* Power * Voltage * Structure Type * Hardware Configuration Initial Concept Optimized Project Conductor Selection * Electric Losses * Maximum Temperature * EM Fields * Material Costs Final Tower Geometry Initial Tower Geometry Technical and Economic Analysis Structural Weight * Bundle Optimization * Insulation Coordination Minimum Conductor Height and Right of Way figure 1. The workflow for the optimization of a transmission-line project. march/april 2020 (a) ku = 1 (b) 4 SIL (Ground Wire) insulator strings. The examined weather conditions include a group of stochastic parameters that must be considered in a statistical analysis of design requirements, that is, meeting criteria for allowable ✔✔ fundamental frequency overvoltages that permit no failures at maximum operating voltage and consider the effects of wind and pollution ✔✔ overvoltages due to switching transients from energization or reclosing that must meet prescribed risks of failure ✔ ✔ over voltages caused by lightning discharges related to direct or indirect strikes (back flashover) that consider a maximum number of expected outages rela- ted to the local lightningstrike density. 3 2 1 (c) (e) (c) (d) (b) (a) (d) (e) 0 5 10 15 5m ns figure 2. The relation between SIL and number of subconductors, n s, for different design approaches. (a) A conservative design using standard hardware and evenly distributed spacing. (b) An EXB, still restricted to a regular shape. (c) A fully optimized design with irregular bundles, resulting in a maximum SIL. (d) Another example of a conservative design using standard hardware and evenly distributed spacing. (e) An additional EXB design, still restricted to a regular shape. ieee power & energy magazine 33