Influence of voltage sags and outage costs on realistic radial and backed-up 20-kV rural and urban networks

This research investigates the cost burden of voltage sags and outages of two feeders in typical rural and urban environments in Finland, and compares the effect of different voltage sags on their adjacent feeders. The two tested feeders were each sampled from two 20-kV distribution networks generated by a Network Topology Optimizing Algorithm (NTOA) based on data from a rural area in Western Finland and from the metropolitan region of Helsinki. This study divides the base year into four seasons and considers load data, features and constraints intrinsic to the local scenarios. As inputs to the cost assessment, the reliability technique estimates important reliability indices at each substation. The residual voltages during contingencies, analytically obtained, define the voltage sag rates at several points of the feeders under focus. As main conclusions, voltage sag costs in the simulated feeders are significantly smaller than the outage costs, but voltage sags originating in certain zones of these feeders directly affect voltage levels in other adjacent feeders and upstream equipment, thus propagating the economic burden to other parts of this network.