Characterisation of the reactive power capability of diverse distributed generators: Toward an optimisation approach

The highly renewable power system cannot assume the ubiquity and constant availability of synchronous plant. For this reason, the provision of ancillary services must shift to renewable generators, concomitant with their rising penetration levels. This work will focus on one aspect of this challenge: the provision of reactive power from distributed generation. As such resources become increasingly important, their incorporation into transmission system operation and planning activities becomes vital. To that end, a capability characterisation appears useful, delineating the range of controllable reactive power available for a given power flow onto a section of distribution network. Work to date has used time series techniques to provide a proxy to this type of capability chart. Distribution system optimisation techniques offer the potential for a more rigorous and general-purpose characterisation methodology. This work will set out how such an optimisation problem may be formulated, and will provide some initial results and validations.