Implementation of a Line Search Algorithm to determine the optimal Trade-off between Grid Operation and Grid Expansion in the German Transmission Grid

The ongoing decarbonization of the power sector evokes a structural change of the electrical power system, especially the transmission grid, making the expansion of the grid unavoidable and a complex task. The expansion measures should be well chosen due to their long operating period and to avoid misinvestments. This paper raises the question of how the grid operational flexibilities can be considered in determining future grid expansion measures to minimize the total cost. For this, an existing sequential structure to determine grid expansion measures at minimal expansion cost and a grid operation optimization is extended with an iterative loop to determine the optimal trade-off between grid expansion and grid operation measures using a line search algorithm. The presented approach is used on a study case of the German transmission grid. The simulation results show that considering operational flexibilities in the TEP can significantly reduce the total cost generated by grid expansion measures and grid operational measures by using the presented approach.