JP2010287426A - Reformer for fixed type power generation plant, fuel cell, and battery managing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a managing system for a fixed type power generation plant for avoiding damage to structural elements due to a temporary failure of a hydrogen level on the positive electrode side of a fuel cell as a result of the fact that a reacting time for controlling the flow of water and fuel in a reformer, controlling the blowing speed of vapor, and controlling the temperature level of the system is longer frequently than desired time. <P>SOLUTION: In a method for operating a power generation system including the fuel cell connected to an electric buffer such as a system battery and also connected to the vapor reformer, the operation of the reformer is controlled in accordance with voltage 302 influenced by the electric buffer while maintaining a rate 322 of vapor to carbon in the reformer for the fuel cell to control the charge of the electric buffer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reformer, a fuel cell, and a battery management system in a stationary power generation facility.

  In a stationary power generation facility, electricity can be generated by oxidizing a hydrogen-enriched raw fuel in a fuel cell stack in which a plurality of fuel cells are stacked. The control system for monitoring the flow through the reformer and the fuel cell stack and the output from them can easily control the operation of the power generation equipment even if the power generation output fluctuates. For example, buffer systems such as batteries and / or supercapacitors can be used to protect the components of the power plant from such transients.

  Maintenance of the amount of electrons through the fuel cell circuit can be achieved by continuously supplying hydrogen to the anode side that dissociates hydrogen into protons and electrons in the presence of the anode catalyst. In the absence of hydrogen, the fuel cell cannot be maintained. Thus, in one approach to operating and controlling the power plant, a large amount of hydrogen at the anode is ensured by using a large fuel cell stack. However, the inventors here recognize that this requires a large amount of fuel and a correspondingly large area to accommodate the fuel.

  It is also desirable to maintain the power output from the fuel cell stack because the power or current derived from the fuel cell affects the amount of loss generated and thus the efficiency of the fuel cell. Also, the activation loss of the fuel cell can lead to a decrease in output voltage. Therefore, as another approach for controlling the operation of the power generation facility, a control system is incorporated so as to adjust the capacity of the reformer in accordance with the current derived from the fuel cell. The hydrogen-enriched fuel level entering the fuel cell stack is adjusted by adjusting the capacity of the reformer by changing the inflow amounts of raw fuel and steam. However, further here the inventors have noticed the disadvantages of such an approach. Specifically, the reaction time for adjusting the water and fuel flow rates of the reformer, adjusting the steam blowing rate, and adjusting the temperature level of the system is often longer than desired. is there. If the reaction time is slow, even if a sufficient amount of fuel is stored, the temporary lack of hydrogen level on the anode side of the fuel cell can lead to component damage. The damage becomes more severe when transient fluctuations occur.

  The above problem can be solved by a method of operating a power generation facility comprising a fuel cell connected to an electrical buffer and further connected to a steam reformer. This method maintains the ratio of steam to carbon in the reformer to control the charging of the electrical buffer by the fuel cell, while the reformer is based on the voltage affected by the electrical buffer. Including coordinating driving. For example, the above method includes compensating for an increase in power demand by supplying current from an electrical buffer before the fuel cell current increases due to adjustment of the reformer.

  Thus, by adjusting the reformer according to voltage, the system can cope with voltage disturbance. Thus, rather than relying on a large fuel storage buffer, for example to reduce the possibility of fuel shortage on the anode side, the electrical buffer is subject to transient conditions (eg auxiliary components such as pumps and blowers react). Therefore, it can be used to compensate for demands under transient conditions.

  It should be understood that the foregoing description introduces some of the concepts further described in the detailed description in a simplified form. It is not intended to identify key or essential features of the claimed subject matter, but the scope of the claimed subject matter is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that solve the problems set forth in this disclosure.

It is the schematic in one Embodiment of stationary power generation equipment. It is the schematic in one Embodiment of the stationary power generation equipment control system which concerns on this indication. FIG. 3 is a detailed explanatory diagram of the embodiment of the stationary power generation facility control system illustrated in FIG. 2. 3 is a flowchart illustrating an example of a method for controlling a stationary power generation facility according to the present disclosure. FIG. 5 is a flowchart showing a simplified routine of the control system in the embodiment shown in FIGS. 3 and 4. FIG.

  FIG. 1 shows an embodiment of a stationary power generation facility 100 (hereinafter referred to as “power generation facility 100”) that generates electricity from hydrogen-enriched raw fuel using fuel cell technology. The stationary power generation facility includes a fuel cell stack assembly 102 that transmits power to a DC bus 106 via a DC-DC converter 104. This DC-DC converter 104 comprises part of the control system described in this disclosure.

  The power generation facility 100 includes a buffer system 108. The buffer system 108 includes, but is not limited to, for example, a voltage / current buffer, a battery or battery group, a super capacitor, or a combination thereof. The balance of plant 110 includes other components, structures, and systems that constitute the power generation facility. The other components, structures and systems that make up the power generation facility are like devices required for safe operation and technical coordination in all parts of the power generation facility. Examples include, but are not limited to, main and auxiliary transformers, cranes and turbines. The DC bus 106 is connected to an inverter 112 that receives DC power generated by the power generation facility 100 and converts the DC power into AC power for subsequent power transmission. In one embodiment of the power generation facility 100, if the power generated in the fuel cell stack layer 102 is not sufficient, the buffer system 108 may be charged with AC power from the inverter 112 as input.

  The control system for the power generation facility described in the present disclosure is first configured to maintain a predetermined system battery voltage. Therefore, the control system responds to system battery voltage variations by appropriately adjusting one component or various components in the power generation facility in a coordinated manner to restore the battery voltage to a target value. . In the above embodiment, if one component (or components) of the power plant does not respond to the correction determined by the controller, the inverter may be used, for example, to charge the system battery and return it to the target value. AC power can be input from the grid.

  FIG. 2 illustrates additional details of a power plant control system 200 that includes the power plant 100 in one embodiment. The system includes a fuel cell stack assembly 102 that includes a raw fuel supply 202 that flows to a steam reformer 210. In the embodiments described herein, a variety of suitable hydrocarbon raw fuels may be used. Suitable raw fuels include but are not limited to biodiesel, vegetable oils and natural gas. Therefore, the reformer 210 is configured to generate hydrogen gas from hydrocarbon raw fuel using steam.

  The system further includes a fuel flow control device 204. This fuel flow rate control device adjusts the flow rate of the raw fuel flowing to the steam reformer 210 via the transmitter 206. The fuel flow control device includes various appropriate components. Examples include, but are not limited to, fuel valves (shown). The flow rate of the fuel monitored by the fuel flow meter 208 is transmitted to the electrical controller 230. The fuel flow adjustment mechanism is based on inputs received from a plurality of power plant components, such as a target value for fuel flow, a measured fuel flow, etc., as described in more detail in this disclosure. Controlled by.

  Steam used for hydrogen concentration in the reformer 210 is generated from the water supply unit 212. The water flow rate controller 214 adjusts the flow rate of the steam or water that flows to the steam reformer 210 via the transmitter 216. The water amount control device includes various appropriate components. Examples of this include, but are not limited to, a blower, a feed pump (shown), or a combination thereof. The water flow monitored by the water flow meter 218 is communicated to the electrical controller 230. The water volume adjustment mechanism is also controlled by the electrical controller 230 based on various operating conditions, such as a target water flow rate and a monitored water flow rate, as will be described in greater detail in this disclosure.

  The hydrogen-enriched fuel produced by the steam reformer 210 is then transmitted to the fuel cell stack 220. The fuel cell stack 220 includes a plurality of coupled fuel cells connected to each other, and uses air supplied from the air supply unit 222 to oxidize the hydrogen-enriched fuel. The air flow rate control device 224 controls the flow rate of air entering the fuel cell stack. The air amount control device 224 includes various appropriate components. Examples include, but are not limited to, a blower (shown). The air flow adjustment mechanism is also controlled by the electrical controller 230 in response to various operating conditions, including the target value of the air flow and the measured air flow. Generation of the input current from the fuel cell stack 220 produces fuel exhaust and air that has used up oxygen as shown in the figure.

  The input current is measured by the current measuring device 226 and then transmitted to the DC-DC converter 104. The DC-DC converter has a maximum current limit value, and when the maximum current is exceeded, the converter enters a current control mode. Further, the DC-DC converter has a set voltage limit value such as 53 V, for example, and the output voltage rises below this value.

  The electric power generated by the power generation facility 100 is transmitted to the DC bus 106 via the DC-DC converter, and is transmitted from there. A buffer system 108 (hereinafter also referred to as a battery) illustrated in FIG. 1 is included in the power generation facility. In this example, an acid-based battery is used, but the buffer system may be constructed by various combinations of other types of batteries. The battery voltage meter 228 determines the voltage of the buffer battery and relays the information to the electronic controller 230.

  The controller receives input related to the input voltage derived from the fuel cell stack from the current meter 226 and also receives input related to the bus current 232 from the bus current meter 234. The controller makes adjustments to the flow rates of air, raw fuel, and water, either alone or in combination, based on the entire received data. For controlling the operation of the fuel cell stack, various methods are used singly or in combination, for example, as described in FIGS.

  Specifically, FIG. 3 illustrates an embodiment of a control system 300 that adjusts the power generation of the power generation facility 100 according to the present disclosure. In one aspect of the embodiment, the control system is used to control the operation and output of a fuel cell stack in a stationary power plant that generates power using fuel cell technology. The components of the inputs sent to the control system and the corresponding outputs affected by them are illustrated.

The first control routine is illustrated as 350 for controlling the operation of the reformer according to the battery voltage by using the first controller 310. Specifically, the indication value of the battery voltage 302 is obtained from the voltage measuring device 228. The measured battery voltage 304 is compared to a predetermined set voltage value 306. For example, in one aspect of the routine, the inventors determine that the target value of the system battery voltage, that is, the bus voltage is 53 V (for example, as the set voltage 306). The deviation or deviation between the measured battery voltage and the set value 306 is transmitted to a lookup table 308 having a non-linear gain function. As an example, the non-linear gain is expressed by an equation (Equation 1).
Here, x is a deviation from the set value 306, and E is an adjustment deviation calculated from the measurement deviation x according to the estimation by the lookup table 328. Other variables are adjusted based on desired performance and experimental testing. In this example, a sinh function is used, but various other nonlinear gains such as a bilinear gain may be used. The output from the lookup table is sent to the controller 310 (shown as “K1”). In one example, the controller K1 includes a proportional-integral-derivative controller (hereinafter referred to as “PID controller K1”) 310 incorporated in the electrical control system 230 in order to appropriately transmit a command signal in accordance with the deviation. The command signal adjusts the water flow control device 214 in this example, for example. Although a PID controller is shown in this example, various other control mechanisms may be used including non-linear controllers, gain scheduling controllers, adaptive controllers, state space controllers, and the like. In this method, feedback control of the battery voltage is used, and by changing the gain of the PID controller to obtain the desired response to control the deviation caused by the disturbance or change of the set voltage. , The controller response is adjusted.

  Addition based on the bus current measured in routine 350 to better estimate the interaction of the various systems and more accurately maintain the target voltage (or bus voltage) of the system battery, such as 53V described above. Feedforward control is performed. The bus current 232 is measured by the bus current meter 234 and analyzed against the lookup table 316. By adjusting the water flow rate controller 214 based on this current value deviation 314 from the target set current value and the input 312 from the controller K1 310, the water flow rate is adjusted appropriately. As a result, the amount of steam flowing into the reformer is adjusted, and as a result, the capacity of the reformer changes. Therefore, as will be explained in more detail in the present disclosure, the combination of the feedback control loop according to the battery voltage and the feedforward control mechanism according to the bus current are used to bring the system battery voltage close to the target value. The operation of the reformer 210 is adjusted.

The second control routine is illustrated as 360 operating in parallel with the first control routine 350. The water flow rate 320 is specifically the flow rate of steam measured by the water flow meter 218 and entering the reformer, and the fuel flow rate is the flow rate of fuel measured by the fuel flow meter 208 and entering the reformer. However, they provide data for the controller to estimate the water to carbon ratio 322, the ratio of steam to raw fuel (hydrocarbon). If a deviation of the estimated steam to carbon ratio 324 from the steam to carbon ratio setpoint 326 is confirmed, the deviation is transmitted to the lookup table 328. This lookup table also has a non-linear gain function. As an example, the non-linear gain is expressed by Expression (Equation 2).
Here, x is a deviation from the set value 326, and E is an adjustment deviation calculated from the measurement deviation x according to the estimation by the lookup table 328. Other variables are adjusted based on desired performance and experimental testing. In this example, a sinh function is used, but various other nonlinear gains such as a bilinear gain may be used. The output from the lookup table is sent to the controller 330 (shown as “K2”). In one example, the controller K2 includes a PID controller (hereinafter referred to as “PID controller K2”) 330 incorporated in the electrical control system 230 in order to appropriately generate a command signal in accordance with the deviation. The command signal adjusts the fuel flow control device 204 in this example, for example. Although a PID controller is used in this example, various other control mechanisms may be used including non-linear controllers, gain scheduling controllers, adaptive controllers, state space controllers, and the like. In this method, feedback control of the steam to carbon ratio is used and the PID controller is used to obtain the desired response to control the deviation caused by the disturbance or change of the steam to carbon ratio setpoint. By changing the gain of the controller, the response of the controller is adjusted.

  In order to better estimate the interaction of the various systems and more accurately maintain the target voltage (or bus voltage) of the system battery, such as 53V described above, additional due to the bus current measured in routine 360 Feedforward control is performed. The bus current 232 measured by the bus current measuring device 234 is transmitted to the lookup table 316. Based on the current value deviation 314 from the target set current value and the input 332 from the controller K2 330, further adjustments to the fuel flow rate are made by appropriately adjusting the fuel flow rate controller 204. Therefore, in order to recover the ratio of steam and carbon to the target value by the combination of the feedback control loop performed according to the ratio of steam and carbon and the feedforward control mechanism performed according to the bus current, the reformer The operation of 210 is adjusted, and as a result, the subsequent operation of the fuel cell stack 220 is adjusted. In this manner, the control routines 350 and 360 can perform feedback control by harmonizing the battery voltage and the ratio of steam to carbon in accordance with feedback from the operation data of the fuel cell stack. Furthermore, they can also be feedforward controlled according to the bus current. By doing so, the control system adjusts the capacity of the reformer according to the capacity of the fuel cell stack and the demand of the system by effectively using the electric buffer system 108.

  FIG. 3 further illustrates a third control routine 370 that operates with the feedforward structure. The feedforward structure is responsive to the input current derived in the power generation facility 100. Specifically, the input current 340 derived from the fuel cell stack 220 is measured by the current measuring device 226 and transmitted to the lookup table 342. Further, data relating to the fuel flow rate from the fuel flow rate measuring device 208 is input to the lookup table 342. Based on the received data, the lookup table analyzes and specifies the maximum limit of current that can be derived from the fuel cell stack. This designated value is transmitted to the DC-DC converter. The DC-DC converter operates in a current control mode as described above to keep the current from exceeding this maximum limit.

  Further, the feedforward control is used to adjust the air flow rate control device 224 according to the input current. In this way, for example, the capacity of the fuel cell stack is adjusted as appropriate in order to keep the value of the input current close to a desired operating state and not to exceed a specified maximum allowable value.

  In another aspect of the routine 370, if the derived current is greater than the maximum allowable value, the DC-DC converter operates to limit the current. On the other hand, the control system operates to adjust the maximum allowable current derived from the fuel cell stack 220. The control system then activates the adjustment of the water flow controller 214 and the fuel flow controller 204 described in the present disclosure via the PID controllers K1 310 and K2 330 in routines 350 and 360 to provide subsequent control. It affects the capacity of the reformer and the fuel cell stack. In another example, if it is determined that the battery voltage is higher than a target set value, the controller reduces the input current derived from the system and restores the system battery voltage to the target set value or By bringing them closer, the water flow rate control device and the fuel flow rate control device are adjusted in a direction that reduces the capacity of the reformer, and hence the fuel cell stack.

  In this way, the present application incorporates a control system according to the voltage in the power generation facility 100. Here, in order to improve the capacity of the reformer and the fuel cell stack, a series of routines illustrated in FIG. 3 are started in parallel or in series. Furthermore, the routine cascade structure allows for quick and high quality harmony of the control system. As an example, an event that causes a change in the amount of steam entering the reformer in routine 350 changes the proportion of steam and carbon in the reformer, and consequently affects the flow of fuel entering the reformer in routine 360. give. As another example, an event that changes the capacity of the reformer in the routine 360 causes a change in the input current 340 derived from the fuel cell stack 220 (by affecting the capacity of the fuel cell stack) To change the air flow rate of the fuel cell stack in the routine 370. As a further example, the change in input current derived from the fuel cell stack 220 changes the voltage of the system battery. This system battery change causes the control system to operate to improve the capacity of the reformer and fuel cell stack. By using a cascade control routine and an electrical buffer, the power plant control system better manages the capacity of the reformer for the inferred conditions, thereby delivering a sufficient amount of hydrogen-enriched fuel to the fuel cell stack. To supply. The cascade control routine also functionally synchronizes the capacity of the reformer and the fuel cell stack, thereby improving the power generation capacity of the equipment under the operating conditions of the existing power equipment.

  In particular, the cascade control routine illustrated in greater detail in FIG. 4 further ensures that the system reduces damage caused by power plant components when a transient change in battery voltage occurs. Work. For example, if the system battery voltage 302 falls below a target setpoint 306, the control system adjusts the reformer 210's reforming capacity and then the fuel cell capacity. Here, the input current 340 derived from the fuel cell stack is increased until the voltage of the system battery falls within the limit value of the set voltage value 306. The capacity of the reformer increases the capacity of the fuel cell stack by adjusting the capacity of the reformer according to the voltage of the system battery before adjusting the capacity of the fuel cell stack. The control system adjusts for the transient drop in battery voltage by increasing the current drawn from the fuel cell / electrical buffer without damaging the fuel cell or other components of the power plant 100. Under such circumstances, when the capacity of the reformer is increased according to the voltage, an appropriate amount of hydrogen on the anode side of the fuel cell stack is maintained.

  The above operation is compared with, for example, a current response control system. In a current-based system, if the transient voltage drop first increases the current derived from the fuel cell stack and then the capacity of the reformer is adjusted accordingly, the reformer Reacts to the current derived from. In this approach, the reaction time for adjusting the water and fuel flow rates of the reformer, adjusting the air volume, and adjusting the temperature level of the system may be longer than desired. If the hydrogen level in the fuel cell is not sufficient when the input current derived from the fuel cell fluctuates rapidly, irreversible damage to the fuel cell may occur.

  As another example, when the battery voltage becomes higher than the target set voltage value, the control system of the present application commands the input current derived from the fuel cell stack 220 to be reduced, while the reformer Delay reduction of reformer capacity. In this situation, the voltage induced delay reacts quickly to a transient decrease in battery voltage. Therefore, by appropriately moving the capacity of the reformer, that is, the capacity of the fuel cell stack, according to the voltage, the control system of the power generation facility can be made to react better to current or / and voltage transients as appropriate. It becomes.

  FIG. 4 is a flowchart illustrating an embodiment of a method for controlling the power generation facility 100 according to the present disclosure. The embodiment uses various control routines illustrated in FIG. 3, for example. The method 400 begins by estimating the system battery voltage 302 at 402 (eg, reading the battery voltage meter 228). At 404, a voltage deviation (x) between the measured battery voltage 302 and the set voltage 306 is measured. As described above, the deviation is transmitted to the lookup table 308 that calculates the adjustment deviation E based on the input deviation x and the nonlinear function.

  The method 400 also provides a command from the controller K1 310 based on the calculated adjustment deviation / deviation of the measured battery voltage 304 from the setpoint 306 at 406, as illustrated in the routine 350 of FIG. In response, the water flow control device 214 is adjusted. Furthermore, an adjustment based on the operation of the feedforward control depending on the bus current received from the lookup table 316 is incorporated. The response to correct the deviation from the set voltage value is to adjust the water supply to the fuel cell reformer via the feedback controller based on the battery voltage deviation and the feed forward input depending on the bus current. This is done properly without the need for extra fuel storage or other resources.

  The method 400 then analyzes the vapor to carbon ratio at 408 as illustrated in the routine 360 of FIG. The appropriate ratio of steam and carbon in the reformer 210 optimizes the capacity of the reformer. If there is a deviation from the set value 326 at 410, the deviation value x is further evaluated in a look-up table 328 to calculate the adjustment deviation E and send it to the controller K2. As illustrated in FIG. 3, additional feedforward adjustments depending on the current bus may be made. According to the input, at 412, the fuel flow rate corresponding to the steam flow rate in the reformer is appropriately adjusted. As a result, the ratio of steam and carbon is readjusted so as to approach the target set value 326. The feedback control loop illustrated in routine 360 adjusts the fuel supply to provide an appropriate response to correct the measured steam to carbon ratio deviation from the predetermined setpoint 326.

  When the capacity of the reformer is adjusted by the control system, this capacity is appropriately matched with the current generation capacity of the fuel cell stack. With respect to this effect, the method 400 further sets 416 the maximum allowable current value derived from the fuel cell stack 220 in the DC-DC converter 104, illustrated in the upper branch of the routine 370 of FIG. The setpoint is based on the flow rate of fuel to the reformer 210 that affects the production of hydrogen-enriched fuel that is subsequently oxidized in the fuel cell stack 220. The input current derived from the fuel cell stack is measured by the current measuring device 226.

  In this way, the fuel cell stack 220, the reformer 210 that supplies the hydrogen-enriched fuel that is supplied as raw hydrocarbon fuel and flows to the fuel cell stack, and consequently improved protection against transient power fluctuations. In addition, it is possible to incorporate a control system in accordance with the voltage in the stationary power generation facility 100 having a battery operation control system that enables quick response. The control system has a predetermined battery voltage setting. By coordinating the reformer and fuel cell stack setpoints, the control system can monitor and maintain the battery voltage close to a predetermined setpoint 306. In one aspect, when the voltage response control system determines that the voltage of the system battery is below the target set point, the control system performs a series of controls to inject additional current necessary to maintain the battery voltage. Do. For example, by limiting the water flow rate control device 214 simultaneously with the fuel flow rate control device 204, the capacity of the reformer can be adjusted without disturbing the required steam to carbon ratio.

  As another aspect, the capacity of the fuel cell can be controlled by providing a DC-DC controller. The DC-DC controller compensates for the maximum allowable current derived from the fuel cell stack based on the fuel flow to the reformer. Further, the capacity of the fuel cell stack can be monitored by controlling an air flow rate control device 224 that supplies steam to the fuel cell stack. The air flow rate control device 224 is controlled according to the input current derived from the fuel cell and transmitted via the look-up table system 342. Further, by incorporating differential control into the control system, improved transient response and disturbance prevention can be achieved. By appropriately moving the capacity of the reformer, that is, the capacity of the fuel cell stack, it is possible to cope with an unpredictable change in the battery voltage.

  Specifically, when the control mechanism measures that the battery voltage has reached the target set value, the DC-DC converter 104 first reduces the input current from the fuel cell stack 220. On the other hand, the reformer 210 exceeds the target value, which allows the system to react more quickly to battery voltage transients. In other words, by incorporating a structure that allows the reformer to exceed the set value but avoids it, the control mechanism can respond more quickly to the transient state of the battery voltage. The controller, which is initially dominated by events that occur sequentially in the feedback control mechanism and cascade control routine, responds quickly to monitor variations in current and voltage values from a given set point, as illustrated in Figure 3. To help.

  It should be noted that the control and estimation routines shown here as examples are used with various system structures. Specific routines described herein are event-driven, interrupt-driven, multitasking, multithreading, and other one or more processing strategies. For example, the various operations, operations, or functions shown may be performed in the order shown, performed in parallel, or omitted. That is, the order of processing is not necessarily required to achieve the example features and advantages described herein, but is provided for ease of illustration and description. One or several of the illustrated actions, operations or functions may be performed repeatedly depending on the strategy used. Furthermore, the described operations, functions or / and actions may be diagrammed as codes in the control system and programmed into a computer readable storage medium.

  FIG. 5 is a flowchart showing the operation of the control system routine shown in FIGS. 3 and 4 in a simplified manner. In method 500, at 502, a system battery voltage is measured using a battery voltage meter 228 as illustrated at 402 in FIG. Thereafter, at 504, method 500 evaluates whether the battery voltage is below target setpoint 306. If so, the deviation is transmitted to the PID controller K1 via the lookup table 308 at 506. The PID controller K1 appropriately adjusts the water flow rate controller 214 of the reformer to increase the amount of water flowing to the reformer 210 as steam. This routine 350 has already been described in FIG.

  In method 500, at 508, the ratio of steam to carbon is evaluated based on measurements of the flow rate of water (steam) and fuel entering the reformer. If this is correct, the current derived from the fuel cell stack at 512 is evaluated via the current measuring device 226 and compared with the value in the current lookup table 342 to be confirmed to be within the maximum allowable limit value. The When this current value is also within an allowable range, the input current is used by the control system to charge a system buffer (battery). Thereafter, at 516, the measured system battery voltage is again checked against the predetermined setpoint 306. However, if it is measured at 516 that the system battery voltage exceeds a predetermined set value 306, the maximum allowable value of current that can be derived from the fuel cell stack 220 is set in the DC-DC converter. In this way, the control system can reduce rapid fluctuations in current that cause irreparable damage to the components of the power generation equipment. At 516, if the system battery voltage does not exceed a predetermined set point, the control system repeats the events in the control loop from step 504 to ensure an appropriate input current. If the appropriate input current is ensured, the system battery can be recovered to the target value.

  On the other hand, if the steam to carbon ratio measured at 508 is not correct, then at 510, the reformer fuel flow control device 204 is adjusted via the PID controller K1. When the feedback control routine 350 is activated, the amount of fuel flowing through the reformer increases, and as a result, the ratio of steam and carbon is corrected. This allows improved utilization of the capacity of the reformer. Alternatively, if, at 512, the current derived from the fuel cell stack is measured to be below a maximum allowable limit value, at 514, to increase the current capacity of the fuel cell stack, as illustrated in routine 370. The fuel cell air flow control device is adjusted. The events at 506, 510 and 514 reflect the cooperating power of the control system to increase the input current derived from the fuel cell by better managing both the reformer and fuel cell capacity. ing. As the input current increases, it is expected that the system buffer battery is recharged.

  In this way, the power plant control system depending on the voltage better copes with various disturbances. The power plant control system includes an electrical buffer and adjusts the components of the system to control the system battery voltage. High gain control systems depending on voltage may be overly responsive and expensive. In contrast, the low gain control system according to the voltage described here can cope with transients in an improved way and is cheap. Also, using a system battery to delay the response time of the electrical controller protects the components of the power generation facility. For example, the reformer is protected when a sudden sudden change in current occurs. If the power generated from the power generation facility is not sufficient, AC power from the system inverter is used. In this manner, the integrated system battery protects the system inverter from irreversible losses that occur when a temporary surge current occurs. By incorporating the buffer system as a relatively small battery, a sufficient amount of hydrogen on the anode side can be maintained without the need for fuel in an excessively large buffer. This saves costs for extra fuel, additional fuel storage and related resources. The robustness of the power plant control system when dealing with transients also eliminates the need for large buffer systems such as large battery systems and supercapacitors. Although the control system balances the dynamic response to transients with a small buffer battery, this approach can also be applied with large buffer systems.

Claims (20)

  A method of operating a power generation system including a fuel cell connected to an electrical buffer and further connected to a steam reformer, wherein the steam in the reformer is controlled to control charging of the electrical buffer by the fuel cell. And a method for operating the power generation system that adjusts the operation of the reformer based on the voltage affected by the electrical buffer while maintaining the proportion of carbon.   The method of operating a power generation system according to claim 1, wherein the increased power demand is compensated by supplying current from an electrical buffer before the current of the fuel cell is increased by adjusting the reformer.   The said electric buffer is connected to the said fuel cell via DC bus, The said electric buffer contains a battery, The said adjustment is performed according to the voltage of the said DC bus. How to operate the power generation system.   In order to maintain the ratio of steam and carbon, the amount of water flowing to the steam reformer is adjusted according to the change in battery voltage, and the fuel flowing to the steam reformer according to the ratio of steam to carbon The method for operating the power generation system according to claim 3, wherein the supply amount of the power generation system is adjusted.   The operation method of the power generation system according to claim 1, wherein a flow rate of water flowing to the reformer increases in accordance with a decrease in the voltage.   The method of operating a power generation system according to claim 1, wherein a mode of a DC-DC converter connected in the power generation system is adjusted based on an input current generated by the fuel cell.   The operation method of the power generation system according to claim 1, wherein a flow rate of fuel flowing to the reformer is adjusted according to a ratio of steam and carbon.   The operation method of the power generation system according to claim 1, wherein an air flow rate of the fuel cell is adjusted according to an input current generated by the fuel cell.   The flow rate of water flowing to the reformer is adjusted according to the voltage, while the flow rate of fuel flowing to the reformer is adjusted according to the ratio of steam and carbon, while being generated by the fuel cell. The method for operating the power generation system according to claim 1, wherein the flow rate of air in the fuel cell is adjusted according to the input current. A fuel cell stack;
A reformer connected to the fuel cell stack and supplying hydrogen-enriched fuel to the fuel cell stack;
A raw fuel supply unit for supplying raw fuel to the reformer;
A water supply unit for supplying water to the reformer;
An air supply unit for supplying air to the fuel cell stack;
A voltage bus electrically connected to the fuel cell stack;
A battery system electrically connected to the voltage bus;
A control system for adjusting water supplied to the reformer according to the voltage of the voltage bus.   The system according to claim 10, wherein the control system also adjusts the raw fuel supplied to the reformer according to a ratio of steam and carbon.   The system according to claim 11, wherein the control system also adjusts air supplied to the reformer according to an input current generated by the fuel cell.   The system of claim 12, wherein the water and raw fuel supplied to the reformer are adjusted independently of the input current.   A DC-DC converter electrically connected to the voltage bus, the voltage bus being a DC voltage bus, and a fuel cell stack being connected to the DC voltage bus through the DC-DC converter. 13. The system according to 13.   The system according to claim 14, wherein the control system also adjusts the operation of the DC-DC converter according to the input current.   The system of claim 15 connected in a stationary power plant. A method of operating a fuel cell stack in a power generation system, wherein the fuel cell stack is connected to an electrical buffer through a DC-DC converter and a DC voltage bus, and further connected to a reformer,
In order to control charging of the electrical buffer by the fuel cell, the operation of the reformer is adjusted based on a target voltage value of a DC bus voltage and a target value of a ratio of steam and carbon in the reformer. ,
The adjustment adjusts the raw fuel supplied to the reformer based on an actual steam to carbon ratio feedback indication, and the reformation based on the actual voltage feedback indication of the DC bus voltage. A method of operating a fuel cell stack, comprising adjusting the water supplied to the vessel.   The fuel cell stack according to claim 17, wherein the increase in power demand is compensated by supplying current from the electrical buffer before the current of the fuel cell is increased by adjusting the reformer. how to drive.   The method of operating a fuel cell stack according to claim 18, wherein the target DC voltage is adjusted by operating parameters.   19. The method of operating a fuel cell stack according to claim 18, wherein the desired steam to carbon target ratio is adjusted by operating parameters.