Ultra-Fast Black-Start Method of the Grid-Forming Converter for Electronic Power Grids with Transformer Soft Magnetization

Black-start capability is an essential service for grid-forming (GFM) converters, enabling the restoration of the electric network after a blackout. However, during black-start, abrupt voltage injection can drive the transformer core into saturation, resulting in excessive inrush current that limits the ability to achieve a fast and reliable start-up. To address this issue, this paper proposes a rapid soft start-up method that actively reshapes the transformer flux trajectory by adjusting the initial voltage injection profile. By compensating the flux-linkage offset, the proposed method effectively prevents core saturation and enables fast energization, significantly reducing the start-up time compared to state-of-the-art methods. Experimental results validate the effectiveness of the proposed approach.