TY - JOUR
T1 - Optimal Controller Design for Transient Stability Enhancement of Grid-Following Converters Under Weak-Grid Conditions
AU - Taul, Mads Graungaard
AU - Wu, Chao
AU - Chou, Shih-Feng
AU - Blaabjerg, Frede
PY - 2021
Y1 - 2021
N2 - Modeling and design-oriented control of transient stability of grid-following converters have attained an increasing interest in recent years. Despite novel nonlinear models enabling a design-oriented enhanced transient stability controller, the focus has so far been limited to study only the synchronization dynamics of the phase-locked loop. To expand upon the knowledge of the large-signal performance and stability, this article proposes a systematic analysis procedure of a grid-following converter under weak-grid conditions and large-signal disturbances including the outer dc-link and ac-side voltage control loops. A reduced-order large-signal model is used to analyze the large-signal nonlinear behavior of the system using the area of the basin of attraction as a measure for large-signal robustness. Here, stabilizing and destabilizing trends for outer-loop controller parameters are given. Through a surrogate-model expensive black-box optimization algorithm, a computational-efficient optimal design of the outer-loop controller parameters is proposed to maximize the large-signal robustness. Finally, a recommendation and a design guideline for converter constraints and outer-loop controller parameters are given. This can be used to identify the influencing parameters for grid-following converters under large-signal disturbances, and as a tool for fast controller optimization toward large-signal robustness.
AB - Modeling and design-oriented control of transient stability of grid-following converters have attained an increasing interest in recent years. Despite novel nonlinear models enabling a design-oriented enhanced transient stability controller, the focus has so far been limited to study only the synchronization dynamics of the phase-locked loop. To expand upon the knowledge of the large-signal performance and stability, this article proposes a systematic analysis procedure of a grid-following converter under weak-grid conditions and large-signal disturbances including the outer dc-link and ac-side voltage control loops. A reduced-order large-signal model is used to analyze the large-signal nonlinear behavior of the system using the area of the basin of attraction as a measure for large-signal robustness. Here, stabilizing and destabilizing trends for outer-loop controller parameters are given. Through a surrogate-model expensive black-box optimization algorithm, a computational-efficient optimal design of the outer-loop controller parameters is proposed to maximize the large-signal robustness. Finally, a recommendation and a design guideline for converter constraints and outer-loop controller parameters are given. This can be used to identify the influencing parameters for grid-following converters under large-signal disturbances, and as a tool for fast controller optimization toward large-signal robustness.
KW - Grid-connected converters
KW - nonlinear analysis
KW - reduced-order modeling
KW - transient stability
UR - http://www.scopus.com/inward/record.url?scp=85103224688&partnerID=8YFLogxK
U2 - 10.1109/TPEL.2021.3066205
DO - 10.1109/TPEL.2021.3066205
M3 - Journal article
SN - 0885-8993
VL - 36
SP - 10251
EP - 10264
JO - IEEE Transactions on Power Electronics
JF - IEEE Transactions on Power Electronics
IS - 9
M1 - 9380162
ER -