Line Sensor Upgrades Support Power Grid Reliability

New technologies for monitoring power lines are emerging around the world, as part of ongoing efforts to strengthen the power grid and increase reliability and resilience. Utilities and other power transmission and distribution (T&D) system operators have made T&D upgrades a priority as power outages become more frequent due to an increase in weather events extremes around the world.

Today’s monitoring technology includes wireless power line sensors, cameras, and fault circuit indicators that can use advanced detection algorithms to detect problems on overhead lines in real time. These systems also go beyond traditional methods of using generators, batteries, or even wind turbines or solar panels powered by fossil fuels to provide the energy needed to operate them. Instead, they adopt “self-harvesting” technology, drawing operating power directly from the power line.

These systems can do more than detect faults. They can also serve as “eyes in the sky” in more remote areas, using cameras to discover problems long before a maintenance person can arrive in the area. These systems can alert utilities and line operators of such things as wildfires, allowing for faster deployment of wildland firefighters. They can pinpoint conditions that could lead to power cable icing or provide visual confirmation of damage or other problems along the line.

Several utilities are taking advantage of new overhead power line sensor solutions, in the United States, Canada and elsewhere. Last year, Minnesota-based Xcel Energy hired LineVision to deploy that company’s technology on transmission lines in part of the utility’s territory in Minnesota, Colorado and Wisconsin. The project is a collaboration that includes Oak Ridge National Lab, with data collected from the project being analyzed in a study of advanced line assessments.

The technology can help reduce congestion on power lines and enable additional feeder capacity on those lines, which, in Xcel’s case, could help the utility add more renewable energy to the grid as part of of its goal of 100% carbon-free electricity by 2050. Xcel, like other utilities that serve drought-stricken parts of the western United States, also uses sensors to identify areas at risk wildfire potential, while determining when line maintenance is needed to alleviate network stress and help suppress power outages.

New technologies have been developed to reduce the maintenance required of sensor systems, with these systems themselves being hardened to better withstand extreme weather and other harsh operating conditions. Several companies, including Ampacimon (Belgium), Heimdall Power (Norway), Gridpulse (Slovenia), Sentient Energy (California) and others are deploying new technologies to improve grid security and reliability, including sensors that operate on energy “harvested” from the power line itself.

1. Osvaldur Knudsen, CEO of Laki Power, and Bjorn Sighvatsson, head of manufacturing for the company, talk about the company’s power line monitoring equipment during a meeting with members of the US media, including POWER, in mid-June. Courtesy of Sigurjon Ragnar

An example of this self-powering technology was developed by Laki Power, an Iceland-based company that was named “Innovation Company of the Year” in 2021 by Samorka, the federation of energy and utility companies in Iceland. Osvaldur Knudsen, CEO of Laki Power, said POWERFUL during a recent meeting (Figure 1) at the company’s headquarters in Reyjkavik, that the company’s products incorporate Laki’s PowerGRAB electromagnetic energy harvesting technology, a system of springs, magnets and coils, where the magnet and the coil move relative to each other. This movement creates a change in the magnetic flux which produces an electromagnetic force.

Knudsen said the technology uses a “cold” power regulation technique to capture high-voltage power line current as usable low-voltage DC output, which he characterized as having up to 100 times greater efficiency than that of other surveillance solutions on the market. This could in practice enable a range of power-hungry peripheral systems, he said.

Knudsen noted several attributes of Laki Power’s system, recounting POWERFUL, “I just think more than anything that we can reduce maintenance by offering a robust system, totally autonomous and therefore much more economical.” Knudsen said there is “additional complexity and cost associated with external power sources – solar panels are covered in snow and dust, wind is intermittent, diesel generators are expensive and require fossil fuels, and fuel cells can be expensive and require maintenance.” He said that while a Laki Power monitoring station “could potentially be significantly cheaper than solutions that rely on an external power supply, I will say that our goal is not necessarily to be the cheapest solution, but the best. “.

Knudsen said PowerGRAB is unaffected by fluctuations in phase wire current flow, making it well suited for sensitive monitoring and measuring devices. It can provide real-time environmental monitoring and thermal event detection to help spot wildfires, ice buildup on power lines, and also provide dynamic line capacity information. The technology is part of Laki’s LKX MULTI system, which is “essentially the monitoring station we used in our pilots with improvements, an improvement over the LKX-201,” Knudsen said, noting that it’s better to use it to determine “icing, vibration and gallop, salinity measurements and sag/ground clearance calculations.

2. A worker installs a Laki Power monitoring station on a power transmission line on top of Alvik mountain in Norway. The line is 1,000 meters, or 3,280 feet, above sea level. Courtesy of Laki Power

The system has been deployed in Iceland with Landsnet, the country’s transmission system operator. Iceland has a problem with ice buildup on power lines, as does Norway, where Statnett, that country’s transmission line operator, installed a Laki Power monitoring station at 1,000 meters in 2020. (3,280 feet) above sea level on Alvik Mountain to monitor frost on power lines from a distance (Figure 2). The area is very exposed to the weather blowing from the fjord, which creates ideal conditions for the accumulation of ice (figure 3) on the pylons, armored cables and phase conductors. Statnett has traditionally used two methods to remove the ice: flying a helicopter to a site to knock the ice off the line with a wooden pole or heating the power lines with increased current, which has been the preferred method. But either method only works well if the line has a small amount of ice, so early warning of ice buildup is necessary.

3. A view of ice on power lines and snow on Ålvik mountain in Norway, taken with a Laki Power monitoring device. Courtesy of Laki Power

Statnett had monitoring devices for its lines, but it had to use external power sources such as diesel generators and solar power. The group recognized the benefits of a self-powered sensor system such as Laki’s. “Being able to use conductor current to power monitoring devices is a huge advantage,” said Miroslav Radojcic, project manager at Statnett. “This reduces costs and provides us with accurate data and a unique point of view since Laki’s power plant is on the driver itself.”

Laki Power has also worked with Manitoba Hydro, a group that began testing line sensors in 2006 and over the years has used a variety of technologies with varying success in the often harsh environment of northern Canada. Manitoba Hydro and Laki Power launched a pilot project earlier this year, as part of Manitoba Hydro’s efforts to effectively monitor and respond to icing and other weather phenomena on the company’s transmission lines. Knudsen said POWERFUL“We just completed two installations with Manitoba Hydro on live lines… [and] this is a huge victory for us.

Knudsen also noted his company’s technology rollout in Greece, which began in May this year in partnership with ipto, the country’s independent power transmission operator. Laki uses his LKX SURV model, which relies on a camera and sensors to help detect excessive heat or evidence of a wildfire. Knudsen said the LKX SURV model is “essentially an improvement on the LKX THERMAL prototype, [as] we add a rotating housing…it is for forest fire detection and can be used for monitoring purposes.

Greece has suffered from numerous forest fires in recent years, and just last June a fire raged through a southern suburb of Athens. The summer of 2021 saw Greece’s most severe heat wave in decades, and fires destroyed nearly 250,000 acres of farmland and forest. It was Greece’s worst wildfire season since 2007.

“Wildfires are a huge problem in Greece, as they are in California and the western United States,” Knudsen said. “We can come in, put sensors on new or existing power lines, provide more security. I think we are the only ones getting so much data and HD [high-definition] images and video in such a compact unit that can be installed in 15 minutes. It’s a constantly evolving technology and we want to be at the forefront.

Darrell Supervisor is associate editor of POWER (@POWERmagazine).

About Bradley J. Bridges

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