Increase of transmission line losses caused by higher harmonic components evaluated by orthogonal decomposition of three-phase currents in the time domain

Abstract

This work analyses transmission line losses in a 35 kV distribution network where currents and voltages contain higher harmonic components. They are caused by a nonlinear load – a rectifier with rated power of 4.7 MVA. In order to evaluate increase of transmission line losses due to the current higher harmonic components, the three-phase current vector is decomposed into two orthogonal components. The first orthogonal component of the three-phase current vector is collinear with the three-phase line voltage vector, while the second one is orthogonal to it. The first one contributes to the active power while the second one does not. It causes additional transmission line losses which could be avoided if the second orthogonal component of the three-phase current vector is minimized. The RMS values of both orthogonal components of the three-phase current vector are used to evaluate the additional transmission line losses.