Transient Stability Analysis of Droop-Controlled Grid-Connected Converters With Inertia Emulating Low-Pass Filters

Abstract

This paper presents a design-oriented transient stability analysis of a droop-controlled voltage-source converter (VSC), where the low-pass filters (LPFs) for inertia emulating are in focus. It reveals that the two LPFs in the active and reactive power loops take opposite effects on the transient stability: the former degrades the stability while the latter improves it. By means of the phase portrait, the mechanism behind this is explicitly elaborated, and the quantitative impacts of the inertia emulating terms are clearly identified. Subsequently, a design guideline of the LPFs for enhancing the transient stability is proposed. Finally, experimental results are provided to verify the theoretical analysis.