Method for Minimizing Grid Fees in Distribution Grids with DC-Links

Distributed generation leads to a significant increase in generation capacity of the distribution grids. Nevertheless, energy generation fluctuates; therefore the ratio of feed-in to load massively varies among distribution grids. Instead of balancing these grids via the transmission grid, coupling of distribution grids via DC-links is a conceivable approach. This paper presents a method of reducing grid fees in distribution grids by using DC-links. The method uses an extended OPF formulation to estimate economic operation points of the grid. The validation is carried out on a modified version of the IEEE96 RTS grid. The results show that the method is applicable in minimizing grid fees for several DSOs. Furthermore, the results show that with DC-links the power losses can also be reduced. The validation indicates that coupling of distribution grids with DC-links is especially beneficial if the feed-in to load ratio of the coupled grids is different.