(John Kemp is a Reuters market analyst. The views expressed are
his own)
LONDON, Aug 1 (Reuters) - The precise cause of widespread
power failures that cut electricity supply on Tuesday to states
where half of India's 1.2 billion people live will take many
months to establish, and may never be known for certain.
So any analysis at present must be speculative.
The most likely explanation is a small localised problem
that rippled across the network as grid managers lost control of
power flows and automatic relays shut down transmission lines
and power plants to prevent further damage to equipment.
India needs more power generation and transmission capacity
but that will not solve the problem on its own. Even more
urgently, India needs investment in grid control technology, a
smarter grid, and a thorough review of operational procedures to
reduce the likelihood that massive power failures will recur.
LOSS OF CONTROL
Cascading power failures are not uncommon in transmission
systems under stress. In 2003, cascading failures knocked out
power to more than 50 million people across the north-eastern
United States and parts of Canada, some for as long as four
days.
On the afternoon of Aug. 14, 2003, a local problem in the
Cleveland-Akron area of Ohio that had been rumbling all
afternoon spread like a tidal wave across the network, shutting
down 508 generating units at 265 separate power plants in less
than five minutes, including emergency stoppages at 10 nuclear
stations.
As automatic relays shut down the most overloaded
transmission lines and vulnerable power generators, electricity
surged around the rest of the network taking increasingly
unpredictable pathways, unbalancing more and more parts of the
system, and forcing further emergency shutdowns, until the grid
and power generation collapsed across the entire region
.
Something similar appears to have occurred in northern India
on July 30, shutting down power supply to nine states including
Delhi on the country's northern grid region. (http://www.powergridindia.com/PGCIL_NEW/exlink.aspx?Pageid=P:2108)
It was followed by an even more widespread collapse the next
day, that included not just the northern grid but also the
eastern and north-eastern power grids, extending power failures
to 18 states and two territories covering half the population.
The country's other two grids (western and southern) appear to
have been unaffected.
On July 30, a disturbance occurred on the northern grid at
2.35 a.m., according to Power Grid Corporation of India, which
manages the network. Power was restored by using
hydro-generation and sourcing electricity from the neighbouring
western and eastern systems to help restart thermal generators
across the northern area, according to the grid controller.
On July 31, however, another disturbance hit the three
northern, eastern and north-eastern regional networks at 1.00
p.m. Power Grid Corporation responded by routing power up from
the unaffected western and southern grids, as well as maximising
hydroelectric generation across the northern region.
LOCAL PROBLEMS
The simple response is to blame a growing imbalance between
supply and demand. The country's aging power system is
struggling to cope with underinvestment and booming demand,
including widespread theft and non-payment problems, as well as
extensive subsidies and artificially low tariffs. India's
rapidly growing economy is bumping up against the limits imposed
by an underdeveloped power generation and transmission system.
But such analysis is simplistic. Even severe imbalances
between supply and demand should not cause widespread grid
collapse.
Properly engineered and run networks have multiple
mechanisms for managing supply/demand imbalances, including:
extra generation from frequency and spinning reserves which can
be called up at short notice; demand management; voltage
reduction; and ultimately forced load shedding, where power is
cut to certain users and areas to protect supplies to the rest
of the network.
In a system under stress, however, even tiny problems can
escalate to knock out power to tens of millions or even hundreds
of millions of users.
In the case of the August 2003 blackout, an extensive
investigation by the U.S. and Canadian governments traced the
failure back to something as apparently trivial as tree growth
and hot summer weather, which caused a handful of small local
transmission lines to overload after sagging in the heat and
becoming entangled in branches.
It escalated into a crisis because of computer system
failures and poor communications and operating practices among
grid controllers. There wasn't even an overall imbalance in
power supply and demand. There was plenty of power, just not the
right sort in the right places ("Final Report on the August 14
2003 Blackout" April 2004).
POLICY LESSONS
In India, the original cause of the power failure is not yet
known (and may never be known because such investigations are
exceptionally complex). Whether a transmission line failed, a
generator went offline unexpectedly, a sudden uptick in demand
exceeded supply, or someone somewhere in the grid control system
made a mistake, or some combination, is not yet known.
But both the August 2003 and August 2012 blackouts are signs
of power systems operating under stress. In the 2003 incident,
the joint U.S.-Canadian task force issued 46 separate
recommendations, mostly focused on improved grid control.
India's problems are more complex and will be more expensive to
resolve.
Soaring power demand has eroded the margin of spare reserves
in the generation system, leaving grid controllers with less and
less room for error. Limited transmission capacity within the
five regional grids as well as between them reduces system
flexibility further in the face of local problems.
There may also have been some element of human error,
computer failure or weaknesses in operating protocols, though
that will only become known after a lengthy enquiry by the grid
company and the government.
Simply adding a few more power plants to boost nationwide
generation capacity would not in itself avoid the kind of
cascading failures reported this week. After all, the United
States and Canada suffered a similar crisis even though there
was no overall shortage of power generation in the region at the
time.
No power system can ever be 100 percent robust. Power
systems are the biggest machines ever built by mankind, and
their interconnectedness means there is always some risk that a
problem with one tiny part will bring widespread collapse.
Problems are not limited to developing countries. In North
America, there have been eight comparable grid failures since
1965, affecting between 2 million and 50 million people each
time, according to a listing presented in the task force's Final
Report.
The North American task force identified a number of common
factors in most of these eight outages, including "(1) conductor
contact with trees; (2) overestimation of dynamic reactive
output of system generators; (3) inability of system operators
or coordinators to visualize events on the entire system; (4)
failure to ensure that system operation was within safe limits;
(5) lack of coordination on system protection; (6) ineffective
communication; (7) lack of 'safety nets'; and (8) inadequate
training of operating personnel."
What India needs is a comprehensive upgrade of its power
system. Upgrades will involve some combination of more
generation capacity, more transmission lines (the often unloved
part of the system), and better grid control, as well as new
pricing and billing systems to ensure customers pay the full
marginal cost of their supply and reduce theft and wasteful use.
Part of that is a smarter power grid. The smart grid concept
is most often associated with the United States, where it has
been heavily promoted by the Obama administration, and
specifically smart metering designed to manage peak-time power
consumption by encouraging more load-shifting and use of
off-peak power by households and small businesses.
But the biggest gains are likely to be in developing
countries, using technology to upgrade grid management and
control. Smart grid technology can report unusual fluctuations
at any point across the grid in a matter of seconds. Linked with
better control systems, it can initiate procedures to protect
the grid and prevent widespread power failures, isolating
problems in a sub-region, rather than letting them spread across
the network like wildfire.
(Editing by Anthony Barker)
