Protection and Management of Internal Faults in Modular Smart Transformer

High penetration of distributed generation and charging stations in the LV distribution grid leads the electric grid to be subjected to violations of voltage and current limits. The Smart Transformer (ST) can effectively solve these challenges by flexible power flow control. Moreover, the ST can provide the DC connectivities. Thus, power control and DC connectivity reduce the reinforcements in the electric grid assets. However, compared to the conventional power transformer, the power electronics-based ST is sensitive to internal faults. Thus, in this paper, the device level short-circuits protection, in particular of SiC-based power semiconductors, is designed first and then a post-fault management solution is proposed to improve the ST capability for fault tolerance and continuous operation. Experimental results are provided to clearly validate the effectiveness of the internal fault protection and management.