μ Analysis on the DC-Link Voltage Control Stability of the Weak-Grid-Connected VSC

Uncertainties accompany practical system inherently complicate the stability analysis for the weak-grid-connected voltage source converter (VSC) under DC-link voltage control (DVC). In this paper, structured singular value (SSV, also called mu)-based approach is proposed to explore the stability region of this (multi-input-multi-output) MIMO system considering parametric uncertainties. First, system small-signal model is established, and the generalized uncertain model is formulated using linear fractional transformation (LFT) algorithm. Then, system stability boundary is determined by the comparison between the value of mu and the criterion, under multiple parametric perturbations. Finally, eigenvalues analysis and time-domain simulation results validate the predictions accuracy of the proposed mu approach.