Distribution grid planning in Switzerland considering local flexibilities

In this paper, the findings of the grid planning studies for 50 HV-MV substations owned by two utilities in Switzerland are presented. The substations exhibit different spatial topologies in urban, mixed and rural regions. The grid planning methodology is presented, demonstrating the impacts of various strategies in the form of flexibility utilization and new operational measures. The planning framework has two pillars: (i) creating the time-series for electric vehicles, heat pumps, generation by solar photovoltaics, conventional demand for residential (i.e., household appliances) and commercial customers, and (ii) performing distribution grid planning by modelling each HV-MV substation and downstream grids. The considered traditional planning principles are cable reinforcement by adding parallel cables or increasing the cross-sectional area, transformer reinforcement by adding parallel transformer(s) or increasing the capacity. In addition, the flexibilities provided by new demand and solar PVs in the form of curtailment and smart grid-friendly operation are implemented. Finally, the benefits of methods such as using reactive power support by solar PVs and operating tap-changing transformers with V(P) characteristics are tested.