An Exact Linearization Method for OLTC of Transformer in Branch Flow Model

TL;DR

This paper introduces an exact linearization technique for on-load tap changers (OLTC) in transformer models within branch flow optimal power flow problems, ensuring convexity and enabling efficient solutions.

Contribution

It proposes a novel linearized transformer OLTC model using binary expansion and big-M methods to maintain convexity in OPF problems.

Findings

Model verified on IEEE 33-bus system

Ensures convexity of OPF with transformer OLTCs

Facilitates efficient solution of distribution network OPF

Abstract

The branch flow based optimal power flow(OPF) problem in radianlly operated distribution networks can be exactly relazed to a second order cone programming (SOCP) model without considering transformers. However, the introdution of nonlinear transformer models will make the OPF model non-convex. This paper presents an exact linearized transformer's OLTC model to keep the OPF model convex via binary expanstion scheme and big-M method. Validity of the proposed method is verified using IEEE 33-bus test system.