This paper addresses the stability issues caused by the dc-link voltage control of grid-connected voltage-source converters. An analytical impedance model is developed first for capturing the interactions between the dc-link voltage control and ac current control of converters, which enables to identify different stability impacts of the dc-link voltage control in the rectifier and inverter operation modes of converters. The impedance model is further transformed from the dq-frame to the αβ-frame, which allows characterizing the frequency-coupling effects of the dc-link voltage control dynamics. The impedance-based analysis reveals that the dc-link voltage control may cause low-frequency oscillations in the rectifier mode and high-frequency oscillations in the inverter mode. Case studies on the rectifier and inverter operation modes are presented, and subsequently validated by using time-domain simulations and experimental tests. The close correlations between the measured results and theoretical analysis demonstrate the effectiveness of the impedance model and stability analysis.
- DC-link voltage control
- Impedance model
- Voltage-source converters (VSCs)
Lu, D., Wang, X., & Blaabjerg, F. (2019). Impedance-Based Analysis of DC-Link Voltage Dynamics in Voltage-Source Converters. IEEE Transactions on Power Electronics, 34(4), 3973-3985. . https://doi.org/10.1109/TPEL.2018.2856745