Reactive power redispatch at the TSO-DSO interface: analysis of the challenges and differences for processual integration

The increasing challenge of maintaining voltage due to reduced reliable reactive power potentials in the transmission grid requires a fast and economically optimal consideration of reactive power in the congestion management processes of transmission system operators. Established processes such as the German Redispatch 2.0 process adjust the dispatch of plants to avoid congestion but do not make use of available reactive power potentials to avoid voltage-related congestion. This work evaluates the suitability of existing processes for application to reactive power. Using a realistic distribution grid, the procedural Redispatch 2.0 specifications for clustering reactive power are applied. It can be shown that the determination of reliable reactive power capability is associated with more dependencies and influencing factors than with active power. This leads to the need for a separate cluster concept and, due to the operating point dependency, for a procedure coordinated with the grid situation.