Impact of Hybrid Grid-Following and Grid-Forming Converters on Post-Fault Overvoltage in Renewable Energy Base

With the integration of renewable energy and power electronic devices, the dynamic characteristics of the power system have become increasingly complex. In order to reveal the post-fault overvoltage mechanism of hybrid grid-following converter (GFL) and grid-forming converter (GFM) systems, this paper analyzes the terminal voltage characteristics among different systems using phasor diagram. Firstly, this paper introduces GFL model and analyzes the terminal voltage in GFL grid-connected system. Next, this paper analyzes hybrid GFL and GFM system, pointing out that GFM can provide voltage support during short-circuit faults, and reduce post-fault overvoltage. Then, the paper discusses the impact of the capacity ratio of GFL to GFM on terminal voltage. Finally, the theoretical analysis in this paper has been verified in different systems.