IMPACT OF THE MODELLING DEPTH OF DISTRIBUTION GRIDS ON THE ACCURACY OF AGGREGATED DISTRIBUTION NETWORKS

The representation of distribution networks within large transmission systems becomes increasingly relevant due to the growing share of distributed generation in lower voltage levels. Modelling detailed distribution networks for large-scale network simulations is infeasible due to the large amount of individual generation units, and thus, the amount of dynamic models. Equivalent dynamic models offer a solution to represent the impact of distribution networks as close as possible. This is achievable using grey-box models, which retain the overall dynamic models and take the grid impedance of the lower voltage levels into consideration without the computational burden. This paper focusses on the required modelling depth of the low voltage level in equivalent distribution networks. Three different approaches are presented and the deviation to a simplified approach and the detailed mode are compared. The deviation between the different modelling depths with equivalent impedances is shown to be marginal, whereas disregarding the distribution network impedance completely leads to large stationary and dynamic errors.