Unlocking the Grid: How Advanced Conductors and Dynamic Line Rating Boost Capacity Without New Lines

The power grid is being defined by its aged infrastructure that dates back to the pre-digital era and it’s not aging gracefully, but there’s a new toolset emerging. It’s a category of unique technological applications that’s been developed specifically to address this situation. They are called grid-enhanced technologies (GETs). According to a Department of Energy report, “A future-ready grid requires infrastructure built with the latest technologies.” Summarizing DOE’s account, GETs can quickly enhance existing power grid infrastructure. GETs save money and avoid the complexity of building new transmission lines.

GETs have long been a subject covered by “Charging Ahead,” and it’s time to update advancements in two valuable GET applications. Advanced conductors and dynamic line rating (DLR) systems have both joined forces with distributed fiber optic sensing (DFOS) technology. Advanced conductors and DLR systems are seen as one way to speedily address the lack of transmission capacity, but when DFOS is added to the mix everything changes. If the trend trackers are correct these three together are about to make a quantum leap forward that’s going to shake things up a bit. A little background is in order before moving forward.

Advanced conductors utilize improved coatings, upgraded production methods, and take advantage of composite cores. That makes them lighter, able to operate at higher temperatures, have improved sag, and increased capacity. Manufacturers say advanced conductors provide double the capacity over those old-style conductors. State and federal regulators are supporting advanced conductors with new policies. They want to shift new and reconductoring transmission projects to advanced conductors. Last December Congress introduced the High-Capacity Grid Act legislation requiring utilities and grid operators to use “the best-available” transmission conductors available.

Sensing Revolution

Whether it’s existing legacy conductors or new advanced conductors, DLR technology can determine the actual physical capacity of a transmission line in real-time. The continuous sensing revolution is benefiting everyone. For DLR, its sensors are being miniaturized, and made more sensitive, which resulted in improved non-contact DLR hardware. That in turn improved data gathering as well as making installations easier, safer, faster, and most importantly cheaper. It’s caused rapid adoption, but that’s only the prelude to what’s taking place currently.

Several years ago, DFOS technology caught the eye of the industrial sector. DFOS is a technology that is sparking a reevaluation of the theory of what sensors and monitoring systems are. The technology transforms a length of optical fiber into an unbroken sensing array. Keeping it simple, a laser-powered interrogation unit injects light pulses through the optical fiber and analyzes the returning backscattered light. The backscatter light changes due to the influences on it. When analyzed it gives information on the physical conditions (i.e., heat, strain, vibration) along the fiber. Experts say this makes the application well suited for infrastructure monitoring like bridges, tunnels, pipe lines and such. Some innovative thinkers started asking what if…

Those theorists realized that optical fibers existed on the transmission system in the form of OPGW (optical ground wire) and OPPC (optical phase conductors). Utilities and grid operators have been installing OPGW for transmission line static shield wires and OPPC was being utilized for communications. The two types of fibering operate differently, but the sensing principles are the same and that’s deep enough for now. Getting back to those inquiring minds. They reasoned that since DFOS worked with either OPGW or OPPC cables an integration of DFOS with either fiber, would lead to an upgrade of DLR technology. In short order the gap between knowing and doing was bridged and there was a fiber-optical sensor-based DLR application.

Fiber-Enhanced DLR

There are several names currently associated with this hybrid approach. It’s been called a fiber-enhanced DLR and FORM (fiber-optics for rating and measurement) DLR are currently leading, but DLR-3.0 is gaining popularity. Since it’s more generational for the power grid let’s stick with DLR-3.0. The major distinction of DLR-3.0 over previous generations is DLR itself has moved from a point-based sensor to a continuous sensor. It utilizes the fiber’s entire length and produces big-data, and it’s being integrated with artificial intelligence (AI).

This is a complicated technology, but by integrating AI, it’s more user-friendly. All this is being seen by the financial marketplace as DLR-3.0 is trending with strong growth. They point out, “the tech is shifting from pilot projects to enterprise-level deployment.” There are no estimates or projections yet about how large the marketplace is, but it’s going to be exciting when they focus specifically on DLR-3.0. A good indication of how much interest is being generated are the numbers of technical papers, studies, reports, and webinars that can be found with a simple search of the web.

Last March, CTC Global sponsored a webinar on their GridVista System. It was presented by T&D World and if you missed it, it’s been archived and is available on-demand until early-September. You can sign up at https://www.tdworld.com/55352218 any time it is convenient. The webinar is a chance to take a look under the hood with some experts see firsthand why this technology is producing so much interest. They’re explaining a technology that’s both a power-carrying medium and a sensor array. CTC’s GridVista System was launched in mid-February. It was developed as a partnership between CTC, Google Cloud and Alphabet’s Tapestry.

An Intelligent Transmission System 

Since it’s almost impossible to add more transmission fast enough to keep up with the rising power demands, this technology really can help. CTC says the GridVista system “redefines transmission line intelligence.” It utilizes optical fiber embedded directly into their ACCC (aluminum conductor composite core) conductor. This specialized optical fiber delivers real-time, high-resolution data about the transmission line’s interaction with its environment. According to Kevin Corbalis, chief technology officer of CTC Global, “the GridVista System is an engineering breakthrough.” The heart of the system is CTC’s ACCC conductor with its integrated optical fiber.

Rather than attaching external sensors, the conductor’s optical fiber acts as an uninterrupted sensor between substations. The brain is Google Cloud’s technologies and Tapestry’s AI-enhanced modeling and analytics. It turns the continuous raw big-data into useful information. CTC experts said the intelligence transforms “transmission lines from static infrastructure into intelligent network assets.” The continuous data is a constant stream of capacity, temperature, strain, sag, ice loading, hot spots, and corona discharge information from the entire length of the conductor.

The Q&A portion of the webinar gave some great “nuts and bolt” discussions of the GridVista System at work. One viewer was concerned with hotspots, galloping, and other abnormalities. Their question was more or less about how such events can be differentiated. Taking it a step further, can its point-location be identified close enough to be meaningful?

David Goekjian, CTC Global’s principal R&D engineering manager indicated that the GridVista System’s modeling and analytics identifies the type of event. It tells operational useful information like what is happening and on what phase it is happening. It identifies a particular phase or has it propagated to an adjacent phase. It identifies the distance of the event within three feet (a meter) over the segment of line.

Capacity Enhancements

This next-gen technology is definitely trending. Earlier this year, AP Sensing, a leader in fiber optic sensing, and Ampacimon a DLR pacesetter, announced a partnership. The two companies are combining “complementary technologies” focused on a new real-time, condition monitoring and DLR system. Their collaboration will utilize existing OPGW located on transmission lines for monitoring physical characteristics and enhanced capacity optimization of the asset. A spokesperson said this approach was ideally suited to high-voltage environments.

There was also a news release from TransnetBW GmbH, one of Germany’s transmission system operators. They announced a partnership with Prisma Photonics to utilize DFOS advanced optical fiber sensing across 74.5 miles (120 kilometers) on three transmission lines in southwest Germany. The two-year project will evaluate using the Prisma Photonics’ technology to turn existing optical fiber in the lines’ OPGW into a continuous monitoring network. It will be used to optimize capacity in the transmission system to handle increased renewable energy and manage congestion.

Conductor monitoring has been around for several decades, and it keeps evolving. This latest iteration is has taken a totally different approach with its optical fibers, DFOS and DLR technologies integrated with AI-enhanced tools. It moved power line management from reactive to a proactive part of the smart grid by adding intelligence. With that comes a shift from real-time monitoring to AI-driven predictive analytics. Instead of just reporting current capacity, this next-gen DLR-3.0 can forecast the transmission line’s ratings for an hour-ahead or a day-ahead.

Moreover, DLR-3.0s’s predictivity allows it to interact with asset management systems, demand management platforms, and other AI-powered situational awareness smart grid systems. These are only a few of the benefits associated with next-gen DLR-3.0, but it’s an interface that improves the management of the power delivery system. It’s one of those intelligent toolsets required to modernize the power grid for the demands of the 21^st century environment!