Power management system

A power management system comprising:

• a power source including a power system configured to provide main power to a load and a renewable energy generation part configured to provide auxiliary power;
• a power conversion part configured to convert a surplus of at least one of the main power and the auxiliary power;
• a water electrolysis part including a water electrolysis device configured to be driven by the surplus converted by the power conversion part, a balance-of-plant (BOP) configured to be driven by a portion branched from the main power, and a hydrogen storage;
• and
• a control part configured to synchronize power applied to the power conversion part and power applied to the water electrolysis device to exchange direct current (DC) power between the power conversion part and the water electrolysis device,
• wherein power is independently provided to the water electrolysis device and the BOP of the water electrolysis part, and
• wherein the water electrolysis device is configured by connecting two or more water electrolysis stacks of different driving power in parallel.