PULLMAN, Wash. - A model developed by Washington State University researchers can predict how transmission towers might fail and collapse in extreme wind events.
The work, reported in the journal, Engineering Structures, could someday help power companies identify the most vulnerable transmission towers in extreme wind events and determine which should have retrofits to reduce the power outage risks.
"This can be really useful from the utility company's perspective because they want to investigate power outage risk within the region, but their power networks are often distributed across multiple counties," said Ji Yun Lee, corresponding author and associate professor in WSU's Department of Civil and Environmental Engineering. "They are dealing with many power grid components and transmission towers. They want to investigate which transmission tower might be the most vulnerable to wind events, and which tower might require some kind of mitigation or structural retrofit, so that they can reduce the power outage risk."
Reliable power delivery around the U.S. and the world depends on numerous interconnected components for power generation, transmission, and distribution. Transmission towers that support high-voltage transmission lines and carry electricity over long distances are particularly vulnerable to natural hazards such as extreme wind. Their thin steel lattices often sit in windy spots, and when a hurricane or tornado occurs, the towers can topple or be damaged, causing power outages over large areas.
Unlike when a power line or power pole is damaged, a transmission tower failure can impact a large community and power network. In the case of one hurricane in 2021, for instance, 150-mile-per-hour winds destroyed hundreds of miles of transmission lines across the state of Louisiana with nearly 1 million people losing power.
Researchers developed a physics-based simulation framework that used surrogate approximations to quickly estimate the likelihood of failure for different transmission tower designs across entire networks.
"Transmission towers are not like individual buildings standing alone," said Abdel-Aziz Sanad, first author and a PhD candidate in the Department of Civil and Environmental Engineering. "They are a network connected together, so it's really important to identify potential failure locations or weakness locations in this network."
Researchers traditionally have looked at historical data for an area or assessed one tower at a time to decide if it is vulnerable, which is impractical for real-world operations to analyze tower designs over a large area simultaneously.
"That is the simplest approach, but it is very specific (to one tower)," said Sanad. "It's hard to generalize to future cases. They don't have a lot of strong predictive capabilities for future events, which is something that is important - we want to use this knowledge for the future."
In their work, the researchers developed a physics-based simulation framework that used surrogate approximations to quickly estimate the likelihood of failure for different transmission tower designs across entire networks. The surrogate accounts for towers that might have different heights and sizes and follows a similar technique that has been used in other areas like, for instance, to understand and predict the behavior of bridges or buildings in earthquakes.
"An approximation reduces the computational time that we need to perform these heavy simulations," said Sanad. "We approximate them, but we still maintain physical consistency and a high level of accuracy. Once these surrogates are created, they are so much faster to use in the real world."
Their framework incorporates several separate factors that might impact a transmission tower and occur concurrently in an extreme wind event, including the wind speed, wind direction, and rainfall intensity. The researchers found that, on average, their model can predict the structural behavior of such towers with 96% accuracy. The work was funded by the U.S. Department of Energy.
