The contribution of distributed flexibility potentials to corrective transmission system operation for strongly renewable energy systems

•Analysis of flexibility options for corrective transmission system operation.•A nationwide, sector-coupled energy system model with regional resolution.•Flexibility options are available at relevant times and in relevant grid segments.•Power-to-heat and curtailed wind power provide fast upward flexibility.•Power-to-heat can compensate 2GW transmission capacity losses in 36% of the cases. Corrective operation of electrical transmission systems requires flexibility degrees of freedom to be reliably available when the system is in a critical state. In this study, we develop a method to quantify flexibility potentials from distributed and sector-coupling energy resources. We develop key performance indicators (KPIs) that correlate these potentials with the occurrence of critical transmission corridor loadings and, by that, quantify how often flexibility degrees of freedom are available when they are required. The method is based on a spatially and temporally resolved techno-economic dispatch optimization model and is tested on the example of Germany embedded in a central European energy system in the year 2030. In the considered strongly renewable scenario (208 GW installed renewable capacity) the supply often exceeds the demand. This leads to large-scale curtailments that can be used as a source for flexibility, particularly flexibility to re-increase generation. We find that, in total, curtailed onshore wind parks in the 110 kV-systems would have the potential to increase their feed-in power by 5 GW (upward flexibility) in the 10% most critical transmission scenarios. Central power-to-heat plants can provide 16.1 GW upward flexibility potential in these scenarios. Analyzing each transmission corridor separately, we find that corrective setpoint adjustments from the same technology combination, wind and power-to-heat, can completely compensate a sudden loss of 2 GW transmission capacity for up to 40% of critical timesteps on the transmission corridors within the given model. These findings indicate that flexibility from sector-coupling elements and decentral energy resources are a relevant resource and can be applied for corrective actions in transmission system operations.