VoltVAR

VoltVAR, short for volt-Var control or volt-Var optimization (VVO), is a distribution-system control strategy that coordinates voltage regulation devices and reactive power sources to maintain voltage within prescribed limits while reducing energy losses. It is commonly implemented in modern smart grids to accommodate increasing distributed energy resources and dynamic loading conditions.

The main goal of VoltVAR is to keep feeder voltages within acceptable ranges (typically around 0.95 to 1.05 per unit, depending on local standards) while minimizing losses and improving power quality. This is achieved by actively managing reactive power injections and voltage setpoints from devices such as capacitor banks, voltage regulators (including on-load tap changers), reactors, and reactive-power-capable distributed energy resources (DERs) like photovoltaic inverters and energy storage systems. In practice, VoltVAR can be deployed as a centralized optimization within a energy management system or as a distributed, local control scheme, often communicating with field devices via SCADA or advanced distribution automation networks.

Operational approaches vary from rule-based volt-Var curves to more sophisticated optimization methods that consider feeder topology, load forecasts, line impedances, and DER output. The outcome is an improved voltage profile, reduced transmission and distribution losses, better loading of network assets, and enhanced hosting capacity for DERs. Challenges include ensuring reliable communication, coordinating multiple devices, avoiding control oscillations, and maintaining protection coordination. VoltVAR is commonly integrated into distribution management systems and may be part of broader DER management or grid modernization initiatives.