Transformerless grid integration of a fuel cell system using high-frequency magnetic link

A novel methodology for integrating a fuel cell stack with a medium-voltage grid is presented in this paper. Instead of relying on a conventional inverter and step-up transformer, the proposed system employs a high-frequency magnetic link and a multilevel cascaded medium-voltage converter to interface a proton exchange membrane fuel cell (PEMFC) directly with the AC distribution grid. The proposed research details the design, analytical modeling, and performance evaluation of the converters when integrated into a grid-connected fuel cell setup, as well as the control scheme developed to regulate power transfer to the grid. The feasibility of the proposed work was demonstrated through simulations on a 1 MW PEMFC system, inclusive of the control system demonstrating optimized performance, connected to an 11 kV grid within the MATLAB/Simulink environment. Supplementary to the simulations, a 400 W experimental prototype was built and tested in the laboratory environment. • Fuel cell connects to the MV grid through HFML and a multilevel converter. • Validated performance of 1 MW PEMFC simulation and 400 W prototype. • The dual-loop PI control kept the 2050 V DC link stable. • Regulated active power flow to the grid ranged from 0.25 MW to 1 MW. • The current THD of 2.58 % complies with IEEE standards and grid code compliance.