Fuel cell system and control method thereof

A fuel cell system comprising a fuel cell that generates power when receiving anode gas and cathode gas, the fuel cell system comprising:

• a cathode gas supplier that supplies cathode gas to a cathode flow path of the fuel cell;
• an anode gas supplier that supplies anode gas to an anode flow path of the fuel cell;
• and
• a controller that operates the cathode gas supplier and the anode gas supplier,
• the cathode gas supplier including cathode seal valves provided on an inlet side and an outlet side of the cathode flow path,
• the anode gas supplier including an anode discharge valve provided on an outlet side of the anode flow path,
• the controller being configured to perform
• a shutdown process for closing the cathode seal valves at a power generation shutdown of the fuel cell, and then stopping supply of anode gas to the fuel cell and closing the anode discharge valve in a state in which the fuel cell has an anode pressure higher than a cathode pressure, and
• a fuel supply process for supplying, when a predetermined start condition is satisfied after completion of the shutdown process, anode gas to the fuel cell until the anode pressure reaches a predetermined completion determination pressure,
• the controller terminating the fuel supply process even if the anode pressure is lower than the completion determination pressure when a range of fluctuation of the anode pressure over a predetermined time is equal to or smaller than a predetermined completion determination range after start of the fuel supply process.