Core Concepts
A nested feedback optimization approach is proposed to achieve stable and efficient distributed voltage regulation in distribution systems, outperforming both centralized and previous distributed methods.
Abstract
The content discusses the problem of voltage regulation in distribution systems with high penetration of distributed energy resources (DERs). It presents an online feedback optimization (OFO) approach to address this challenge in a distributed manner, without requiring a centralized communication architecture.
The key points are:
Centralized OFO approaches rely on a gather-and-broadcast communication model, which lacks robustness to single-point failures.
Previous distributed OFO approaches, such as the two-metric approach, may lead to algorithm instability and divergence.
To address this, the paper proposes a nested feedback optimization approach, where the outer loop performs the OFO iterations to obtain tentative reactive power setpoints, and the inner loop solves a non-Euclidean projection problem to map the tentative setpoints to actual feasible setpoints.
The proposed approach only requires short-range communication between physical neighbors, and simulation results show that it achieves even better voltage regulation performance than the centralized approach, while being more robust to system uncertainties and disturbances.
The nested approach does not extend to joint active and reactive power control, but the authors suggest deploying separate active and reactive power feedback controllers at different sampling times as a potential solution.
Stats
The average voltage violation (AVV) values are:
1.9 × 10^-4 pu for the centralized approach
1.3 × 10^-4 pu for the proposed approach
4.6 × 10^-3 pu for the two-metric approach
Quotes
"While the two-metric approach does not converge and fails to regulate voltages, our proposed approach converges quickly after approximately 154 iterations, which correspond to around 22 outer and 132 inner iterations."
"Our simulation results showed that the approach achieved even better voltage regulation than a centralized approach while only requiring short-range communication between physical neighbours."