Coordinated two-stage volt/var management in distribution networks

This paper investigates daily volt/var control in distribution networks using feeder
capacitors as well as substation capacitors paired with on-load tap changers. A twostage
coordinated approach is proposed. Firstly, the feeder capacitor dispatch schedule
is determined based on reactive power heuristics. Then, an optimisation model is
applied to determine the dispatch schedule of the substation devices taking into account
the control actions of the feeder capacitors. The reference voltage of the substation
secondary bus and the tap position limits of transformers are modified such that the
model adapts to varying load conditions. The optimisation model is solved with a
modified particle swarm optimisation algorithm. Furthermore, the proposed method
is compared with conventional volt/var control strategies using a distribution network
case study. It is demonstrated that the proposed approach performs better than the
conventional strategies in terms of voltage deviation and energy loss minimisation.