Grid transmission lines are given static ratings based on maximum ampacity and temperature limits. The weather conditions used by regulators in these methods are typically constant values year-round or with seasonal patterns and are set using conservative assumptions for the conditions. By not accounting for additional cooling during periods of high wind or low ambient temperature, there is likely unused head room on many overhead transmission lines.
Dynamic Line Rating (DLR) is a changing transmission line rating based on local conditions rather than a static rating assumption and provides additional ampacity capacity to a transmission line. The U.S. Department of Energy has identified DLR as a transmission and distribution infrastructure solution to defer upgrades, support line outages and increase yields of distributed power. DLR is one of many solutions known as Grid Enhancing Technologies. Idaho National Laboratory is leading research and analysis on industry hardware and software DLR solutions. The conservative nature of transmission line standards and the regional transmission operators can be hard to adjust, so research showing the benefits of DLR is important to prove the benefits of the method.
The ampacity of transmission lines is defined as the maximum amount of current the conductor can safely carry. It is necessary for transmission line operators to apply ampacity limits due to the thermal properties of the conductor. Dynamic Line Rating (DLR) is a technology and technique that uses the environmental conditions or a set of the conditions to calculate the ampacity of the conductor. The way the DLR is calculated has depended upon some amount of physical technology to implement the solution.