If your load requirement is 50GW, kindly consider that you using single source (fuel cell) or with multiple sources like (solar, wind, battery etc).
Step 1: Specify the individual specification for the renewable energy sources like 1MW or 2MW etc Step 2: Use appropriate energy conversion to fed the input to the common DC bus (using a DC/DC converter) Step 3: Use a three phase inverter and provide appropriate switching using 120 degree mode Step 4: Connect the output of the inverter to the loads.