FUEL CELL SYSTEM AND VALVE CONTROL METHOD FOR FUEL CELL SYSTEM

A control unit of a fuel cell system estimates an amount of nitrogen in an anode flow field, performs a first comparison by comparing the estimated amount of nitrogen with a first threshold amount, performs a second comparison by comparing a target power generation amount as a target amount of power generation by a fuel cell stack with a second threshold amount in a case where the estimated amount of nitrogen in the anode flow field exceeds the first threshold amount in the first comparison, and controls opening and closing of a first valve and opening and closing of the second valve based on a result of the first comparison and a result of the second comparison.