Aggregated Model of Load, Grid Forming, and Grid Following Inverters for an Unbalanced System

Abstract

The distribution system is known for its inherent unbalanced nature and complex modelling. To decrease complexity when modeling the system to evaluate the dynamic analysis, the aggregated model is developed for load, grid following control inverter-based resource (IBR), and grid forming control IBR. Furthermore, to consider the imbalance of the system, the approximation methodology to estimate the parameters of each phase is proposed for each aggregated model. The proposed approach significantly contributes to the field by offering a simplified yet accurate method for dynamic analysis of unbalanced distribution systems. Validation of the approach is performed through study cases on the IEEE 13-bus system and the known parameters, limited to only the voltage and current of each phase at the connection point and each component's total power. Furthermore, the dynamic response of the aggregated model is compared to the actual system of IEEE 13 -bus. The results indicate that the unparameterized aggregated model exhibits significant error, while the response of the parameterized aggregated model is similar to that of the actual system, validating the effectiveness of the proposed parameter estimation methodology.