PNNL

Abstract

Conservation voltage reduction (CVR) is employed in electric power distribution systems to reduce the feeder power consumption by operating the system closer to the lower acceptable voltages limits. In this paper, we propose a coordinated centralized and local control scheme to manage the operation of the system’s voltage control devices. The centralized controller utilizes a threephase unbalanced linear power flow formulation and solves a mixed integer linear program (MILP). However, the variability in power production by the photovoltaics (PVs) results in a deviation in nodal voltages compared to the reference voltages obtained after implementing centralized control decisions. To achieve the CVR objective with variable PV generation, we propose local control schemes for PV smart inverters that provide fast reactive power support to restore nodal voltages to their reference values. Two local control methods are proposed: (1) based on equivalent Thevenin impedance, (2) based on power flow measurements. The proposed coordinated control framework is validated using IEEE-123 bus and PNNL 329-bus three-phase unbalanced test systems. It is demonstrated that the coordinated control approach is effective in simultaneously achieving the CVR objective while reducing the nodal voltage deviations due to PV generation variability.