An Optimal Power Flow Algorithm for the Simulation of Energy Storage Systems in Unbalanced Three-Phase Distribution Grids

Lukas Held,Felicitas Mueller,Thomas Leibfried,Michael R Suriyah,Sina Steinle,Mohammed Barakat

doi:10.3390/en14061623

Lukas Held, Felicitas Mueller + Show 4 more

Open Access

https://doi.org/10.3390/en14061623

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Journal: Energies	Publication Date: Mar 15, 2021
Citations: 13	License type: CC BY 4.0

Affiliation: Karlsruhe Institute of Technology

Abstract

An optimal power flow algorithm for unbalanced three-phase distribution grids is presented in this paper as a new tool for grid planning on low voltage level. As additional equipment like electric vehicles, heat pumps or solar power systems can sometimes cause unbalanced power flows, existing algorithms have to be adapted. In comparison to algorithms considering balanced power flows, the presented algorithm uses a complete model of a three-phase four-wire low voltage grid. Additionally, a constraint for the voltage unbalance in the grid is introduced. The algorithm can be used to optimize the operation of energy storage systems in unbalanced systems. The used grid model, constraints, objective function and solver are explained in detail. A validation of the algorithm using a commercial tool is done. Additionally, three exemplary optimizations are performed to show possible applications for this tool.

Highlights

The planned reduction of carbon dioxide emissions leads to a transition of the energy system towards a renewable energy based generation in many countries worldwide
The compliance with given grid limits is ensured through the battery storage system
The battery storage system is optimized such that a given voltage unbalance limit is not exceeded

Summary

Introduction

The planned reduction of carbon dioxide emissions leads to a transition of the energy system towards a renewable energy based generation in many countries worldwide. Several renewable generation units like solar power systems are connected on low voltage level. New loads such as electric vehicles or heat pumps are integrated into the power grid. These systems are mainly connected on low voltage level as well. The new equipment increases fluctuations in the power flow ([1,2]) due to their high power demand and the planning processes are getting more complicated for low voltage grids.

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Conclusion