Harmonic background amplification in long asymmetrical high voltage cable systems

This paper presents an analysis of a harmonic problem encountered on the Danish island of Anholt and its mitigation. Time synchronized power quality measurements are presented at transmission and island nodes. Harmonic phase gain factors are calculated from the transmission system to the island and a simulation model is constructed and used to explain the reason for the very high gain factors encountered. A resonance problem is identified and a recommendation is made for the use of phase-domain modelling for long asymmetrical cable systems. At the end of the paper, a harmonic filter design process is presented.