Substituting fossil fuels with renewable energy carriers enabling a sustainable energy generation requires significant changes in energy infrastructures, particularly regarding electrical grids. Efficiently integrating renewable energies needs to ensure the availability of electricity at all times and the compliance with stability limits, despite the fluctuation in energy generation. The future advancement of electrical networks can be supported by corresponding models. Due to the high time resolution required and the associated computational effort of today´s modeling tools, simplifications which influence the model accuracy must be made. The methodology presented in this paper for accurately modeling electrical networks regarding active and reactive power uses the cellular approach for aggregating network structures, thus, enabling the required simplifications. This allows preserving the electrical behavior of the initial grid as well as fast calculations of complex power systems. Models within the cellular approach enable efficiently designing and planning of cross energy carrier systems as well as storages. Since plants for renewable energy generation are used centrally and decentrally in different sizes and therefore at different voltage levels, the applicability of the methodology is tested according to the specific topologies and characteristics at distinct voltage levels.