Distributed Optimal Conservation Voltage Reduction in Integrated Primary-Secondary Distribution Systems

TL;DR

This paper introduces an asynchronous distributed control method for conservation voltage reduction in unbalanced distribution systems, leveraging smart inverters and a novel linear approximation to enable fast, robust, and scalable voltage management.

Contribution

It presents a new asynchronous distributed leader-follower control approach that considers integrated primary-secondary networks and load dependencies, improving scalability and robustness.

Findings

Effective voltage reduction demonstrated on a real distribution feeder.

Method achieves fast tracking of system variations.

Robust against communication delays and failures.

Abstract

This paper proposes an asychronous distributed leader-follower control method to achieve conservation voltage reduction (CVR) in three-phase unbalanced distribution systems by optimally scheduling smart inverters of distributed energy resources (DERs). One feature of the proposed method is to consider integrated primary-secondary distribution networks and voltage dependent loads. To ease the computational complexity introduced by the large number of secondary networks, we partition a system into distributed leader-follower control zones based on the network connectivity. To address the non-convexity from the nonlinear power flow and load models, a feedback-based linear approximation using instantaneous power and voltage measurements is proposed. This enables the online implementation of the proposed method to achieve fast tracking of system variations led by DERs. Another feature of the proposed method is the asynchronous implementations of the leader-follower controllers, which makes it compatible with non-uniform update rates and robust against communication delays and failures. Numerical tests are performed on a real distribution feeder in Midwest U. S. to validate the effectiveness and robustness of the proposed method.