Decomposition Approaches for Dynamic Line Switching and Rating

Economic transmission switching is a new practice to improve the economics of electric power systems. Nevertheless frequently switching lines into or out of service is a disruptive action to the system and can create undesirable effects. In this work we describe an economic seasonal transmission switching model where transmission switching occurs only once at the beginning of a time period (season) and then the transmission topology remains unchanged during that period. We develop a novel decomposition method that decomposes the seasonal problem into one-hour problems which are then solved efficiently. The dynamic thermal rating is another new technology that utilizes the capacity of power transmission lines based on the ambient factors and the line condition. It usually offers higher thermal capacity than the traditional static rating. We propose a multi-period mixed integer programming model and find the optimal investment plan for the dynamic ratings using Benders Decomposition. Our studies show that the utilization of the dynamic ratings and the practice of transmission switching are complementary and can reduce the costs significantly.