A hierarchical optimization framework for aggregating thermostatically controlled loads to minimize real-time thermal rating of overhead distribution lines

A hierarchical optimization algorithm is presented in this study to optimize the aggregated thermostatically controlled loads (TCLs) to ensure the thermal rating of distribution lines is not violated. The key objective of the upper-level model is to minimize the thermal temperature of distribution lines and ensure it within the thermal rating. Meanwhile, the lower-level model is intended to strictly follow the dispatch instructions from the upper-level decision-maker by designing appropriate dispatch strategies for each aggregated TCLs in a specific time horizon. The developed models are solved by two different optimization software tools. Finally, a 10 kV overhead distribution line is studied to demonstrate the performance of the developed model and methodology.