Analysis of the harmonic resonance during energizing the primary restorative transmission systems

Power system restoration following a massive or complete blackout starts with energizing primary restorative transmission systems. During this primary restoration process, unexpected over-voltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This is known as the harmonic resonance phenomenon that may cause burning out of transformer or other devices. By now the harmonic resonance has been reported in some extra high voltage systems. This paper reports the possible existence of the harmonic resonance in Korean power system. Analysis of the harmonic over-voltage is presented based on various PSCAD/EMTDC simulations.