Small-Signal Stability Study of AC/DC Hybrid Weak Microgrid

In this paper, the concept of ac/dc hybrid weak microgrid is introduced and the short-circuit ratio (SCR) is reintroduced to analyze the microgrid strength. The eigenvalue analysis of the detailed model of the weak microgrid demonstrates that under very weak conditions, system instability is due to the presence of low-and mid-frequency modes. This makes the stability problem more complex as compared to typical ac microgrids and weak grids. Time-domain simulation results are provided to verify the analytical findings.