Expanding and integrating renewable energy sources (RES) challenges today's energy systems, especially, electrical grids. Therefore, efficient RES integration methods have to be developed. This work chooses a multi-energy systems (MES) approach using the modelling framework HyFlow, developed at the Chair of Energy Network Technology. For this approach, simplified cellular-based electrical network models are developed using a specific network reduction method that enables these models to be used as an equivalent of the complex original grid since it shows equal electrical behaviour. As an example, this work uses a medium-voltage European test grid with massive volatile RES (wind and photovoltaic) expansion. This will show how this method can stabilize the grid and improve power quality using hybrid flexibility technologies (heat pumps (HP) and Power-to-Gas units (PtG)). Thus, grid expansion measures can be avoided, and self-sufficiency can be increased by this approach.