Investigation of the Voltage Stability in the Integrated Energy System of Northern Germany

Integrated Energy Systems (IES) with the coupling of the energy sectors electricity, heat and gas are assumed to be the concept for future energy systems with a high share of renewable energies. The primary coupling technologies like Power-to-Gas and Power-to-Heat connect the three subsystems electricity, heat and gas on a dynamic physical level. However, these interactions can be a risk to the overall system stability. Concerning the electric grid, the voltage stability is consid-ered most critical in IES and this stability phenomenon is further investigated in this paper. As a proper methodology for investigation, a combined steady state and dynamic investigation method including grid reduction is suggested. This method is applied to different test grids representing the IES of Northern Germany. The results show that the Northern German electric grid features high voltage stability, which is hard to influence by a well-prepared transformation to an IES.