Aggregation of Flexibility Potentials from Active Distribution Grids and Subsequent Usage in Overlaying Grid Operational Management

Abstract:
The power systems are undergoing a paradigm shift, where the phasing out of the thermal power plants potentially hampers grid operation and stability, as flexible active and reactive power reserves decrease as a consequence. The renewables supplanting the conventional generation are expected to fill the resulting gap towards maintaining stable grid operations. The distribution grids, where the renewable based energy sources are predominantly installed, are therefore required to assume an active role. Active distribution networks (ADNs) are required to achieve reliable and stable grid operations at the local level, and simultaneously contribute active and reactive power flexibility (PQ-flexibility) to the overlaying grids. This necessitates an increased planning and coordination effort between the overlaying grid and underlying grid operators. The paper summarizes the concepts regarding the mapping of the PQ-flexibility potentials and the corresponding usage in the overlaying grid operational management and proposes strategies to consider the volatile renewable power infeed uncertainties. Robust PQ-flexibility maps are demonstrated from which flexibility can be reliably procured by the overlaying grid operator in an optimization based grid operational management.