Unbalanced Distribution Network Reduction by Multi-Port Synthesis in DIgSILENT PowerFactory

Network equivalencing techniques are a powerful tool to reduce the complexity of large-scale transmission and distribution networks, leading to a considerable saving in simulation times. Among them, those based on the Ward and radial equivalent independent have become so widespread in the power system realm that they are also implemented in the largely adopted commercial simulator DIgSILENT PowerFactory®. However, these techniques are not compatible with unbalanced operating conditions, which are common in distribution grids. To address this issue, we propose a reduction method implemented on DIgSILENT PowerFactory, that can be executed by a user available Python script. The method reduces grids of any size (be them balanced or unbalanced, three-phase, single-phase, with or without neutral) by replacing them with a Multi-Port, implemented through current and voltage dependent (possibly multi-phase) sources. Simulation results of distribution feeders highlight the features of the proposed method.