An Argument-Principle Based Stability Assessment Method for Grey-Box DFIG Systems
It addresses the stability analysis problem for grey-box DFIG systems, which are common in practice due to proprietary models, but the method is domain-specific and incremental.
This paper proposes an Argument-principle based stability assessment method for grey-box doubly fed induction generator (DFIG) systems, which are challenging due to commercial confidentiality and frequency coupling. The method uses frequency sweeping to acquire a MIMO model and a determinant trajectory-based stability criterion, validated through simulation and hardware-in-loop experiments.
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.