Fuel cell control system

A fuel cell control system comprising:

• a plurality of fuel cell systems in which a plurality of fuel cell systems are provided in parallel, each of the plurality of fuel cell systems including a fuel cell that performs power generation through an electrochemical reaction between fuel gas supplied to an anode and oxidant gas supplied to a cathode;
• a cathode shutoff valve that is provided on an upstream side and a downstream side of the cathode of the fuel cell in each of the fuel cell systems, and changes a supply amount of the oxidant gas to the cathode in accordance with an opening degree of the cathode shutoff valve;
• a voltage detection unit that detects an output voltage of the fuel cell in each of the fuel cell systems;
• and
• an oxygen consumption control unit that executes oxygen consumption control in which, when stopping operation of the plurality of fuel cell systems, power generation of the fuel cell in each of the fuel cell systems is continued in a state where the cathode shutoff valve is closed, to consume oxygen remaining in the fuel cell,
• wherein the oxygen consumption control unit executes, when stopping operation of the plurality of fuel cell systems, in a case where the detected output voltage of the fuel cell in one selected fuel cell system is higher than a first threshold voltage that is higher than an output voltage during normal power generation, first drop processing of decreasing the output voltage of the fuel cell in the one selected fuel cell system at a first voltage drop rate, and executes, in a case where the detected output voltage of the fuel cell has become equal to or lower than the first threshold voltage, second drop processing of decreasing the output voltage of the fuel cell in the one selected fuel cell system at a second voltage drop rate having a larger change amount per unit time than the first voltage drop rate, and
• in a case where the first drop processing in the one selected fuel cell system is completed, the oxygen consumption control unit starts execution of the first drop processing in a next one of the fuel cell systems.