Planning transmission lines upside down: How earth cables are combined with overhead lines

Abstract

The grid extension in Europe is in full swing and thereby, citizens’ demand on earth cables instead of overhead lines is steadily increasing. The keyword often used in this context is partial underground cabling, as the Swiss jurisprudence compels grid planners to suggest not only an overhead line but also a partial underground cabling when a new trans-mission line is planned. However, where can the areas suitable for partial underground cabling be located? Geographic Information Systems in combination with Multi-Criterial Decision Analysis offer established tools for determining an optimal transmission line path. However, the approaches used so far do not offer satisfactory solutions when planning a combined – overhead or underground – transmission line. Therefore, we propose a procedural method that turns the planning process upside down by determining for each section the optimal path.