Enhancement of real-time operational efficiency by applying dynamic line ratings

Facing the challenges posed by the penetration of a new fleet of renewable energy resources which are variable and distributed in nature, transmission organizations and grid operators around the world are in the process of enhancing their dispatch systems with broader capabilities and higher economic efficiency. Traditionally, static line rating (SLR) of a line is conservatively calculated under the “worst-case” operating conditions and are updated infrequently. These conservative assumptions may restrict the line capacity whenever the real weather condition is less stressful. More accurate assessment of transmission flow limits will directly impact the efficiency of system operations. Weather-based real-time dynamic line rating (DLR) is the current limit determined by real-time measurements of weather conditions surrounding the conductor. Increasing thermal line ratings, DLR has the potential to reduce transmission congestion and enhance operational efficiency. This paper applies DLR to the co-optimization problem of real-time energy and reserves using a security constrained economic dispatch (SCED) algorithm. Using real-time DLR, we demonstrate that the real-time SCED is able to dispatch the system more economically, relieve transmission congestion and reserve scarcity, and as a whole improved operational efficiency without compromising system security. Case studies are performed on a large power system of 48,000 transmission lines.