| Title |
Control Parameter Selection of Inverters Based on Modal Analysis for Weak-Grid Stability |
| Authors |
김준선(Junsun Kim) ; 장성호(Sung Ho Chang) ; 명성호(Seongho Myeong) ; 남태식(Taesik Nam) ; 심재웅(Jae Woong Shim) |
| DOI |
https://doi.org/10.5370/KIEE.2026.75.8.1686 |
| Keywords |
Eigenvalue/Eigenvector; Grid-following inverter; Oscillation; Participation factor; Weak grid |
| Abstract |
This paper proposes a modal-analysis-based tuning framework for mitigating oscillatory instability in a grid-following inverter under reduced system-strength conditions by identifying a key tuning parameter and deriving its feasible stability region. A linearized state-space model is established, and the oscillatory behavior is investigated through eigenvalue analysis, modal assurance criterion (MAC)-based mode tracking, and participation factor analysis. The analysis reveals that the tracked oscillatory mode is not dominated by a single control loop, but instead exhibits substantial participation from PLL dynamics, P/Q outer loop states, and dq current dynamics. Based on this result, the outer loop integral gain is identified as the key tuning parameter, and its admissible range is determined by jointly considering the stabilization boundary of the high-frequency mode and the stability boundary of the low-frequency mode. The proposed approach provides a systematic procedure for selecting a critical outer loop tuning parameter and establishing a practical stability region for grid-following inverters under reduced system-strength conditions. |