Impact of Power Uprating Methods on Existing Overhead lines’ Reliability

To avoid the expensive solution of building new overhead lines (OHL) to meet the ever increasing power demand and reduce the carbon footprint, power utilities are urged to optimize the existing OHL corridors by implementing flexible Uprating methods (UM) to increase the network’s power transfer capacity. This paper attempts to quantify the effects of increasing the power transfer capacity of OHLs via Re-conductoring and Re-tensioning on the reliability of supporting structures, insulators, and conductors. An analytical tool was developed to quantify the effects of the UMs on the OHL stressing mechanisms (thermal and vibration fatigue) and their impact on the OHL components’ reliability. The results presented in the paper are based on an uprating case study of a 138 kV, 605.3 MVA (DRAKE) double circuit steel pole OHL via (a) Re-tensioning and (b) Re-conductoring. Re-tensioning this steel grade S275 pole from 20% to 24% RBS resulted in an estimated reliability drop from 63.22-50.21%, while re-conductoring with MOOSE or PLOVER would result in an estimated reliability ranging between 44.43-25.78% or 14.93-4.93%, respectively.