Reactive Current Response of Grid-Forming Converters During Low-Voltage-Ride-Through: Analysis of Test Method Impact

This paper presents an examination of grid-forming converters (GFM) under low-voltage-ride-through (LVRT) conditions. It emphasizes the influence of inner loop control strategies, and grid topologies on GFM performance. The study introduces a versatile equivalent modeling methodology suitable for different inner loop control strategies. Additionally, it evaluates three LVRT testing devices: the shunt impedance based voltage sag generator (SIVSG), programmable voltage source with impedance (PVS), and Hardware-in-the-Loop (HIL) system, highlighting their differences in simulating grid fault characteristics. The results indicate that SIVSG and PVS have limitations in mimicking actual grid fault scenarios, potentially leading to GFMs erroneously passing LVRT tests. Conversely, HIL-based testing methods more accurately replicate grid faults, offering a more reliable assessment of GFM performance.