Some Atomic Insights readers don’t like it when I use the term “unreliables” to describe weather dependent power sources like wind and solar energy. They believe that word is demeaning and not entirely accurate, especially in certain system designs where wind turbines are partnered with hydro or pumped storage.
Even in that situation, however, the wind is not under the control of automated systems or human operators, so it can disappear when it is most needed or blast in when it is not wanted. Recently, the Bonneville Power Administration (BPA) which operates a grid supplied with a large fraction of hydro, 4,500 MWe of distributed wind turbines and a small amount of thermal generation experienced some of the wild weather gyrations that are not actually uncommon.
Here are the tweets I posted to highlight the challenges the weather was imposing on the system operators.
Since link to BPA is dynamic, I thought I’d capture the past 7 day image for posterity pic.twitter.com/XG4gL5d6TR
— Rod Adams (@Atomicrod) November 21, 2014
After a week in which the wind barely whispered, it returned with a vengeance, ramping from zero to 4,000 MWe within 12 hours. During part of that time, the slope of increased generation approached a vertical line.
On Nov 21, wind woke up and roared back into the BPA grid – from zero to 4,000 MWe in just 12 hours. Quite a ramp. pic.twitter.com/qh4ZWVQGRq
— Rod Adams (@Atomicrod) November 22, 2014
I suspect that the dip in wind production at midnight on November 22 came as a result of curtailing wind generators to prevent grid instability as the wind generation approached 75% of the total load on the system at that time of day.
It must have been an interesting time to be in the grid control room.
Update: (Posted 11/25/2014 at 17:00) An Atomic Insights reader reviewed the detailed history files available at the BPA web site and informed me that there was no curtailment of wind turbines at midnight on November 22. I responded to his comment. The above post has also been modified to remove the phrase “In fact,” before the words “I suspect.”