Loss of wind causes Texas power grid emergency

http://www.reuters.com/article/idUSN2749522920080228">Loss of wind causes Texas power grid emergency

It's also more than a month old.

WHY THE TEXAS RELIABILITY EVENT ON FEBRUARY 26, 2008
RAISES NO CONCERNS ABOUT MUCH HIGHER WIND PENETRATION

On February 26, 2008, a drop in frequency on Texas’s transmission grid caused the
Electric Reliability Council of Texas (ERCOT) to put in place an Emergency Electric
Curtailment Plan. The event was reported in some media outlets as having been caused
by a sudden drop in output from wind projects. In fact, as the information below makes
clear, other factors had a greater impact in this particular incident. Over the 40-minute
period preceding the start of load curtailment, wind generation declined by 80 MW
relative to its schedule, non-wind generation decreased by 350 MW relative to its
schedule, and load rapidly increased to a level that was 1,185 MW more than forecast.
More generally, disturbances of this type routinely involve conventional power plants.
The incident in reality shows that the key to successful electric system management lies
in a diverse power supply, of which wind can reliably be a large part. AWEA (the
American Wind Energy Association) has pulled together the following background
information and highlights from the report issued by ERCOT on the event. This provides
both perspective on the event and insights into the issues going forward.

ERCOT's full report is available at:
http://interchange.puc.state.tx.us/WebApp/Interchange/Documents/27706_114_577769.PDF

Complex electric systems are comprised of many dynamic parts, including power plants,
fuel supplies, power delivery infrastructure, and aggregate levels of consumption.
Maintaining the reliability of an electric system requires robust operating procedures to
handle contingencies, including multiple simultaneous events. As this report establishes,
ERCOT has such procedures in place and they work. Yet, particularly as regional fuel
sources and power options are diversified, there are improvements to grid operating
procedures that can and should be made. As an action item in response to this event,
ERCOT has determined to incorporate wind forecasting into short term planning to better
inform its capacity procurement needs. The wind industry supports and applauds that
conclusion, as it will enable continued diversification of power supplies while
maintaining the robustness and reliability of the grid. As a GE study commissioned by
ERCOT recently reported, with the use of wind forecasting wind energy deployment in
Texas can be more than tripled to at least 15,000 MW without negative consequences for
system reliability.

GE’s study is available at:
http://www.ercot.com/meetings/ros/keydocs/2007/1022/Variablity_and_Predictability_draft_dlvd_2
a.zip

Some observations regarding the February 26, 2008 ERCOT event:

1. The drop in frequency was successfully managed and no customers involuntarily
lost power. The event was the result of several factors including sudden output
shortfalls from conventional generators and a much slower decline in wind output.
To the extent that changes in wind were a contributing factor during the passage of the
February 26 cold front, that can be resolved by integrating the use of wind forecasting
into electric system management, as ERCOT is planning to do.

2. Wind is not dispatchable, but it is generally predictable, and therefore can be
successfully and reliably integrated into electric system management. Wind
forecasting accurately predicted ERCOT's February 26 decrease in wind generation. This
event illustrates that wind forecasting is an important tool for the successful management
of large amounts of wind generation on a grid. ERCOT’s wind forecasting system is
under development and they plan to accelerate its implementation. When it is in place,
such changes in wind output would not be expected to contribute to any system problems.

3. Unlike other sources of generation that can go offline in 1/60th of a second, wind's
declining output tends to be gradual over a matter of hours, giving system operators
more time to respond to changes. Fossil and nuclear power plants can and frequently
do trip offline instantaneously, as the power outage on February 26 in Florida
demonstrated. In ERCOT, 13 conventional generating plants instantaneously tripped
offline during the week following February 26th. In the largest of these incidents, 420
MW, 500 MW, 540 MW, 582 MW, and 650 MW were instantaneously lost because a
conventional generating unit tripped offline. The February 26th incident was preceded
by the loss of a 150 MW non-wind generating unit that tripped offline at 5:44 PM. In
comparison, wind generation decreased steadily on February 26 by about 8 MW/minute,
during a 3-hour interval.

4. The event was caused by a combination of factors, one of which was non-wind
generators falling short of their scheduled output. The activation of responsive
reserves and interruptible load reserves at 6:49 PM on February 26 immediately followed
a 40-minute period during which conventional generation dropped by 350 MW relative to
its schedule. Although wind was consistently below its scheduled output during this time
period, from 6:27 to 6:50 wind output gradually increased by 40 MW relative to its
schedule.

5. Another factor that contributed to the event was the rapid rate of load increase
that evening. The load increase on the evening of February 26th was 3,150 MW larger
than the previous evening’s load increase. As a result, ERCOT’s short-term load forecast
underestimated the actual load at 6:45 PM by 1,185 MW.

6. To sum up, over the 40-minute period preceding the start of load curtailment,
wind generation declined by 80 MW relative to its schedule, non-wind generation
decreased by 350 MW relative to its schedule, and load rapidly increased to a level
that was 1,185 MW more than forecast.

7. The use of “demand response” is not unusual and is a proven tool in cost-
effectively maintaining grid reliability. ERCOT is a leader in the use of paid voluntary
interruptible loads (demand response) to accommodate significant variations in load, the
sudden loss of conventional generation plants, and to avoid subjecting customers to
involuntary power outages. For example, on December 12, 2007, three conventional
generation plants totaling 1,022 MW tripped offline. Frequency on the ERCOT grid
dropped from 60 to 59.787 Hz, significantly worse than the drop from 60 to 59.85 Hz that
was registered on February 26. According to ERCOT, this qualified as a potential NERC
Disturbance Control Standard event, while the February 26th event did not. In the
December 12th incident, ERCOT was able to prevent an involuntary power outage by
deploying all of the interruptible load reserves that were available.

I was going to point out that conventional plants have the same sort of problems in unusual weather, but I didn't think it was worth it.

But I'm glad you did it. :)

I guess it's OK when you do it.

This one specific item easily verified item totally refutes the assertion in the OP:

To sum up, over the 40-minute period preceding the start of load curtailment,
wind generation declined by 80 MW relative to its schedule, non-wind generation
decreased by 350 MW relative to its schedule, and load rapidly increased to a level
that was 1,185 MW more than forecast.


The unscheduled loss of non-wind generation was 4X the loss from wind, and the increase in demand was about 15X the drop in wind.

You are dripping drool again...

not too be to bitchy but still pissed off over what the Bush Cabal did to California.
we are going to have too have more wind energy but the backup systems / intelligent grid is still along way off