Optimal Power Flow for Integrated Primary-Secondary Distribution Networks with Center-Tapped Service Transformers

TL;DR

This paper develops a convex optimization-based optimal power flow model for integrated primary-secondary distribution networks with center-tapped service transformers, enabling more accurate and holistic power system management.

Contribution

It introduces a novel convex relaxation and linearization approach for center-tapped transformer constraints within SDNet OPF models, integrating them into existing primary distribution network frameworks.

Findings

Model effectively handles nonlinear constraints.

Demonstrates improved accuracy and efficiency.

Validated on case studies with positive results.

Abstract

Secondary distribution networks (SDNets) play an increasingly important role in smart grids due to a high proliferation of distributed energy resources (DERs) in SDNets. However, most existing optimal power flow (OPF) problems do not take into account SDNets with center-tapped service transformers. Handling the nonlinear and nonconvex SDNet power flow constraints is still an outstanding problem. To meet this gap, we first utilize the second-order cone programming relaxation and linearization to make center-tapped service transformer constraints convex, respectively. Then, a linearized triplex service line power flow model, including its compact matrix-vector form, is further developed to compose the SDNet OPF model with our proposed center-tapped service transformer model. This proposed SDNet OPF model can be easily embedded into existing primary distribution network (PDNet) OPF models, resulting in a holistic power system decision-making solution for integrated primary-secondary distribution networks. Case studies are presented for two different integrated primary-secondary distribution networks that demonstrate the effectiveness and superiority of this model.