The Guest Editors are inviting submissions to a Special Issue of Energies on the upgrading and uprating of transmission and subtransmission systems. Existing HV and EHV AC networks are being affected by the ongoing change in generation and load in different ways. The increasing reliance on distributed generation and renewable energy sources (RES) leads to a drastic alteration and overall reduction of power flows at the transmission (EHV) level, possibly creating new bottlenecks, whereas HV subtransmission networks in high-RES penetration are becoming “active”, collecting RES generation and becoming increasingly stressed. The utilities’ response to this paradigm shift must take into account the difficulty of reinforcing the network. This Special Issue will deal with techniques for operating and upgrading AC subtransmission systems. Topics of interest for publication include, but are not limited to: Planning criteria for active subtransmission networks; Partial or total undergrounding of HV subtransmission networks; “Mixed” overhead-cable AC lines; Overhead line reconductoring/uprating; Conventional or controllable series and shunt compensation; Operation and control of active subtransmission networks; Unscheduled power flows; Overvoltages, neutral grounding, and protective issues for active subtransmission networks; Distributed temperature sensing/dynamic line rating.
Keywords: Power transmission; Power system operation; Power system planning; Overhead lines; Underground cable lines; Voltage control; Overvoltages and overcurrents; Network reconfiguration.