Adaptive Anti-Saturation Control Design of Transformers in Converter-Based Grid Emulators

Transformer saturation is a common issue in megawatt converter-based grid emulators (GEs) when emulating grid faults. This problem necessitates the use of anti-saturation control (ASC) with GEs. However, conventional ASC methods tend to distort the emulated grid voltage or even interact with the voltage control (VC) of GEs, causing instability in the system. This article, thus, proposes an adaptive ASC method and superimposes its output command to both modulation and VC references, which not only alleviate transformer saturation with the lower output voltage distortion, but mitigate its adverse interaction with the VC of converter-based GEs. Experimental results confirm the effectiveness of the adaptive ASC.