Evaluation of Equivalent Dynamic Active Distribution Network Models with Individual and Aggregated Consideration of Grid Forming Converters

Detailed active distribution network modeling in the context of stability studies of future power systems can be avoided by applying complexity-reduced equivalent dynamic models. Previous work developed an approach to derive such equivalent dynamic network models of systems dominated by grid following and grid forming converters. Nevertheless, this approach lacks an investigation of the aggregation of multiple grid forming converters to one equivalent component. Also, the approach needs to be evaluated for a closed ring topology to substantiate its validity independent of the detailed network topology. This work applies and validates the developed approach on active distribution networks in the context of three scenarios. The detailed and equivalent network models are simulated for three events and the results are used to compare the models with respect to accuracy and complexity. The derived equivalent dynamic network models with an individual representation of grid forming converters reproduce the dynamic behavior of the corresponding detailed networks very well. The aggregation of grid forming converters results in an adequate reproduction of the detailed network's dynamic behavior under the constraint of aggregating only neighboring grid forming converters of one branch. This allows for the consideration of the detailed network's topology in the corresponding equivalent dynamic model.