Single-Phase Synchronous Inverter Control for Fault Management using Emulation Signal Generators

Grid-forming (GFM) inverters are promising solutions for future power systems with high penetration of renewables. The successful design of GFM inverters is crucial for achieving current limiting, enabling them to withstand disturbances such as voltage sags and phase jumps in grid voltages. However, when the parameters are not properly tuned, a cascaded voltage and current controller can compromise grid stabilization performance due to issues like controller windup, postfault recovery failure, and harmonic instability. To address this challenge, this paper proposes a dual control scheme consisting of GFM and current control that work in parallel. The dual control scheme incorporates emulation signal generators integrated with the dual controllers. This integration allows for adjusting their internal states during standby mode to track to references, enabling a seamless transition between the running and standby modes. Numerical simulations and experiments demonstrate that the proposed controller exhibits promising performance under both normal and faulted conditions.