How does the solar wind affect power grids?

[rachelph]

I'm reading about solar wind and the effects it has on Earth. The charged particles from the solar wind have the potential to affect power grids which can cause outages. I know that it is related to electromagnetism, but how exactly does this happen?

 

[anorlunda]

I'm reading about solar wind and the effects it has on Earth. The charged particles from the solar wind have the potential to affect power grids which can cause outages. I know that it is related to electromagnetism, but how exactly does this happen?

That's a good question.

Solar discharges (https://en.wikipedia.org/wiki/Solar_storm) can and do effect the power grid (and satellites, and pipelines, and communications as well as making beautiful aurora in the sky). They have caused power outages, most notably in Quebec in 1989. However, since 1989 we have experienced hundreds of solar storms stronger than the 1989 one. Almost all of those were greeted by newspaper and Internet forecasts of widespread blackouts and societal chaos. None happened. I think it is safe to conclude that power companies have figured out how to withstand them pretty well. But it requires effort and vigilance to protect the grid. I have a friend employed by TVA who's full time job is to research ways to harden the grid against such disturbances.

The mechanism is pretty simple. Usually, the electric potential of the Earth is pretty much the same everywhere. We like to call it ground and to arbitrarily say that is "zero voltage". When there is a solar storm, charged particles hit the Earth's surface in some places distorting the Earth's magnetic field causing voltage gradients in the ground. I just tried looking up the numbers for the voltage gradients, but I failed (I used to have shelves of reference books, and piles of technical journals, but today I only have Google.) Years ago, I recall hearing that the voltage gradients caused by solar storms were millions of volts over thousands of miles.

If you want a more technical (and boring) description of what happens, try this.

Geomagnetic disturbances pose a hazard to power systems because the [Ground Induced Current] flow through transformer windings and create a magnetic field that can saturate the core of the transformer. This causes the normal (60 Hz or 50 Hz) AC magnetic flux to spread out through the windings and structural members of the transformer producing eddy currents that can cause hot-spots which may severely damage the transformer. Also, the extra magnetising current drawn by the transformer for the part of each AC cycle when it goes into saturation results in a very spikey AC waveform with a high harmonic content. These increased harmonics can initiate resonance or cause faulty operation of relays and other equipment on the system leading to problems ranging from trip-outs of individual lines to collapse of the whole system (Kappenman, 1996).

 

[davenn]

However, since 1989 we have experienced hundreds of solar storms stronger than the 1989 one. Almost all of those were greeted by newspaper and Internet forecasts of widespread blackouts and societal chaos. None happened. I think it is safe to conclude that power companies have figured out how to withstand them pretty well. But it requires effort and vigilance to protect the grid. I have a friend employed by TVA who's full time job is to research ways to harden the grid against such disturbances.

have we ?? ... not that I'm aware of
the last solar max was very poor

there's only been a couple of geomagnetic storms as large /larger than the 1989 event

The Halloween solar storms were a series of solar flares and coronal mass ejections that occurred from mid-October to early November 2003, peaking around October 28–29.[1][2] This series of storms generated the largest solar flare ever recorded by the GOES system, modeled as strong as X45 (initially estimated at X28 due to overloading GOES' detectors).[3][4] Satellite-based systems and communications were affected, aircraft were advised to avoid high altitudes near the polar regions,[5] and a one-hour-long power outage occurred in Sweden as a result of the solar activity.[2] Aurorae were observed at latitudes as far south as Texas[2] and the Mediterranean countries of Europe.[5]

and the

The Bastille Day Flare or Bastille Day Event was a powerful solar flare on July 14, 2000, the national day of France, occurring near the peak of the solar maximum in solar cycle 23.[1][2] The X5.7-class flare originated from a sunspot known as Active region 9077, which subsequently caused an S3 radiation storm on Earth fifteen minutes later as energetic protons bombarded the ionosphere.[1][3] It was the biggest solar radiation event since 1989.[3] The proton event was four times more intense than any previously recorded since the launches of SOHO in 1995 and ACE in 1997.[1] The flare was also followed by a full-halo coronal mass ejection[1] and a geomagnetic super storm on July 15–16. The geomagnetic storm peaked at the extreme level, G5, in the late hours of July 15.

The other 100's of ones you mention are all very much smaller ones
We have even been in geomagnetic storming over the last 3 days.

The mechanism is pretty simple. Usually, the electric potential of the Earth is pretty much the same everywhere. We like to call it ground and to arbitrarily say that is "zero voltage". When there is a solar storm, charged particles hit the Earth's surface in some places distorting the Earth's magnetic field causing voltage gradients in the ground.

no they don't, fortunately for us. The Earth's magnetic field protects us from them. It is the wavering/motion of the geomagnetic field that induces large currents into long pipelines and power transmission line runs

Dave

 

[anorlunda]

have we ?? ... not that I'm aware of
the last solar max was very poor

The solar max refers to the frequency of solar storms, not necessarily to their intensity. But I think you're right, I overstated when I said 100s of equal size. It just seems like once per month or so that I read of another impending storm in the news.

 

[davenn]

The solar max refers to the frequency of solar storms, not necessarily to their intensity. But I think you're right, I overstated when I said 100s of equal size. It just seems like once per month or so that I read of another impending storm in the news.

continue reading what I wrote

 

[davenn]

The solar max refers to the frequency of solar storms, not necessarily to their intensity. But I think you're right, I overstated when I said 100s of equal size. It just seems like once per month or so that I read of another impending storm in the news.

you should spend some time in the astronomy section of the forum where I regularly post about the sun, flares, coronal holes geomagnetic storms and aurora I have also asked for this thread to be moved to the astronomy section

 

[anorlunda]

continue reading what I wrote

I may be wrong again , but it's unclear. The Wiki article plots # of sunspots versus time, but the only thing about intensity is this.

Large solar flares often occur during a maximum. For example, the solar storm of 1859 struck the Earth with such intensity that the northern lights were visible as far from the poles as Cuba and Hawaii.[2

It would be hard to get clean statistics because there a three factors. 1) The frequency, 2) The intensity, and 3) Their direction which can be towards or away from Earth. Perhaps you know. Of every 100 solar flares, how many intercept Earth's atmosphere?

But one thing we can never change, no matter how much experience we have, someone can always write an article predicting that tomorrow's storm will bring the grid down. The same applies to articles about cyber attacks.

 

[rootone]

The same applies to articles about cyber attacks.

Best strategy is turn your modem/router off, then get some sleep.

 

[davenn]

I may be wrong again , but it's unclear. The Wiki article plots # of sunspots versus time, but the only thing about intensity is this.

The Sun goes through an 11 year solar cycle. That is every 11 years we reach a peak in activity where there are many more spots visible than at the minimum times. Yes there are many more flares during maximum years than during the minimum years, because there are more spots. Currently we are pretty close to the minimum of cycle 24 and even at this time the sun can surprise us. It was only a month and a bit ago (7th Sept) that one particular spot group really fired up and produce several X class flares. The largest of them, a X9.3, was the largest flare in the last 10 - 12 years.
See posts 5, 6, and 7 in this thread -- https://www.physicsforums.com/threads/solar-imaging-and-techniques.925656/
showing sunspots I imaged during that burst of activity.

The size of the flare is not always an indication of if it will produce strong geomagnetic storming or not. It has been recorded over the years, that sometimes smaller flares can produce stronger geomagnetic storming than larger ones. This is because not all flares, large or small, are associated with coronal mass ejections (CME's). Some flares can be stronger in the radio and X-ray emissions than with the ejection of protons and electrons (CME constituents)

It would be hard to get clean statistics because there a three factors. 1) The frequency, 2) The intensity, and 3) Their direction which can be towards or away from Earth.

All these 3 things are well known for every significant flare.
There are 4 classes of flares, B, C, M and X. It's the M and X class flares that cause noticeable to severe geomagnetic storming particularly if the spot group that produces them is reasonably central to the centre of the solar disk ( anywhere near directly facing us). Their effectiveness drops off the closer to the edge of the disk they get.

Perhaps you know. Of every 100 solar flares, how many intercept Earth's atmosphere?

If they are face on to the Earth ... all of them will interact with the Earth environment in one way or another. What that interaction will be will depend on
what the flare emitted/ejected. Let's take an example of what can happen ...

A strong M 7.7 flare that has strong radio, X-ray and CME
... Effects ... radio emission will cause huge bursts of noise right across the spectrum from HF through VHF and into UHF
... Effects ... X-ray emission will cause HF radio SWF's (shortwave fadeouts) to complete blackouts worldwide. This is because the X-rays ionise the D-Layer (lowest layer) of the ionosphere and this stops the HF (1 - 30MHz) frequencies from reaching and refracting of the F-Layer that they rely on for long haul propagation. These can be seen on lower latitude radio paths are sometimes restricted to the polar regions with what are called PCA events
(Polar Cap Absorption events).
... Effects ... CME's are what cause the auroral displays at both poles. They consist of large numbers of high speed (600 - 1200km/second) protons and electrons that get trapped in the Earths magnetic field and spiral down the field lines towards the north and south magnetic poles. Once these charges particles penetrate the atmosphere deep enough, they collide with atoms of oxygen and nitrogen in the upper atmosphere at ~ 50 to 100km causing these atoms to be ionised and glow in the same way a neon tube shop sign does.
During this time that the Earths magnetic field is being buffered by this particle onslaught, it is continuously pulsating and changing in strength and density.
It is this that is causing the huge induced currents into long runs of pipelines and power grids ... stationary conductors in a moving/varying magnetic field.There can be no end to the variations of the above example as no two flares are the same in their amounts of emission in those three main area.Dave