Incorporating dynamic line ratings in real-time dispatch of market and system operations

Facing the challenges posed by the penetration of a new fleet of renewable energy resources which are variable and a lot of them are distributed in nature, transmission organizations and transmission operators around the world are in the process of enhancing their dispatch systems with a broader capability 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 and market operations. Weather-based real- time dynamic line rating (DLR) is the current limit determined by real-time measurements of weather conditions surrounding the conductor. DLR has the potential to increase the line rating, reduce transmission congestion and enhance market efficiency. In North America, RTOs are fundamentally reliant on optimization techniques to dispatch generation resources and serve the native load in large geographical regions. This paper applies DLR to the optimization problem of a real-time market (RTM) and simulations of case studies are carried out for a large power network. The benefits of DLR in RTM are presented to demonstrate the effectiveness in reducing transmission congestion and generation costs.