JP6264247B2 - Fluctuation mitigation battery system for renewable energy - Google Patents

Description

  The present invention relates to a renewable energy fluctuation mitigating storage battery system for mitigating fluctuations in generated power using renewable energy such as wind power.

  In recent years, power generation using renewable energy such as wind power and sunlight has been widely performed. Since the electric power obtained by such power generation varies greatly depending on the weather and the like, it has a great influence on the power transmission and distribution system. Therefore, in power generation sites that perform power generation using such renewable energy, storage battery systems that reduce fluctuations in generated power using a plurality of storage battery cells connected in series or in parallel are widely used.

  In the control of storage batteries connected in parallel, a method of performing current limitation based on threshold determination of the deviation of current between storage batteries connected in parallel is disclosed in Patent Document 1 below.

JP 2011-250622 A

  In recent years, power generation sites that use renewable energy as described above have increased in power that can be generated due to the increase in scale, and with this, there is a need to increase the capacity of storage battery systems used for mitigating fluctuations. Yes. Increasing the capacity of a storage battery system can generally be achieved by increasing the number of storage battery cells, but as the number of storage battery cells increases, the probability that a storage battery cell with a large difference in electrical characteristics from the standard will be generated accordingly. Will also increase.

  If the storage battery system operation is continued with the storage battery cells in a state where the electrical characteristics differ greatly from the standard, the charge and discharge will be performed in a biased state from the original design value. The life of other storage battery cells may be affected. In particular, lead-acid batteries do not detect the voltage of individual cells like lithium-ion batteries. Therefore, when a large number of battery cells are connected in series, there is a large difference in electrical characteristics from the standard. It is difficult to detect a storage battery cell in a state.

  In view of the above situation, the main object of the present invention is to provide a storage battery system for alleviating fluctuations in generated power using renewable energy, and any storage battery cell has a large difference in electrical characteristics from the standard. Even if a situation arises, it is to reduce the influence and continue the operation of the system.

A fluctuation mitigation storage battery system for renewable energy according to an aspect of the present invention is a storage battery system for mitigating fluctuations in generated power using renewable energy, wherein one or two or more storage battery cells are connected in series, respectively. A storage battery bank having a plurality of storage battery strings configured, a converter in which the plurality of storage battery strings are connected in parallel to charge and discharge the storage battery bank, and a current for detecting a current flowing through each of the storage battery strings A detector, a current comparison unit that compares the current of each storage battery string detected by the current detector, a charge / discharge control unit that controls charging / discharging of the storage battery bank by the converter, and the current comparison unit Based on the current comparison results, there are battery cells in the battery bank that have a large difference in electrical characteristics from the standard. And determining that there is a storage battery cell with a large difference in electrical characteristics from the standard, at least the upper limit of the depth of discharge when charging and discharging the storage battery bank and at least the maximum continuous discharge charge amount A mode setting unit for changing one of them.
A fluctuation mitigation storage battery system for renewable energy according to another aspect of the present invention is a storage battery system for mitigating fluctuations in generated power using renewable energy, wherein one or more storage battery cells are connected in series. A plurality of storage battery strings each having a plurality of storage battery strings, a converter in which the plurality of storage battery strings are connected in parallel and charging / discharging the storage battery bank, and each storage battery cell forming each of the plurality of storage battery strings A voltage detector for detecting the voltage of the battery, a voltage comparison unit for comparing the voltage of each storage battery cell detected by the voltage detector, a charge / discharge control unit for controlling charge / discharge of the storage battery bank by the converter, Based on the comparison result of the voltage by the voltage comparison unit, the storage battery bank has a large electrical characteristic gap from the standard. When determining whether or not a battery cell exists, and determining that there is a storage battery cell with a large difference in electrical characteristics from the standard, an upper limit value and a maximum continuous discharge depth when charging and discharging the storage battery bank A mode setting unit that changes at least one of the discharge charge amounts.

  According to the present invention, in a storage battery system for mitigating fluctuations in generated power using renewable energy, even when any of the storage cells has a large difference in electrical characteristics from the standard, The system operation can be continued with reduced impact.

It is a figure which shows the structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 1st Embodiment of this invention. It is a figure which shows the processing flow of the soundness mode change task in 1st Embodiment. It is a figure for demonstrating the setting method of a threshold value. It is a figure which shows the structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 2nd Embodiment of this invention. It is a figure which shows the processing flow of the soundness mode change task in 2nd Embodiment. It is a figure which shows the structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 3rd Embodiment of this invention. It is a figure which shows the processing flow of an alternative mode transfer operation | work task. It is a figure which shows the structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 4th Embodiment of this invention. It is a figure which shows the processing flow of an alternative combination operation | movement task. It is a figure which shows the example of 1 structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 5th Embodiment of this invention. It is a figure which shows another example of a structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 5th Embodiment of this invention. It is a figure which shows the structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 6th Embodiment of this invention.

(First embodiment)
FIG. 1 is a diagram showing a configuration of a renewable energy fluctuation mitigating storage battery system according to a first embodiment of the present invention. This storage battery system is a system for reducing fluctuations in generated power using wind power, which is one of renewable energy, and is connected to a bus 109 provided between the wind power generator 110 and the power transmission and distribution system 108. ing. The storage battery system shown in FIG. 1 includes a plurality of storage battery banks 112 each having two storage battery strings 111 each formed by connecting a plurality of storage battery cells 101 in series, and a plurality of converters connected to each storage battery bank 112. 102 and a leveling control device 103.

  In FIG. 1, a plurality of storage battery cells 101 are connected in series to form the storage battery string 111, but one storage battery cell 101 may be used as the storage battery string 111. Further, the storage battery bank 112 includes two storage battery strings 111, but three or more storage battery strings 111 may be provided in the storage battery bank 112.

  The wind power generator 110 generates power using a generator driving force obtained by receiving wind power from a rotary blade or the like, and outputs the power obtained by the power generation to the power transmission and distribution system 108 via the bus 109. The amount of electric power generated by the wind power generator 110 varies depending on the wind power, and thus varies greatly. In many cases, it is difficult to link the power transmission / distribution system 108 with the external power transmission / distribution system 108 without reducing the fluctuation of the power generated by the wind power generator 110 in consideration of the influence on the power transmission / distribution system 108. Therefore, the storage battery system of the present embodiment alleviates such fluctuations in generated power by controlling the converter 102 by the leveling control device 103 to charge and discharge the storage battery bank 112.

  Here, the reason why the plurality of storage battery cells 101 are connected in series to form the storage battery string 111 is to ensure a predetermined charge / discharge voltage so that the converter 102 can perform sufficiently efficient conversion. Further, the two storage battery strings 111 in the storage battery bank 112 are connected in parallel to one converter 102. This is because the charge / discharge current corresponding to the amount of current per converter 102 is secured by parallelization because there is a limit to increasing the capacity of the single storage battery cell 101.

  In the storage battery bank 112, a current detector 120 for detecting a current flowing through each storage battery string 111 is provided. The measurement data indicating the current detection result of each storage battery string 111 by the current detector 120 is output from the current detector 120 to the leveling control device 103.

  The converter 102 performs charging / discharging of the corresponding storage battery bank 112, respectively. Here, as shown in FIG. 1, with the increase in capacity of the wind power generator 110 in recent years, a plurality of converters 102 are often connected to the bus 109 in parallel.

  As shown in FIG. 1, the leveling control device 103 includes measurement data indicating the generated power of the wind power generator 110, measurement data indicating the output power to the power transmission and distribution system 108, and each storage battery string 111 by the current detector 120. Measurement data indicating the current detection result is input. The leveling control device 103 controls the converter 102 based on these measurement data. Specifically, the storage battery bank 112 is charged / discharged via the converter 102 so that the charge / discharge power from the storage battery bank 112 is approximately in reverse phase with respect to the fluctuation of the power generated by the wind power generator 110. . Thereby, the fluctuation amount of the electric power generated by the wind power generator 110 is leveled to the extent that the wind power generator 110 can be linked to the power transmission and distribution system 108.

  The leveling control device 103 includes a current comparison unit 104, a charge / discharge control unit 105, a mode setting unit 106, and a control constant holding unit 107.

  The current comparison unit 104 compares the currents of the storage battery strings 111 detected by the current detector 120 and outputs the comparison result to the charge / discharge control unit 105 and the mode setting unit 106. Specifically, a difference between current values of two storage battery strings 111 connected in parallel is calculated, and it is determined whether or not the difference is less than a predetermined threshold.

  The charge / discharge control unit 105 performs a control calculation on the converter 102 using various control constants held in the control constant holding unit 107, and outputs a control signal corresponding to the calculation result to the converter 102. Thereby, charging / discharging of the storage battery bank 112 by each converter 102 is controlled.

  Based on the comparison result of the current of each storage battery string 111 by the current comparison unit 104, the mode setting unit 106 determines whether or not the storage battery cell 101 having a large difference in electrical characteristics from the standard exists in any storage battery bank 112. Judging. As a result, when it is determined that there is a storage battery cell 101 with a large difference in electrical characteristics from the standard, a command to change the upper limit value of the depth of discharge (DOD) when charging / discharging the storage battery bank 112 Is output to the control constant holding unit 107 and an alarm 113 is output as a control signal to the outside. Here, the storage battery cell 101 having a large difference in electrical characteristics from the standard here generally leads to a decrease in charge / discharge capability, such as a decrease in voltage and current during charge / discharge and an increase in internal resistance. It is.

  The control constant holding unit 107 stores and holds various control constants for use in the control calculation performed by the charge / discharge control unit 105. This control constant is set according to the electrical characteristics of the storage battery string 111 of each storage battery bank 112, and the upper limit value of the depth of discharge when charging / discharging each storage battery bank 112 (the battery capacity that can be charged / discharged). Range), maximum continuous discharge charge amount (maximum value of charge amount that can be continuously discharged), and the like.

  FIG. 2 is a diagram illustrating a processing flow of the soundness mode change task executed by the leveling control apparatus 103 according to the first embodiment of the present invention. The soundness mode change task shown in this processing flow is executed when the storage battery system of FIG. 1 is activated or every predetermined processing cycle.

  Here, the soundness mode is a variable that is set for each storage battery bank 112 depending on whether or not there is a storage battery cell 101 having a large difference in electrical characteristics from the standard as described above. Specifically, for a storage battery bank 112 in which there is no storage battery cell 101 with a large difference in electrical characteristics from the standard, the value of the soundness mode is used to indicate that the storage battery bank 112 is in a normal state. Is set to 0. On the other hand, for the storage battery bank 112 in which the storage battery cell 101 having a large difference in electrical characteristics from the standard exists, the value of the soundness mode is set to 1 to indicate that the storage battery bank 112 is in a state to be warned. Set to. Hereinafter, the case where the soundness mode value is set to 0 is referred to as “normal (0)”, and the case where the soundness mode value is set to 1 is referred to as “warning (1)”.

  Hereinafter, the case where the storage battery system of FIG. 1 has n storage battery banks 112 and the process of FIG. 2 is performed on the n storage battery banks 112 will be described as an example.

  In step S501, the mode setting unit 106 sets normal (0) as the initial value of the soundness mode for each of the n storage battery banks 112. Note that after the first activation, the mode previously set for each storage battery bank 112 may be stored in a data storage unit (not shown), and the mode may be set in step S501.

  In step S <b> 502, the current comparison unit 104 and the mode setting unit 106 start loop processing for each storage battery bank 112. Here, the loop process of steps S504 to S507 described below is performed for the kth storage battery bank 112 (k = 1 to n) among the n storage battery banks 112. Note that the value of k is incremented by 1 each time loop processing is performed.

  In step S503, the current comparison unit 104 acquires the current values flowing through the two storage battery strings 111 included in the kth storage battery bank 112 from the current detector 120 as string current values I1-k and I2-k. .

  In step S504, the current comparison unit 104 calculates a difference between the string current value I1-k and the string current value I2-k acquired in step S503, and determines whether this difference is larger than a predetermined threshold. As a result, if the difference is larger than the threshold value, the process proceeds to step S505, and if the difference is less than the threshold value, the process proceeds to step S508.

  In order to improve reliability, the determination process may be performed by performing the processes in steps S503 and S504 a plurality of times. As an example of this determination process, there is a method of performing sampling of the string current value a plurality of times and determining whether or not each difference continuously exceeds a threshold value. Alternatively, in addition to the number of times, the determination process may be performed based on a duration for which the difference exceeds the threshold. Such a determination process may be realized by software, or may be realized by hardware by a method of appropriately combining a comparator and a timer.

  In step S505, the mode setting unit 106 determines that there is a storage battery cell 101 having a large difference in electrical characteristics from the standard in the kth storage battery bank 112, and sets the soundness mode for the storage battery bank 112 to warning (1). Set.

  In step S506, the mode setting unit 106 determines that there is a storage battery cell 101 having a large difference in electrical characteristics from the standard in step S505, and sets the soundness mode to the kth storage battery bank 112 that has been set to alert (1). On the other hand, a command to change (decrease) the upper limit value of the discharge depth corresponding to the storage battery bank 112 is output to the control constant holding unit 107. In response to this command, the control constant holding unit 107 changes (decreases) the upper limit value of the discharge depth among the control constants set for the storage battery bank 112.

  For example, when the soundness mode is normal (0), the upper limit value of the discharge depth is set to 70%, and the storage battery bank 112 is operated in a state of charge (SOC: State Of Charge) of 90% to 30%. In this case, when the soundness mode is set to vigilance (1), the upper limit value of the discharge depth is changed to 60% (SOC is 90% to 40%). Here, in the storage battery cell 101 in which the separation of the electrical characteristics from the standard is large, the separation of the electrical characteristics (for example, the terminal voltage) is larger in the range where the SOC is lower than the other storage battery cells 101. On the other hand, when the SOC is high, the electrical characteristic gap tends to be relatively small. Therefore, by reducing the upper limit value of the depth of discharge as described above and not operating with a low SOC, one of the storage battery cells 101 is in a state where there is a large difference in electrical characteristics from the standard. Even in this case, the system operation can be continued while the current imbalance between the two storage battery strings 111 of the storage battery bank 112 is changed at a relatively small value. As a result, even when a storage battery cell 101 having a large difference in electrical characteristics from the standard appears, adverse effects on other storage battery cells 101 are suppressed, and eventually the characteristics of many storage battery cells 101 are changed or replaced. The situation can be avoided. Moreover, by continuing the operation of the storage battery system, it is possible to contribute to securing profits of the power generation site using renewable energy.

  In general, in the case of storage batteries connected in parallel, if there is an unbalance in electrical characteristics between the storage batteries, the unbalance usually proceeds in the direction of further expansion by repeating charge and discharge. In a power generation site using renewable energy, a large number of expensive storage batteries are used, and it is necessary to secure a predetermined life of the storage batteries. Therefore, it is important to secure a balance between the storage batteries connected in parallel. . Therefore, in this embodiment, when it is determined that the electrical characteristics of any of the storage battery cells 101 are significantly different from the standard, the charge / discharge is performed by referring to the upper limit value of the new discharge depth set in step S506. The control unit 105 instructs the converter 102 to charge / discharge necessary for fluctuation mitigation.

  For the charge / discharge control unit 105, lowering the upper limit value of the depth of discharge for the storage battery bank 112 reduces (decreases) the apparent capacity of the storage battery bank 112. However, in general, power generation sites that use renewable energy often have extra storage battery capacity in preparation for aging, etc., so even if the apparent storage battery capacity is reduced (decreased), The probability of having a significant impact on operation is low. Even when the capacity of the storage battery is not sufficient, the timing when the maximum storage battery capacity is required is, for example, when the maximum generated power continues for a long time, and the frequency is relatively small. Therefore, even in this case, the effect of reducing the apparent storage battery capacity is limited.

  In addition, when the soundness mode is set to alert (1) when the charge / discharge control unit 105 performs control assuming the remaining capacity of the storage battery bank 112 until then, the upper limit value of the discharge depth after the change May be applied from the next control cycle. Further, a bias may be applied to the normal charge / discharge current value, and the transition may be made so as to gradually adapt to the condition of the depth of discharge after the change.

  In step S507, the mode setting unit 106 outputs a predetermined alarm 113 to the outside. This alarm 113 is output to a control console of a renewable energy utilization site (not shown), a host system controller, a remote monitoring system, etc. via a network or communication path (not shown). By confirming the alarm 113 output in this way, the operator of the renewable energy utilization site recognizes the appearance of the storage battery cell 101 that needs to be inspected and replaced because there is a large difference in electrical characteristics from the standard. Thus, for example, necessary measures can be taken quickly, such as arranging for a substitute for the next inspection.

  In step S508, if there is a storage battery bank 112 that has not been subjected to loop processing, current comparison unit 104 and mode setting unit 106 return to step S502 to continue loop processing, and for all n storage battery banks 112, If the loop processing has been performed, the loop processing is terminated. When the loop process is finished, the process flow of FIG. 2 is finished, and the execution of the soundness mode change task is completed.

  In the processing flow of FIG. 2 described above, a plurality of levels may be provided in the soundness mode set when there is a storage battery cell 101 having a large difference in electrical characteristics from the standard. For example, if the threshold value used for the determination in step S504 is set in two stages and the difference between the string current values is larger than the upper threshold value, it is determined in step S505 that stronger vigilance is required, and the value of the soundness mode Is set to 2. Hereinafter, the case where the value of the soundness mode is set to 2 is referred to as “strict warning (2)”. When the soundness mode of the strict warning (2) is set, in step S506, the upper limit value of the discharge depth of the storage battery bank 112 is changed to a smaller value than when the warning (1) is set. It is preferable. Furthermore, the process of the charge / discharge control unit 105 may be interrupted, and the charge / discharge of the storage battery bank 112 may be immediately stopped. Or you may charge / discharge the said storage battery bank 112 preferentially as needed. For example, if the storage battery cell 101 having a large difference in electrical characteristics from the standard is in a low SOC state, charging is started immediately, whereas if it is in a high SOC state, discharging is started immediately. However, such immediate charging / discharging may affect the fluctuation mitigation operation of the original generated power, so it is preferable to perform it carefully. More generally, it is only necessary to determine whether or not to immediately stop charging / discharging after making a trade-off between the cost of the storage battery and the penalty of deviation from the fluctuation value of the wind power.

  Moreover, when the two storage battery strings 111 in the storage battery bank 112 are directly connected in parallel, the charge current imbalance between them is reduced by the circulating current that flows after the charge / discharge is stopped. For example, when a low SOC storage battery cell 101 exists in one storage battery string 111, the storage battery string 111 is charged to some extent by circulating current flowing from the other storage battery string 111 to the storage battery string 111. Therefore, it may be possible to take an emergency measure simply by stopping charging / discharging.

  In the above example, when it is determined that there is a storage battery cell 101 having a large difference in electrical characteristics from the standard, among the constants stored in the control constant holding unit 107, the storage battery bank 112 is charged / discharged. The upper limit of the depth of discharge was changed (decreased). However, other constants may be changed. For example, even if the maximum continuous discharge charge amount is changed, an effect similar to that obtained by changing the upper limit value of the discharge depth can be obtained. This is because even if the electrical characteristics (for example, voltage) of the storage battery cell 101 in which the difference in electrical characteristics from the standard is large deviates significantly from the other storage battery cells 101, the time This is because, in a range where the continuous discharge amount (continuous discharge amount only for discharge without interposing charging and resting) is small, the influence is difficult to be surfaced. Further, both the upper limit value of the discharge depth and the maximum continuous discharge charge amount may be changed. That is, when it is determined that there is a storage battery cell 101 having a large difference in electrical characteristics from the standard, at least one of the upper limit value of the discharge depth and the maximum continuous discharge charge amount when charging / discharging the storage battery bank 112 is changed. Therefore, the operation of the storage battery system can be continued while suppressing the influence of the storage battery cell 101 having a large difference in electrical characteristics from the standard.

  The effects obtained by the processing as described above include the reliability of the estimated SOC value calculated based on the voltage of the storage battery string 111 in addition to maintaining the current balance of the plurality of storage battery strings 111 connected in parallel. There is a point to improve. That is, when obtaining the SOC based on the voltage of the storage battery string 111 (for example, the closed circuit voltage), the variation in the voltage of each storage battery cell 101 changes with a small value by reducing the upper limit value of the discharge depth or reducing the maximum continuous discharge charge amount. To do. Therefore, even when the storage battery cell 101 having a large difference in electrical characteristics (closed circuit voltage) is present in the storage battery string 111, it is easy to calculate a correct SOC value from the voltage. On the contrary, when the upper limit value of the discharge depth is not reduced or the maximum continuous discharge charge amount is not reduced, the voltage of the storage battery cell 101 having a large difference in electrical characteristics is significantly different from the others in the low SOC range. Therefore, the SOC value of the storage battery string 111 may be underestimated.

  A significant change in the terminal voltage in some of the storage battery cells 101 may give an error of 10% or more in terms of SOC to the entire storage battery string 111 depending on the situation. This is presumably because, in addition to the decrease in electromotive force, a considerable voltage drop due to the discharge current and internal resistance occurs. As described above, if the SOC is underestimated based on the terminal voltage value that is significantly reduced in the low SOC range, there is a discrepancy between the subsequent charge amount and the SOC value obtained from the recovered terminal voltage. Occurs. Therefore, when the determination process based on the difference between the string current values obtained by sampling a plurality of times as described above is performed, it is misidentified as a battery abnormality, or the SOC value in the time average of the storage battery string 111 is misidentified. There is a possibility of biasing the direction.

  FIG. 3 is a diagram for explaining a threshold setting method in the current comparison unit 104.

  FIG. 3A shows the variation in current and voltage of each storage battery cell group measured in the measurement period before the storage battery cell 101 having a large difference in electrical characteristics from the standard is generated. On the other hand, FIG. 3 (b) is measured in the period including the measurement period after the generation of the storage battery cell 101 having a large difference in electrical characteristics from the standard in addition to the measurement period in FIG. 3 (a). The variation of the current and voltage of the storage battery cell group is shown. 3A and 3B, the storage battery cell group is a group of the storage battery cells 101 of the two storage battery strings 111 in the storage battery bank 112, and the variations in the measurement results of the current and voltage are shown. Show. FIG. 3B shows a measurement result when the measurement is continued without changing the upper limit value of the discharge depth as described in FIG.

3 (a) and 3 (b), the horizontal axis represents the variation in current of each battery group under the condition that the discharge current is about 0.13 CA or more. Here, the current variation of each battery cell group was calculated using the following formula (1) based on the string current values I1-k and I2-k. On the other hand, the size of the vertical axis represents the variation in the voltage of each storage battery cell group under the condition that the discharge current is about 0.13 CA or more, as a standard deviation.
| ((I1-k)-(I2-k)) / (I1-k) | (1)

  The threshold for determination in the current comparison unit 104 can be set in consideration of the distribution of current variations during normal times shown in FIG. For example, as shown in FIG. 3C, a value obtained by adding 4σ (σ is a standard deviation) to the average value is set as a threshold value, and the current comparison unit 104 determines whether or not the difference between the string current values exceeds the threshold value. judge. As a result, when it is determined that the difference between the string current values exceeds the threshold value, the mode setting unit 106 sets the soundness mode to alert (1). Further, a value obtained by adding 5σ to the average value is set as a threshold value, and the current comparison unit 104 determines whether or not the difference between the string current values exceeds the threshold value. As a result, when it is determined that the difference between the string current values exceeds the threshold value, the mode setting unit 106 sets the soundness mode to strict alert (2).

  Note that the above threshold value is merely an example. For example, when the distribution of current variation is not a normal distribution, the threshold value may be increased or decreased as appropriate. In addition, since variations in current and voltage generally increase according to the secular change of the storage battery cell 101, the threshold value may be increased or decreased with the passage of the period from the start of operation in consideration of this. . In addition, some lead storage batteries have a period in which the storage battery capacity increases as the total charge / discharge amount increases after the start of use. After the period shown on the left, the storage battery capacity starts to decrease as the total charge / discharge amount increases. Therefore, during the period including cells in which the storage battery capacity increases as the total charge / discharge amount increases, the nature of the variation naturally changes, so measures such as adjusting the threshold value as appropriate can be considered.

  In addition, in the storage battery system as shown in FIG. 1, generally, an operation called equal charge is periodically performed at a cycle of, for example, two weeks in order to correct the variation in the state of charge between the storage battery cells 101. In the interval period from the end of the equal charge to the start of the next equal charge, the variation of the individual storage battery cells 101 tends to increase as it becomes later. For this reason, the threshold value may be reduced at the beginning of the interval period, and the threshold value may be increased stepwise or continuously as time elapses within the interval period.

  According to the 1st Embodiment of this invention demonstrated above, there exist the following effects.

  The renewable energy fluctuation mitigating storage battery system shown in FIG. 1 includes a current comparison unit 104 and a mode setting unit 106. The current comparison unit 104 compares the currents of the storage battery strings 111 detected by the current detector 120 (step S504). Based on the comparison result of the current by the current comparison unit 104, the mode setting unit 106 determines whether or not the storage battery cell 101 having a large difference in electrical characteristics from the standard exists in the storage battery bank 112 (step S505). When it is determined that there is a storage battery cell 101 with a large difference in electrical characteristics from the standard, at least one of the upper limit value of the discharge depth and the maximum continuous discharge charge amount when charging / discharging the storage battery bank 112 is changed (step) S506). Since it did in this way, even when the state where the gap of the electrical characteristic from a standard arises in any of the storage battery cells 101, the influence can be reduced and system operation can be continued.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  In the first embodiment described above, the voltage variation shown on the vertical axis in FIGS. 3A and 3B is compared with the current variation shown on the horizontal axis in FIGS. The amount of change between (b) is large. Therefore, when the voltage of the storage battery cell 101 can be measured individually, the presence or absence of the storage battery cell 101 in which the difference in electrical characteristics from the standard is large can be determined with higher accuracy based on the variation in the voltage. Furthermore, if both voltage and current variations are used, it is possible to further increase the certainty of the determination of the generation of storage battery cells with a large difference in electrical characteristics from the standard, so the time until the final determination can be shortened. Connection and storage battery protection can be enhanced. In that case, it is not always necessary to measure the voltage of each storage battery cell 101. For example, ten storage battery cells 101 can be collectively used as a unit of voltage measurement. In this way, compared with the case where the voltage of each storage battery cell 101 is measured, the accuracy (sensitivity) of occurrence detection of the storage battery cell having a large difference in electrical characteristics from the standard is slightly reduced, but the cost is reduced. Can be planned.

  In the present embodiment, based on the above, in addition to the current variation of each storage battery string 111, there is also a storage battery cell 101 having a large difference in electrical characteristics from the standard by using the voltage variation of each storage battery cell 101. An example of determining whether or not to perform will be described.

  FIG. 4 is a diagram showing a configuration of a renewable energy fluctuation mitigating storage battery system according to the second embodiment of the present invention. Compared with the storage battery system according to the first embodiment shown in FIG. 1, this storage battery system further includes a voltage detector 130 in the storage battery bank 112, and a voltage comparison unit in the leveling control device 103. The difference is that 131 is further provided.

  The voltage detector 130 detects the voltage of each storage battery cell 101 that constitutes each of the two storage battery strings 111 provided in each storage battery bank 112, and outputs the detection result to the leveling control device 103.

  The voltage comparison unit 131 compares the voltages of the storage battery cells 101 detected by the voltage detector 130 and outputs the comparison result to the mode setting unit 106. Specifically, a standard deviation or the like is calculated as an index of variation in the voltage value of each storage battery cell 101, and it is determined whether or not the value is less than a predetermined threshold value.

  Based on the comparison result of the current of each storage battery string 111 by the current comparison unit 104 and the comparison result of the voltage of each storage battery cell 101 by the voltage comparison unit 131, the mode setting unit 106 sets one of the storage battery banks 112 from the standard. It is determined whether or not there is a storage battery cell 101 with a large difference in electrical characteristics. As a result, if it is determined that there is a storage battery cell 101 with a large difference in electrical characteristics from the standard, the upper limit value of the depth of discharge when charging and discharging the storage battery bank 112 is changed as in the first embodiment. Is output to the control constant holding unit 107, and an alarm 113 is output as a control signal to the outside.

  FIG. 5 is a diagram illustrating a processing flow of the soundness mode change task executed by the leveling control apparatus 103 according to the second embodiment of the present invention. The soundness mode change task shown in this processing flow is executed when the storage battery system of FIG. 4 is activated or every predetermined processing cycle. In FIG. 5, the same step numbers are used for the processing steps that execute the same processing as the processing flow of the soundness mode change task in the first embodiment shown in FIG. In the following, the description of the processing steps having the same step numbers as those in FIG. 2 will be omitted unless particularly necessary.

  In step S510, as in step S503 of FIG. 2, the current comparison unit 104 determines the current values flowing through the two storage battery strings 111 included in the kth storage battery bank 112 as string current values I1-k and I2- k is obtained from the current detector 120. On the other hand, the voltage comparison unit 131 uses the cell voltages V1-k, V2-k,... V2m-k for each storage battery cell 101 of the two storage battery strings 111 of the kth storage battery bank 112. As obtained from the voltage detector 130. Here, an example will be described in which two storage battery strings 111 collectively have 2m storage battery cells 101, and the voltage values of the 2m storage battery cells 101 are respectively acquired.

  In step S511, the current comparison unit 104 calculates the difference between the string current value I1-k and the string current value I2-k acquired in step S510, as in step S504 in FIG. It is determined whether or not it is larger. On the other hand, the voltage comparison unit 131 calculates the variation (standard deviation) of the cell voltages V1-k, V2-k,... V2m-k acquired in step S510, and determines whether this variation is larger than a predetermined threshold value. Determine whether. As a result, if any value is larger than the threshold value, the process proceeds to step S505, and if at least one of the values is equal to or less than the threshold value, the process proceeds to step S508.

  As in FIG. 2, the determination process may be performed by performing the processes in steps S <b> 510 and S <b> 511 a plurality of times in order to improve reliability. In this case, it is possible to determine with high accuracy whether or not there is a storage battery cell 101 having a large difference in electrical characteristics from the standard, by performing the determination process fewer times than the processing flow of FIG. When the storage battery cell 101 having a low SOC exists in the storage battery string 111 due to an increase in variation in electrical characteristics, the voltage value of the storage battery cell 101 generally decreases sharply with discharge as compared with other storage battery cells 101. To do. Therefore, speeding up the determination process as described above is preferable from the viewpoint of preventing sulfation, which is a deterioration mode of the storage battery.

  In step S511, only one of the difference between the string current values and the variation in cell voltage is determined as a threshold value, and the battery cell has a large difference in electrical characteristics from the standard depending on whether the value exceeds the threshold value. It may be determined whether or not 101 exists. In that case, in step S510, the measurement value that is not used for the determination in step S511 may not be acquired. That is, in step S511, the storage battery cell 112 has a large difference in electrical characteristics from the standard based on at least one of the string current comparison result by the current comparison unit 104 and the cell voltage comparison result by the voltage comparison unit 131. It can be determined whether or not 101 exists. In addition, when calculating variations such as the standard deviation of the cell voltage, in the previous example, an example was shown in which 2m voltage values were combined for two strings. Variations may be evaluated for each voltage value. By evaluating the variation in voltage for each individual storage battery string, it is possible to obtain a material for determining which storage battery string includes a storage battery cell having a large difference in electrical characteristics from the standard. Furthermore, it is possible to determine a storage battery string that includes storage battery cells that have a large difference in electrical characteristics from the standard by using the voltage variation of only one of the two storage battery strings and the comparison result of the string current. . Utilization of voltage variation on only one side can be realized at a lower cost because the number of cell voltage measurement points can be reduced. Further, in the above-described step S511, when only the cell voltage variation is determined as a threshold value, it can be applied not only to a configuration using a plurality of storage battery strings connected in parallel but also to a configuration using a single storage battery string.

  According to the 2nd Embodiment of this invention demonstrated above, there exist the following effects.

  The renewable energy fluctuation mitigating storage battery system shown in FIG. 4 includes a current comparison unit 104, a mode setting unit 106, and a voltage comparison unit 131. The current comparison unit 104 compares the currents of the storage battery strings 111 detected by the current detector 120, and the voltage comparison unit 131 compares the voltages of the storage battery cells 101 detected by the voltage detector 130 (step S511). ). Based on at least one of the current comparison result by the current comparison unit 104 and the voltage comparison result by the voltage comparison unit 131, the mode setting unit 106 has the storage battery cell 112 with a large difference in electrical characteristics from the standard. 101 is determined (step S505), and when it is determined that there is a storage battery cell 101 having a large difference in electrical characteristics from the standard, the upper limit value of the depth of discharge when charging / discharging the storage battery bank 112 At least one of the maximum continuous discharge charge amount is changed (step S506). As described above, as in the first embodiment, even when any of the storage battery cells 101 has a large difference in electrical characteristics from the standard, it is possible to reduce the influence and operate the system. Can continue. In addition, it is possible to more quickly and accurately determine whether or not there is a storage battery cell 101 that has a large difference in electrical characteristics from the standard as compared to the first embodiment.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the present embodiment, an example will be described in which another storage battery bank 112 is operated instead of the storage battery bank 112 including the storage battery cell 101 that has a large difference in electrical characteristics from the standard.

  FIG. 6 is a diagram showing a configuration of a renewable energy fluctuation mitigating storage battery system according to the third embodiment of the present invention. This storage battery system is different from the storage battery system according to the first embodiment shown in FIG. 1 in that an alternative operation control unit 114 is further provided in the leveling control device 103.

  When the mode setting unit 106 determines that the storage battery cell 101 having a large difference in electrical characteristics from the standard is present in any of the storage battery banks 112, the alternative operation control unit 114 removes the storage battery bank 112. Any one of the storage battery banks 112 is operated as an alternative to the storage battery bank 112. This alternative operation is performed when the health mode of any battery bank 112 is higher than warning (1), that is, when warning (1), or when severe warning (2) as described above (three or more modes) In the same way, the other storage battery bank 112 is used to provide various assistance so as not to further expand the state in which the difference in electrical characteristics from the standard of the storage battery cell 101 is large. It is.

  For example, when the soundness mode of a certain storage battery bank 112 is higher than warning (1), even if measures such as reducing the upper limit of the discharge depth as described above are taken, unexpected current instability or In some cases, an event such as a voltage drop occurs. This is because when a lead storage battery is used as the storage battery cell 101, it is difficult to grasp the exact battery state due to the nature of the lead storage battery, so there is a limit in grasping the SOC, and there are various deterioration modes. This is due to certain things.

  Therefore, in this embodiment, when the soundness mode is alert (1) or higher, the other storage battery bank 112 is set in a standby state to prepare the storage battery bank 112 as a standby storage battery bank. As a result, even when the storage battery bank 112 having a soundness mode of warning (1) or higher stops charging / discharging due to a sudden change in state or the like, the fluctuation of the generated power is performed using the storage battery bank 112 prepared as a standby storage battery bank. The relaxation operation is continued. However, there is a penalty for exceeding the link requirement with the power transmission / distribution system 108, that is, the requirement to link the output of the fluctuating wind power generator 110 to the external power transmission / distribution system 108, and another battery bank 112 It is also possible to select not to prepare the standby storage battery bank after making a trade-off with the efficiency reduction due to the state.

  As an example of the efficiency reduction due to the preparation of the standby storage battery bank, there is a reduction in the degree of freedom of equal charge scheduling. Normally, the storage battery bank 112 that is not involved in the fluctuation mitigation operation is charged evenly at the most efficient timing as seen from the whole fluctuation mitigation battery system or from the entire wider system including neighboring renewable energy utilization sites. You can start. For example, if there is an internal / external storage battery bank 112 that is adjusted and used from a full charge to a certain SOC value, the exchange of the charge of the storage battery bank 112 is assigned to the charge to the storage battery bank 112 that performs equal charge Is possible. However, when a standby storage battery bank is prepared, during the standby period, it is not possible to perform equal charge at an optimal timing from the viewpoint of the entire fluctuation mitigating storage battery system as described above. Therefore, it can be a factor of efficiency reduction.

  The alternative operation control unit 114 performs standby storage battery bank assignment for substituting the storage battery bank 112 whose health mode is warning (1) or higher, and control related thereto.

  FIG. 7 is a diagram illustrating a processing flow of an alternative mode transition operation task executed by the alternative operation control unit 114 according to the third embodiment of the present invention. The alternative mode transition operation task shown in this processing flow is executed every predetermined processing cycle.

  In step S520, the alternative operation control unit 114 confirms the presence or absence of the storage battery bank 112 in which the soundness mode is set to alert (1) or more among the storage battery banks 112. Specifically, by checking the mode setting information held in the mode setting unit 106 or the control constant holding unit 107, the presence or absence of the storage battery bank 112 whose health mode is higher than warning (1) is confirmed. Can do. Alternatively, when mode setting information is held in each storage battery bank 112, it may be scanned. As a result, if there is a storage battery bank 112 (hereinafter referred to as “substitute battery bank to be replaced”) having a soundness mode equal to or higher than warning (1), the process proceeds to step S521; otherwise, the process proceeds to step S525. .

  In step S521, the alternative operation control unit 114 confirms the presence or absence of the storage battery bank 112 in a dormant state. Here, the storage battery bank 112 in the dormant state is the storage battery bank 112 that does not contribute to the fluctuation mitigation operation in the storage battery system of FIG. In general, in a fluctuation mitigation battery system composed of a large number of storage battery banks, the operation rate is improved by performing equalization charging sequentially to some of the storage battery banks and performing fluctuation mitigation operations using other storage battery banks. There is a case to let you. In such a storage battery system, a storage battery bank during equal charge or complete charge equalization can be operated as a standby storage battery bank as required. Therefore, in step S521, such a storage battery bank is recognized as a storage battery bank in a dormant state. Note that the information indicating which storage battery bank is in the dormant state may be held by the charge / discharge control unit 105 that performs scheduling of equal charge during normal times, for example. Alternatively, the alternative operation control unit 114 may override the uniform charging scheduling and hold information on which storage battery bank is in the dormant state. As a result, if there is a storage battery bank 112 that is in a dormant state, the storage battery bank 112 is set as a standby storage battery bank, and the process proceeds to step S522. If not, the process proceeds to step S525.

  In step S522, the alternative operation control unit 114 sets the soundness mode for the storage battery bank 112 set as the standby storage battery bank in step S521 to alternative (−1), and stores this information in the mode setting unit 106.

  In step S523, the alternative operation control unit 114 recognizes that the standby storage battery bank set in step S521 is an alternative target of the alternative storage battery bank determined in step S520, and starts the alternative operation. This alternative operation makes the standby storage battery bank stand by in preparation for a case where the replacement storage battery bank whose soundness mode is warning (1) or higher suddenly stops charging and discharging. As a simple technique, it is possible to synchronize the SOCs of the substituting storage battery bank and the standby storage battery bank. This makes it possible to use the standby storage battery bank as an alternative to the replacement storage battery bank at any timing.

  Here, the reason why the SOC synchronization is effective is as follows. During fluctuation mitigation operation, the SOC of the substituting battery bank becomes high only for a time longer than the time constant of fluctuation mitigation (for example, 200 minutes when the allowable power fluctuation rate in 20 minutes is 10%). It can be considered that the output from the wind power generator 110 continues to be high, and accordingly, the output from the wind power generation site to the power transmission and distribution system 108 is increased to the vicinity of the rating. In such a state, it is necessary to set the SOC of each storage battery bank 112 including the substituting storage battery bank to a value close to the upper limit of the operation range in preparation for cutoff of the wind power generator 110 caused by further increase of the wind speed. On the other hand, when the wind is weak and the output of the wind power generator 110 is close to 0, the SOC of each battery bank 112 is set so that power can be absorbed in preparation for a sudden increase in wind speed. Must be low.

  Therefore, when the standby storage battery bank is used as an alternative to the alternative storage battery bank, after the alternative storage battery bank suddenly stops charging and discharging, the standby storage battery bank substitutes and discharges the amount of charge that the alternative storage battery bank should originally discharge. As much as possible, if importance is attached to the efficiency of power generation, both of them need to have SOC values of at least the same level. Similarly, in the low SOC state, it is necessary to set the SOC of the standby storage battery bank to an SOC value that can absorb the amount of charge that can be originally charged by the replacement storage battery bank.

  However, when the output of the wind power generator 110 can be adjusted, or it is composed of a plurality of wind power generators, and the output of the wind power generator 110 can be adjusted by arbitrarily starting or stopping each power generator. In some cases, this is not the case. This is characteristic for mitigating fluctuations for wind power generation, and is because the remaining charge capacity and the remaining discharge capacity of the storage battery are asymmetric in the charge direction and the discharge direction. For example, if the wind power generator continues to generate electricity at the maximum output for a long time, the discharge capacity is sufficient to gradually reduce the power to the system in the allowable change range from the maximum power value in preparation for a sudden cut-off with increasing wind speed. Must be provided. On the other hand, when there is a wind that can be generated by the wind power generator at maximum output from the no wind condition, the operation in the direction of decreasing the power generation output is possible by the adjustment described above, so the remaining power capacity does not necessarily correspond to the maximum power output You don't have to have the amount you want. Therefore, although the efficiency of power generation is reduced, it is possible to make the standby storage battery bank stand by with a high SOC value. Waiting at a high SOC value is advantageous in terms of preventing sulfation and securing a reference point for calculating SOC by integrating current.

  In step S524, the alternative operation control unit 114 causes the standby storage battery bank that has started the alternative operation in step S523 to start a backup operation of the alternative storage battery bank. Here, first, SOC adjustment is performed to bring the SOC of the standby storage battery bank closer to the SOC of the alternative storage battery bank. Thereafter, a predetermined backup operation is started as necessary. One example of this backup operation is to operate the standby storage battery bank and the substitutable storage battery bank with the same SOC.

  For example, when the standby storage battery bank and the substituting storage battery bank are each configured by one storage battery bank 112, the upper limit values of the discharge depths of both are operated at a half the normal size. In this way, when the substituting storage battery bank suddenly stops charging / discharging, the standby storage battery bank alone can cover both the discharge charge amount and the charging charge amount of the substituting storage battery bank. At this time, it is preferable to change the central value of the SOC range in which charging / discharging is performed as necessary.

  Further, when the standby storage battery bank is configured by x storage battery banks 112 and the replacement storage battery bank is configured by y storage battery banks 112, if the upper limit value of the discharge depth is normal y / (x + y) Good. However, it is preferable that this value does not exceed the upper limit of the depth of discharge when the soundness mode of the standby storage battery bank is higher than warning (1).

  In step S525, the alternative operation control unit 114 determines whether or not to end the alternative mode transition operation task shown in FIG. If the alternative mode transition operation task has not been finished yet, the process returns to step S520, and if finished, the processing flow of FIG. 7 is finished.

  In step S521, the standby storage battery bank is selected from the storage battery banks 112 that are in the inactive state. However, the standby storage battery bank may be selected from the storage battery banks 112 that are used for the fluctuation mitigation operation. . In this case, according to the above-described method, the same effect as described above can be obtained by changing the upper limit value of the discharge depth of the storage battery bank 112 and the center value of the SOC range in which charging / discharging is performed at a predetermined ratio.

  As described above, when the wind power generator 110 capable of adjusting the output is used, the SOC of the standby storage battery bank and the substituting storage battery bank is not necessarily strictly synchronized because there is a certain degree of freedom particularly on the low SOC side. There is no need. In addition, the degree of synchronization of the SOCs of the standby storage battery bank and the substituting storage battery bank can be appropriately adjusted in accordance with the characteristics of each site such as power consumption in the site.

  During the alternative operation, the standby storage battery bank cannot be charged uniformly. Therefore, perform equal charging at the same time as the replacement battery bank, or perform the equal charge by sequentially replacing the role of the standby storage battery bank among the plurality of storage battery banks 112 whose health mode is normal (0). Is preferred. Alternatively, assuming that there is a low probability that a sudden charge / discharge stop occurs simultaneously for a plurality of substituting storage battery banks, the role of the standby storage battery bank is assigned to another storage battery bank 112 whose sanity mode is alert (1). May be. Further, depending on the situation, the soundness mode may be assigned to the storage battery bank 112 that is strictly alert (2).

  The above-mentioned alternative operation reduces the efficiency of sites that use renewable energy. However, it is best to trade off the decrease in profits due to this decrease in efficiency, the penalty due to deviation from fluctuation mitigation requirements, and the cost of battery deterioration. You may choose a measure. For example, if the deviation rate, which represents the percentage of time that the output power to the transmission / distribution system deviates from the specified value during the specified period, has a margin for the required value of the transmission / distribution system, priority is given to efficiency, and the alternative operation There are also options that do not. On the other hand, the deterioration of the storage battery may progress in proportion to the accumulated value such as the total charge / discharge amount, or may proceed in a discrete manner due to a single event such as disconnection or short circuit. Therefore, when the latter deterioration is assumed, it is advantageous in terms of cost to give priority to the protection of the storage battery over the efficiency of power generation.

  According to the 3rd Embodiment of this invention demonstrated above, there exist the following effects.

  The renewable energy fluctuation mitigating storage battery system shown in FIG. 6 includes an alternative operation control unit 114. When the mode setting unit 106 determines that there is a storage battery cell with a large difference in electrical characteristics from the standard, the alternative operation control unit 114 excludes the storage battery bank 112. The storage battery bank 112 is operated as an alternative to the storage battery bank 112 (steps S523 and S524). Since it did in this way, even if the storage battery bank 112 judged that there exists the storage battery cell 101 with a large electrical characteristic gap from a standard stops charging / discharging, the fluctuation | variation reduction operation | movement of generated electric power can be continued.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. In the present embodiment, an example in which a storage battery bank 112 including a storage battery cell 101 that has a large difference in electrical characteristics from the standard and another storage battery bank 112 are virtually combined as one storage battery bank 112 and operated. Will be explained.

  FIG. 8 is a diagram showing a configuration of a renewable energy fluctuation mitigating storage battery system according to the fourth embodiment of the present invention. This storage battery system is different from the storage battery system according to the first embodiment shown in FIG. 1 in that a combination control unit 115 is further provided in the leveling control device 103.

  When the mode setting unit 106 determines that the storage battery cell 101 having a large difference in electrical characteristics from the standard exists in any of the storage battery banks 112, the combination control unit 115 removes other storage batteries excluding the storage battery bank 112. Any one of the banks 112 and the storage battery bank 112 are virtually combined as one storage battery bank 112 (hereinafter referred to as “virtual storage battery bank”) and operated. The advantage of this combination operation is that the charge / discharge operation can be performed with substantially the same exchange (interface) as seen from the charge / discharge control unit 105. As a result, even when the charge / discharge control unit 105 is configured with complicated logic, it can be handled with relatively small modifications.

  The combination control unit 115 is interposed between the output from the charge / discharge control unit 105 to the converter 102 and the input from the control constant holding unit 107 to the charge / discharge control unit 105. As a result, the values of various control constants representing the configuration and state of the storage battery bank 112 output from the control constant holding unit 107 to the charge / discharge control unit 105 are replaced with the values of the virtual storage battery bank. Further, the charge / discharge control signal for the virtual storage battery bank output from the charge / discharge control unit 105 to the converter 102 is replaced with the charge / discharge control signal for the original storage battery bank 112.

  FIG. 9 is a diagram illustrating a processing flow of an alternative combination operation task executed by the combination control unit 115 according to the fourth embodiment of the present invention. The alternative combination operation task shown in this processing flow is executed every predetermined processing cycle.

  In step S540, the combination control unit 115 sets the storage battery bank 112 (substitute battery bank) for which the soundness mode is set to warning (1) or higher among the storage battery banks 112 as a standby storage battery bank as a replacement target thereof. Select. Here, the standby storage battery bank can be selected by performing the same operations as in steps S520 to S522 of FIG. 7 in the third embodiment described above.

  In step S541, the combination control unit 115 sets a combination of the substituting storage battery bank and the standby storage battery bank selected in step S540 as a virtual storage battery bank. And the specification value with respect to this virtual storage battery bank is set. For example, the upper limit of the depth of discharge (the setting method has already been described in the third embodiment) and the battery capacity (such as the sum of the battery capacities of both) in the combination of the substituting storage battery bank and the standby storage battery bank The upper limit value of the discharge depth and the battery capacity are set, and the soundness mode of the virtual storage battery bank is set to virtual (−2). At this time, even if the SOC of the virtual storage battery bank is calculated as the average value of the SOCs of the alternative storage battery bank and the standby storage battery bank, the operation is not affected. This is because the upper limit value of the discharge depth of the virtual storage battery bank is smaller than the upper limit value of the discharge depth before the original combination, and therefore, there is a low possibility of deviating from the SOC operating range due to the SOC error. . In addition, since the number of storage battery banks 112 viewed from the charge / discharge control unit 105 is changed by generating one virtual storage battery bank by combining the alternative storage battery bank and the standby storage battery bank, in the charge / discharge control unit 105, A function corresponding to the case where the number of storage batteries dynamically changes during the fluctuation mitigation operation is necessary. The charge / discharge control unit 105 can easily implement a dynamic change in the number of storage batteries or a change in the upper limit value of the above-described discharge depth as a part of the function of the dynamic fluctuation of the SOC value. This is because it is generally difficult to ascertain the SOC value of a lead-acid battery, and a function corresponding to discontinuous changes in the SOC value is necessary even in conventional operation.

  It should be noted that the charge / discharge control unit 105 is controlled by the charge / discharge control unit 105 to change the specification value of the substituting storage battery bank and the standby storage battery bank before the original combination to the specification value of the virtual storage battery bank set as described above. When reading the control constant from 107, the combination control unit 115 is interposed. On the other hand, the control constant holding unit 107 stores information on control constants according to the actual specification values of each storage battery bank 112 as in the conventional case. Of course, the charge / discharge control unit 105 can directly access the control constant holding unit 107 as necessary, although it is not included in the principle of the same interface.

  In step S542, the combination control unit 115 performs settings for distributing the charge / discharge command for the virtual storage battery bank set in step S541 to the original storage battery bank to be replaced and the standby storage battery bank before the combination. For example, when the storage battery bank 112 having the same capacity is used as the replacement storage battery bank and the standby storage battery bank, the discharge command for the virtual storage battery bank is set to be equally distributed to the replacement storage battery bank and the standby storage battery bank. That is, for example, a setting is made so that a 1 kW discharge command for the virtual storage battery bank is converted into a 0.5 kW discharge command for the replacement storage battery bank and the standby storage battery bank. Other than this, according to the capacities of the substituting storage battery bank and the standby storage battery bank, the distribution setting can be performed with an arbitrary distribution.

  In step S543, the combination control unit 115 treats the virtual storage battery bank as an integral unit according to the distribution set in step S542, and starts charging / discharging of the virtual storage battery bank.

  In step S544, the combination control unit 115 determines whether to end the alternative combination operation task shown in FIG. If the alternative combination operation task is not yet finished, the process returns to step S540, and if finished, the processing flow of FIG. 9 is finished.

  According to the 4th Embodiment of this invention demonstrated above, there exist the following effects.

  The renewable energy fluctuation mitigating storage battery system shown in FIG. 8 includes a combination control unit 115. When the mode setting unit 106 determines that there is a storage battery cell having a large difference in electrical characteristics from the standard in any of the plurality of storage battery banks 112, the combination control unit 115 removes the storage battery bank 112. Any one of the storage battery banks 112 and the storage battery bank 112 are virtually combined and operated as one storage battery bank (steps S541 to S543). Since it did in this way, similarly to 3rd Embodiment, even when the storage battery bank 112 judged that there exists the storage battery cell 101 with the large gap of the electrical characteristic from a standard stops charging / discharging, the fluctuation | variation of generated electric power The relaxation operation can be continued. Furthermore, such a process can be easily realized without modifying the charge / discharge control unit 105.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. In the present embodiment, an example will be described in which functions similar to those of the combination control unit 115 described in the fourth embodiment are realized by an API (Application Programming Interface).

  FIG. 10 is a diagram showing a configuration example of a renewable energy fluctuation mitigating storage battery system according to the fifth embodiment of the present invention. This storage battery system is different from the storage battery system according to the first embodiment shown in FIG. 1 in that a virtualization API 116 and a charge / discharge lower layer driver 118 are further provided in the leveling control device 103. .

  As described in the fourth embodiment, when there is a storage battery cell 101 having a large difference in electrical characteristics from the standard, a plurality of storage battery banks 112 are virtually combined as one storage battery bank 112 and operated. Has many advantages. However, in order to incorporate such a virtual storage battery combination function into the leveling control device 103, a lot of knowledge about the storage battery bank 112 is required. Therefore, when the developer of the storage battery bank 112 and the developer of the leveling control device 103 are different, the degree of difficulty in implementation is high. Therefore, in the present embodiment, the developer of the storage battery bank 112 has developed a virtualized API 116 for realizing the function of the combination control unit 115 as described in the fourth embodiment, and this is developed as a leveling control device 103. To be included in. As a result, the developer of the leveling control device 103 can realize a virtual storage battery combination function with the same interface as before without particularly modifying the charge / discharge control unit 105 and the control constant holding unit 107. .

  The charge / discharge lower layer driver 118 is a part that bears the lower layer interface for driving the converter 102, and outputs a charge / discharge control signal based on the charge / discharge command output from the charge / discharge control unit 105 and converted by the virtual API 116. Output to the converter 102.

  FIG. 11: is a figure which shows another example of a structure of the fluctuation | variation relaxation storage battery system for renewable energy which concerns on the 5th Embodiment of this invention. This storage battery system is different from that shown in FIG. 10 in that the functions of the current comparison unit 104, the mode setting unit 106, and the control constant holding unit 107 are realized by the virtualized API 117.

  In the configuration of FIG. 11, it is determined whether or not there is a storage battery cell 101 having a large difference in electrical characteristics from the standard, and the above-described processes performed when the storage battery cell 101 has a large difference in electrical characteristics from the standard, that is, The virtualization API 117 provides a process for changing the upper limit value of the discharge depth and for the standby storage battery bank and the virtual storage battery bank. Thereby, the charging / discharging control part 105 can always perform charging / discharging control as the healthy storage battery bank 112, without being especially conscious of the presence or absence of the storage battery cell 101 with the large gap of the electrical characteristic from a standard.

  The charge / discharge control unit 105 needs to dynamically respond to changes in various specifications related to the storage battery bank 112. In this regard, as in the case of the fourth embodiment, the charge / discharge control unit 105 performs control on the assumption that a certain amount of error is included in the obtained measurement value. Therefore, even if the charge / discharge control unit 105 performs control while dynamically updating the control constant as in the present embodiment, no particular problem occurs.

  According to the fifth embodiment of the present invention described above, the same operational effects as described in the fourth embodiment can be obtained.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described. In the present embodiment, a storage battery control unit (BCU) 121 is provided between the storage battery bank 112 and the leveling control device 103, and the storage battery control device 121 allows the above-described current comparison unit 104, mode setting unit 106, and An example of realizing each function of the control constant holding unit 107 will be described.

  FIG. 12 is a diagram showing a configuration of a renewable energy fluctuation mitigating storage battery system according to the sixth embodiment of the present invention. This storage battery system is different from the storage battery system according to the first embodiment shown in FIG. 1 in that a storage battery control device 121 is provided.

  The storage battery control device 121 is connected to the storage battery bank 112, and includes a current comparison unit 104, a mode setting unit 106, a control constant holding unit 107, a BCU control unit 122, and an update backup unit 125. The current comparison unit 104, the mode setting unit 106, and the control constant holding unit 107 have the same functions as those described in the above embodiments.

  The BCU control unit 122 integrally controls the above-described portions that the storage battery control device 121 has functionally, and performs communication of various control information performed with the leveling control device 103. A local console 123 can be connected to the BCU control unit 122. Using the local console 123, function update of each part of the BCU control unit 122, reading of control information about each storage battery bank 112 from the BCU control unit 122, etc. It can be performed. When the storage battery bank 112 is checked, the BCU control unit 122 sets the soundness mode for the storage battery bank 112 to be checked to check (−4). Thus, the storage battery bank 112 can be inspected while excluding the storage battery bank 112 from the target of the fluctuation relaxation operation and continuing the fluctuation relaxation operation as the entire power generation site.

  The BCU control unit 122 is connected to the external communication network 124, and can update the functions of the aforementioned parts by using update information provided via the external communication network 124. Further, by accessing the BCU control unit 122 via the external communication network 124, the state of each storage battery bank 112 can be remotely monitored. The state of each storage battery bank 112 obtained by remote monitoring can be used for production planning of storage batteries for replacement. That is, unlike each storage battery cell 101 used in the storage battery bank 112, a storage battery used for mitigating fluctuations in power generation at a power generation site using renewable energy is different from that used in mass-produced products such as automobiles. It is often produced according to the plan. Therefore, if a production plan is made after a formal replacement request is made by the site administrator, the lead time for procurement becomes excessive. On the other hand, it is possible to shorten the lead time by making a production plan by predicting demand, but it is likely to be wasted in a production plan based on a demand forecast with a weak basis. Therefore, by using the state of each storage battery bank 112 obtained by remote monitoring, for example, when the soundness mode is warning (1), the demand is predicted to be 20%, and when severe warning (2) is 40%, By using this as the basis for the production plan, production efficiency can be improved.

  The update backup unit 125 temporarily substitutes the operation performed by the BCU control unit 122 when the function of the BCU control unit 122 is being updated. In general, the update of the BCU control unit 122 and the update of the leveling control device 103 are not always performed at the same time. For this reason, during an update operation that involves stopping or restarting the BCU control unit 122, the update backup unit 125 temporarily substitutes the necessary function of the BCU control unit 122 at this time. The function of the update backup unit 125 may be realized by a computer connected via the local console 123 or the external communication network 124.

  The leveling control device 103 includes the charge / discharge control unit 105 and the charge / discharge lower layer driver 118 described above, and an interface unit 119. The interface unit 119 converts a signal input to and output from the charge / discharge control unit 105 in accordance with a predetermined conversion law, and has the same function as the virtualization API 116 described in the fifth embodiment. Thereby, similarly to the fifth embodiment, the developer of the leveling control device 103 can realize a virtual storage battery combination function with the same interface as the conventional one. Moreover, since the current comparison unit 104, the mode setting unit 106, and the control constant holding unit 107 are provided in the storage battery control device 121, the configuration of the leveling control device 103 can be simplified. Therefore, the manufacturing process of the leveling control device 103 can be simplified and the amount of work can be greatly reduced.

  On the other hand, the developer of the storage battery bank 112 can easily optimize the control for realizing the function according to the present invention by manufacturing the storage battery bank 112 and the storage battery control device 121 together. Further, by obtaining the consent of the manager of the power generation site to which the storage battery system of FIG. 12 is connected, various control constants and various functions can be easily updated without using the leveling control device 103. Can do.

  According to the sixth embodiment of the present invention described above, the following operational effects are obtained.

  The renewable energy fluctuation mitigating storage battery system shown in FIG. 12 includes a storage battery control device 121 and a leveling control device 103. The storage battery control device 121 is connected to the storage battery bank 112 and includes a current comparison unit 104 and a mode setting unit 106. The leveling control device 103 is connected to the storage battery control device 121, and includes a charge / discharge control unit 105 and an interface unit 119 that converts signals input to and output from the charge / discharge control unit 105. Since it did in this way, even when the developer of the storage battery bank 112 and the developer of the leveling control apparatus 103 differ, each work efficiency can be improved.

  In each of the embodiments described above, an example of mitigating fluctuations in generated power using wind power, which is one of renewable energy, has been described. However, generated power using other renewable energy such as sunlight, for example. The present invention can also be applied to a power storage system that alleviates fluctuations.

  Moreover, you may combine each embodiment described above arbitrarily, respectively.

  Each embodiment and various modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 101 Storage battery cell 102 Converter 103 Leveling control apparatus 104 Current comparison part 105 Charging / discharging control part 106 Mode setting part 107 Control constant holding part 108 Power transmission / distribution system 109 Bus 110 Wind generator 111 Storage battery string 112 Storage battery bank 113 Alarm 114 Alternative operation Control unit 115 Combination control unit 116, 117 Virtualization API
118 Charge / Discharge Lower Layer Driver 119 Interface Unit 120 Current Detector 121 Storage Battery Control Unit 122 BCU Control Unit 123 Local Console 124 External Communication Network 125 Update Backup Unit 130 Voltage Detector 131 Voltage Comparison Unit

Claims (6)

A storage battery system for mitigating fluctuations in power generation using renewable energy,
A storage battery bank having a plurality of storage battery strings each configured by connecting one or more storage battery cells in series;
A plurality of storage battery strings connected in parallel, and charging and discharging the storage battery bank; and
A current detector for detecting a current flowing through each of the plurality of storage battery strings;
A current comparator for comparing the current of each storage battery string detected by the current detector;
A charge / discharge control unit for controlling charge / discharge of the storage battery bank by the converter;
Based on the comparison result of the current by the current comparison unit, it is determined whether or not there is a storage battery cell having a large electrical characteristic separation from the standard in the storage battery bank, and the electrical characteristic separation from the standard. A mode setting unit that changes at least one of an upper limit value of a depth of discharge and a maximum continuous discharge charge amount when charging and discharging the storage battery bank when it is determined that a large storage battery cell exists. Fluctuation mitigation storage battery system for possible energy. In the fluctuation relaxation storage battery system for renewable energy according to claim 1,
A voltage detector for detecting a voltage of each storage battery cell constituting each of the plurality of storage battery strings;
A voltage comparison unit for comparing the voltage of each storage battery cell detected by the voltage detector,
The mode setting unit is a storage battery cell having a large difference in electrical characteristics from the standard in the storage bank based on at least one of the current comparison result by the current comparison unit and the voltage comparison result by the voltage comparison unit. It is determined whether or not there is a fluctuation-reducing storage battery system for renewable energy. In the fluctuation relaxation storage battery system for renewable energy according to claim 1,
A plurality of the storage battery bank and the converter, respectively,
When it is determined by the mode setting unit that any of the plurality of storage battery banks has a large separation of electrical characteristics from the standard, any of the other storage battery banks excluding the storage battery bank, A fluctuation mitigating storage battery system for renewable energy, further comprising an alternative operation control unit that operates as an alternative to the storage battery bank. In the fluctuation relaxation storage battery system for renewable energy according to claim 1,
A plurality of the storage battery bank and the converter, respectively,
When it is determined by the mode setting unit that any one of the plurality of storage battery banks has a large difference in electrical characteristics from the standard, one of the other storage battery banks excluding the storage battery bank and the storage battery A fluctuation mitigation storage battery system for renewable energy, further comprising a combination control unit for operating the bank in combination as a virtual storage battery bank. In the fluctuation relaxation storage battery system for renewable energy according to claim 1,
A storage battery control device connected to the storage battery bank and having the current comparison unit and the mode setting unit;
The leveling control device, which is connected to the storage battery control device and includes the charge / discharge control unit and an interface unit that converts a signal input / output to / from the charge / discharge control unit. Fluctuation mitigation storage battery system for renewable energy. A storage battery system for mitigating fluctuations in power generation using renewable energy,
A storage battery bank having a plurality of storage battery strings each configured by connecting one or more storage battery cells in series;
A plurality of storage battery strings connected in parallel, and charging and discharging the storage battery bank; and
A voltage detector for detecting a voltage of each storage battery cell constituting each of the plurality of storage battery strings;
A voltage comparison unit for comparing the voltage of each storage battery cell detected by the voltage detector;
A charge / discharge control unit for controlling charge / discharge of the storage battery bank by the converter;
Based on the comparison result of the voltage by the voltage comparison unit, it is determined whether there is a storage battery cell having a large electrical characteristic separation from the standard in the storage battery bank, and the electrical characteristic separation from the standard. A mode setting unit that changes at least one of an upper limit value of a depth of discharge and a maximum continuous discharge charge amount when charging and discharging the storage battery bank when it is determined that a large storage battery cell exists. Fluctuation mitigation storage battery system for possible energy.

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