The power electronic transformer is a novel power electronic conversion device designed for medium-voltage grids, enabling AC/DC voltage transformation and flexible control of electrical energy. It is primarily applied in AC/DC distribution networks and flexible DC systems. Compared to traditional transformers, it achieves coordinated control among "source-grid-load-storage" components, better managing power distribution in the grid. Additionally, it offers fault current limiting and self-healing capabilities, enhancing the economic efficiency and reliability of grid operations.