An Argument-Principle Based Stability Assessment Method for Grey-Box DFIG Systems

TL;DR

This paper introduces an Argument-principle based method for assessing the stability of grey-box DFIG systems, overcoming challenges posed by confidentiality and frequency coupling.

Contribution

It develops a novel stability assessment approach that does not require detailed system models, using frequency sweeping and determinant trajectory analysis.

Findings

The method effectively analyzes stability through simulations and hardware-in-loop tests.

It provides a way to estimate dominant modes using trajectory information.

The approach handles grey-box MIMO systems without detailed models.

Abstract

Considerable efforts have been made to analyze the small-signal stability of doubly fed induction generator (DFIG) systems. However, commercial confidentiality and frequency coupling make the DFIG system a grey-box multiple-input-multiple-output (MIMO) system with highly challenging stability analysis. This paper proposes an Argument-principle based stability assessment method to analyze the stability of the grey-box DFIG system. The frequency sweeping technique is first used to acquire the MIMO model of the black-box device, as well as the determinant of the system's return difference matrix. Then a stability criterion based on the determinant trajectory is presented. This criterion applies to the stability analysis of grey-box MIMO systems without detailed system models. Further, acritical-pole estimation method with trajectory information is developed to assess the dominant mode of the target system. The simulation and hardware-in-loop experiment results demonstrate the effectiveness of the proposed method. Finally, some concerns about this method, such as model selection, estimation errors and application potential, are thoroughly analyzed and clarified.