JP5284560B2 - Operation method of redox flow battery system - Google Patents

Description

  The present invention supplies power to a load by adding a redox flow battery to a power generation facility with irregular power generation such as wind power generation or solar power generation, or a load with irregular power consumption such as an electric railway or an electric furnace. The present invention relates to a method for operating a redox flow battery system that is optimal for stabilizing the power consumption and the power consumption of a load. In particular, the present invention relates to a method for operating a redox flow battery system that can reduce the size of a redox flow battery.

  In recent years, power generation using so-called natural energy has progressed. The wind power generator and the solar power generator used for this power generation are preferable power generators because they generate power using natural wind and sunlight and have a very small influence on the environment. However, since the power of wind power generators and solar power generators is uncertain, the output is irregular. In thermal power generators and hydroelectric power generators, power is generated in response to fluctuations in power consumption of the load, that is, so-called simultaneous equal amounts that match the power supplied to the load by the generator and the power required by the load. You can drive in. On the other hand, in a power generation facility such as a wind power generator, since the power generation output is irregular as described above, it is desired to stabilize the power generation output.

  On the other hand, loads such as electric railways and electric furnaces have irregular power consumption, and the same amount is used simultaneously by the above-mentioned thermal power generators, etc., but power consumption is stabilized to make power generation easier to follow. In other words, it is desirable to make the power generation amount of the thermal power generation equipment constant.

  In order to stabilize these irregular power generation output and power consumption, it is considered to smooth the power generation output and power consumption by combining a redox flow battery with a power generation facility or load. For example, Patent Document 1 and Non-Patent Document 1 propose a redox flow battery system in which a redox flow battery is combined with a wind power generator. In the redox flow battery system described in Non-Patent Document 1, a target composite value of power supplied to the load is determined based on the power generation output of the wind power generator, and low-pass filter calculation is performed so as to satisfy this target composite value. The output of the redox flow battery is combined with the generated power output, and this combined output is supplied to the load.

  In the above redox flow battery system, the voltage of the monitor cell is measured, and adjustment is made by offset so that the remaining capacity of the battery is within a certain range (Non-patent Document 1, Fig. 2.3.3-2, Output smoothing control) (See block diagram). Specifically, when the measured voltage is smaller than the threshold value, that is, when the remaining capacity is smaller than the offset threshold value, the battery has a large chargeable capacity and a small dischargeable capacity. Therefore, in order to ensure a certain dischargeable capacity, appropriate charging is performed to offset the remaining capacity to the discharge side. On the contrary, when the measured voltage is larger than the threshold value, that is, when the remaining capacity is larger than the offset threshold value, the battery has a large dischargeable capacity and a small chargeable capacity. Therefore, in order to ensure a constant chargeable capacity, appropriate discharge is performed to offset the remaining capacity to the charging side. Thus, in the conventional redox flow battery system, the remaining capacity is controlled so that the remaining capacity of the battery changes between the offset threshold value in the charging direction and the offset threshold value in the discharging direction.

JP2003-317763A NEDO Technical Information Database Title: Feasibility study on wind power generation with storage battery February 2002 Research Institute for Energy, [Search April 23, 2004], Internet <URL: http://www.tech. nedo.go.jp/servlet>

  By combining the output of the redox flow battery and the output of the wind power generator (calculated value) as described above, the output of the irregular wind power generator is smoothed, and even if the power consumption of the load changes suddenly, Power can be stably supplied to the load. In addition, by adding an offset, the redox flow battery can always maintain a certain range of remaining capacity. Similarly, by combining the output of the redox flow battery and the power consumption of an electric railway or the like, the power consumption of an irregular load can be smoothed and the power consumption of the load can be stabilized. The control of the remaining capacity can also be applied to a case where a redox flow battery is provided along with a load such as an electric railway.

  However, in order to obtain a battery having charging power and discharging power that may be required for a redox flow battery while maintaining a certain remaining capacity, the battery capacity is set large, that is, a large battery is used. It is necessary to prepare a large number of batteries having a small battery capacity. Therefore, there exists a problem that a redox flow battery system will enlarge.

  FIG. 17 (A) is a graph showing the relationship between the output range of the battery and the remaining capacity in the conventional redox flow battery system. FIG. 17 (B) shows the power that may be required for the battery. FIG. 18 is a graph showing the relationship between the range in which the battery can output, the remaining capacity, and the range of power that may be required for the battery. In the conventional redox flow battery, as shown in FIG. 17A, for example, when the remaining capacity is 100%, the dischargeable output is large, the chargeable output is small, and conversely, the remaining capacity is 0%. When the output that can be charged is large, the output that can be discharged is small. On the other hand, as shown in the graph of FIG. 17 (B), the electric power that may be required for the battery is desired to be a constant amount of charging power and discharging power regardless of the remaining capacity of the battery. Therefore, as shown in the graph of FIG. 18, for example, when the remaining capacity is 100%, a power (output) P1 larger than the chargeable power (output) C3 is required, or when the remaining capacity is 0%, Electric power (output) P2 larger than the electric power (output) D1 that can be discharged may be required. When trying to answer these requirements, the battery should be placed so that when the remaining capacity is 100%, the rechargeable power C3 is P1, and when the remaining capacity is 0%, the dischargeable power D1 is P2. Need to design. That is, the battery capacity can be increased so that the output range of the redox flow battery can be changed from the area surrounded by C1, C3, D3, D1 to the area surrounded by C2, P1, P3, P2 (D2). It is necessary to use a plurality of batteries with small capacities. Therefore, it is desired to reduce the battery (or a plurality of battery groups) by reducing the battery capacity (or the number of batteries) set in advance to be smaller (or smaller).

  Accordingly, the main object of the present invention is to stabilize the power supply to the load by adding it to a power generation facility with unstable power generation output such as a wind power generator or a load such as an electric railway where power consumption is likely to fluctuate. In a redox flow battery system, it is providing the operating method of a redox flow battery system which can improve battery efficiency and can reduce a battery size.

  The present invention achieves the above object by changing the remaining capacity of the redox flow battery in accordance with the output fluctuation of the power generation facility or the fluctuation of the power consumption of the load.

(Pattern 1 in which a redox flow battery is installed in a power generation facility)
That is, the present invention comprises a power generation facility with irregularly generated power and a redox flow battery attached to the power generation facility, and the power generation output of the power generation facility and the battery output of the redox flow battery are combined to create an irregularity. This is a method for operating a redox flow battery system that smoothes the power generation output and supplies the smoothed power to a load. Then, a target composite value is determined based on the output value of the power generation facility, and the redox flow battery is charged and discharged so that the difference between the remaining capacity of the redox flow battery and the target composite value is within a set range.

(Pattern 2 where a redox flow battery is added to the load)
Another aspect of the present invention includes a redox flow battery in which power is supplied from a regular power generation facility, and the power consumption is irregularly provided, and the power consumption of the load and the battery output of the battery are This is a method of operating a redox flow battery system that combines and smoothes irregular power consumption. Then, based on the power consumption of the load, a target value of a combined input of the power consumption of the load and the battery output is determined. Similarly to the pattern 1, the remaining capacity of the redox flow battery and the target value are summed. The redox flow battery is charged and discharged so that is within the set range.

  When adjusting the remaining capacity by adding an offset so that the remaining capacity is within a certain range like a conventional redox flow battery, in order to make a battery with sufficient power that may be required, Even if the battery capacity is set large or the battery capacity is small, a plurality of batteries must be used. Therefore, the redox flow battery itself and the battery group have become large. Accordingly, as a result of various studies to reduce the size (or decrease the number) of redox flow batteries, the present inventors perform offset control to keep the remaining capacity within a certain range, that is, the output of the power generation equipment The knowledge that battery efficiency can be improved by changing the remaining capacity based on the output of the power generation facility and the power consumption of the load, rather than making the remaining capacity constant regardless of the power consumption of the load and the load. Obtained. Specifically, when a redox flow battery is installed in the power generation facility, the target composite value is determined based on the output of the power generation facility, and the difference between the remaining capacity and the target composite value becomes 0, that is, the remaining It has been found that charging and discharging the redox flow battery so that the capacity is substantially equal to, preferably equal to, the target composite value contributes to improvement of battery efficiency. In addition, when a redox flow battery is installed in a load with irregular power consumption, the target composite value is determined based on the power consumption of the load, and the sum of the remaining capacity and this target composite value is approximately 1. It was found that controlling the remaining capacity to charge / discharge the redox flow battery so that it is preferably 1 (100%) contributes to the improvement of battery efficiency. Hereinafter, the case of pattern 1 in which the redox flow battery is provided in the power generation facility will be described.

  Consider the relationship between the output of the power generation facility (hereinafter referred to as the power generation output) and the combined output (hereinafter simply referred to as the combined output) of this power generation output and the output of the redox flow battery (hereinafter referred to as the battery output). FIG. 11 is a graph showing the relationship between the power generation output and the combined output. As shown in the graph of FIG. 11, the range of output that can be taken for both the power generation output and the combined output is 0 to 100%. For example, if the combined output is 100%, the generated output will be 100% if all the combined output is covered by the generated output, and part of the combined output will be covered by the battery output and the rest will be covered by the generated output. Then, the power generation output is the ratio of the remainder. Similarly, when the combined output is 0%, the generated output may be 0%, or the redox flow battery can be charged with the generated output, and thus the generated output may be 100%.

  Next, consider the relationship between the combined output and the output required for the redox flow battery (hereinafter referred to as the battery required output). FIG. 12 is a graph showing the relationship between the combined output and the battery required output. First, when the combined output is 0%, the power generation output takes 0 to 100% as shown in the graph of FIG. Here, in pattern 1, the battery output is the difference between the combined output and the power generation output. Since the combined output is 0% and the power generation output is 0 to 100%, the battery required output is 0 to 100%. At this time, since the redox flow battery is only required to be charged and there is no possibility of being required to be discharged, the required battery output ranges from 0% charge to 100% charge. On the other hand, when the combined output is 100%, the power generation output is 0 to 100%, so the battery required output is 0 to 100%. At this time, since the redox flow battery is only required to be discharged and there is no possibility that charging is required, the battery required output ranges from 0% discharge to 100% discharge.

  On the other hand, consider the relationship between the capacity of the battery and the remaining capacity of the redox flow battery. FIG. 13 is a graph showing the relationship between the capacity of the battery and the remaining capacity. As shown in the graph of FIG. 13, the redox flow battery has the maximum charge capacity when the remaining capacity is 0%, the charge capacity and the discharge capacity are almost even when the remaining capacity is 50%, and the remaining capacity is 100%. %, The discharge capacity is maximized. That is, in order to make the best use of the capacity of the redox flow battery, it is preferable to charge when the remaining capacity is 0%, and it is preferable to discharge when the remaining capacity is 100%. Therefore, in the redox flow battery, the required output of the battery is preferably charge power when the remaining capacity is 0%, and the required output of the battery is preferably discharge power when the remaining capacity is 100%.

  From these facts, when the battery capacity and the required output of the battery are made to correspond to each other, and finally matched, the battery capacity can be utilized to the maximum extent. At this time, the graph shown in FIG. 12 and the graph shown in FIG. 13 are matched. Therefore, it is understood that the remaining capacity of the battery may be controlled so that the remaining capacity of the redox flow battery matches the combined output. Qualitatively, an increase in the combined output is regarded as an increase in the power generation output. And when a power generation output becomes large, it is desirable for a redox flow battery to charge the surplus power generation part of power generation equipment. Therefore, the remaining capacity of the battery is increased by charging. On the other hand, a decrease in the combined output is regarded as a decrease in the power generation output. And when a power generation output becomes small, it is desirable for a redox flow battery to discharge the insufficient power generation of a power generation facility. Therefore, the remaining capacity of the battery is reduced by discharging. Thus, since the remaining capacity increases as the combined output increases and the remaining capacity decreases as the combined output decreases, it can be said that the combined output and the remaining capacity have a similar relationship. In particular, when ignoring the loss due to charge / discharge for smoothing, it can be said that there is a complete similarity. That is, it can be said that the composite output and the remaining capacity have a desirable relationship when expressed as in the graph shown in FIG. Based on the above knowledge, the present invention of the above pattern 1 is defined.

  Next, the case of pattern 2 in which a redox flow battery is provided in a load with irregular power consumption will be described. A combined input (hereinafter simply referred to as combined input) of the power of the load with irregular power consumption (hereinafter referred to as load power) and the load power and the output of the redox flow battery (hereinafter referred to as battery output). Think about the relationship. FIG. 14 is a graph showing the relationship between load power and composite input. As shown in the graph of FIG. 14, the range of inputs that can be taken for both the load power and the combined input is 0 to 100%. For example, if the combined input is 100%, if all the combined inputs are based on load power, the load power is 100%, and if some of the combined inputs are battery output (charging power) and the rest is load power The load power is the remaining ratio. Similarly, when the composite input is 0%, the load power may be 0%, or the redox flow battery may be discharged, and the load power may be 100%.

  Next, consider the relationship between the composite input and the output required for the redox flow battery (hereinafter referred to as the battery required output). FIG. 15 is a graph showing the relationship between the combined input and the battery required output. First, when the combined input is 0%, the load power takes 0 to 100% as shown in the graph of FIG. Here, in pattern 2, the battery output is the difference between the combined input and the load power. Since the combined input is 0% and the load power is 0 to 100%, the required battery output is 0 to 100%. At this time, since the redox flow battery is only required to be discharged and is not likely to be charged, the battery required output ranges from 0% discharge to 100% discharge. On the other hand, when the combined input is 100%, the load power is 0 to 100%, so the required battery output is 0 to 100%. At this time, since the redox flow battery is only required to be charged and there is no possibility of being required to be discharged, the battery required output ranges from 0% charge to 100% charge.

  On the other hand, as shown in the graph of FIG. 13, in the redox flow battery, the required output of the battery is preferably charging power when the remaining capacity is 0%, and the required output of the battery is when the remaining capacity is 100%. Discharge power is preferred. Therefore, in order to utilize the battery capacity as much as possible, it is desired that the battery capacity and the required output of the battery are made to correspond to each other, as in the case of Pattern 1. At this time, the graph shown in FIG. 13 and the graph shown in FIG. 15 are made symmetrical. Therefore, it is understood that the remaining capacity of the battery may be controlled so that the remaining capacity of the redox flow battery and the composite input are symmetric. Qualitatively, an increase in the combined input is regarded as an increase in load power. And when load electric power becomes large, it is desirable for a redox flow battery to discharge to load. Therefore, the remaining capacity of the battery is reduced by discharging. On the other hand, a decrease in the combined input is regarded as a reduction in load power. And when load electric power becomes small, it is desirable to charge a redox flow battery. Therefore, the remaining capacity of the battery is increased by charging. Thus, since the remaining capacity decreases as the combined input increases, and the remaining capacity increases as the combined input decreases, it can be said that the combined output and the remaining capacity are in a symmetrical relationship. That is, it can be said that the composite input and the remaining capacity are in a desirable relationship when expressed as in the graph shown in FIG. Based on the above knowledge, the present invention of the above pattern 2 is defined. Hereinafter, the present invention will be described in more detail.

  In the present invention, examples of the power generation equipment provided with the redox flow battery system include those in which the power generated by a wind power generator or a solar power generator is irregular and fluctuates with time. A known power generation facility may be used. In addition, the load in which the redox flow battery is additionally provided includes, for example, a load that is irregular in power consumption such as an electric railway or an electric furnace and fluctuates with time. Such a load is connected to a power plant that performs hydroelectric power generation or thermal power generation in addition to a redox flow battery, and steady power supply is performed. If the power consumption of the load fluctuates and the steady power is insufficient, the redox flow battery is discharged to compensate for the shortage. If the steady power is excessive, the battery is charged and the excess is stored in the battery.

  In the present invention, a redox flow battery system includes a battery having a redox flow battery cell, a tank for storing an electrolyte supplied / discharged to the cell, and an electrolyte transportation path connecting the cells to each other. A configuration is mentioned. In addition, a pump may be provided in the transport path so that the electrolyte can be easily supplied from the tank to the cell. The redox flow battery cell includes a positive electrode cell and a negative electrode cell through a diaphragm. As the electrolyte, 1. High electromotive force 2. High energy density 3. Since the electrolyte is a single element system, it can be regenerated by charging even if the cathode electrolyte and anode electrolyte are mixed Vanadium ion solutions having many advantages such as being possible are preferred. A known redox flow battery system may be used.

  In the present invention, the remaining capacity is controlled by a predetermined procedure described later. Therefore, the redox flow battery system may include a computer that inputs a control program. At this time, the redox flow battery system controls the remaining capacity in accordance with an instruction from the computer, thereby realizing improvement in battery efficiency.

  The remaining capacity of the redox flow battery is controlled as follows. First, a target composite value is determined based on the generated power of the power generation facility. Then, by charging / discharging the redox flow battery so that the target composite value and the remaining capacity are ultimately equal so that the difference between the target composite value and the remaining capacity of the battery is within the set range. Do. Alternatively, based on the power consumption of the load, a target value (hereinafter referred to as a target composite value) of a combined input of the power consumption of the load and the battery output is determined. Then, the redox flow battery is charged and discharged so that the sum is 1 (100%) so that the sum of the target composite value and the remaining capacity of the battery is within the set range. .

  In pattern 1 in which a redox flow battery is installed in the power generation facility, the target composite value is expressed by combining the power generation output and the battery output. The planned output after a certain time is obtained from the current power generation output. However, with this planned output, it may be excessive or insufficient with respect to the power required by the load. Therefore, the planned output of the redox flow battery for compensating for the excess or deficiency of the planned output is obtained so as to meet the demand of the load, and both the planned outputs are synthesized to obtain a smooth output, that is, the target synthesized value. The redox flow battery can perform stable power supply to the load by charging or discharging the scheduled output that satisfies the target composite value. On the other hand, in the pattern 2 in which the redox flow battery is provided side by side with the load, the target combined value is expressed by combining the power consumption of the load and the battery output. Although the planned power after a certain time can be obtained from the current power consumption, it is considered that the planned power is excessive or insufficient with respect to the power generation output (a constant value) from the power generation facility. Therefore, in order to make the power generation output from the power generation facility constant with respect to the power consumption of the load, that is, to smooth the power consumption of the load, the planned output of the redox flow battery is obtained, and the planned power and the planned output are synthesized. Smooth input, that is, a target composite value. At this time, the redox flow battery stabilizes the power consumption of the load by charging or discharging the scheduled output that satisfies the target composite value.

  The target composite value can be obtained by performing appropriate arithmetic processing on the power generation output or power consumption. Examples of the arithmetic processing include 1. low-pass filter calculation and 2. moving average calculation. Conventional arithmetic processing may be used. For example, the target composite value may be determined in the same manner as in Non-Patent Document 1.

When performing a low-pass filter calculation, since the power generation output (or power consumption) and the target composite value are both functions of time s, they are set to x (s) and y (s), respectively. When the transfer function from the load power consumption) to the target composite value is the first order (first-order lag system), the target composite value y (s) is y (s) = {1 / (1 + s)} x x (s). Also, when the transfer function is second order, if the parameter of this transfer function is α, the target composite value y (s) = {1 / (s ² + α × s + 1)} × x (s) Become. When performing a low-pass filter operation, the transfer function may be either a first order or a second order or higher order. When performing the moving average calculation, the target composite value y (s) is y (s) = {(1−e ^−s ) / s} × x (s).

  In the present invention, the redox flow battery smoothes the power generation output of the power generation facility to stably supply power to the load, or smoothes the power consumption of the load, in addition to improving the battery efficiency. In addition to smoothing charge / discharge, charge / discharge for improving battery efficiency is performed. Specifically, the remaining capacity of the redox flow battery is measured, and charging / discharging is performed so that the difference between the remaining capacity and the target composite value (the sum for pattern 2) is within a set range.

  The remaining capacity of the redox flow battery is correlated with the cell voltage. Therefore, for example, the remaining capacity is formed in advance by measuring the voltage of the battery cell (monitor cell) by arranging voltage measuring means such as a voltmeter in the monitor cell provided separately from the battery cell or the cell to be charged / discharged. It may be obtained by comparing the measured voltage against the relational value data indicating the relation between the voltage of the battery cell (monitor cell) and the remaining capacity. Further, the charge depth may be measured and read as a voltage. The depth of charge is the ratio of the ion concentration present in the electrolyte. For example, when a vanadium solution is used as the electrolyte, the depth of charge is high: positive electrode: “pentavalent V ion concentration / 4 valence + 5 The ratio of “valent ion concentration” is large, and the ratio of negative electrode: “divalent V ion concentration / 2 valence + trivalent ion concentration” is large.

In the present invention, when the difference between the remaining capacity and the target composite value (the sum of pattern 2) is within the setting range, charging / discharging for improving battery efficiency is not performed, and when it is outside the setting range, for improving battery efficiency. The same charging or discharging is performed. At this time, you may perform operation which compensates the loss part by charging / discharging for smoothing. For example, the point (value) at which charging is started and the point at which the charging ends are different. Specifically, for example, in the case of Pattern 1, charging is started when the difference between the remaining capacity and the target composite value exceeds m, and charging is performed until the difference becomes m ₁ (m> m ₁ ). Is mentioned. By shifting the charging start point and end point in this way, it is possible to compensate for the loss due to charge / discharge for smoothing. Similarly, the point at which discharge starts and the point at which it ends may be different.For example, in the case of pattern 1, when the difference between the remaining capacity and the target composite value is less than n, the discharge is started and the difference is Discharging may be performed until n ₁ (n ₁ > n) is satisfied. At this time, there are a first set range where charging / discharging is not performed: n to m and a second setting range: n ₁ to m _{1 which} is a charging / discharging end range. In addition, when the difference between the remaining capacity and the target composite value is outside the set range, charging with a loss is performed, and when within the set range, only charging for compensating for the loss is performed.

  As described above, in the present invention, the redox flow battery is charged and discharged so that the difference between the target composite value and the remaining capacity (the sum in the case of pattern 2) is included in the set range, thereby smoothing the power generation output by the battery. In addition, the power consumption of the battery and the load can be smoothed, the battery efficiency can be improved, the battery capacity of the battery used can be reduced, and the number of batteries used can be reduced. In addition to performing such charge and discharge for improving battery efficiency, in the redox flow battery used in the present invention, the effect of smoothing by the battery can be further improved by devising the set value of the battery capacity. it can. Specifically, when using the low-pass filter calculation to calculate the target composite value, the transfer function of the low-pass filter is a first-order lag system, the time constant is τ, and the set output of the power generation equipment (or the set power of the load) is When X is set, the battery capacity of the redox flow battery is preferably set to A × X × τ (where 0.8 ≦ A ≦ 1.2). When the transfer function of the low-pass filter is nth order (n ≧ 2), the first order coefficient is α, the time constant is τ, and the set output of the power generation equipment (or set power of the load) is X, the battery of the redox flow battery The capacity is preferably set to A × α × X × τ (where 0.8 ≦ A ≦ 1.2). Also, when using the moving average calculation to calculate the target composite value, in the moving average calculation, when the moving average time window is τ and the set output of the power generation equipment (or the set power of the load) is X, the redox flow The battery capacity of the battery is preferably set to B × X × τ (where 0.3 ≦ B ≦ 0.6).

  The remaining capacity of the redox flow battery varies depending on the loss of the battery and the time integration of the output. For this reason, if the remaining capacity and the target combined value are strictly matched, or if the remaining capacity and the target combined value are symmetric, it is desirable to supplement the loss. It is also desirable to add an offset in order to eliminate the difference between the change in remaining capacity due to charge / discharge for smoothing and the change in the target composite value. However, when the offset is performed, there is a difference between the output capability and the output required for smoothing in the redox flow battery. Therefore, as a result of the study by the present inventors, when the battery capacity of the redox flow battery is set as A × X × τ, A × α × X × τ, and B × X × τ as described above, the battery loss is excluded. Thus, since the change in the remaining capacity matches the change in the target composite value, that is, there is no difference between the change in the remaining capacity and the change in the target composite value, it is only necessary to perform supplementary charging for the battery loss. By setting the battery capacity of the redox flow battery as described above, the difference between the output including auxiliary charging and the output required for smoothing in the battery is reduced, so the effect of smoothing by the battery Can be further enhanced. In addition, the supplementary charging may be performed by performing an operation to compensate for the loss.

(Battery capacity: A × X × τ, 0.8 ≦ A ≦ 1.2)
Consider a case where the target composite value is calculated by a low-pass filter operation and the transfer function of the low-pass filter is a first-order lag system. At this time, since the output of the power generation facility (or the power consumption of the load), the output of the redox flow battery, and the target composite value are all functions of time s, x (s), z (s), y (s ), The target composite value y (s) is a composite of the power generation output (or power consumption of the load) and the battery output.
y (s) = z (s) + x (s) ... Equation 1
It becomes.
Next, assuming that the transfer function from the power generation output (or power consumption of the load) to the target composite value is F (s), the target composite value y (s) is
y (s) = F (s) x x (s) ... Equation 2
It becomes.
Further, when the transfer function from the power generation output (or load power consumption) to the battery output is G (s), the battery output z (s) is
z (s) = G (s) x x (s) ... Equation 3
It becomes.
Substituting Equation 2 and Equation 3 into Equation 1 above,
G (s) = F (s) -1 ... Equation 4
It becomes.
If the battery capacity (set value) of the redox flow battery is C, the remaining capacity of the battery is α (s), the transfer function H (s) from the battery output to the change in capacity of the battery, and the loss is ignored, the remaining capacity α (s ) By battery output z (s) and transfer function H (s)
α (s) = H (s) x z (s) ... Formula 5
It is expressed as Also, substituting equation 3 into equation 5,
α (s) = H (s) × G (s) × x (s) ... Equation 6
It is expressed as
Since the loss is ignored, when the transfer function H (s) is specifically shown, using the battery capacity C,
H (s) = (-1) / (C × s) ... Equation 7
It is expressed as
Since the transfer function F (s) is a first order lag system, when the transfer function F (s) is specifically expressed,
F (s) = 1 / (1 + s) ... Equation 8
Substituting Equation 8 into Equation 4, the transfer function G (s) is
G (s) = (-s) / (1 + s) ... Equation 9
It is expressed as Therefore, substituting Equation 7 and Equation 8 into Equation 6, the remaining capacity α (s) is
α (s) = {1 / [C × (s + 1)]} × x (s) ... Equation 10
It is expressed as Also, by substituting Equation 8 into Equation 2, the target composite value y (s) is
y (s) = {1 / (1 + s)} × x (s) ... Equation 11
It is expressed as
Therefore, from Equation 10 and Equation 11, if the difference between the remaining capacity α (s) and the target composite value y (s) is set to 0, that is, if both are made to coincide, the battery capacity C is set to C = 1. I understand that Similarly, in order to set the sum of the remaining capacity α (s) and the target composite value y (s) to 1, it is understood that the battery capacity C should be C = 1. Therefore, when setting the battery capacity (time capacity) of the redox flow battery based on the set output of the power generation equipment (or the set power of the load), it is preferable to set 1 × set output (set power) × time constant. Recognize. Therefore, 0.8 ≦ C ≦ 1.2 is appropriate for making the difference between the remaining capacity α (s) and the target composite value y (s) close to 0 (in pattern 2, the sum is close to 1). I understand that. Therefore, when setting the battery capacity (time capacity) of a redox flow battery based on the set output of the power generation facility (or set power of the load), A x set output x time constant (however, 0.8 ≤ A ≤ 1.2) It turns out that it is preferable.

(Battery capacity: α × A × X × τ, 0.8 ≦ A ≦ 1.2)
Consider a case where the target composite value is calculated by low-pass filter calculation, and the transfer function of the low-pass filter is set to a second or higher order. Here, the second-order case is handled. At this time, Formulas 1 to 7 are the same as those in the first-order lag system. Since the transfer function F (s) is quadratic, it has a parameter α. Using this α, the transfer function F (s) is specifically expressed as
F (s) = 1 / (s ² + α × s + 1) ... Equation 2-1
It becomes.
Substituting Equation 2-1 into Equation 4, the transfer function G (s) is
G (s) = (-s ² -α × s) / (s ² + α × s + 1) ... Equation 2-2
It is expressed as Therefore, substituting Equation 7 and Equation 2-2 into Equation 6, the remaining capacity α (s) is
α (s) = {(s + α) / [C × (s ² + α × s + 1)]} × x (s) Equation 2-3
It is expressed as Further, by substituting Equation 2-1 into Equation 2, the target composite value y (s) is
y (s) = {1 / (s ² + α × s + 1)} × x (s) ... Equation 2-4
It is expressed as From Formula 2-3 and Formula 2-4, if the difference between the remaining capacity α (s) and the target composite value y (s) is set to 0, that is, if both are to be matched, the battery capacity C is set to C = α It can be seen that = (1 × α). Similarly, in order to set the sum of the remaining capacity α (s) and the target composite value y (s) to 1, it is understood that the battery capacity C should be C = α = (1 × α). Therefore, when setting the battery capacity (time capacity) of the redox flow battery based on the set output of the power generation equipment (or the set power of the load), it is preferable that α × set output (set power) × time constant. Recognize. Therefore, to make the difference between the remaining capacity α (s) and the target composite value y (s) close to 0 (the sum is close to 1 when pattern 2), 0.8 × α ≦ C ≦ 1.2 × α Is suitable. Therefore, when setting the battery capacity (time capacity) of a redox flow battery based on the set output of the power generation equipment (or the set power of the load), A x α x set output x time constant (0.8 ≤ A ≤ 1.2) It turns out that it is preferable.

Note that it is preferable to add a restriction to the parameter α so that the fluctuation is not amplified at any period. Assuming that the angular velocity of fluctuation of the power generation equipment (or load) is ω and the imaginary unit is j, the above limit is in the range of ω to -∞ to + ∞.
| F (jω) | ≦ 1 ... Equation 2-5
It is expressed as From equation 2-2 to equation 2-5,
F (jω) × F (-jω) ≦ 1 ... Equation 2-6
It becomes. Substituting Equation 2-1 into Equation 2-6 and performing variable transformation of t = ω ² ,
1 / {(1-t) ² + α ² × t} ≦ 1 ... Equation 2-7
It becomes. Transforming Equation 2-7,
t × (t + α ² -2) ≧ 0 ... Equation 2-8
It becomes. Α satisfying Expression 2-8 is α ≧ √2. Therefore, α ≧ √2 satisfies the condition of the parameter α. Note that the battery capacity C has a minimum value of C = α = √2 under the restriction that the fluctuation is not amplified at any period. At this time, the low-pass filter operation is a second-order Butterworth low-pass filter operation.

Also, when the transfer function of the low-pass filter is higher than the third order, assuming that the parameter α and the pole of the low-pass filter are β, the transfer function F (s) is
F (s) = β / (… + s ² + α × s + β) Equation 2-9
It is expressed as Using this transfer function F (s), the battery capacity of the redox flow battery is required to be preferably A × α × set output × time constant (however, 0.8 ≦ A ≦ 1.2) by the same procedure as above. .

(Battery capacity: B x X x τ, where 0.3 ≤ B ≤ 0.6)
Consider a case where the target composite value is calculated by moving average calculation. At this time, Expressions 1 to 7 are the same as those in the case of the first-order lag low-pass filter calculation. When the transfer function F (s) is specifically expressed,
F (s) = (1-e- ^s ) / s ... Equation 3-1
It becomes.
Substituting Equation 3-1 into Equation 4, the transfer function G (s) is
G (s) = (1-e ^-s -s) / s ... Equation 3-2
It is expressed as Therefore, substituting Equation 7 and Equation 3-2 into Equation 6, the remaining capacity α (s) is
α (s) = {(s + e ^−s −1) / (C × s ² )} × x (s) Formula 3-3
It is expressed as In this ^{case, e -s = 1-s +} s 2/2-s 3/6 + ... a because,
α (s) = {(s 2/2-s 3/6 + ...) / (C × s 2)} × x (s) = {(1/2-s / 6 + ...) / C} × x (s) ... Formula 3-4
It becomes. Also, by substituting Equation 3-1 into Equation 2, the target composite value y (s) is
y (s) = {(1 -e -s) / s} × x (s) = {(ss 2/2 + s 3/6 ...) / s} × x (s)
= (1-s / 2 + s 2/6 ...) × x (s) ... formula 3-5
It is expressed as According to Equations 3-4 and 3-5, when the difference between the remaining capacity α (s) and the target composite value y (s) is set to 0, that is, when both are made to coincide, the battery capacity C is set to C = 1 / It can be seen that 2 = 0.5. Similarly, in order to set the sum of the remaining capacity α (s) and the target composite value y (s) to 1, it is understood that the battery capacity C should be C = 1/2 = 0.5. Therefore, when setting the battery capacity (time capacity) of the redox flow battery based on the set output of the power generation equipment (or the set power of the load), it is preferable to set 0.5 × set output (set power) × time constant. Recognize. For these reasons, 0.3 ≦ C ≦ 0.6 is appropriate to make the difference between the remaining capacity α (s) and the target composite value y (s) close to 0 (to make the sum close to 1 for pattern 2). I know that there is. Therefore, when setting the battery capacity (time capacity) of a redox flow battery based on the set output of the power generation equipment (or the set power of the load), B x set output x time constant (however, 0.3 ≤ B ≤ 0.6) It turns out that it is preferable.

Specific procedures of the operation method of the present invention include, for example, the following procedures. At this time, the following procedure may be used as a control program, the control program may be input to a computer, and the remaining capacity may be controlled in accordance with an instruction from the computer.
1. Steps to measure the power generation output (or load power consumption) of the power generation equipment
2.Calculating a target composite value (or target value of composite input of load power consumption and battery output) based on power generation output (or load power consumption)
3. Step to measure the remaining capacity of redox flow battery
4.Step of calculating difference (or sum) between target composite value and remaining capacity
5. Step of determining whether the above difference is included in the setting range
6. If the above difference is outside the set range, charge and discharge the redox flow battery so that it is within the set range.

  In the above step 2, the target composite value is obtained by performing an appropriate calculation on the power generation output (or power consumption of the load). Examples of the calculation method include the low-pass filter calculation and the moving average calculation. Further, the target composite value may be a unitless value by performing appropriate arithmetic processing in addition to the above-described arithmetic operations such as the low-pass filter arithmetic operation and the moving average arithmetic operation. For example, a calculation value obtained by performing a low-pass filter operation on the power generation output is a unit value similar to the unit MW of the power generation output. Therefore, a value obtained by dividing this calculated value by the set output of the power generation facility (for example, maximum output; MW) and having no unit may be used as the target composite value.

  In the case where the target composite value is a unitless value, it is preferable that the remaining capacity is subjected to an appropriate calculation process in step 3 to obtain a unitless value. For example, the time capacity (MWh) of the redox flow battery can be detected from the cell voltage. This time capacity may be used as the remaining capacity. For example, this time capacity may be divided by the set time capacity (MWh) of the redox flow battery to obtain a unitless value, and this unitless value may be used as the remaining capacity.

  In addition, when performing step 6 above, the same difference (sum for pattern 2) as the charge / discharge amount required to bring the difference between the target composite value and the remaining capacity (sum for pattern 2) within the set range The relationship value data is obtained in advance, and this relationship value data is input in advance to the storage means of the computer. The computer obtains the charge / discharge amount by comparing the difference between the calculated target composite value and the remaining capacity (sum for pattern 2) and the related value data called from the storage means. At this time, relation value data in consideration of a loss due to charge / discharge for smoothing may be created and used. Furthermore, the operating conditions of the redox flow battery system corresponding to the charge / discharge amount (control of the orthogonal converter, the operating time of the pump, the flow rate of the electrolyte, etc.) are determined in advance, and these operating conditions are also stored in the computer storage means in advance. You may enter it. And if a computer selects the suitable driving | running condition with respect to the calculated | required charge / discharge amount, and it will comprise the command which operates a redox flow battery system by the selected condition, control can be performed easily.

  As described above, according to the present invention, the remaining capacity of the redox flow battery can be changed in accordance with fluctuations in the output of the power generation facility and the power consumption of the load, so that the capacity of the battery can be used efficiently, and the battery can be reduced in size. Can be Therefore, by applying the present invention, it is possible to stabilize the power to the load without using a battery with a large battery capacity or using a plurality of batteries in order to cover the required power as in the prior art. be able to.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram showing a redox flow battery system to which the operation method of the present invention is applied. This system 1 includes a battery 10 having a battery cell, a tank 11 for storing an electrolyte supplied / discharged to the cell, an electrolyte transport path 12 connecting the cell and the tank 11, and the transport path 12 And a pump 13 for supplying the electrolytic solution from the tank 11 to the cell. The system 1 is connected to the power generation facility 2 and the load (system) 4 via the orthogonal transformer 3. This power generation facility 2 has irregular power generation, and a wind power generator is used in this example. In this way, the redox flow battery system 1 is installed in the power generation facility 2 with irregular power generation so that the power required by the load 4 can be stably supplied and the power output of the power generation facility 2 and the battery output of the battery 10 ( Charging or discharging) and supplying this combined output to the load 4.

In this example, the battery 10 has a stacked structure in which a plurality of battery cells are stacked. The redox flow battery cell is separated into a positive electrode cell and a negative electrode cell by an ion exchange membrane (diaphragm), the positive electrode cell contains a positive electrode, the negative electrode contains a negative electrode, and each electrode has a positive electrolyte solution and a negative electrode electrolyte solution, respectively. Is supplied. In this example, a positive electrode electrolyte solution containing V ⁵⁺ and a negative electrode electrolyte solution containing V ²⁺ were used. In FIG. 1, only one tank is shown, but actually a positive electrode electrolyte tank and a negative electrode electrolyte tank are provided. Similarly, the electrolyte solution transport paths are actually provided for the positive electrode electrolyte and the negative electrode electrolyte, respectively.

  In the present invention, in order to improve the battery efficiency, the battery 10 can be stably supplied even if the battery 10 has a small battery capacity setting value (so-called rated capacity). To control the remaining capacity. Specifically, the remaining capacity is changed with the fluctuation of the power generation output of the power generation facility 2. More specifically, the target composite value is determined based on the power generation output of the power generation facility 2, and the battery is charged / discharged so that the difference between the remaining capacity of the battery and the target composite value is within the set range. To control. Therefore, in this example, in order to measure the remaining capacity, a monitor cell 14 is provided separately from the battery cell, and a voltmeter (not shown) is arranged on the monitor cell 14 and wiring is performed so that the measurement result is sent to the computer 15. The computer 15 is connected at. This computer 15 is also connected to the power generation facility 2 via wiring, and the power generation output of the power generation facility 2 is sent, and the calculation to obtain the target composite value based on the obtained power generation output, An operation for obtaining a difference between the remaining capacity and the target composite value, a determination as to whether the difference is within a set range, and the like are also performed. Further, the computer 15 is also connected to the pump 13 and the orthogonal transformer 3 through wiring, and the drive of the pump 13 and the orthogonal converter 3 can be controlled by a control signal. With this configuration, when the difference between the remaining capacity and the target composite value is outside the set range, the computer 15 controls the orthogonal transformer 3 and drives the pump 13 to charge / discharge the battery.

  In the redox flow battery system having the above configuration, the control procedure of the remaining capacity of the battery will be specifically described. First, the power generation output X of the power generation facility is measured, the measurement result is transmitted to the computer, and the target composite value Y is calculated from the power generation output by the calculation method described later. On the other hand, the voltage of the cell is measured with a voltmeter arranged in the monitor cell, the measurement result is transmitted to a computer, and the measurement result is read as the remaining capacity α. Then, the computer calculates a difference K between the target composite value and the remaining capacity, and determines whether or not this difference K is included in the set range (n or more and m or less) input to the storage means of the computer. When the difference K is outside the setting range, that is, when the difference K is less than n or more than m, charging / discharging is performed. When it is within the set range, charging / discharging is not performed. When charging / discharging, the difference K calculated from the relationship value data between the target composite value stored in advance in the computer and the remaining capacity and the charge / discharge amount necessary for this difference to be within the set range. The amount of charge / discharge at is determined. Charging / discharging is performed based on this charge / discharge amount. In this example, a condition suitable for the charge / discharge amount at the difference K is selected from the battery operating conditions stored in advance in the computer, and based on this condition, the driving of the orthogonal transformer and the pump is controlled to charge / discharge. I do.

  FIG. 2 is a flowchart showing a control procedure of the operation method of the redox flow battery system of the present invention. First, the power generation output X of the power generation facility is measured, and the measurement result (electrical signal) is input to the signal receiving unit of the computer (step S1). At this time, the computer temporarily stores the input electrical signal in the storage means.

Next, the computer calls the power generation output X stored in the storage means, performs arithmetic processing by the arithmetic means, and calculates a target composite value (step S2). In this example, a first-order lag low-pass filter calculation is used as the calculation method. Specifically, the generated power is x (s), the target composite value is y (s), and the target composite value y (s) is obtained from {1 / (1 + s)} × x (s). Further, the power generation output X is usually expressed as a value having a unit (for example, MW). Accordingly, the target composite value y (s) is also a value having the same unit (same) as the power generation output X. In this example, the target composite value y (s) is the maximum value of the set power (so-called rated power; MW) so that the target composite value y (s) is a unitless value. An arithmetic process of dividing is performed, and this value is set as the target composite value Y. Then, the computer stores the obtained target composite value Y in the storage means.

  On the other hand, in order to obtain the remaining capacity of the battery, the voltage of the cell is measured with a voltmeter, and the result (electrical signal) measured by the voltmeter is input to the signal receiver of the computer (step S3). In this example, the time capacity is used as the remaining capacity. Therefore, the computer replaces the input electric signal with the time capacity (MWh). Further, the computer performs a calculation process of dividing the read time capacity by the set time capacity (so-called rated time capacity; MWh) of the redox flow battery so that the read time capacity is set to a unitless value like the target composite value Y. At the same time, this value is temporarily stored in the storage means as the remaining capacity α.

  Next, the computer calls the target composite value Y and the remaining capacity α stored in the storage means, and calculates the difference K = Y−α between the target composite value Y and the remaining capacity α by the arithmetic means (step S4), the difference K is temporarily stored in the storage means. In this example, the difference K is Y-α, but α-Y may of course be used.

  Next, the computer calls the lower limit value n and the upper limit value m of the setting range stored in the storage unit, and determines whether or not the calculated difference K is included in the setting range (step S5). When the difference K is included in the set range, that is, when n ≦ K ≦ m, the computer determination unit determines that charging / discharging for improving battery efficiency is unnecessary (step S6), and ends the control.

  On the other hand, when the difference K exceeds the upper limit value m of the setting range, the target composite value Y is a large value in this example. When the target composite value Y takes a large value, it is desirable to increase the remaining capacity, that is, to charge the battery. Therefore, the determination means of the computer determines that charging is necessary to improve battery efficiency (step S8), and performs a charging operation (step S10). Specifically, first, a required charge amount is obtained. In this example, the relationship value data of the difference between the target composite value and the remaining capacity and the charge amount or discharge amount necessary for this difference to be included in the set range is input in advance to the storage means of the computer, The computer calls the relation value data from the storage means, and obtains the charge amount by comparing the difference K with this data. Based on the obtained charge amount, an appropriate condition is selected from the operation conditions for each charge amount or discharge amount that has been input to the computer in advance, and the drive of the orthogonal transformer and the pump is controlled based on this condition. Then, charging is performed, and when charging is completed, the control operation is terminated.

  On the other hand, when the difference K does not exceed the upper limit value m of the setting range, the difference K is less than the lower limit value n. Since the difference K is less than the lower limit value n, the target composite value Y is a small value in this example. When the target composite value Y takes a small value, it is desirable to reduce the remaining capacity, that is, to discharge. Therefore, the determination means of the computer determines that discharging is necessary for improving battery efficiency (step S9), and performs a discharging operation (step S10). Specifically, the required amount of discharge is obtained by the same procedure as in the case of charging, and an appropriate operating condition is selected based on this amount of discharge, and the orthogonal transformer and pump are controlled to discharge. When the discharge is finished, the control operation is finished.

  When the difference K is α−Y, the determination is reversed. Specifically, when the difference K exceeds the upper limit value m, the remaining capacity has a large value. That is, the target composite value Y is a small value. At this time, since it is desired to reduce the remaining capacity, the determination means of the computer determines that discharge is necessary. On the other hand, if the difference K does not exceed the upper limit m, that is, if the difference K is less than the lower limit n, the remaining capacity takes a small value and the target composite value Y takes a large value. The determination means of the computer determines that charging is necessary.

  In this example, the charge amount or discharge amount of the relation value data, and the amount necessary for the difference K to be the lower limit value n or the upper limit value m are used. Therefore, in this example, as shown in FIG. 3, discharging is performed when the difference K is less than the lower limit value n, discharging is stopped when the difference K reaches the lower limit value n, and charging is performed when the difference K is greater than the upper limit value m. When the difference K reaches the upper limit m, charging is stopped.

  By applying the operation method of the present invention as described above, the redox flow battery installed in the power generation facility with irregular power generation output can stabilize the power supplied to the load and improve the battery efficiency. The set battery capacity of the battery to be used can be reduced, and the number of batteries to be used can be reduced. Therefore, it is possible to reduce the size of the redox flow battery system.

In the redox flow battery shown in the first embodiment, an operation for compensating for loss due to charging / discharging for smoothing the generated power of the power generation facility may be performed. FIG. 4 is a graph showing the relationship between the difference between the target composite value and the remaining capacity, and how to give charge / discharge for improving battery efficiency, and shows the case where the start point and end point are different in charging and discharging. . For example, set n ₁ satisfying n <n ₁ <m, and start discharging when the difference K is less than the lower limit n, and stop discharging when the difference K becomes a value n ₁ greater than n. Also good. At this time, in addition to charging and discharging amount required for the cell efficiency, so that the loss is discharge electric accessory. In addition, m ₁ satisfying n <n ₁ <m ₁ <m is set, and charging is performed when the difference K exceeds the upper limit m, and charging is performed when the difference K becomes a value m ₁ smaller than m. You may make it stop. Upon this operation, in step S8, S9, relation value data used in determining the charge and discharge amount may want to create a plus supplemental discharge coulometric of loss. Note that, in this example, when the difference K is not less than the lower limit value m and not more than the upper limit value n, charging / discharging for improving battery efficiency is not performed in the same manner as in Example 1.

  A method different from that of the second embodiment will be described as an operation for compensating for the loss. FIG. 5 is a graph showing the relationship between the difference between the target composite value and the remaining capacity and how to give charge / discharge for improving battery efficiency, and the amount of loss when charge / discharge for improving battery efficiency is not performed. The case where auxiliary charge is performed is shown. In Examples 1 and 2, when the difference K is not less than the lower limit n and not more than the upper limit m, charging for loss compensation is not performed in addition to charging / discharging for improving battery efficiency. However, since loss occurs when the redox flow battery is charged / discharged to stabilize the power supplied to the load, it is desirable to perform charging for loss compensation as much as possible. Therefore, as shown in FIG. 5, even when the difference K is 0, that is, the target composite value Y and the remaining capacity α are equal, the loss is charged. In performing such an operation, if the difference K is outside the setting range, in step S8 or S9, the relational value data used when determining the charge / discharge amount is prepared by adding the loss. Good. If the difference K is within the set range, after step S6, charging for loss compensation is performed without charging / discharging for improving battery efficiency. At this time, it is preferable to set a charge amount necessary for loss compensation in advance and also set a control condition of the orthogonal transformer and a drive condition of the pump based on the charge amount.

  In order to more closely match the remaining capacity of the redox flow battery and the target composite value, in addition to compensating for the loss as in Examples 2 and 3, the remaining capacity due to charge / discharge for smoothing In order to eliminate the difference between the change in the target value and the change in the target composite value, it is desirable to add an offset. However, when an offset is added, in the redox flow battery, there is a difference between the output capability and the output required for smoothing. Therefore, in this example, in order to eliminate the difference between the output capability and the required output, the setting of the battery capacity of the redox flow battery is devised. Specifically, when the set output of the power generation facility (in this example, the set battery capacity) is X (MW) and the time constant is τ, the set capacity of the battery (in this example, the set battery capacity) is 1 × X Xτ. Thus, by setting the setting capacity | capacitance of a redox flow battery, in addition to the effect by this invention operating method, the effect of the smoothing by a battery can be heightened more.

In the above embodiment, the first-order lag low-pass filter calculation is used as the calculation method for calculating the target composite value, but a second-order or higher-order low-pass filter calculation may be used. For example, when using a second-order low-pass filter operation, if the power generation output is x (s), the target composite value y (s), and the transfer function parameter is α, the target composite value y (s) is {1 / (s ² + α × s + 1)} × x (s). Control methods other than the calculation method may be performed in the same manner as in the above embodiment.

  In addition, when performing the second-order low-pass filter calculation, the set capacity of the battery is set such that the set output of the power generation facility (in this example, the set battery capacity) is X (MW) and the time constant is τ, If it is set to 1 × α × X × τ, the smoothing effect by the battery can be further enhanced as in the fourth embodiment.

In addition to the above low-pass filter calculation, a moving average calculation may be used as a target composite value calculation method. At this time, if the power generation output is x (s) and the target composite value y (s), the target composite value y (s) is obtained from {(1-e ^−s ) / s} × x (s). Control methods other than the calculation method may be performed in the same manner as in the above embodiment.

  In addition, when performing a moving average calculation, the battery capacity setting is 0.5 x X x τ, where X (MW) is the set output of the power generation facility (in this example, the set battery capacity) and τ is the time constant. As in Examples 4 and 5, the effect of smoothing by the battery can be further enhanced.

  In the above Examples 1 to 6, the form of the pattern 1 in which the redox flow battery is provided in the power generation facility has been described. The present invention operation method can also be applied to the form. FIG. 6 is a schematic configuration diagram showing a redox flow battery system to which the operation method of the present invention is applied, and shows an example in which a redox flow battery system is provided in a load with irregular power consumption. The battery system 1 is the same as that shown in FIG. 1, and the detailed description of the configuration is omitted. In this example, the system 1 is connected to a load 20 and a power generation facility 30 such as a thermal power plant or a hydroelectric power plant via an orthogonal transformer 3. The load 20 has irregular power consumption, and in this example, is a railway. In this way, in order to install the redox flow battery system 1 on the load 20 with irregular power consumption and make the power generation amount of the power generation facility 30 constant, the battery 10 discharges the shortage to the load 20 with respect to this power generation amount. The battery 10 charges the excess of the power generation amount to the load 20 to consume the power generation amount without excess or deficiency.

  In the present invention, the remaining capacity of the battery 10 is reduced in order to improve battery efficiency so that the power consumption of the load 20 can be smoothed even if the battery 10 has a small battery capacity setting value (so-called rated capacity). Control. Specifically, the remaining capacity is changed as the power consumption of the load 20 varies. More specifically, the target composite value is determined based on the power consumption of the load 20, and the battery is charged and discharged so that the sum of the remaining capacity of the battery and the target composite value is within the set range, and the remaining capacity is reduced. Control. Therefore, also in this example, the battery system 1 includes a monitor cell 14, a voltmeter (not shown), and a computer 15. The computer 15 is connected to the pump 13, the monitor cell 14, the orthogonal transformer 3, and the load 20 through wiring, respectively, so that the power consumption (signal) of the load 20 is transmitted and obtained. An operation for obtaining a target composite value based on power consumption, an operation for obtaining the sum of the remaining capacity and the target composite value, and a determination as to whether or not the sum is within a set range are also performed. When the sum of the remaining capacity and the target composite value is outside the set range, the computer 15 controls the orthogonal transformer 3 and drives the pump 13 to charge / discharge the battery.

  In the redox flow battery system having the above configuration, the control procedure of the remaining capacity of the battery will be specifically described. First, the power consumption W of the load is measured, the measurement result is transmitted to the computer, and the target composite value Z is calculated from the power consumption W by the calculation method described later. On the other hand, the voltage of the cell is measured with a voltmeter arranged in the monitor cell, the measurement result is transmitted to a computer, and the measurement result is read as the remaining capacity α. Then, the computer calculates the sum L of the target composite value and the remaining capacity, and determines whether the sum L is included in the set range (p or more and q or less) input to the storage means of the computer. When the difference L is outside the set range, that is, when the sum L is less than p or more than q, charge / discharge is performed. When it is within the set range, charging / discharging is not performed. When charging / discharging, the sum L calculated from the relation value data of the target composite value stored in advance in the computer and the remaining capacity and the charge / discharge amount necessary for this sum to be within the set range. The amount of charge / discharge at is determined. Charging / discharging is performed based on this charge / discharge amount. In this example, a condition suitable for the charge / discharge amount in the sum L is selected from the battery operating conditions stored in advance in the computer, and based on this condition, the driving of the orthogonal transformer and the pump is controlled to charge / discharge. I do.

  FIG. 7 is a flowchart showing the control procedure of the operation method of the redox flow battery system of the present invention in which the redox flow battery system is provided in a load with irregular power consumption. First, the power consumption W of the load is measured, and the measurement result (electric signal) is input to the signal receiving unit of the computer (step S21). At this time, the computer temporarily stores the input electrical signal in the storage means.

  Next, the computer calls the power consumption W stored in the storage means, and performs arithmetic processing by the arithmetic means to calculate a target composite value (step S22). In this example, a first-order lag low-pass filter calculation is used as the calculation method. Specifically, the power consumption is w (s) and the target composite value z (s), and the target composite value z (s) is obtained from {1 / (1 + s)} × w (s). The power consumption is usually expressed as a value with a unit (for example, MW). Therefore, the target composite value z (s) is also a value having the same unit (same) as the power consumption. In this example, the target composite value z (s) is the maximum value of the set power (so-called rated power; MW) so that the target composite value z (s) is a unitless value. An arithmetic process of dividing was performed, and this value was set as the target composite value Z. Then, the computer stores the obtained target composite value Z in the storage means.

  On the other hand, in order to obtain the remaining capacity of the battery, the voltage of the cell is measured with a voltmeter, and the result (electric signal) measured by the voltmeter is input to the signal receiving unit of the computer (step S23). In this example, the time capacity is used as the remaining capacity. Therefore, the computer replaces the input electric signal with the time capacity (MWh). Further, the computer performs a calculation process of dividing the read time capacity by the set time capacity (so-called rated time capacity; MWh) of the redox flow battery so that the read time capacity becomes a unitless value like the target composite value Z. At the same time, this value is temporarily stored in the storage means as the remaining capacity α.

  Next, the computer calls the target composite value Z and the remaining capacity α stored in the storage means, and calculates the sum L = Z + α of the target composite value Z and the remaining capacity α by the calculating means (step S24). The sum L is temporarily stored in the storage means.

  Next, the computer calls the lower limit value p and the upper limit value q of the setting range stored in the storage means, and determines whether or not the calculated sum L is included in the setting range (step S25). When the sum L is included in the set range, that is, when p ≦ L ≦ q, the computer determining unit determines that charging / discharging for improving battery efficiency is unnecessary (step S26), and ends the control.

  On the other hand, when the sum L exceeds the upper limit value q of the setting range, the target composite value Z is a large value in this example. When the target composite value Z takes a large value, it is desirable to reduce the remaining capacity, that is, to discharge. Therefore, the determination means of the computer determines that discharging is necessary for improving battery efficiency (step S28), and performs a discharging operation (step S30). Specifically, first, a required discharge amount is obtained. In this example, the relation value data of the sum of the target composite value and the remaining capacity and the charge amount or the discharge amount necessary for the sum to be included in the set range are input in advance to the storage means of the computer, The computer calls the relation value data from the storage means, and obtains the discharge amount by comparing the sum L with this data. Based on the obtained discharge amount, an appropriate condition is selected from the operation conditions for each charge amount or discharge amount that has been input to the computer in advance, and the driving of the orthogonal transformer and the pump is controlled based on this condition. Then, discharge is performed, and when the discharge is finished, the control operation is finished.

  On the other hand, when the sum L does not exceed the upper limit value q of the setting range, the sum L is less than the lower limit value p. Since the sum L is less than the lower limit p, the target composite value Z is a small value in this example. When the target composite value Z takes a small value, it is desired to increase the remaining capacity, that is, to charge the battery. Therefore, the determination means of the computer determines that charging is necessary to improve battery efficiency (step S29), and performs a charging operation (step S30). Specifically, the required amount of charge is obtained by the same procedure as in the case of discharging, and an appropriate operating condition is selected based on this amount of charge, and charging is performed by controlling the drive of the orthogonal transformer and pump. When the charging is finished, the control operation is finished.

  In this example, the charge amount or the discharge amount of the relation value data is an amount necessary for the sum L to be the lower limit value p or the upper limit value q. Therefore, in this example, as shown in FIG. 8, charging is performed when the sum L is less than the lower limit p, charging is stopped when the sum L reaches the lower limit p, and discharging is performed when the sum L exceeds the upper limit q. The discharge is stopped when the sum L reaches the upper limit q.

By applying the present invention operating method as described above, the redox flow battery power consumption was juxtaposed to irregular loads, with stabilized power supplied to the load, it is possible to improve cell efficiency, using Battery capacity can be reduced, or the number of batteries used can be reduced. Therefore, it is possible to reduce the size of the redox flow battery system.

In the redox flow battery shown in Example 7 above, an operation for compensating for loss due to charging / discharging for smoothing the power consumption of the load may be performed. FIG. 9 is a graph showing the relationship between the sum of the target composite value and the remaining capacity and how to give charge / discharge for improving battery efficiency, and shows a case where the start point and the end point are different in charging and discharging. . For example, set p ₁ that satisfies p <p ₁ <q, start charging when the sum L is less than the lower limit p, and stop charging when the sum L becomes a value p ₁ greater than p. Also good. At this time, in addition to the charge / discharge amount necessary for improving battery efficiency, the loss is supplementarily charged. In addition, set q ₁ that satisfies p <p ₁ <q ₁ <q, and discharge when the sum L exceeds the upper limit q, and discharge when the sum L becomes a value q ₁ smaller than q. You may make it stop. Upon this operation, in step S28, S29, relation value data used in determining the charge and discharge amount may want to create a plus supplemental discharge coulometric of loss. Note that, in this example, when the sum L is not less than the lower limit p and not more than the upper limit q, charging / discharging for improving battery efficiency is not performed in the same manner as in Example 7.

  As an operation for compensating for the loss, a method different from that in Embodiment 8 will be described. FIG. 10 is a graph showing the relationship between the sum of the target composite value and the remaining capacity and how to give charge / discharge for improving battery efficiency, and the amount of loss when charging / discharging for improving battery efficiency is not performed. The case where auxiliary charge is performed is shown. In Examples 7 and 8, when the sum L is not less than the lower limit p and not more than the upper limit q, charging for loss compensation is not performed in addition to charging / discharging for improving battery efficiency. However, since loss occurs when the redox flow battery is charged / discharged to stabilize the power supplied to the load, it is desirable to perform charging for loss compensation as much as possible. Therefore, as shown in FIG. 10, even when the sum L is 1, the loss is charged. In performing such an operation, if the sum L is out of the setting range, in step S28 or S29, the relationship value data used when determining the charge / discharge amount is prepared by adding the loss. Good. If the sum L is within the set range, after step S26, charging / discharging for improving battery efficiency is not performed, and charging for loss compensation is performed. At this time, it is preferable to set a charge amount necessary for loss compensation in advance and also set a control condition of the orthogonal transformer and a drive condition of the pump based on the charge amount.

  In order to more closely match the remaining capacity of the redox flow battery and the target composite value, in addition to compensating for the loss as in Examples 8 and 9 above, the set power of the load (in this example, the setting power) When the capacity is X (MW) and the time constant is τ, it is preferable that the set capacity of the battery (in this example, the set battery capacity) is 1 × X × τ. Thus, by setting the setting capacity | capacitance of a redox flow battery, in addition to the effect by this invention operating method, the effect of the smoothing by a battery can be heightened more.

In the above embodiment, the first-order lag low-pass filter calculation is used as the calculation method for calculating the target composite value, but a second-order or higher-order low-pass filter calculation may be used. For example, when using a second-order low-pass filter operation, assuming that the load power is w (s), the target composite value z (s), and the transfer function parameter is α, the target composite value z (s) is {1 / (s ² + α × s + 1)} × w (s). Control methods other than the calculation method may be performed in the same manner as in the above embodiment.

  In addition, when performing the second-order low-pass filter calculation, the set capacity of the battery is set using the above parameter α when the set power of the load (in this example, the set capacity) is X (MW) and the time constant is τ. Assuming that 1 × α × X × τ, as in Example 10, the effect of smoothing by the battery can be further enhanced.

In addition to the above low-pass filter calculation, a moving average calculation may be used as a target composite value calculation method. At this time, if the load power is w (s) and the target composite value z (s), the target composite value z (s) is obtained from {(1-e ^−s ) / s} × w (s). Control methods other than the calculation method may be performed in the same manner as in the above embodiment.

  In addition, when performing the moving average calculation, the set capacity of the battery is set to 0.5 x X x τ when the set power of the load power (in this example, the set capacity) is X (MW) and the time constant is τ. Similar to Examples 10 and 11, the effect of smoothing by the battery can be further enhanced.

  The present invention is optimally used in order to stably supply power to a load by providing a redox flow battery in a power generation facility with irregular power generation output such as a wind power generator or a solar power generator. In particular, by using the operation method of the present invention, it is possible to reduce the set battery capacity of the redox flow battery used as compared with the conventional one. Therefore, this invention contributes to size reduction of a redox flow battery system.

It is a schematic block diagram which shows the redox flow battery system to which this invention operating method is applied. It is a flowchart which shows the control procedure of the operating method of this invention redox flow battery system. It is a graph which shows the relationship between the difference of a target synthetic | combination value and remaining capacity, and how to give charging / discharging for battery efficiency improvement. It is a graph which shows the relationship between the difference of a target synthetic value and remaining capacity, and how to give charge / discharge for battery efficiency improvement, and shows the case where the start point and end point of charge and discharge differ. It is a graph showing the relationship between the difference between the target composite value and the remaining capacity and how to give charge / discharge for improving battery efficiency, and even when charging / discharging for improving battery efficiency is not performed, The case of charging is shown. It is a schematic block diagram which shows the redox flow battery system to which this invention operating method is applied, and shows the example which made the redox flow battery system add to the load with irregular power consumption. It is a flowchart which shows the control procedure of the driving | running method of this invention redox flow battery system, and shows the example which made the redox flow battery system add to the load where power consumption is irregular. It is a graph which shows the relationship between the sum of a target synthetic | combination value and remaining capacity, and how to give charging / discharging for battery efficiency improvement. It is a graph which shows the relationship between the sum of a target synthetic | combination value and remaining capacity, and how to give charge / discharge for battery efficiency improvement, and shows the case where the start point and end point of charge and discharge differ. It is a graph showing the relationship between the sum of the target composite value and the remaining capacity and how to give charge / discharge for improving battery efficiency, and even when charging / discharging for improving battery efficiency is not performed, The case of charging is shown. It is a graph which shows the relationship between a power generation output and a synthetic | combination output. It is a graph which shows the relationship between a synthetic | combination output and a battery request | requirement output. It is a graph which shows the relationship between the capability which a battery has, and a remaining capacity. It is a graph which shows the relationship between the power consumption of load, and a synthetic | combination input. It is a graph which shows the relationship between a synthetic | combination input and a battery request | requirement output. (A) is a graph showing a preferable relationship between the combined output and the remaining capacity, and (B) is a graph showing a preferable relationship between the combined input and the remaining capacity. (A) is a graph showing the relationship between the output range of the battery and the remaining capacity in the conventional redox flow battery system, and (B) shows the range of power that may be required for the battery. It is a graph which shows the relationship with remaining capacity. It is a graph which shows the relationship between the range which can output a battery, a remaining capacity, and the range of the electric power which may be requested | required of a battery.

Explanation of symbols

1 Redox flow battery system
10 Battery 11 Tank 12 Transport route 13 Pump 14 Monitor cell
15 computer
2 Power generation equipment 3 Quadrature converter 4 Load
20 Load 30 Power generation equipment

Claims (12)

It has a redox flow battery attached to a power generation facility whose power generation is irregular and fluctuates over time. The power generation output of the power generation facility and the battery output of the battery are combined to smooth the irregular power generation output. An operation method of a redox flow battery system for supplying converted electric power to a load,
Wherein a value obtained by facilities low-pass filter calculation or moving average operation in the power generation output of the power generation facility, determined is regarded as the power generation output of the power generation facility and target combined value obtained by synthesizing the cell output of the redox flow battery,
Measure the remaining capacity of the redox flow battery,
Find the difference between the remaining capacity as a unitless value and the target composite value as a unitless value,
When the difference is outside the set range, the redox flow battery system is charged and discharged based on a charge / discharge amount necessary for the difference to be within the set range. Set the start and end points for charging and discharging, n <n ₁ <M ₁ <When m
  Charging is started when the difference exceeds the charging start point m, and the difference is the charging end point m. ₁ Charge until
  The discharge starts when the difference is less than the discharge start point n, and the difference is the discharge end point n. ₁ 2. The operating method of a redox flow battery system according to claim 1, wherein the loss of the battery is compensated by discharging until When the difference is outside the set range, charge / discharge is performed based on the charge / discharge amount including the loss of the battery as the charge / discharge amount,
2. The method for operating a redox flow battery system according to claim 1, wherein charging for loss compensation is performed when the difference is within a set range . In the low-pass filter calculation, when the transfer function of the low-pass filter is a first-order lag system, the time constant is τ, and the set output of the power generation equipment is X, the battery capacity of the redox flow battery is A × X × τ (however, 0.8 ≦ The operating method of the redox flow battery system according to any one of claims 1 to 3, wherein A≤1.2) is set. In the low-pass filter calculation, when the transfer function of the low-pass filter is n-order (n ≧ 2), the primary parameter is α, the time constant is τ, and the set output of the power generation facility is X, the battery capacity of the redox flow battery 4 is set to A × α × X × τ (where 0.8 ≦ A ≦ 1.2), The operating method of the redox flow battery system according to any one of claims 1 to 3 . In the moving average calculation, when the moving average time window is τ and the set output of the power generation facility is X, the battery capacity of the redox flow battery is set to B × X × τ (where 0.3 ≦ B ≦ 0.6). The operating method of the redox flow battery system according to any one of claims 1 to 3 . The power generated is supplied from a regular power generation facility, the power consumption is irregular, and the redox flow battery is added to the load that fluctuates over time, and the power consumption of the load and the battery output of the battery are combined. An operation method of a redox flow battery system for smoothing irregular power consumption,
A value obtained by facilities low-pass filter calculation or the moving average operation on the power consumption of the load, determines regarded as the target value of the composite input between the power consumption and the battery output of said load,
Measure the remaining capacity of the redox flow battery,
Find the sum of the remaining capacity as a unitless value and the target value as a unitless value,
When the sum is outside the set range, the redox flow battery system is charged and discharged based on a charge / discharge amount necessary for the sum to be within the set range. Set the start and end points for charging and discharging, p <p ₁ <Q ₁ <When q
  Charging is started when the sum is less than the charging start point p, and the sum is the charging end point p. ₁ Charge until
  The discharge starts when the sum exceeds the discharge start point q, and the sum is the discharge end point q. ₁ 8. The operating method of the redox flow battery system according to claim 7, wherein the loss of the battery is compensated by discharging until When the sum is outside the set range, charge / discharge is performed based on the charge / discharge amount to which the loss of the battery is added as the charge / discharge amount,
8. The operation method of a redox flow battery system according to claim 7, wherein when the sum is within a set range, charging for loss compensation is performed . In the low-pass filter calculation, when the transfer function of the low-pass filter is a first-order lag system, the time constant is τ, and the set power of the load is X, the battery capacity of the redox flow battery is A × X × τ (where 0.8 ≦ A The operating method of the redox flow battery system according to any one of claims 7 to 9, characterized in that it is set to ≤ 1.2). In the low-pass filter calculation, when the transfer function of the low-pass filter is n-order (n ≧ 2), the primary parameter is α, the time constant is τ, and the load power setting is X, the battery capacity of the redox flow battery is 10. The operating method of the redox flow battery system according to claim 7, wherein A × α × X × τ (where 0.8 ≦ A ≦ 1.2) is set. In the moving average calculation, when the moving average time window is τ and the set power of the load is X, the battery capacity of the redox flow battery is set to B × X × τ (where 0.3 ≦ B ≦ 0.6). The operating method of the redox flow battery system according to any one of claims 7 to 9 .

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