JP6896612B2 - Fuel cell system and fuel cell stop determination method in the system - Google Patents

Description

The present invention relates to a fuel cell system that supplies power to a load unit by using both the generated power of the fuel cell and the power purchased from an electric power company. More specifically, the present invention relates to a fuel cell system capable of determining an outage period during which a fuel cell has been stopped based on the actual amount of purchased electric power. It also covers the fuel cell shutdown determination method, which determines the fuel cell shutdown period in the system.

Conventionally, electric power consumers have been equipped with fuel cells as so-called distributed power sources, and the generated electric power and the electric power purchased from electric power companies are used in combination to meet their own electric power demand. By utilizing the power generation capacity of the fuel cell in this way, it is possible to suppress the purchase of electric power from the electric power company. Fuel cells for power generation in this type of fuel cell system are basically used in a continuous operation state at a rated output. In many cases, fuel cells as such distributed power sources are of the type that uses gas fuel. The gas fuel is the same as the fuel as a heat source. For this type of fuel cell, it is necessary to provide a regular outage period. This is for gas leak inspection of gas meters. This suspension period is provided once in a period of about one month, and the length of one suspension period is about one day.

On the other hand, from the viewpoint of the power supplier or the manager of the fuel cell system, it is necessary to know the total amount of power demand of the consumer. This is because of electricity demand forecasting and other business needs. As an estimation technique that can be used for that purpose, for example, the “method of estimating power generation output” disclosed in Patent Document 1 can be mentioned. In the technology of the same document, the power generation output of the distributed power source is estimated using the voltage, current, and power factor measured in the distribution line.

Japanese Unexamined Patent Publication No. 2016-158371

However, the above-mentioned conventional technique has the following problems. That is, in the estimation method of the same document, as shown in FIG. 1 and the like, power generation of a distributed power source is performed by taking steps such as calculation of active power and ineffective power, calculation of their fluctuations, and calculation of tidal current fluctuations. Estimate the output. Therefore, various data such as voltage, current, and power factor are required. In this way, there are problems that the estimation calculation process is complicated and that various data are required. Therefore, it was not possible to easily determine the shutdown period of the fuel cell.

The present invention has been made to solve the problems of the above-mentioned conventional techniques. That is, the subject is to provide a fuel cell system and a method for determining the shutdown of the fuel cell in the system, which can determine the shutdown period of the fuel cell by a simple procedure based on the data of the amount of electricity purchased from the electric power company. There is.

The fuel cell system according to one aspect of the present invention includes a fuel cell, a power receiving unit that receives electric power from an electric power company, and a load unit that consumes electric power, and the electric power generated by the fuel cell and the electric power received by the electric power receiving unit. In a fuel cell system that supplies power to the load unit in combination with, the baseline acquisition unit that acquires the baseline, which is the standard daily pattern of the power received by the power receiving unit, and the power receiving unit actually receive power. The error judgment unit and the error judgment unit determine whether or not the baseline error, which is the difference between the generated power and the power at the corresponding time in the baseline, is equal to or greater than the reference value based on the rated output of the fuel cell. It has a stop period determination unit that determines that the period in which the ratio of "greater than or equal to the reference value" in the determination is equal to or greater than a predetermined threshold value is the stop period during which the fuel cell has been stopped.

In the fuel cell system in the above aspect, the actual amount of power received from the electric power company by the power receiving unit is acquired. This acquisition is iterative. On the other hand, the baseline is acquired by the baseline acquisition unit. In the error judgment unit, whether or not the baseline error is "above the reference value" is determined by comparing the measured value of the received power amount, the power at the corresponding time in the baseline (baseline data), and the reference value. It is judged. Then, the suspension period determination unit determines that the period in which the proportion of "above the reference value" in the determination result is high is the suspension period. As described above, in this embodiment, since the necessary data regarding the power supply is only the measured value of the received power amount, the determination can be easily performed. Still, the judgment accuracy is high.

In the fuel cell system of the above aspect, the error determination unit further includes an error calculation unit that calculates the baseline error and a reference value determination unit that compares the baseline error with the reference value and determines whether or not it is equal to or greater than the reference value. It is preferable to have and. As a result, it is appropriately determined whether the measured value of the amount of power received should be "above the reference value" or not. Therefore, the determination accuracy is high.

In the fuel cell system of any of the above embodiments, the stop interval, which is the frequency at which the fuel cell enters the stop period, is predetermined, and the stop period determination unit occupies "above the reference value" during the stop interval. When there are a plurality of periods in which the ratio is equal to or higher than the threshold value, it is desirable to determine that only the period in which the ratio of "more than the reference value" occupies the highest among the plurality of periods is the suspension period. .. This is because even if there are a plurality of periods in which the ratio of "above the reference value" is high during the stop interval, only one of them is the true stop period.

In the fuel cell system of any of the above embodiments, a stop candidate time zone, which is a time zone during which the fuel cell can be stopped, is predetermined, and the stop period determination unit corresponds to the stop candidate time zone in the day. It is preferable that only the period during which the operation is performed is subject to the determination of whether or not the period is a suspension period. The stop candidate time zone may be set depending on the convenience of the fuel gas supply side used by the fuel cell. In this case, the period corresponding to the time zone deviated from the stop candidate time zone does not completely coincide with the stop period. Therefore, the accuracy of the determination can be further improved by using this aspect.

In the fuel cell system of any of the above embodiments, it is desirable that the error determination unit uses a value within the range of 0.3 to 0.7 times the rated output of the fuel cell as a reference value. By doing so, the accuracy of determining whether or not the baseline error is equal to or greater than the reference value can be improved as much as possible. This also contributes to the determination accuracy of the stop period.

The method for determining the stoppage of a fuel cell in a fuel cell system according to another aspect of the present invention includes a fuel cell, a power receiving unit that receives power from an electric power company, and a load unit that consumes electric power, and the fuel cell generates power. This is a fuel cell stop determination method that determines the stop period during which the fuel cell has been stopped in a fuel cell system that supplies power to the load unit by using both the power to be generated and the power received by the power receiving unit. The baseline acquisition process, which acquires the baseline, which is the standard daily pattern of the power received by the unit, and the baseline, which is the difference between the power actually received by the unit and the power at the corresponding time in the baseline. The period during which the ratio of "greater than or equal to the reference value" in the error judgment process for determining whether or not the error is greater than or equal to the reference value based on the rated output of the fuel cell and the determination by the error determination process is greater than or equal to the predetermined threshold value. This is a fuel cell stop determination method by performing a stop period determination process for determining that the fuel cell has been stopped.

According to this configuration, a fuel cell system and a method for determining the shutdown of a fuel cell in the system are provided, which can determine the shutdown period of the fuel cell by a simple procedure based on the data of the amount of electricity purchased from the electric power company. ..

It is a schematic diagram which shows the fuel cell system which concerns on embodiment. It is a graph which shows an example of the time-dependent pattern of the electric power received from an electric power company. It is a graph which shows an example of the time pattern of a baseline error. It is a graph which shows the probability distribution which the value of the calculated baseline error appears. It is a graph which shows the transition of the number of samples whose baseline error is more than a reference value.

Hereinafter, embodiments embodying the present invention will be described in detail with reference to the accompanying drawings. This embodiment is the fuel cell system 7 shown in FIG. 1, and is configured to implement the fuel cell stop determination method according to the present invention. The fuel cell system 7 is provided in the consumer 1, and has a load unit 2, a fuel cell 3, a wattmeter 4, a distribution board 9, and an analysis unit 8. The fuel cell system 7 is connected to the electric power company 6 via the grid line 5.

The load unit 2 is a group of power consuming devices in the consumer 1 such as lighting and air conditioning. The fuel cell 3 is a battery that generates electricity by using a part of gas fuel used as a heat source for hot water supply and cooking by the consumer 1. In the fuel cell system 7, the power generated by the fuel cell 3 is used by the load unit 2, so that the amount of power purchased from the electric power company 6 is suppressed. The operation mode of the fuel cell 3 in the fuel cell system 7 is continuous operation at the rated output. However, the fuel cell 3 sometimes has a stop period as described above. Further, the interconnection form between the fuel cell system 7 and the grid line 5 is a form in which reverse power flow to the grid line 5 is allowed in a situation where the power generated by the fuel cell 3 exceeds the power demand of the load unit 2.

The distribution board 9 is a portion that receives power supply from the electric power company 6. The distribution board 9 receives the electric power generated by the fuel cell 3 in addition to the electric power supplied by the electric power company 6, and supplies the electric power to the load unit 2. The power meter 4 has a function of measuring the amount of power received from the power company 6. The amount of power received is constantly measured. As a result, for example, a time-dependent pattern as shown in the graph of FIG. 2 can be obtained. Of these, the part where the amount of power received is negative is the time zone of reverse power flow. The analysis unit 8 determines the stop period of the fuel cell 3 based on the data output by the power meter 4. However, the power received data output by the power meter 4 is once supplied to the analysis unit 8 via the power company 6. Further, since the analysis unit 8 is installed in the operator of the fuel cell system 7, it is located outside the customer 1 in FIG.

The method of determining the stop period of the fuel cell 3 in the fuel cell system 7 as described above will be described. This method is carried out by executing the following procedure in the analysis unit 8.
1. 1. Obtaining a baseline 2. Calculation of baseline error 3. Comparison of baseline error and reference value 4. Judgment of suspension period based on comparison results

"1. Acquisition of baseline"
The baseline is a standard pattern of the amount of power received by the consumer 1 over time in a day. The baseline can be obtained as the average power reception pattern at each time based on the past data of the power reception amount as shown in FIG. 2 for the consumer 1. Alternatively, a standard pattern in a group of consumers equivalent to that of the consumer 1 can be obtained from the electric power company 6 and stored in the analysis unit 8 and used as a baseline. It is also possible to use different baselines for each attribute of the day, such as the day of the week and the season. The baseline is generally low at midnight and dawn, with a high curve from daytime to evening and midnight. At the baseline of the consumer 1 who has the fuel cell 3 and is allowed to reverse power flow, the value at midnight or early dawn is a negative value.

"2. Calculation of baseline error"
The baseline error is the difference between the amount of power received as an actually measured value actually measured by the power meter 4 and the amount of power received data at the same time in the baseline. This is a concept that includes a sign. If the baseline error R (t) is positive, it means that the measured value Wa (t) is larger than the baseline data Wb (t), and if the baseline error R (t) is negative, the measured value Wa (t) It means that t) was smaller than the baseline data Wb (t). That is, assuming that the measured value of the amount of power received at time t is Wa (t) and the amount of power received data in the baseline is Wb (t), the baseline error R (t) is expressed by the following equation.
R (t) = Wa (t) -Wb (t)

The baseline error R (t) is calculated each time the measured value Wa (t) is obtained. Since the measured value Wa (t) is periodically output from the power meter 4 (for example, every 30 minutes, hereinafter referred to as “frame”), the baseline error with respect to the measured value Wa (t) at each output time. R (t) is calculated. Whereas the baseline has the pattern as described above, the baseline error R (t) forms a line that randomly swings up and down around zero. Therefore, it is easier to handle than the baseline itself. An example of the temporal pattern of the baseline error R (t) is shown in FIG.

"3. Comparison between baseline error and reference value"
The reference value referred to here is a threshold value for considering the value of the baseline error R (t) as large or small. When the fuel cell 3 is in the stopped period, the measured value Wa (t) of the amount of received power becomes larger than in the normal state because the generated power cannot be used. However, the baseline does not consider the shutdown of the fuel cell 3. Therefore, during the shutdown period of the fuel cell 3, the baseline error R (t) becomes larger than during the operating period. It is the reference value that separates this. That is, assuming that the reference value is "B", it is determined which of the following two equations holds.
R (t) ≧ B
R (t) <B

Of course, this determination is made for the calculated baseline error R (t) of each frame. In FIG. 3, the reference value B appears as a straight line parallel to the horizontal axis. If the determination result is "reference value B or more", the baseline error R (t) naturally goes above the horizon of the reference value B or overlaps with the horizon. If the determination result is not "more than or equal to the reference value B", the baseline error R (t) is below the horizontal line of the reference value B.

As the reference value B used here, a value predetermined based on the rated output of the fuel cell 3 is used. The reason based on the rated output of the fuel cell 3 is that the difference in the measured value Wa (t) between the stopped period and the operating of the fuel cell 3 is almost the same as the rated output of the fuel cell 3. That is, it can be said that the baseline error R (t) calculated during the stop period is a value obtained by adding the rated output of the fuel cell 3 due to the stop period. Therefore, it is preferable that the reference value B, which is a threshold value for determining whether or not the fuel cell is in the shutdown period, is determined based on the rated output of the fuel cell 3.

It is conceivable to use the rated output as the reference value B as it is, but it is better to set it to a smaller value. This is because the measured value Wa (t) contains noise, and the rated output is not always reflected as it is. Specifically, it is preferable that the rated output is multiplied by a positive coefficient smaller than 1. The positive coefficient is more preferably a value near 0.5. For example, when the rated output of the fuel cell 3 is 700 W and 0.5 is used as the coefficient, the value of the reference value B is 350 W.

The coefficient will be further described. The accuracy of the determination result for the baseline error R (t) depends on the setting of this coefficient. The determination accuracy referred to here is a high degree of correlation between the determination result being "reference value B or more" and the baseline error R (t) being during the stop period. .. In other words, if it is during the stop period, it is judged that it is "reference value B or more", and if it is not during the stop period, it is likely that it is not "reference value B or more", which means that the judgment accuracy is high. Is. In other words, it is determined that "it is not above the reference value B" even though it is in the suspension period (F described later), or "it is above the reference value B" even though it is not during the suspension period (G described later). Is an event that lowers the judgment accuracy.

The higher the coefficient (closer to 1), the higher the probability that the baseline error R (t) obtained during the stop period will be determined not to be "reference value B or higher". On the other hand, the lower the coefficient (closer to 0), the higher the probability that the baseline error R (t) obtained during operation is determined to be "reference value B or more". This will be described with reference to FIG. FIG. 4 is a graph of the probability distribution of the values calculated as the baseline error R (t). In short, the processing in this comparison step is whether the calculated baseline error R (t) is to the right (greater than the reference value B) or to the left of "B" in FIG. 4 (less than the reference value B). ), Is the judgment. However, during the shutdown period of the fuel cell 3, the comparison is not with "B" but with "BP" (P is the rated output of the fuel cell 3). This is because the measured value Wa (t) is increased by the rated output P and the baseline error R (t) is also increased, so that amount needs to be subtracted.

The probability of occurrence of the above-mentioned event that lowers the determination accuracy corresponds to the area of the hatched “F” and “G” regions in FIG. Making the total area of these two regions as small as possible improves the accuracy of determining the baseline error R (t). For that purpose, the arrow P in FIG. 4 is arranged at the center in the left-right direction. The reference value B in that case corresponds to half of the rated output P. This is the reason why the coefficient was set to 0.5 in the above example. Although the probability distribution is drawn as if it were a normal distribution in FIG. 4, the actual probability distribution is not always the same as the normal distribution. However, even if it is not a normal distribution, the above holds as it is if it is a symmetrical probability distribution. Since the actual probability distribution does not become extremely asymmetrical, the coefficient may be set to 0.5 as described above. Moreover, the coefficients do not have to be exactly 0.5. If it is in the range of 0.3 to 0.7, it is practically sufficient. It is better if it is in the range of 0.4 to 0.6.

"4. Judgment of suspension period based on comparison results"
When the baseline error R (t) is determined as described above, the stop period can be determined. That is, in FIG. 3, it can be said that the section in which the probability that the determination result for the baseline error R (t) is “reference value B or more” is high is the section in which the fuel cell 3 is likely to be stopped. .. Therefore, such a section is determined to be a stop period. In FIG. 3, the section indicated by the arrow A is the section determined to be the stop period. In the section A in FIG. 3, most of the baseline errors R (t) are above the reference value B. On the other hand, in the sections other than the section A, the probability that the baseline error R (t) is higher than the reference value B is clearly low. On the other hand, in FIG. 2, although the measured value Wa (t) of the amount of received power tends to be higher in the section A than in the other sections, it is not as clear as in FIG.

Basically, the threshold value for judgment is set in advance. Then, when the ratio of the "reference value B or more" in all the baseline errors R (t) in the determination target section is equal to or more than the threshold value, the target section is determined to be the stop period. For example, 0.5 can be used as the determination threshold value. That is, when the total number of baseline errors R (t) in the target section is K, the number of "reference value B or more" is M, and the judgment threshold is S, the target section is the stop period. The condition to be determined to be is that the following equation is satisfied.
M / K ≧ S

The determination of the suspension period will be further described. Looking at FIG. 3, it is not only the interval A that the baseline error R (t) is above the reference value B (arrow C). However, it is not always preferable to determine all the sections where the baseline error R (t) is higher than the reference value B as the stop period. Since the stop period is provided for gas leak inspection as described above, the length is determined by the convenience of the gas supply system and is about 24 hours. Here, it is assumed that the length of the suspension period is fixed to 24 hours. In FIG. 3, the length of the section A is exactly 24 hours. The length of each section (arrow C) in which the baseline error R (t) is higher than the reference value B other than the section A is shorter than 24 hours. Therefore, only the section A is determined to be the stop period.

In FIG. 5, based on the comparison result between the baseline error R (t) and the reference value B in FIG. 3, only the section “above the reference value B” is shown with hatching. And the curve D is superimposed on it. Curve D shows the transition of the ratio of the section of “reference value B or more” to the subsequent 24 hours at each time point in FIG. The horizontal axis is the passage of time, but since one frame is 30 minutes, half of the displayed numbers correspond to the time (60 minutes).

Looking at the curve D, it has remained at a low level at the beginning, but it has risen almost linearly from the time D1. This is because the end of the "subsequent 24 hours" is applied to the section A, so that the ratio of "reference value B or more" increases with time. Then, the curve D is the highest at the starting point of the section A. At this time, "the next 24 hours" and the section A coincide with each other, and most of them are "reference value B or more". After that, on the contrary, the curve D descends almost linearly. This is because the end of the "subsequent 24 hours" deviates from the section A. After the end point of the section A, the curve D is at a low level as at the beginning of FIG.

From this, in FIG. 5, the time (frame) at which the curve D peaks may be set as the start of the stop period, and the frame 24 hours after that time may be set as the end of the stop period. With this, it can be determined that the 24 hours with the highest ratio of "reference value B or more" is the stop period. Section A in FIG. 3 is a section defined to fit the section A.

In addition, there may be a case where the ratio of "reference value B or more" is higher in each of two or more 24-hour sections separated from each other as compared with the sections before and after the section. In such a case, it is not always good to judge all of those sections (hereinafter referred to as "high sections") as stop periods. Therefore, the determination of the suspension period in such a case will be described.

There are two independent high sections, and both of them can be determined as a stop period when the interval between the high section and the high section is greater than or equal to the predetermined reference interval. As described above, the suspension period is set once every one month or so. If the suspension period is set once a month, the reference interval may be set to a length equivalent to about 25 days. This is because when the intervals are so wide, both of the two independent high sections are considered to be stop periods.

On the contrary, if the interval between the high intervals is less than the above-mentioned reference interval, the true stop period is considered to be only one of them. In that case, among those high sections, only the one with the highest ratio of "reference value B or higher" is determined as the stop period. In such a case, it is considered that in the high section that was not determined to be the stop period, the ratio of "reference value B or more" happened to be slightly higher due to the random appearance of the baseline error R (t). .. For this reason, there is often a clear difference in the ratio of "reference value B or higher" between the high section determined to be the stop period and the other high sections.

In addition, the start time of the stop period on one day may be fixed at a certain fixed time (for example, midnight) due to the convenience of the gas supply system. In that case, the time that can be the starting point of the section A in FIG. 3 may be limited to that time.

Next, the verification result regarding the accuracy of the determination of the stop period in the above embodiment will be described. Here, the power received amount data was collected from the power smart meters of a large number of consumers 1 equipped with the fuel cell system 7 and the above determination was attempted. The conditions were as follows.
Number of households: 885 Period: Approximately 3 months Total number of data: 3,738,240 Set suspension period: 26th day of January, 20th day of 2nd month, 14th day of 3rd month (anyday) From 0:00 to 24:00)

As a result, the incidence of false positives was less than 0.04%. In addition, the number of customers 1 that had a misjudgment was only 8 out of the total number of households mentioned above. It was confirmed that a sufficiently higher judgment accuracy could be obtained.

As described in detail above, according to the present embodiment, when the measured value Wa (t) of the received power is obtained, the baseline error R (t), which is the difference between the measured value Wa (t) and the baseline data Wb (t), is obtained. It is supposed to be calculated. Then, it is determined whether or not the baseline error R (t) is equal to or greater than the reference value B. Since this determination is made periodically, the period in which the ratio of the frame of the determination result of the reference value B or more is equal to or more than the threshold value is determined as the stop period. As a result, a fuel cell system and a method for determining the shutdown of a fuel cell in the system have been realized, which can determine the shutdown period of the fuel cell by a simple procedure based on the data of the amount of electricity purchased from the electric power company.

It should be noted that the present embodiment is merely an example and does not limit the present invention in any way. Therefore, as a matter of course, the present invention can be improved and modified in various ways without departing from the gist thereof. For example, the consumer 1 is not limited to a residential property but may be a business property. Further, in the above-described embodiment, in "3. Comparison between baseline error and reference value", the baseline error R (t) was first calculated and compared with the reference value B. However, the same is true even if the total of the baseline data Wb (t) and the reference value B is subtracted from the actually measured value Wa (t) to determine whether the value is positive or negative.

Further, in FIG. 5, on the premise that the length of the suspension period is fixed, the start period of the suspension period is first determined, and the end period is determined based on the start period. However, the present invention is not limited to this, and the end of the suspension period may be set first, and the start may be set based on the end. Alternatively, if the length of the suspension period is not fixed, one of the start or end of the suspension period may be determined first, and the other may be determined by fine-tuning the length of the suspension period. That is, the other is determined so that the ratio of "reference value B or more" is the highest. The analysis unit 8 may be installed individually in each customer 1. It is also possible to configure the power meter 4 to directly supply the power received data to the analysis unit 8 without going through the power company 6.

2 Load unit 3 Fuel cell 4 Power meter (power receiving unit)
7 Fuel cell system 8 Analysis unit 9 Distribution board (power receiving unit)

Claims (6)

It has a fuel cell, a power receiving unit that receives power from an electric power company, and a load unit that consumes power, and the power generated by the fuel cell and the power received by the power receiving unit are used in combination to supply the load unit. A fuel cell system that supplies power
A baseline acquisition unit that acquires a baseline that is a daily standard pattern of the power received by the power receiving unit, and a baseline acquisition unit.
It is determined whether or not the baseline error, which is the difference between the power actually received by the power receiving unit and the power at the corresponding time in the baseline, is equal to or greater than the reference value based on the rated output of the fuel cell. Error judgment unit and
It has a stop period determination unit that determines that the period in which the ratio of "greater than or equal to the reference value" in the determination by the error determination unit is equal to or greater than a predetermined threshold value is the stop period during which the fuel cell has been stopped. A fuel cell system featuring. The fuel cell system according to claim 1, wherein the error determination unit is used.
An error calculation unit that calculates the baseline error and
A fuel cell system comprising a reference value determination unit that compares the baseline error with the reference value and determines whether or not the error is equal to or greater than the reference value. The fuel cell system according to claim 1 or 2.
The stop interval, which is the frequency with which the fuel cell enters the stop period, is predetermined.
When there are a plurality of periods in which the ratio of "reference value or more" is equal to or greater than the threshold value during the stop interval, the stop period determination unit determines "more than or equal to the reference value" among the plurality of periods. A fuel cell system characterized in that only the period having the highest proportion is determined to be the stop period. The fuel cell system according to any one of claims 1 to 3.
A candidate stop time zone, which is a time zone that can be the stop period of the fuel cell, is predetermined.
The fuel cell system is characterized in that the stop period determination unit targets only a period corresponding to the stop candidate time zone in one day as a target for determining whether or not the stop period is set. The fuel cell system according to any one of claims 1 to 4.
The fuel cell system, wherein the error determination unit uses a value within the range of 0.3 to 0.7 times the rated output of the fuel cell as the reference value. It has a fuel cell, a power receiving unit that receives power from an electric power company, and a load unit that consumes power, and the power generated by the fuel cell and the power received by the power receiving unit are used in combination to supply the load unit. It is a fuel cell stop determination method that determines the stop period during which the fuel cell has been stopped in a fuel cell system that supplies power.
The baseline acquisition process for acquiring the baseline, which is the daily standard pattern of the power received by the power receiving unit, and
It is determined whether or not the baseline error, which is the difference between the power actually received by the power receiving unit and the power at the corresponding time in the baseline, is equal to or greater than the reference value based on the rated output of the fuel cell. Error judgment process and
The period in which the ratio of "greater than or equal to the reference value" in the determination by the error determination process is equal to or greater than a predetermined threshold value is the stop period determination process in which the fuel cell is determined to be the stop period in which the fuel cell has been stopped. A method for determining the stoppage of a fuel cell in a fuel cell system.

Images