Distributed Power Flow and Distributed Optimization -- Formulation, Solution, and Open Source Implementation

TL;DR

This paper introduces a flexible, open-source framework for distributed power flow computation using novel formulations and solution methods, with guarantees and practical performance demonstrated on large systems.

Contribution

It proposes two physically consistent distributed power flow formulations and solution methods, including convergence guarantees for Aladin, along with an open-source MATLAB tool for rapid prototyping.

Findings

Aladin converges in about six steps for large systems.

The approach is modular, reproducible, and compatible with existing power system tools.

Simulation on systems up to 4662 buses demonstrates scalability and efficiency.

Abstract

Solving the power flow problem in a distributed fashion empowers different grid operators to compute the overall grid state without having to share grid models-this is a practical problem to which industry does not have off-the-shelf answers. In cooperation with a German transmission system operator we propose two physically consistent problem formulations (feasibility, least-squares) amenable to two solution methods from distributed optimization (the Alternating direction method of multipliers (ADMM), and the Augmented Lagrangian based Alternating Direction Inexact Newton method (Aladin)); with Aladin there come convergence guarantees for the distributed power flow problem. In addition, we provide open source matlab code for rapid prototyping for distributed power flow (rapidPF), a fully matpower-compatible software that facilitates the laborious task of formulating power flow problems as distributed optimization problems; the code is available under https://github.com/KIT-IAI/rapidPF/. The approach to solving distributed power flow problems that we present is flexible, modular, consistent, and reproducible. Simulation results for systems ranging from 53 buses (with 3 regions) up to 4662 buses (with 5 regions) show that the least-squares formulation solved with aladin requires just about half a dozen coordinating steps before the power flow problem is solved.