Operational characteristic analysis of renewable energy power systems with high penetration of grid-forming converters

With the integration of a high proportion of renewable energy into the power grid, the stability of power systems faces significant challenges, particularly in terms of reduced inertia and weakened voltage support capabilities. As a novel power electronic device, the grid-forming converter (GFM) has the advantages of voltage source characteristics, providing virtual inertia and voltage regulation capabilities. However, the static operating characteristics of systems with high GFM proportions have not been thoroughly investigated. This paper presents a static power flow mathematical model suitable for both grid-forming and grid-following converter nodes and uses simulations to analyze the impact of a high proportion of GFM capacity on the system's voltage distribution, reactive power allocation, and network losses. The results show that a high proportion of GFM integration leads to reactive power circulation, increased network losses, and potential local voltage stability issues. Specifically, as the load increases gradually, the reactive power support capability of GFM nodes depletes, affecting the overall voltage stability margin of the system. This paper systematically reveals the mechanism of GFM node type conversion and delves into the static voltage stability issues in high GFM scenarios, providing an important theoretical basis for steady-state analysis in future power systems with high renewable energy penetration.