The nation’s electrical grid, which until recently had the luxury of operating under a relatively static set of principles, is in the middle of a dramatic transformation. Improved computing capacity, faster communications, and the integration of renewable energy resources from remote locations are proving to be game changers as utilities seek to expand, and make better use of existing, infrastructure. In this environment, unlocking extra capacity within existing transmission lines is likely to offer huge advantages in immediate and cost-effective transformations that shore up grid efficiency and reliability.
Around 2010, researchers at the U.S. Department of Energy’s Idaho National Laboratory (INL), studying wind power plants, approached EERE’s Wind Energy Technologies Office and sought to begin studying the fact that transmission lines being cooled by the wind are capable of handling more electricity. Power transfer capacity is affected by three main elements: stability, voltage limits, and thermal ratings, with the last representing the greatest opportunity to quickly, reliably and economically improve the grid’s capacity. INL’s wind power team surmised that if they could come up with a reliable system for dynamic line rating to replace the conservative static line ratings in use, system planners and grid operators might have access to greater transmission capacity.
The first step was to find a computational fluid dynamics software (CFD) program that could be integrated and tested against actual wind and weather station data. Coordinating with a CFD program from WindSim, the INL team developed General Line Ampacity State Solver (GLASS), which offers the ability to blend data from weather monitors and electric utility system data with CFD-enhanced weather analysis algorithms.
Since 2010, INL has collaborated with Idaho Power Company on dynamic line rating concepts, and recently finished a full instrumentation of two test beds with weather stations and line rating software in Idaho. INL also has completed a cooperative research and development agreement with AltaLink LLC—Alberta, Canada's largest regulated electric transmission company—on a field study of four transmission line segments in support of a wind project’s expansion request.
“From what we’ve seen, it’s working,” said Phil Anderson, project leader for Idaho Power. “Our greatest challenge was to come up with a standard design that didn’t cost a fortune.” With GLASS, Idaho Power has been gathering weather data and the ability to calculate steady state, transient, and what INL calls “true dynamic liner rating” ampacities (ampacity is the amounts of current a line can carry). The next step is ramping up the software to calculate forecasted line ampacities and temperatures. “It really shows the viability of weather-based dynamic line rating,” Anderson said.
While WindSim was originally a software program designed to optimize placement and performance of wind turbines, the company’s collaboration with INL has allowed the company to broaden their solutions, said Catherine Meissner, WindSim’s software development manager. “The next current challenge is “de-risking the path to market and deployment,” Meissner said.
In recognition of its potential to strengthen and secure the power grid, GLASS was named a finalist for the 2017 R&D 100 Awards, which recognize and celebrate the top 100 technology products of a given year. INL has also received a Technology Commercialization Fund award from the U.S. Department of Energy Office of Technology Transfer. In 2018 and 2019, INL plans to refine the GLASS software with another industry partner, testing endurance and possibilities for commercialization.
In its seven-year evolution, GLASS has undergone three formal peer reviews and two merit reviews. The work has not gone unnoticed. More than 70 people from around the world, representing the utility industry, academia, and local, state and federal government, came to Idaho Falls Nov. 7–8 for an INL-hosted Dynamic Line Rating workshop.