PIK Researchers Devise Ways To Protect An Electrical Grid From More Powerful Storms

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Researchers at the Potsdam Institute For Climate Impact Research, known as PIK, using a statistical model of the Texas electrical grid, say they have found a way to guard against widespread power outages from more powerful storms and hurricanes by better protecting a few critical grid components. Their research was published in the journal Nature Energy on March 1, 2024. Here is the abstract of that report:

“The Texas power grid on the Gulf Coast of the United States is frequently hit by tropical cyclones causing widespread power outages, a risk that is expected to substantially increase under global warming. Here we introduce a new approach that combines a probabilistic line failure model with a network model of the Texas grid to simulate the spatio-temporal co-evolution of wind induced failures of high voltage transmission lines and the resulting cascading power outages from seven major historical TCs.

“The approach allows reproducing observed supply failures. In addition, compared to existing static approaches, it provides a notable advantage in identifying critical lines whose failure can trigger large supply shortages. We show that hardening only 1% of total lines can reduce the likelihood of the most destructive type of outage by a factor of between 5 and 20. The proposed modelling approach could represent a so far missing tool for identifying effective options to strengthen power grids against future TC strikes, even under limited knowledge.” PIK scientist and study author Frank Hellmann said.

“For the first time, our analysis shows how an electric network reacts to evolving storms. By simulating the co-evolution of wind-induced failures of high-voltage transmission lines and the resulting cascading power outages, we discovered which parts of the electricity network are most critical as their failures have cascading impacts leading to major power outages. This appears to be a property of the network itself, rather than the storm’s precise path.”

The scientists coupled a model of the evolution of the wind fields of tropical cyclones with a dynamic model of the Texas power grid that helped to describe the evolution of storm induced cascading power outages. “This is a challenging task, as the time scales at which storms and power outages evolve can be very different. By combining PIK expertise on the event-based modeling of tropical storms and power grids, we managed to identify the critical lines, whose failure can trigger large blackouts,” says scientist Mehrnaz Anvari, who conducted the research at PIK and is now group leader of Network Evaluation Technologies at the Fraunhofer Institute for Algorithms and Scientific Computing.

Preventing Major Electrical Grid Failures

“We found that the failures of certain lines can trigger large scale outages affecting whole regions or cities. Regions or cities fail in one major cascade, rather than gradually. Our research shows that such cascades can be avoided almost entirely if less than 1 percent of the overall grid — this is 20 lines in the case of the Texas power grid — is protected against storm damages, for example by reinforcing transmission towers or using underground cables. This way, the risk of outages in major population centers can be significantly reduced. Notably, protecting the same small set of relevant lines works for all seven historical hurricanes considered,” said study author and PIK scientist Christian Otto.

The Texas electric power system, which is frequently exposed to hurricanes and weaker tropical storms, provided the perfect context to study these complex effects and potential adaptation options in depth. The scientists developed a model that simulates the storms’ damages to the Texas power grid and studied 10,000 realizations of potential damages for each of seven historical tropical cyclones, including the major hurricanes Harvey (2017) and Ike (2008). Their approach allowed the researchers to reproduce the electrical grid failures that occurred as a result of those storms.

“Tropical cyclones are one of the most destructive categories of extreme weather events. As peak wind speeds of the most intense storms are projected to increase with global warming, the damage caused by these storms is likely to increase unless we adapt accordingly. Our new method gives grid operators a crucial tool to identify effective adaptation options and can help make our infrastructure networks fit for a new climate reality,” says Katja Frieler, the head of the research department at PIK.

Hardening Critical Electrical Grid Lines

The researchers found that hardening as few as twenty critical power lines — by placing then underground, for instance — can dramatically reduce the likelihood of electrical grid outages. “We order the lines according to their priority index and evaluate the impact of the tropical cyclone on the system after hardening the most critical one to 20 lines. The probability of large power outages is reduced smoothly when the number of hardened lines is increased.”

“After hardening the 20 most critical lines identified by the co-evolution model, the probability of large scale outages is reduced by a factor 5 to 20. Smaller storms rarely trigger large power outages and cascading failures anymore, and the probability is dramatically reduced for the most damaging storms Harvey and Ike.

“The level of outage reduction reached by hardening the lines according to the priority index derived from the co-evolution model is generally higher than the protection of the same number of lines selected according to the priority index derived by the static model.

“The static model allows identifying some of the most critical lines, but the marginal reduction in large outage probability saturates already after 6 – 10 lines. For the co-evolution model, additional hardening continues to be effective until at least 20 lines. This demonstrates that the latter, with its detailed picture of the partially destroyed states, reveals genuine and critical information for increasing the resilience of the system. These results are robust when assuming randomized failure rates.”

The trick, of course, is knowing with 20 lines need hardening. That’s what the PIK method is designed to find out so grid operators can take appropriate action.

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The Trigger Effect

Many of you may be familiar with the work of James Burke, who created a PBS show called Connections — An Alternative View Of Change. It was a fascinating series that in one episode focused on the Great Blackout that plunged the entire Northeast corner of the United States into darkness in 1965.

Ultimately, the cause was traced to one circuit breaker on a high voltage transmission line in Canada that failed and caused a cascade of other failures until millions of people were affected. That episode of Connections was called The Trigger Effect and presaged Malcom Gladwell’s The Tipping Point that came along a few decades later.

If you are not familiar with James Burke, YouTube is your friend. That episode is shown in full in the video below and is well worth watching if you have the time.