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How researchers aim to protect the power grid from the northern lights’ dark twin

Magnetic currents from the sun can damage the power grid while the northern lights dance across the sky. Researchers now have new methods that can make us better prepared.

Green aurora above a power line in northern Norway at night
Northern lights over the Skillemoen-Skaidi power line in northern Norway. But what’s happening beneath the Earth's crust?
Hege Tunstad Hege Tunstad Hege Tunstad Journalist at Norwegian SciTech News
Presented by: Presented by: Presented by: SINTEF
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Activity on the sun is at its strongest right now. Periods of such intense activity occur about every 11 years and follow a well-known cycle.

While the northern lights splash their colourful displays across the sky, researchers are studying its dark twin: geomagnetic storms.

These are magnetic storms that come from the sun. They ‘shake' their way into the ground, spread outwards, and can create problems for transformer stations.

A transformer is an electrical device that changes the voltage of electricity, either up or down. In the power grid, these are used to make electricity safe to transport over long distances and safe to use at home.

But not all transformer stations are at risk, just a few. Some stations are located in more sensitive locations than others. Why is that?

Illustration of the Sun’s eruption and its charged particles impacting Earth’s magnetic field.
The sun ejects particles that create both beautiful auroras and dangerous space weather. It creates a geomagnetic effect that we don’t know enough about.

This is one of the questions that researchers are seeking answers to. That is why they are studying how magnetic storms induce electrical currents in the ground.

Part of the answer may lie in events that have occurred in the Norwegian municipalities of Namsos and Sandnes. 

In both places, transformers were manually disconnected at the start of a strong solar storm.

This was done because monitoring measurements showed that they were about to be overloaded.

Vibrations that disrupt alternating current

But what are these events?

“Geomagnetic storms are like nature’s bass frequencies. They’re invisible, but when they hit the right spot, they can cause a transformer to crackle – just like a speaker that is pushed too hard,” says Kristian Solheim Thinn, a researcher at SINTEF Energy.

Portrait photo of man
Kristian Solheim Thinn is an expert in electrical power supply – more specifically power cables, solar storms, and electromagnetic fields. Here he shows the insides of a power cable.

A geomagnetic storm is nature’s way of cranking up the volume in the Earth’s magnetic field. 

This creates an electric field in the Earth’s crust that can push unwanted and harmful currents into power lines and transformers – all without anyone having touched a switch.

Graph
The blue graph shows how great the geomagnetic activity is, so the effect of the solar storm on the ground. The grey dotted line shows when the transformer station in Namsos was affected.

This is exactly what happened in Namsos in 2024. 

A transformer received so much low-frequency 'noise' from the ground that it simply gave up and was disconnected from the power grid. 

The vibration in the area was strong enough to be felt in the very heart of the power system.

“We can compare them, but transformer stations aren’t loudspeakers. And they react a little differently,” says Spencer Hatch. 

He is a researcher at the University of Bergen and heads a project called New model of induced currents in Norwegian transformer stations.

Induced means that something is set in motion by something else. When a geomagnetic storm hits Earth, it can create induced currents that may affect the power supply.

“In other words, changes in the magnetic field, and not the absolute volume, are what have an impact. These changes become particularly strong when something large coming from the sun first hits the Earth’s magnetic field and triggers the storm,” he explains.

Selfie of man climbing the mountains with an orange helmet
Spencer Hatch is a researcher at the University of Bergen.

Not exactly off-the-shelf goods

Solheim Thinn explains that geomagnetic storms cannot be stopped. It's therefore necessary to be prepared.

“In the worst case, the storm could result in major consequences for our transformer stations if we don't catch this in advance. We're now working on finding out exactly what happened in Namsos and elsewhere in the country. Then we can update the models we use to monitor the load our power grid is exposed to,” he says.

Engineer in high-visibility gear installing solar storm meters on a large power transformer.
Installation of solar storm metres on a Norwegian transformer. Disturbances caused by solar storms can create strong direct currents that can damage transformers.

Strange magnetic phenomena

The currents that spread in the ground are conducted in different ways depending on the local ground conditions. 

Researchers will therefore create a new map of how these geomagnetically induced currents can spread. These will then be combined with an overview of what the power system looks like today.

Once they have stitched all this information together into a new model, they will be able to both understand past events and simulate extreme events before they happen, such as a once-in-a-century solar storm. 

Such a storm could likely occur within just a few years.

Weather map for magnetic fields in the ground

To find out how solar storms create electric fields in the ground, researchers must first understand how the magnetic field over Norway behaves from second to second. 

Researchers have measurements from a whole chain of magnetometres, or solar storm sensors, located around the Nordic region.

“Instead of looking at one sensor at a time, we use a method that allows us to stitch together all the measurements into a kind of weather map of the magnetic field variations, such as how the field shakes and undulates over the ground in real time,” says Hatch.

Once this map is in place, it will be combined with information about the type of bedrock and soil layers that exist beneath us. 

Different types of rock conduct electricity differently. This affects how strong the electric fields become when the magnetic field fluctuates.

Finally, the researchers will use this combination – the magnetic field map and knowledge of the ground – to calculate how strong the electric fields are along the power lines around a transformer station. 

In this way, they can assess how much storm force a station can withstand.

A crystal ball for weather predictions

The new model will not only explain what is happening in and around Norwegian transformer stations right now.

It will also make it possible to look a little further into the future.

The model is fed with real-time measurements from Norwegian and Nordic magnetometers. It runs continuously while the magnetic field above us is fluctuating.

“The model will give us a good decision-making basis for operating the power system safely and reliably. We don’t want to overload and thereby destroy the transformers. On the other hand, we also don't want to disconnect them until it's absolutely necessary, when the storms are at their worst and can lead to power outages over large areas,” Thinn says.

A concrete warning system aimed at the power grid could be in place in a short time. It will be based on the research currently being conducted by the University of Bergen, SINTEF, Statnett, and UiT The Arctic University of Norway.

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