Downstream Network Modeling With Generalized Distribution Networks for Harmonic Studies

Abstract

The harmonic impedance of the grid needs to be calculated for the harmonic assessment of new connections in the high voltage (HV) network. For these studies, one of the elements is the modeling of the downstream distribution networks. In the Netherlands, these medium voltage (MV) networks are cabled with a length between 20 to several hundreds km. These distribution networks could have a significant impact on the network impedance. For the HV network operator, it is almost impossible to model these networks in detail as not all information of the distribution network operators is readily available. The aim of this paper is to present a simplified representation for the distribution networks and develop a method to determine the parameters to be used in the model via a clustering method. To verify the method of clustering and compare the various equivalents, a comparison is made with an exact representation of a distribution grid. A sensitivity analysis has been performed on the most important parameters. It has been found that the Type-2 load model gives the best result compared the conventional ones. If the network information is known by the transmission system operators (TSOs), the Type-2 load model can be constructed directly. Otherwise the approach based on the clustering process as described in this paper can be used as an alternative.