Hierarchical Hybrid Architecture for Volt/Var Control of Power Distribution Grids

Abstract

This paper presents a hierarchical-hybrid architecture for Volt/Var control of distribution grids in the presence of high penetration of distributed generators (DGs). The architecture includes three layers with specific operational goals associated with each layer based on data resolution, communication network, and control device response time. The top layer carries out central optimization and seeks to minimize power losses via optimal 15-minute scheduling of load tap changers (LTCs), voltage regulators (VRs), and capacitor banks (CBs), and DGs. The middle layer ensures voltage regulation using a distributed approach for reactive power provisioning by fast response DGs. The bottom layer carries out local decision making that enlists edge intelligence to operate LTCs, VRs and CBs to cope with fast and real-time changes in DGs and loads. The top layer generates overall references for the lower layers optimized over a 24-hour horizon, updated at 15-minute intervals, which are then suitably corrected at faster time-scales of seconds in the middle and bottom layers. Appropriate coordination is introduced between each layer so as to meet combined goals of optimization and accommodation of load and generation uncertainties in near real-time. The proposed method is validated using a modified IEEE 34 bus test feeder and at 80% penetration of DGs.