Dynamic equivalencing of active distribution grids

摘要

The increased penetration level of distributed renewable energy sources (DRESs) into the existing distribution grids changes the dynamic properties of conventional systems, creating new challenges for power system operators. Therefore, new dynamic equivalent models are required to evaluate the dynamic behavior and stability margins of active distribution networks. For this purpose in this paper, a generic, input-output equivalent model is formulated, suitable for dynamic simulations of active distribution grids with high penetration level of DRESs. The developed model employs variable-order transfer functions, enabling the accurate representation of complex power system dynamics. The optimal order of the transfer functions is automatically determined through an iterative procedure, while the required model parameters are identified from measurements using the Vector Fitting method. Various network topologies and a diverse range of DRESs are considered to validate the accuracy of the developed model and demonstrate its generic properties. Finally, the performance of the proposed model is thoroughly compared with other conventional equivalent models, using error indexes.