Evaluation of Grid Reduction Techniques for Distribution Networks with a High Penetration of Inverter-based Generation

This paper compares the most common practice used by utilities and transmission system operators for the reduction of distribution networks with a high penetration of inverter-based generation (IBG), when conducting electrical studies. For modelling a high share of IBG, three potential reduction techniques for the distribution networks were identified and applied to a test grid: the netting, the WECC, and the german academic approach (GAA). The frequency excursion after the occurrence of an active power imbalance resulting from a short circuit was compared for the original grid and the three reduced models. The results have shown that the GAA is the only approach capable of accurately replicate the dynamic response of the original grid. However, this approach neglects different voltages at the point of common coupling (PCC) of IBG systems in the original grid, which can lead to different simulation results between the reduced and original grid.