Control of a Three-Phase Power Converter Connected to Unbalanced Power Grid in a Non-Cartesian Oblique Frame

Grzegorz Iwanski,Sebastian Wodyk,Tomasz Luszczyk

doi:10.1109/tpel.2021.3098697

Grzegorz Iwanski, Sebastian Wodyk + Show 1 more

Open Access

https://doi.org/10.1109/tpel.2021.3098697

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Abstract

The article presents a new approach to positive and negative sequence current vector control of a grid-connected three-phase three-wire power electronic converter operating under grid voltage imbalance conditions. The concept utilizes the representation of unbalanced converter current in the new coordinates frame in which the current vector components are constant. The nonlinear trigonometric transformation of two-dimensional current vector components from the stationary frame to the new frame is found online depending on the reference current asymmetry. The presented concept of new coordinates utilization allows implementation of proportional-integral terms as current regulators without the use of resonant terms and without the use of the measured current symmetrical sequences decomposition. The article presents the theoretical approach, simulation results, as well as laboratory tests results.

Highlights

POWER electronics converters used as grid interfaces between energy sources, energy storage systems and loads can nowadays be treated as mature technology
Some recent grid codes take into consideration assistance of energy conversion systems in the field of negative sequence management during asymmetrical grid voltage sags aiming at power system stability increase and improvement of energy quality [1]
Slight over-regulation in the first period occurs. In both cases of DSFR control four regulators are responsible for current control and multiple Park’s transformations used

Summary

Introduction

POWER electronics converters used as grid interfaces between energy sources, energy storage systems and loads can nowadays be treated as mature technology. They are used as single-phase systems for fractional power and threephase systems for kW range and above. Some recent grid codes take into consideration assistance of energy conversion systems in the field of negative sequence management during asymmetrical grid voltage sags aiming at power system stability increase and improvement of energy quality [1].

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Results

Conclusion