Optimized Positioning of DC Links in Medium-Voltage Grids

The demand for grid expansion at the medium-voltage level is expected to increase due to the growing penetration of decentralized generation plants and increasing electrification. In addition to the conventional expansion measures in medium-voltage grids, an alternative expansion with DC links is possible, which enables the possibility of power flow control and is becoming increasingly economically attractive due to the further cost degression of power electronics. Within this paper, a method based on a genetic algorithm is presented to optimize the positioning of DC links concerning the total cost of expansion in medium-voltage grids, as well as to optimize the set points of these DC links. For the resulting hybrid AC/DC grids, an economic evaluation of these grids is carried out compared to an estimation of a conventional expansion for different assumptions of converter costs.