Multivariable Grid-Forming Converters with Direct States Control

TL;DR

This paper introduces an improved multivariable grid-forming converter control method that directly manages frequency and internal voltage states, effectively reducing high-frequency disturbances without added complexity, validated through experiments.

Contribution

It proposes a novel control approach using direct state variables and H-infinity tuning to enhance robustness of grid-forming converters.

Findings

Enhanced robustness against high-frequency disturbances

Effective control without increasing system complexity

Validated performance improvements through experiments

Abstract

A multi-input multi-output based grid-forming (MIMO-GFM) converter has been proposed using multivariable feedback control, which has been proven as a superior and robust system using low-order controllers. However, the original MIMO-GFM control is easily affected by the high-frequency components especially for the converter without inner cascaded voltage and current loops and when it is connected into a strong grid. This paper proposes an improved MIMO-GFM control method, where the frequency and internal voltage are chosen as state variables to be controlled directly. In this way, the impact of high-frequency components is eliminated without increasing the complexity of the control system. The H-infinity synthesis is used to tune the parameters to obtain an optimized performance. Experimental results verify the effectiveness of the proposed method.