Remember Northern Pass, that 1,200 MW transmission line through New Hampshire to Quebec that never got built because people balked at putting it through the White Mountains? Imagine how much easier life would have been if they just could have just pushed that much more electricity through existing lines.
That is the idea behind dynamic line rating, which uses a combination of sensors, weather forecasting, analytical models and digital systems to let grid operators know when they can safely send more energy through transmission lines than they thought they could.
“In some cases, that additional capacity can reduce or defer the need for costly upgrades, such as building a new line or adding a substation,” said Junbo Zhao of the Thayer School of Engineering at Dartmouth College.
His team and Eversource have received federal go-ahead to implement such a system throughout the utility’s 4,000 miles of transmission lines in New Hampshire, Massachusetts and Vermont. It’s a four-year, $95 million project, half of which comes from a federal grant and half will be paid by Eversource ratepayers in the three states.
“Many places in the U.S. are doing pilots … each utility wants to have its own pilot. This is the natural further step,” said Zhao. “Everybody’s very excited about this technology and wants to see it scale up, to see the full benefits.”
It might be exciting, but the project won’t be very visible, at least not to you and me.
“Unless folks are climbing up transmission towers, I don’t think anybody is going to see anything different,” said Ben D’Antonio, director of economic analysis and strategy for transmission for Eversource. The sensors, he said, “look like a small solar panel and a camera.” Nothing more noticeable, like drones, is involved.
What really matters for this project and will take the most practice is deciding where to put sensors – which parts of the network could benefit the most — and then figuring what to do with the resulting deluge of data.
“An important part of our project is that we need to gather all of this information and need to decide what and how we’re going to do anything with it,” said D’Antonio.
All the rage
DLR, as it is inevitably called, is all the rage in power circles as we scramble to upgrade a power grid that is struggling to handle distributed energy, renewables and a sudden spike in demand from electrification and data centers. Getting more use out of what we already built is a good way to cope while we figure out the future.
America’s power grid was built with very conservative assumptions because nobody wants it to fail. Consider weather.
The maximum rating for any line — the total amount of electricity that operators are told can be safely sent through it — assumes hot temperatures, lots of sunshine and little wind to cool things off. All of these reduce the line’s carrying capacity partly because heat causes lines to sag, which leads to other issues, including fear of sparking wildfires.
When it’s cool or windy or cloudy, however, the line can safely carry much more energy than its rating says. But right now, grid operators rarely have accurate enough information to know when that happens, so they can’t take advantage of it. DLR can make that possible.
Importantly, it makes it possible much more cheaply and quickly than building a new transmission line.
Dartmouth’s project team will include two faculty members and approximately 10 Ph.D. students and postdoctoral researchers, Zhao said. The project will also create opportunities for workforce development, including hands-on training for undergraduate and graduate students in a field expected to grow in the coming years.
The first year will focus on planning, including identifying sensor locations, and training on the project’s digital tools, Zhao said. Sensor installation is scheduled for the second year, followed by two years of operating, evaluating and refining the system.
It’s not clear at the moment exactly how much a difference DLR can make in New England, but it will certainly help as we figure out how to change a century-old system for producing and distributing electricity. The Eversource/Dartmouth project is part of a federal Speed to Power (SPARK) program (I don’t know why there’s a K on the acronym) that hopes to speed up the change.
