The German transmission grid expansion in long-term perspective — What is the impact of renewable integration?

The German power sector will face a profound change from conventional power generation to an energy system with a high share of intermittent renewable energy sources. The following analysis addresses the future transmission grid design for Germany in 2030 in a context of different renewable integration schemes. Therefore a DC load flow model is set-up, which deals with the trade-off between grid expansion and regional renewable integration. Two scenarios concerning different renewable feed-in design options are considered: curtailment of renewables only at negative prices in the height of their individual levelized costs of electricity, and curtailment at marginal costs (tending to zero). To cope with the large-scale network capacity expansion problem, Benders Decomposition and DC-load flow approximation are applied. The results show that the different renewable integration schemes have different effects on the AC grid expansions in contrast to High-Voltage-Direct-Current (HVDC) connections.