An online observation method of an anode nitrogen concentration for a proton exchange membrane fuel cell is disclosed. Firstly, a dynamic model of anode nitrogen concentration is established based on a gas transmembrane penetration model and an anode material conservation model of a fuel cell, and then an average voltage degradation value between a nitrogen partial pressure and an average monolithic cell voltage is obtained as online feedback information, an online observer of anode nitrogen concentration is established based on the dynamic model of anode nitrogen concentration and the online feedback information, and the anode nitrogen concentration of the fuel cell is obtained by the online observer. The new method solves the problem of online observation of anode nitrogen concentration during the operation of a proton exchange membrane fuel cell engine system under dynamic conditions.

A fuel cell system with a plurality of fuel cell modules connected to form a fuel cell group having first and second electrical supply terminals that terminate to an electrical load; a measuring device connected to the fuel cell modules that measures a load current of the respective fuel cell modules; and a controller that detects a respective operating state of the fuel cell modules. The controller is connected to and controls operation of the fuel cell modules, and detects whether the operating state is in a respective partial load range of the respective fuel cell module. The controller provides a load current demanded by the load in a first partial-load operating mode of the load by operating all fuel cell modules of the fuel cell group such that all of the fuel cell modules are within the respective partial load range of the respective fuel cell module.

A fuel cell controller for controlling the operation of a fuel cell system comprising a plurality of fuel cells arranged together to provide electrical current at an output, the controller configured to actively set an upper limit on the rate of change in current provided by the fuel cell system at the output based on at least one electrical parameter of one or more of the fuel cells such as the lowest voltage (V.sub.MCV) of an individual fuel cell among a plurality of fuel cells.

A fuel cell system includes a fuel cell stack that generates electricity using fuel and oxidant gases, a reformer that produces the fuel gas by reforming a raw material, a raw material feeder that supplies the raw material to the reformer, a combustor that combusts anode off-gas discharged from the anode of the fuel cell stack, and a controller that controls the raw material feeder. The period of a load-following operation in which the power output of the fuel cell stack shifts from a lower level to a higher level, is divided into multiple sub-periods. For each sub-period, a ratio is determined from the increase amounts in the flow rate of the raw material during the sub-period and the length of the sub-period. The controller controls the raw material feeder to make a ratio on the higher output side smaller than another on the lower output side.

A fuel cell system includes: a fuel cell; a target operating point determination unit that determines a warm-up target operating point based on a required electric power amount during warm-up and a required heat generation amount during warm-up; an operation control unit; and a failure state identification unit that identifies whether an electric power consumption device that operates by consuming generated electric power generated by the fuel cell has failed. When a failure of the electric power consumption device is identified, the target operating point determination unit determines an operating point that satisfies a required electric power amount during a failure that is set to be smaller than the required electric power amount during the warm-up and a required heat generation amount during the failure that is set to be smaller than the required heat generation amount during the warm-up as a target operating point during the failure.

The low efficiency power generation part of a control device is provided with an operating point setting part setting a target current and a target voltage defining an operating point of the fuel cell at the time of low efficiency power generation and a generated electric power control part making the generated electric power of the fuel cell increase and decrease at the time of low efficiency power generation by controlling the current of the fuel cell to the target current while making the flow rate of feed of oxidizing agent gas supplied to the fuel cell fluctuate so that the voltage of the fuel cell increases and decreases above and below the target voltage within a range where the charged and discharged electric powers of the rechargeable battery do not become larger than the allowable charged and discharged electric powers.

The control device is configured so that when a temperature of the fuel cell at the time of start of power generation of the fuel cell is less than a standard temperature, it makes the fuel cell generate power so that the amount of heat generation of the fuel cell accompanying the power generation loss becomes a first amount of heat generation and so that when a cumulative value of current of a time period during which the fuel cell is made to generate power so that the amount of heat generation becomes the first amount of heat generation is equal to or greater than a predetermined cumulative value, it makes the fuel cell generate power so that the amount of heat generation becomes a second amount of heat generation larger than the first amount of heat generation.

A fuel cell system herein may include a battery configured to supply electric power to a fuel cell auxiliary device used for activating a fuel cell stack. When remaining electric energy in the battery is higher than an electric energy threshold upon activation of the fuel cell stack, a controller of the fuel cell system may start outputting current from the fuel cell stack after a fuel concentration in the fuel cell stack reaches a predetermined fuel concentration threshold, and when the remaining electric energy decreases below the electric energy threshold while the fuel concentration is being increased, the controller may start outputting current from the fuel cell stack regardless of the fuel concentration in the fuel cell stack. The current can be obtained from the fuel cell stack even when the remaining electric energy in the battery is low.

Proposed are a fuel cell system and a method of controlling the fuel cell system. The fuel cell system includes: a hydrogen supply unit connected to a hydrogen inlet side of a fuel cell stack, with a supply valve and a sensor being provided in the hydrogen supply unit; a hydrogen discharge unit connected to a hydrogen outlet side of the fuel cell stack, with a water trap and a purge valve being provided in the hydrogen discharge unit; and a controller configured to calculate an amount of hydrogen discharged through the purge valve from an amount of hydrogen supplied to the fuel cell stack and an amount of hydrogen consumed therein, and to perform compensation control of the supply valve when the amount of the discharged hydrogen is at or above a reference value.

A power production system includes a fuel cell separation system configured to receive a flue gas and to produce electrical power therefrom; a flue gas polishing system positioned upstream of the fuel cell separation system and configured to remove contaminants in the flue gas; a flue gas analyzer configured to measure in real-time an amount of the contaminants in the flue gas; and a plant control system operatively coupled to the flue gas polishing system, the flue gas analyzer, and the fuel cell separation system and configured to adjust operational parameters of the flue gas polishing system.