Impact of distribution network modelling on harmonic impedance in the HV grid

Frequency impedance scans are required for the harmonic assessment of new connections in the High Voltage grid. Most of the HV substations are connected to Distribution System Operators (DSO). In the Netherlands these MV grids are cabled with a typical length between 2 to 300 km. These downstream voltage networks may have significant influence on the total system impedance. For the HV network operator, it is almost impossible to model these grids in detail, so a simplification is therefore required. In this paper, a method to derive the simplified model of distribution networks based on a limited number of generalized MV feeders through a clustering process is described. After that, the parameter values (R, L, C’s) for equivalent models based on the generalized DSO networks are calculated and compared with other equivalent models found in the literature.