Volt-Var Optimization
About this Technology
Distribution voltage control involves strategies used to maintain acceptable voltage levels at all points along a distribution feeder under all loading conditions to ensure that the voltage delivered to consumers remains within acceptable limits. This technology enables voltage stability, which is required to maintain optimal power quality and minimize energy losses.
Substation adjustments are often made using seasonal rules of thumb based on experience, engineering analysis, and the measured output voltage. Absent sensing and communications to capacitors located along the feeder, voltage levels are often set manually and on a seasonal basis. Improvements in Advanced Metering Infrastructure (AMI) technologies have enabled voltage optimization at the edge by providing real-time voltage readings at meter end points. Distributed energy resources management systems (DERMS) have further provided capabilities in voltage optimization leveraging real and reactive power capabilities of distributed energy resources (DERs).
Source. Networked Energy Services.
Source. Networked Energy Services.
Source. Networked Energy Services.
Use in the Modern Grid
FERC Order 2222 is expected to result in significant penetration and engagement of many types of DERs via aggregators in wholesale markets in Phase II. Advanced Volt-var Control (VVC) will be needed to manage voltages within service limits due to highly variable power injections (generators, PV solar, batteries), withdrawals for charging (batteries & EVs), and sudden load switching (demand response, EVs). It will also be needed by distribution utilities exercising their oversight role to justify any refusal for proposed DER wholesale transactions due to violations of voltage constraints. In Phase III, distribution utilities will integrate aggregated DERs into their VVC systems to leverage their capabilities to help manage voltage, allowing higher rooftop solar hosting capacity and preventing undue deterioration on tap changers and capacitor banks due to rapid switching.
Physical Location
Control equipment is at the head of each service feeder in distribution substations and, increasingly, downstream along the feeder and embedded in customer DERs in the future. Voltage optimization algorithms are also commonly run centrally with the advanced distribution management system (ADMS) or in the enterprise or cloud for DERMS.
Demonstration Project
In 2008, American Electric Power coordinated the deployment of an VVO system across 11 distribution feeders at five substations throughout the Northeast Columbus Ohio area. In this demonstration project, AEP both modeled and then analyzed field data to show benefits from the project. See the project abstract for more information. Currently, AEP has VVO technologies operating on over 100 distribution circuits across multiple states.
How mature is the Technology?
Widely deployed | Variations of the VVO technology have been deployed for well over 20 years. Currently there are many commercial vendors with VVO offerings, providing a range of functionalities. The ability to address complex system reconfiguration and the integration of DER exist, and capabilities vary by specific vendor offering.
More Information
Explore these resources to learn more about VVO.
