Abstract
Virtual synchronous machine (VSM) based high voltage dc systems enhance the inertia of the power system. However, the dynamic interactions between the VSM-based rectifier station, the inverter station, and the grid could induce the system oscillation, which has been investigated in this article. At first, the hybrid ac-dc impedance models of the VSMs considering the coupling between the ac and dc dynamics are established. Then, the relationships between the dc impedance, dq-frame impedance, and the hybrid ac-dc impedance are presented. It is found that the dc impedance of the VSM-based inverter station and the d-d channel impedance of the dq-frame impedance of the rectifier station behave as negative resistors in the low-frequency range. Moreover, a five-dimensional impedance stability criterion based on the hybrid ac-dc impedance and generalized inverse Nyquist criterion is proposed to assess the system stability. The analysis results show that the low-frequency oscillation occurs when the grid short-circuit ratio of the rectifier station is small. Finally, the simulation and experimental results verify the impedance models and the stability criterion.
Original language | English |
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Journal | IEEE Transactions on Industrial Electronics |
Volume | 69 |
Issue number | 4 |
Pages (from-to) | 3752-3763 |
Number of pages | 12 |
ISSN | 0278-0046 |
DOIs | |
Publication status | Published - Apr 2022 |
Bibliographical note
Publisher Copyright:IEEE
Keywords
- Hybrid AC/DC impedance model
- Impedance stability criterion
- Virtual synchronous machine
- VSC-HVDC system