Hierarchical Optimal Power Flow with Improved Gradient Evaluation

TL;DR

This paper improves a hierarchical AC-OPF algorithm by developing a more accurate gradient evaluation method, which enhances voltage safety without sacrificing computational efficiency, addressing risks from linearization.

Contribution

The paper introduces a novel gradient evaluation technique for hierarchical AC-OPF that reduces voltage violation risks caused by linear approximations.

Findings

Enhanced voltage safety in IEEE network tests

Maintained computational efficiency with the new method

Reduced voltage violation risks from linearization

Abstract

Existing algorithms to solve alternating-current optimal power flow (AC-OPF) often exploit linear approximations to simplify system models and accelerate computations. In this paper, we improve a recent hierarchical OPF algorithm, which rested on primal-dual gradients evaluated in a linearized distribution power flow model. Specifically, we identify a risk of voltage violation arising from the model linearization, and propose a more accurate gradient evaluation method to eliminate that risk. We further develop a hierarchical primal-dual algorithm to solve OPF based on the proposed gradient evaluation method. Numerical results on IEEE networks show that our algorithm can enhance voltage safety with satisfactory computational efficiency.