Impact of distribution system quality on DG interconnection protection

This paper has analyzed the impact of distribution power quality, especially unbalancing and triplen harmonic, on DG interconnection protection. We explored that the unbalanced single phase loads increase neutral current at DG interconnect transformer by analysis of measured data and simulation of PSCAD/EMTDC. An impact of triplen harmonic on DG interconnection transformers which are grounded wye (utility)-delta (DG) was also studied in same method. We confirmed that the power quality should be considered carefully for setting of ground overcurrent trip pick up level.