Enhancing Fault-Ride-Through Performance of a Virtual-Synchronous-Machine-Based Grid-Forming Inverter

Date

2026-1-06

Author

Derogarian Miandoab, Mohammad

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With the increasing use of inverter-based resources, carbon emissions in the power sector can be reduced, but these units also introduce new challenges for grid stability due to their low inertia and sensitivity to frequency disturbances. Grid-forming (GFM) inverters have been proposed to address these issues, yet their behaviour during faults remains a key limitation. This thesis studies the modelling, control, and fault response of a synchronverter-based GFM inverter for low-voltage weak grid. A plant model that includes the grid impedance was developed to support more accurate controller design, and the synchronverter structure together with an "abc" frame proportional resonant (PR) controller was used to provide virtual inertia and damping. Both simulations and a real-time LabVIEW implementation confirmed that the inverter can deliver the expected inertial behaviour. The inverter’s response to symmetrical voltage sags was then analysed. A voltage-dependent active-power modifier was introduced to keep the load angle within a safe range, and a hybrid current-limiting scheme combining the sinusoidal current reference limiter (SCRL) and the unified nonlinear transient virtual resistance (UNLTVR) was implemented in the natural "abc" frame. Finally, an auxiliary controller was proposed to prevent excessive growth of the internal voltage reference during faults. Simulation and experimental results showed that this controller stabilises the voltage reference and improves the overall fault and post-fault behaviour of the GFM inverter.

Subject Keywords

Auxiliary control, Current limiting, Fault ride-through, Grid-forming inverter, Synchronverter

URI

https://hdl.handle.net/11511/118382

Collections

Graduate School of Natural and Applied Sciences, Thesis