The four German transmission system operators 50Hertz, Amprion, Tennet and TransnetBW (TSOs) have submitted the Sensitivity Analysis 2013 report on relevant variables influencing the need for grid expansion („Einflussgrößen auf die Netzentwicklung – Sensitivitätenbericht 2013“). The report examines the need for grid expansion based on three variables (sensitivities): the net electricity demand and annual peak load, a cap of supply peaks as well as a stronger “regionalisation” of the expansion of renewable power plants.
The report uses the the grid topology (Netztopologie) of the lead scenario B 2023 of the Electricity Grid Development Plan 2013 (NEP 2013). When approving the scenario framework for NEP 2013, the Federal Network Agency (BNetzA) had asked the TSOs to examine the impact of the above-mentioned three variables on the measures contained in scenario B 2023. The TSOs welcomed this and said the findings of the first definition of sensitivities and the analysis of their impact should be used for defining (and examining) new influencing variables.
1. First Sensitivity: Net Electricity Demand and Annual Peak Load
The first simulation concerning the net electricity demand and the annual peak load works with the assumption of a slightly declining load and demand (“etwas verringertem Last- und Verbrauchsverhalten”). Due to the integration of Germany into the European electricity market a decline would lead to an increase of the electricity exports to neighbouring countries. This would change load flows, but not result in a significant change of the need for grid expansion, the TSOs say.
2. Second Sensitivity: Supply Peak Cap
The second simulation works with the scenario that a uniform cap on wind power input in all the sixteen German states was applied at 80% of the installed capacity. With 1.1 TWh less fed into the grids (equalling 1% of the annual output of onshore wind power), an effect for the AC grids would be felt in some regions leading to a lower need for grid expansion, the TSOs say. Besides, the need for DC transport capacity between Bad Lauchstädt and Meitingen would be reduced from 4 GW to 2 GW. A 2 GW capacity was laid down in the Federal Requirement Plan, the TSOs point out, adding that in another location a AC grid enhancement was needed. They highlight the general importance of a renewable feed-in management for grid expansion.
3. Third Sensitivity: Regionalisation
The third simulation assumes a greater regionalisation, i.e. regional distribution, of the expansion of renewable power plants in Germany. A cumulative analysis of a change in more than one parameter, e.g. simultaneous regionalisation of wind power, PV and biomass, however, did not give clear indications on the impact of only one parameter. Besides the predefined modifications were too small to result in significant effects for grid expansion, the TSOs say. They point out that a stronger shift of the growth of renewable power plants from the north of Germany to the south or the assumption of a slower growth of offshore wind power plants could result in significant indications for changes of the need for grid expansion.
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