happen. Western Disturbance The first inquiry report on the grid disturbance highlighted these points — the already weak transmission lines, and the large excess power demand from northern states. But through the CERC orders, it's also clear that western states such as Gujarat, Madhya Pradesh and Maharashtra were also to blame for deviating from their planned power schedules — guilty of drawing far less power than they had 'scheduled'. Here's the clue as to why the frequency of the grid was just slightly below normal — while states like Uttar Pradesh were drawing more power than 'scheduled', there was also a greater supply of power in the system to match that demand, from the western states. The grid frequency, which indicates the extent to which demand and supply are out of whack, hence seemed close to normal. But in the context of a weakened transmission system, a large amount of surplus power available from the west for the north meant huge flows of power over key transmission lines, far exceeding their capacity. In such a scenario, it was as essential for grid operators to get western states to cut surplus power they were supplying to the grid, as it was to get the northern states to curtail their demand. At the time of the collapse, the 'surplus' power injected into the grid was 837 MW by Gujarat, 437 MW by Madhya Pradesh and 537 MW by Maharashtra. It's clear that grid operators at the time recognised this danger. But western states at least did not see themselves as being part of the problem. On July 29, the operator of the western grid asked Maharashtra to curtail its surplus power. Maharashtra responded by pointing to the frequency of the grid which was slightly below 50 Hz, technically indicating that there was excess demand for power in the grid. In such a scenario, according to the Maharashtra view, it was the job of the northern states to cut their demand, rather than that of the western states to reduce power surpluses. And this is where the money comes in as well. If Maharashtra and other western states are supplying their surplus power to the grid at a time when there is excess demand, they are earning extra-high tariffs for doing so. Therefore there is little incentive for them to reduce generation and lose revenue. "The Commission observed that during crises, delay in response or lack of response to the instructions of the [grid operators] is not acceptable," said the CERC. Two hours before the grid collapse on July 30, the western region operator asked National
  5. 5. Thermal Power Corporation (NTPC) to 'back down' a unit of its power plant at Sipat. A series of dialogues ensued and the end result was that NTPC did not reduce generation from its Sipat unit. "The Commission ... observed that NTPC should have reduced the Sipat generation...and if NTPC felt that the instructions were unreasonable, it was at liberty to approach the Commission." "What is also of importance is the flow on the transmission lines," says Puneet Chitkara, director at AF-Mercados EMI, a consultancy. "Many experts had pointed out that the frequency of the grid should not be the only focus, but practically that advice was ignored till now." A recent paper by the CERC proposes much tighter bands for the frequency of the grid,and penalties against those who deviate from their power 'schedules'. Lessons Learnt? Since the grid collapse, a series of changes have been put in place in the way the grid operates. Drawing or supplying more power than 'scheduled' is now heavily frowned upon, and is less widespread than it used to be. "Perhaps the biggest lesson has been in terms of controls at each point, from the level of the individual power station onward, so as to be able to respond to fluctuations in demand," points out Chitkara. With South India likely to be integrated into the national grid by 2014, engineers and grid planners face a race against time to upgrade infrastructure and enforce regulations. The costs of any failure will now be much higher than they were last year. India's biggest blackout continues to make its presence felt long after the lights came back on.

×