Experience on diagnosis of MV cable in wind farm

Abstract

This paper shows the diagnostic technology of cable system in the wind farm. We diagnose the 22.9kV MV cable system which had occurred breakdown at several times at low wind speed generation. First of all, partial discharge is measured using on-line PD measurement system and oscilloscope because insulation of cable system is vulnerable in PD signal. Power quality is measured using power analyser for checking the condition of cable system. Power quality can affect insulation performance by generating the over-heat and additional losses. Power fluctuation, power factor, voltage & current and waveform and current unbalances of each phase are checked for identifying the power quality. We measured the harmonics by 50th orders and analysed the THDs of voltage and current. Recently, harmonics in voltage and current are increased due to non-linear components and loads in the power system. Especially, wind power system among the renewable energy system makes much harmonics and steep signal like flicker from power electronic devices. These extremely high frequency signals are accelerating the degradation of insulation and reducing the life of cables than power frequency signal. Therefore harmonics measurements of voltage and current have conducted.