Influence of the network impedance on distribution system harmonic Norton models

The purpose of this paper is to study the influence of the network structure on a harmonic Norton model for a distribution network, estimated using measurements from different changes in the supply system. Using a simulated test system and a method of estimating a frequency coupled Norton admittance matrix (Y_N-matrix) of the modeled network, information about important parameters that influence the estimated Norton models can be found. The results received show that small off-diagonal elements of the network Y_N-matrix might result in different harmonic Norton models. The off-diagonal elements make the estimated harmonic Norton models sensitive to the change in the supply system. Since the change in harmonic voltage usually is greater for the lower harmonics, the results received for the lower harmonics will be better than for the higher harmonics. The results also show that the type of converters present in the network and the amount of capacitor banks connected in the network are the parameters that have the largest influence on the estimated harmonic Norton models