Numerical Comparisons of Linear Power Flow Approximations: Optimality, Feasibility, and Computation Time

TL;DR

This paper evaluates various linear power flow approximations in large-scale optimal power flow problems, focusing on their accuracy, feasibility, optimality, and computational efficiency across multiple test systems.

Contribution

It provides a comprehensive comparison of linear power flow models based on four key criteria, highlighting their strengths and weaknesses for practical OPF applications.

Findings

Linear models vary significantly in accuracy and feasibility.

Some models offer a good balance between accuracy and computation time.

Feasibility issues are critical for practical implementation.

Abstract

Linear approximations of the AC power flow equations are of great significance for the computational efficiency of large-scale optimal power flow (OPF) problems. Put differently, the feasibility of the obtained solution is essential for practical use cases of OPF. However, most studies focus on approximation error and come short of comprehensively studying the AC feasibility of different linear approximations of power flow. This paper discusses the merits of widely-used linear approximations of active power in OPF problems. The advantages and disadvantages of the linearized models are discussed with respect to four criteria; accuracy of the linear approximation, optimality, feasibility, and computation time. Each method is tested on five different systems.