Investigating the impacts of feeder reforming and distributed generation on reactive power demand of distribution networks

The rapid integration of the distributed generations (DGs) in distribution grids could result in voltage control issues. These issues are more noticeable in grids, which are reformed from overhead wires to underground cables. Different values of line characteristics, particularly the charging capacitance, differently influence the power flow results. The higher capacitance value of underground cables leads to increased reactive power generation of lines and a lower amount of imported reactive power from the transmission network. However, it is not an issue of distribution grids with overhead lines. The augmented effect of the cable-generated reactive power coincident with the active power of renewable generation units such as photovoltaics (PVs) may deteriorate the voltage control procedures. Accordingly, investigating the impacts of feeder reforming strategies with different cable structures and of DGs penetration seems to be of great importance in power system planning and operation studies. Different scenarios are defined for the undergrounding of overhead wires and PVs' penetration levels to assess the changing trend of the reactive power demand of distribution networks. The Danish network is used as a test system for investigating these scenarios. In each scenario, the imported reactive power from the transmission network and the voltage profile of the test system are investigated. The obtained results are discussed in depth. (c) 2020 Elsevier Ltd. All rights reserved.