Impedance-Based Stability Analysis and On-Site Stability Evaluation of Three-Phase Active Voltage Conditioner Embedded System

The active voltage conditioners (AVCs), which refers to a class of series voltage compensators in this article, have been employed in increasingly complex applications in recent years. Therefore, the stability of the AVC-embedded system, i.e., the interconnected system of the grid, the AVC, and loads, becomes a serious issue to be considered. To deal with the stability of the AVC-embedded system, the interactions among the grid, the AVC, and loads are supposed to be studied, and the stability of the AVC-embedded system is recommended to be dealt with on site considering the diversity of the field conditions. For the three-phase AVC-embedded system, this article presents the small-signal linearized model of the AVC with complex transfer functions, based on which it is revealed that the grid and the AVC are in series with interactions, constituting the AVC-embedded grid. Then, considering the AVC-embedded system as the interconnected system of the AVC-embedded grid and loads, the
$\alpha \beta$
-frame impedance model of the AVC-embedded system is presented with the complex transfer matrices, based on which the stability criterion and the stability evaluation are discussed using the determinant of the characteristic transfer matrix, i.e., the DoCTM. Furthermore, the on-site stability evaluation of the AVC-embedded system is introduced. Finally, based on a given three-phase AVC-embedded system, the interactions between the grid and the AVC, as well as the impedance-based stability analysis of the AVC-embedded system, are verified using simulations and experiments, the on-site stability evaluation is also demonstrated.