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Transient Stability Analysis for Grid-Forming Inverters Transitioning from Islanded to Grid-Connected Mode.pdf (946.04 kB)
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Transient Stability Analysis for Grid-Forming Inverters Transitioning from Islanded to Grid-Connected Mode

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posted on 17.05.2022, 02:40 authored by Teng LiuTeng Liu, Xiongfei WangXiongfei Wang, Fangcheng Liu, Xin Kai, Yunfeng Liu

This paper addresses the transient stability of grid-forming (GFM) inverters when transitioning from the islanded to grid-connected mode. It is revealed that the reconnection of the GFM inverters to the main grid can be equivalent to a step change of the active power reference, whose impact is closely related with the local load, active power reference of GFM inverter, and short-circuit ratio (SCR) of the grid. Such equivalent disturbance may cause GFM inverters lose the synchronism with the grid. To avoid loss of synchronization, the existence of equilibria of GFM inverter after reconnecting it with the grid is examined, considering the varying SCR. Then, the parametric effects of power controllers on the transient stability are characterized by using phase portraits, which shed clear insights into the controller design for reliably reconnecting GFM inverters with grid. Lastly, all the theoretical findings are confirmed by experimental tests.

History

Email Address of Submitting Author

teli@energy.aau.dk

ORCID of Submitting Author

0000-0003-1211-5510

Submitting Author's Institution

Aalborg University

Submitting Author's Country

Denmark