Harmonic resonances due to transmission-system cables

Abstract

This paper gives some examples of harmonic issues that can occur when long ac cables are connected in the transmission grid. The main impact is that resonances can occur at much lower frequencies than when only overhead lines are present. Two illustrative case studies are presented: one for a 275-kV cable, one for a 400-kV cable in combination with a 132-kV capacitor bank. A simple rule-of-thumb is given, to decide if a detailed harmonic study is needed. Some guidelines for such a study are given as well.