Conservation voltage reduction of networked microgrids

Abstract

This study proposes a strategy for coordinated operation of networked microgrids (MGs), distributed energy resources (DERs), and volt-VAR control devices in the implementation of volt-VAR optimisation (VVO). The authors’ formulation is focused on implementing conservation voltage reduction, although it can be extended for any other VVO problems. They consider the voltage–power control modes of DERs contemplated in IEEE Std. 1547, namely, constant power factor, voltage–reactive power, active–reactive power, and constant reactive power. DERs are considered at the distribution network (DN) and within the MGs. The problem is formulated as a bi-level optimisation problem where the DN operator (DNO) is in the upper-level and each MG in the lower-level. The DNO and each MG are assumed to be players with their individual objective functions. Finally, they validate their formulation in two test systems: a 9-node system and a modified IEEE 33-node system. On average the proposed method can improve the efficiency of the grid by 4% compared to the economic operation scenario. The results of the study show that the different control modes of the DERs can have better performance depending on the objective of the VVO formulation. The findings of this study are compelling for the implementation of VVO in active distribution systems with networked MGs.