JP6300568B2 - Power supply system - Google Patents

Description

  The present invention provides a plurality of self-systems having an AC line to which a plurality of power consumers are connected, a power storage device, and a self-supporting inverter device that connects the power storage device and the AC line using a self-connection line. And connecting the power storage device of one self-system and the AC line of the other self-system using interconnection lines so that a plurality of self-systems are electrically connected in series The present invention relates to a power supply system including an inverter device between self systems.

  Conventionally, a power supply system has been proposed that includes a plurality of self-systems having an AC line to which a plurality of power consumers are connected, a power storage device, and a self-supporting inverter device that connects the power storage device and the AC line. Has been. For example, a power supply system described in Patent Document 1 (International Publication No. 2010/103650) includes a power storage device included in one self-system and another one so that a plurality of self-systems are electrically connected in series. The inverter system which connects the alternating current line which one self system has is provided between self systems. Furthermore, each of the self-supporting inverter devices of the plurality of self-systems has a target frequency at which the voltage of the power on the AC line becomes the target voltage and the frequency of the power on the AC line is determined according to the amount of power stored in the power storage device. For two self-systems that are electrically connected via a single inverter device, power is transferred from the self-system with the higher target frequency to the self-system with the lower target frequency. The operation of the connected inverter device is controlled so as to be supplied. That is, since the frequency of the power on the AC line of each self system is a value reflecting the amount of power stored in the power storage device, the connected inverter device is connected to each AC line with respect to the two electrically connected self systems. It is possible to know which power storage amount of the power storage device of the self system is large only by detecting the frequency of. And according to the magnitude of the detected frequency value, it is possible to equalize the amount of power stored in the power storage device of each self system by performing power interchange between the self systems.

International Publication No. 2010/103650

  FIG. 6 of Patent Document 1 describes an example of the relationship between the amount of power stored in the power storage device and the target frequency. However, Patent Document 1 describes a general example where the change in the amount of electricity stored in the power storage device and the change in the target frequency are in a linear relationship, and in the case of actually operating the power supply system However, it does not describe from what point of view the target frequency should be determined.

  For example, it is assumed that the power consumer of the power consumer connected to the AC line is originally operated by the power supplied from the commercial power system. That is, the power consuming device is designed to operate according to the frequency of power supplied from the commercial power system. Therefore, strictly speaking, when the frequency of supplied power changes, the operating state of the power consuming device also changes. Therefore, it is necessary to determine the target frequency from the viewpoint of normally operating the power consumer of the power consumer connected to the AC line.

  Further, in Patent Document 1, even if the power storage amount of each power storage device can be equalized by performing power interchange control, the power storage amount of each power storage device of each self system is equalized with any value. It is unknown whether it can be done. For this reason, the power storage amount of each power storage device is balanced with a very small amount of power storage between two self systems, and the power storage amount of each power storage device with a very large value of power storage between the other two self systems. It is possible that things will be balanced.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to determine the AC line target frequency to a value that is preferable for power consumers, and to store the power of each power storage device within a predetermined power storage range. It is in providing a power supply system that can equalize the amount.

In order to achieve the above object, the characteristic configuration of the power supply system according to the present invention includes an AC line to which a plurality of power consumers are connected, a power storage device, and a self-connection between the power storage device and the AC line. A plurality of self-systems having a self-supporting inverter device connected using wires,
An interconnection line is used between the power storage device of one self system and the AC line of the other self system so that a plurality of the self systems are electrically connected in series. A power supply system comprising a connected inverter device to be connected between the self systems,
Power control is performed on the self-supporting inverter device, and a control device is provided that performs power interchange control on the connected inverter device,
The controller is
As the power quality control, with respect to the independent inverter device included in one self-system, in the one self-system, the power voltage in the AC line becomes a target voltage and the power in the AC line. Power is supplied to the AC line so that the frequency becomes a target frequency determined according to the amount of power stored in the power storage device, and
As the power interchange control, when power is interchanged from one self system to another self system using the interconnect line, the first interconnect line and the second interconnect constituting the interconnect line are used. Relative to the connected inverter device provided between the power line and the power supply amount of the power storage device based on the target frequency on the AC line in each of the one self system and the other self system. Power from a large self-system to a self-system with a relatively small amount of electricity stored in the power storage device,
In each of the plurality of self-systems,
The self-supporting inverter device determines the target frequency according to the power storage amount of the power storage device according to a relational expression between the power storage amount of the power storage device and the target frequency,
In the relational expression between the power storage amount of the power storage device and the target frequency,
The target frequency is not less than a lower limit target frequency set from the viewpoint of frequency quality of power in the AC line and is limited to a range not more than an upper limit target frequency,
The reference change in which the absolute value of the rate of change of the target frequency with respect to the change of the storage amount of the power storage device is set relatively large in the relational expression between the storage amount of the power storage device and the target frequency A rate region is set, and the target frequency with respect to the change in the storage amount of the power storage device is set on the small storage amount side and the large storage amount side of the storage amount range of the power storage device corresponding to the reference change rate region. A first small change rate region and a second small change rate region are set in which the absolute value of the change rate is relatively smaller than the absolute value of the change rate of the target frequency in the reference change rate region. In the point.

  According to the above characteristic configuration, when the target frequency is determined, the range is limited to a range that is equal to or higher than the lower limit target frequency set from the viewpoint of the frequency quality of the power on the AC line and lower than the upper limit target frequency. . As a result, it is possible to prevent the operation of the device of the power consumer connected to the AC line from being hindered.

  In addition, when power interchange control is performed, the linked inverter device has a target frequency on the AC line in each of the two self-systems (the frequency of power on the actual AC line may be regarded as the same as the target frequency). Based on the above, electric power is accommodated from the self system in which the power storage amount of the power storage device is relatively large to the self system in which the power storage amount of the power storage device is relatively small. In other words, the frequency of the power on the AC line in both self-systems is compared, and it is then decided whether to become the self-system that supplies power or the self-system that receives power. . For this reason, in the self system that supplies power, the amount of power stored in the power storage device decreases, and in the self system that receives power, the decrease in the power storage amount of the power storage device is suppressed or the power storage amount increases.

  However, in this characteristic configuration, in the relational expression between the storage amount of the power storage device and the target frequency, the reference change in which the absolute value of the change rate of the target frequency with respect to the change of the storage amount of the power storage device is set relatively large The absolute value of the change rate of the target frequency with respect to the change in the storage amount of the power storage device on the small storage amount side and the large storage amount side of the storage amount range of the storage device corresponding to the reference change rate region. However, a first small change rate region and a second small change rate region that are relatively smaller than the absolute value of the change rate of the target frequency in the reference change rate region are set. In other words, in the reference change rate region where the storage amount is relatively intermediate, if there is a change in the storage amount, the change is greatly reflected in the change in the target frequency. It becomes easy to change depending on the change in the amount of stored electricity. That is, it becomes easy to switch between the power receiving side and the power supplying side, and the storage amount balance is achieved within the storage amount range corresponding to the reference change rate region.

  On the other hand, in the small change rate region where the storage amount is relatively small, even if the storage amount of the power storage device increases due to the supply of power by power interchange control, the increase in the storage amount Since the target frequency does not change greatly, power supply continues to be received. And it transfers so that it may return to the said reference | standard change rate area | region where the electrical storage amount of an electrical storage apparatus is in the middle relatively. Similarly, in the small change rate region where the storage amount is relatively large, even if the power storage control reduces the storage amount of the power storage device by supplying power to another self-system through power interchange control, the decrease in the storage amount Since the target frequency does not change greatly with respect to the change, power supply to other self-systems is continued. And it transfers so that it may return to the said reference | standard change rate area | region where the electrical storage amount of an electrical storage apparatus is in the middle relatively.

  As described above, the first small change rate region, the reference change rate region, and the second small change rate region are sequentially set as the amount of power stored in the power storage device increases, so that The amount of electricity stored in the device is balanced within the range of the amount of electricity stored corresponding to the reference change rate region.

Another characteristic feature of the power supply system according to the present invention, the relational expression, the target frequency, converges to the number of the upper limit target frequency with an increase of the storage amount of the electrical storage device with large storage amount side, the small power storage or a relational expression converges to the number of the lower limit target frequency with decreasing the storage amount of the electricity storage device in an amount side, or the target frequency, the with an increase in the storage amount of the electrical storage device with large storage amount side This is a relational expression that converges to the lower limit target frequency and converges to the upper limit target frequency in accordance with a decrease in the amount of electricity stored in the electricity storage device on the small electricity storage amount side .

With the above construction, the relation between the storage amount and the target frequency of the power storage device, the target frequency is converged to the number of upper limit target frequency in a large storage amount side, the lower the target frequency in the small storage amount side or converge, or target frequency is converged to the lower limit target frequency in a large storage amount side, it converges to upper bound the target frequency with a small charged amount side. That is, by determining the target frequency using this relational expression, the target frequency can be changed to the maximum between the upper limit target frequency and the lower limit target frequency.

Still another characteristic configuration of the power supply system according to the present invention is that the target operation area related to the storage amount of the power storage device determined in consideration of the life of the power storage device includes a target lower limit storage amount and the target lower limit storage amount Stipulated in the area between the target upper limit storage amount larger than the amount,
A region between the target lower limit charged amount and the target upper limit charged amount related to the charged amount of the power storage device corresponds to the reference change rate region.

The power storage device connected to the AC line is deteriorated by repeating charging and discharging. However, if charging and discharging are repeated within a specific amount of power storage, the deterioration rate is slow. That is, it is known that the lifetime is extended. Therefore, it is preferable that the power storage device can determine the target frequency from the viewpoint of using the power storage device while repeating charging and discharging within the range of the power storage amount as much as possible.
Therefore, in this feature configuration, the target operation area related to the storage amount of the power storage device determined in consideration of the life of the power storage device is between the target lower limit storage amount and a target upper limit storage amount larger than the target lower limit storage amount. The region between the target lower limit storage amount and the target upper limit storage amount related to the storage amount of the power storage device corresponds to the reference change rate region. As a result, as described above, the power storage amount of the power storage device returns to the reference change rate region (target operation region) that is relatively intermediate, or the power storage amount of the power storage device deviates from the target operation region. It will be suppressed. That is, the power storage device is used within the range of the power storage amount (within the target operation area) so that the life of the power storage device is extended.

  Another characteristic configuration of the power supply system according to the present invention is that, in the relational expression between the power storage amount of the power storage device and the target frequency, the target frequency is determined by a function of the power storage amount of the power storage device. The frequency fluctuation value to be calculated is added to the reference frequency of the AC line.

  According to the above characteristic configuration, when the target frequency is derived by adding a frequency fluctuation value determined by a function of the amount of power stored in the power storage device to the reference frequency of the AC line, the target frequency is the power on the AC line. The frequency fluctuation value is limited within a range that is not less than the lower limit fluctuation value and not more than the upper limit fluctuation value so as to be equal to or higher than the lower limit target frequency set from the viewpoint of frequency quality.

  Still another characteristic configuration of the power supply system according to the present invention is that the range between the upper limit target frequency and the lower limit target frequency set from the viewpoint of frequency quality of power in the AC line is connected to the AC line. This is in a range that is set in order for the device being operated to operate normally.

  According to the above characteristic configuration, it is ensured that the device connected to the AC line operates normally.

It is a figure which shows the structure of an electric power supply system. It is a figure which shows the relationship between the electrical storage amount of an electrical storage apparatus, and the frequency fluctuation value of a target frequency.

The power supply system according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a power supply system. This power supply system includes an AC line 1 to which a plurality of power consumers D are connected, a power storage device 4, and a self-standing inverter device that connects the power storage device 4 and the AC line 1 using a self-connection line 2. The power storage device 4 of one self-system 10 and the alternating current of the other self-system 10 are provided so that the plurality of self-systems 10 are electrically connected in series. A connected inverter device 9 for connecting the line 1 with the interconnect line 3 is provided between the self systems 10. Self-connecting line 2 includes first self-connecting line 2 a (2) for connecting self-standing inverter device 5 and power storage device 4, and second self-connecting line for connecting self-standing inverter device 5 and AC line 1. 2b (2). The interconnection line 3 includes a first interconnection line 3 a (3) for connecting the linked inverter device 9 and the power storage device 4, and a second interconnection line for connecting the linked inverter device 9 and the AC line 1. 3b (3). In addition, the power supply system includes a control device C that causes the independent inverter device 5 to perform power quality control and causes the connected inverter device 9 to perform power interchange control. Although FIG. 1 illustrates a state in which two self systems 10, that is, the self system 10 </ b> A (10) and the self system 10 </ b> B (10) are connected via the linked inverter device 9, the self system provided in the power supply system There is no limit to the number of ten.

  The power consumer D has a power consuming device 6 that consumes the power supplied from the AC line 1. Alternatively, the power consumer D may have the power generation device 7 in addition to the power consumption device 6. As the power consuming device 6, not only a general device such as a lighting device or an air conditioner, but also various devices that consume power for its operation can be used. As the power generation device 7, various devices such as a solar power generation device and a wind power generation device that generate power using natural energy such as sunlight and wind power, and a fuel cell that generates power using fuel can be used. As shown in FIG. 1, in the self system 10, the power generator 7 may be connected to the AC line 1 as a single unit. Further, the number of power consumers D connected to the AC line 1 and the numbers and combinations of the power consuming devices 6 and the power generators 7 included in the power consumers D are not limited to the illustrated example.

  The power storage device 4 can use a storage battery (chemical battery) such as a lithium ion battery, a nickel metal hydride battery, or a lead battery.

  The self-supporting inverter device 5 and the linked inverter device 9 are power conversion devices that can convert input power into power having a desired voltage, frequency, and phase and output the converted power. For example, the self-supporting inverter device 5 and the linked inverter device 9 include a circuit unit (not shown) having a semiconductor switching element and a control unit (not shown) that controls the switching operation of the semiconductor switching element. The And the power conversion operation | movement from input electric power to output electric power is performed by switching on / off of those semiconductor switching elements.

  The control device C is a device capable of controlling operations of the self-supporting inverter device 5 and the linked inverter device 9. For example, the control device C is a device having an information input / output function, a storage function, an arithmetic processing function, and the like. The function of the control device C is that any one of the control units (not shown) included in each of the self-supporting inverter device 5 and the linked inverter device 9 functions as a master control unit, and the other control unit is a master control unit. This can be realized by functioning as a slave control unit while performing information communication. Or the function of the control apparatus C is provided separately from the control part (not shown) which each of the independent inverter apparatus 5 and the connection inverter apparatus 9 has, and the master control part comprised so that information communication with those control parts is possible Can be realized.

  Then, the control device C performs power quality control in each self system 10 and power interchange control among the plurality of self systems 10. The power quality control is control for the purpose of keeping constant the quality of power on the AC line 1 of the own system 10. The power interchange control is control for the purpose of equalizing the amount of power stored in the power storage device 4 of each self system 10.

  Supplementing the power quality control, the power of the AC line 1 is consumed by the power consuming device 6 of the power consumer D. The power consuming device 6 is usually an external commercial power system separate from this power supply system. It is assumed that it operates with the electric power supplied from. That is, the power consuming apparatus 6 is designed to operate according to the frequency of power supplied from the commercial power system. Therefore, if the frequency of the power supplied to the power consuming device 6 is different, strictly speaking, the operation of these devices will also be different. Therefore, it is necessary to perform power quality control that keeps the frequency of power on the AC line 1 of each self system 10 within a predetermined range.

  Therefore, as the power quality control, the control device C is configured so that the voltage of the power on the AC line 1 becomes the target voltage in the one self-system 10 with respect to the self-supporting inverter device 5 included in one self-system 10. And the electric power supply to the AC line 1 is performed so that the frequency of the electric power in the AC line 1 becomes a target frequency determined according to the amount of power stored in the power storage device 4.

  Supplementing the power interchange control, in each self system 10, the function of maintaining the power quality of the AC line 1 is carried out by the power quality control of the self-supporting inverter using the power storage device 4, but the power quality control is performed. Thus, how much the power storage amount of the power storage device 4 increases or decreases varies among the plurality of self systems 10. Therefore, with the passage of time, a difference may occur in the amount of power stored in the power storage device 4 of each self system 10. In such a case, if power can be exchanged from the self system 10 having a large amount of power stored in the power storage device 4 to the self system 10 having a small amount of power stored in the power storage device 4, the power storage devices 4 between the self systems 10. Is preferable for equalizing the amount of electricity stored.

  Therefore, as power interchange control, when the control device C interchanges power from one self system 10 to another self system 10 using the interconnect line 3, the control device C configures the first interconnect line 3. With respect to the connected inverter device 9 provided between the connection line 3a (3) and the second interconnection line 3b (3), the AC line 1 in each of the one self system 10 and the other self system 10 On the basis of the target frequency, power is accommodated from the self system 10 in which the power storage amount of the power storage device 4 is relatively large to the self system 10 in which the power storage amount of the power storage device 4 is relatively small.

  For example, as shown in FIG. 1, with respect to two self-systems 10A and 10B that are electrically connected through one linked inverter device 9 and are adjacent to each other, the one linked inverter device 9 Based on the target frequency determined according to the amount of power stored in the power storage device 4, the self system 10 in which the power storage amount of the power storage device 4 is relatively large changes to the self system 10 in which the power storage amount of the power storage device 4 is relatively small. And power interchange. Specifically, the linked inverter device 9 acquires information on the frequency fA of the AC line 1 of the own system 10A and information on the frequency fB of the AC line 1 of the own system 10B, compares these values, and stores Power is accommodated from the self system 10 in which the power storage amount of the device 4 is relatively large to the self system 10 in which the power storage amount of the power storage device 4 is relatively small. Here, the information regarding the frequency of the AC line 1 acquired by the connected inverter device 9 is a value obtained by detecting the frequency (= target frequency) of the actual power in the AC line 1 of each of the own systems 10A and 10B. Alternatively, it may be a target frequency value transmitted from the self-supporting inverter device 5 that determines the target frequency.

Next, how the target frequency is determined in the power quality control described above will be described.
In the present embodiment, the self-supporting inverter device 5 performs control so that the frequency of power on the AC line 1 becomes a target frequency that is determined so as to increase as the amount of power stored in the power storage device 4 increases. As an example of this relational expression, a frequency fluctuation value determined by a function of the amount of power stored in the power storage device 4 (for example, a relationship in which the frequency fluctuation value increases as the power storage amount increases) is set to the reference frequency (for example, 60 Hz) of the AC line 1 In some cases, the target frequency is a value obtained by addition. In this case, the relationship between the target frequency: f, the reference frequency: f0, and the frequency fluctuation value: Δf can be expressed by the following (Formula 1).

f = f0 + Δf (Equation 1)

  FIG. 2 is a diagram illustrating a relational expression between the amount of power stored in the power storage device 4 in the present embodiment: SOC and the frequency fluctuation value of the target frequency: Δf. Since the target frequency: f is determined by the sum of the reference frequency: f0 and the frequency fluctuation value: Δf, the relational expression shown in FIG. 2 is the relationship between the storage amount: SOC of the power storage device 4 and the target frequency: f. It can be said that it shows a relational expression. In FIG. 2, the horizontal axis represents the amount of power stored in the power storage device 4: SOC (%), and the vertical axis represents the frequency fluctuation value: Δf (Hz). In the present embodiment, Δf takes a positive value and a negative value as can be seen from FIG.

  As shown in FIG. 2, in the relational expression between the storage amount of the power storage device 4: SOC and the frequency fluctuation value of the target frequency: Δf, the self-supporting inverter device 5 sets the frequency fluctuation value of the target frequency: Δf to the AC line. 1 is limited to a range that is greater than or equal to the lower limit frequency fluctuation value set from the viewpoint of the frequency quality of power and less than or equal to the upper limit frequency fluctuation value. Since the target frequency: f is determined by the sum of the reference frequency: f0 and the frequency fluctuation value: Δf, the relational expression shown in FIG. 2 indicates that the target frequency: f is the viewpoint of the frequency quality of power on the AC line 1. This indicates that the frequency is limited to a range that is equal to or higher than the lower limit target frequency set from (1) to the upper limit target frequency. In this relational expression, the target frequency converges to the upper limit target frequency as the amount of power stored in the power storage device 4 increases on the large power storage amount side, and reaches the lower limit target frequency as the power storage amount of the power storage device 4 decreases on the small power storage amount side. Converge. That is, by determining the target frequency using this relational expression, the target frequency can be changed to the maximum between the upper limit target frequency and the lower limit target frequency.

Thus, even if the self-supporting inverter device 5 intentionally changes the frequency of the power on the AC line 1, the frequency change range is the lower limit target set from the viewpoint of the frequency quality of the power on the AC line 1. The frequency is limited to be equal to or higher than the frequency (= the sum of the reference frequency and the lower limit frequency fluctuation value) and lower than the upper limit target frequency (= the sum of the reference frequency and the upper limit frequency fluctuation value). As a result, the operation of the device connected to the AC line 1 can be prevented from being hindered in terms of quality.
For example, since the power consuming apparatus 6 that operates by consuming the power of the AC line 1 is supposed to operate by the power supplied from the commercial power system, if the frequency of the supplied power changes, The operating state of the power consuming device will also change. However, as in this embodiment, by limiting the frequency range of the power of the AC line 1 that is changed by the independent inverter device 5 to a range that is equal to or higher than the lower limit target frequency and lower than the upper limit target frequency, the AC line 1 It is ensured that the power consuming device 6 connected to the device operates normally.
When the power generation device 7 that supplies power to the AC line 1 determines that the frequency of the power on the AC line 1 is not normal, the power generation device 7 itself is disconnected from the AC line 1 or power to the AC line 1 is reached. There is a case where protection control for stopping the supply is performed. That is, the power generation device 7 may not normally supply power to the AC line 1 in some cases. Even in such a case, the frequency range of the power of the AC line 1 that is changed by the independent inverter device 5 is the range in which the power generation device 7 determines that the frequency of the power of the AC line 1 is normal (that is, the above-described range). The above-described protection control of the power generation device 7 can be prevented from being executed by limiting to the lower limit target frequency and the upper limit target frequency.

  In addition, in the relational expression between the power storage amount of the power storage device 4 and the frequency fluctuation value (that is, the relational expression between the power storage amount of the power storage device 4 and the target frequency) shown in FIG. A reference change rate region in which the absolute value of the change rate of the target frequency with respect to the change in amount is set to be relatively large is set, and the storage amount is smaller than the range of the storage amount of the power storage device 4 corresponding to the reference change rate region The absolute value of the change rate of the target frequency with respect to the change of the storage amount of the power storage device 4 is relatively smaller than the absolute value of the change rate of the target frequency in the reference change rate region. The small change rate region and the second small change rate region are set. However, in the relational expression between the power storage amount of the power storage device 4 and the target frequency, the target frequency changes monotonously with respect to the change in the power storage amount of the power storage device 4.

When the first small change region, the large change region, and the second small change region as described above are set in the relational expression between the power storage amount of the power storage device 4 and the target frequency, the following advantages are obtained. is there.
First, when power interchange control is performed, the linked inverter device 9 determines that the target frequency on the AC line 1 in each of the two self-systems 10 (the frequency of power on the actual AC line 1 is also the same as the target frequency). Power may be accommodated from the self system 10 in which the power storage amount of the power storage device 4 is relatively large to the self system 10 in which the power storage amount of the power storage device 4 is relatively small. In other words, the frequency of the power on the AC line 1 in both self systems 10 is compared, and then the self system 10 on the power supply side or the self system 10 on the power receiving side is obtained. Is determined.

For this reason, the self-system 10 on the power supply side further reduces the amount of power stored in the power storage device 4, and the self-system 10 on the side receiving power suppresses the decrease in the power storage amount of the power storage device 4. Will increase.
However, in the present embodiment, as described above, in the relational expression between the storage amount of the power storage device 4 and the target frequency, the first small change rate region, the reference change rate region, and the second small change rate region are These are set in order as the amount of power stored in the power storage device 4 increases. That is, in the reference change rate region in which the amount of power storage is relatively intermediate, if there is a change in the amount of power stored in the power storage device 4, the target frequency also changes greatly with the change. Thus, the fact that the target frequency changes greatly means that in the power accommodation control based on the comparison result of the target frequency, it is easier to switch between the power receiving side and the power supplying side. It is. That is, it becomes easy to switch between the power receiving side and the power supplying side, and the power storage amount of each power storage device 4 is balanced between the adjacent self-systems 10.

On the other hand, in the small change rate region (the first small change rate region or the second small change rate region) in which the power storage amount of the power storage device 4 is relatively smaller or larger than the reference change rate region, Changes in the amount of power stored in the device 4 are not greatly reflected in changes in the target frequency. For example, in the small change rate region where the amount of stored electricity is relatively small, even if the amount of stored power of its own power storage device 4 increases due to the supply of power from another self system 10 in the power interchange control, the target frequency is Does not change significantly. As a result, in the power interchange control, the supply of power from the other own system 10 is continued, and thereafter, the power storage amount of the power storage device 4 returns to the reference change rate region in the middle.
Similarly, in the small change rate region on the side where the amount of stored electricity is relatively large, even if the amount of stored power of its own power storage device 4 is reduced by supplying power to another self-system 10 in the power interchange control, the target The frequency does not change greatly. As a result, power supply control continues to supply power to other self-systems 10 and then returns to the reference change rate region in which the power storage amount of the power storage device 4 is relatively intermediate.

  As described above, when the power storage amount of the power storage device 4 is in the small change rate region, it is easy to return to the reference change rate region in which the power storage amount is relatively intermediate by power interchange control. Further, when the power storage amount of the power storage device 4 is in the reference change rate region, it becomes easier to switch to the power receiving side or the power supply side by the power interchange control (that is, the power storage device). No. 4 power storage amount remains in the reference change rate region). Accordingly, the first small change rate region, the reference change rate region, and the second small change rate region are sequentially set as the amount of power stored in the power storage device 4 increases, so that The storage amount of the device 4 is balanced within the storage amount range corresponding to the reference change rate region.

  Further, as shown in FIG. 2, in the relational expression between the power storage amount of the power storage device 4 and the target frequency, the region between the target lower limit power storage amount and the target upper limit power storage amount with respect to the power storage amount of the power storage device 4 is the above reference. It is set to correspond to the change rate region. Here, an area between the target lower limit power storage amount and the target upper limit power storage amount that is larger than the target lower limit power storage amount is the target operation region related to the power storage amount of the power storage device 4 determined in consideration of the life of the power storage device 4 Stipulated in In the present embodiment, as described above, when the power storage amount of the power storage device 4 is in the small change rate region, it is easy to return to the reference change rate region in which the power storage amount is relatively intermediate by power interchange control. When the power storage amount of the power storage device 4 is in the reference change rate region, the power storage amount remains in the reference change rate region by the power interchange control. The reference change rate area corresponds to a target operation area related to the amount of power stored in power storage device 4 determined in consideration of the life of power storage device 4. That is, it is possible to prevent the amount of power stored in the power storage device 4 from deviating from the target operation area, or to easily return the amount of power stored in the power storage device 4 to the target operation area. As a result, the power storage device 4 is used within the range of the power storage amount (within the target operation area) so that the life of the power storage device 4 is prolonged.

  This target operation area is set for each type of power storage device 4. For example, it is known that if the power storage device 4 is repeatedly charged and discharged within a specific power storage range, its deterioration rate is slow, that is, the life is long. And the range of the electrical storage amount which can achieve such a lifetime improvement differs for every kind of electrical storage apparatuses 4, such as a lithium ion battery, a nickel hydride battery, and a lead battery. Therefore, for each type of power storage device 4, the range of the power storage amount that can achieve a longer life may be set as the target operation area.

<Another embodiment>
In the above-described embodiment, the relational expression between the power storage amount of the power storage device 4 and the target frequency (frequency fluctuation value) as illustrated in FIG. 2 is illustrated, but FIG. 2 is merely a relational expression illustrated for illustrative purposes. These can be changed as appropriate.
For example, the relational expression shown in FIG. 2 is a relationship in which the target frequency monotonously increases as the amount of power stored in the power storage device 4 increases. Conversely, as the amount of power stored in the power storage device 4 increases. The target frequency may be monotonously lowered. In the case of such a relationship, the relational expression shown in FIG. 2 indicates that the target frequency converges to the lower limit target frequency as the amount of power stored in the power storage device 4 increases on the large power storage amount side, and The relational expression converges to the upper limit target frequency as the amount of stored electricity decreases.
In FIG. 2, the relational expression between the power storage amount of the power storage device 4 and the target frequency (frequency fluctuation value) is defined by a point-symmetric curve with the reference change rate region as the center. You may prescribe | regulate the relational expression between the electrical storage amount of the apparatus 4, and a target frequency (frequency fluctuation value). Further, in the relational expression shown in FIG. 2, the magnitude of the rate of change of the target frequency (frequency fluctuation value) with respect to the change in the amount of power stored in the power storage device 4 can be changed as appropriate.

  INDUSTRIAL APPLICABILITY The present invention can be used in a power supply system in which the target frequency of the AC line 1 is determined to be a preferable value for the power consumer D and the power storage amount of each power storage device 4 can be equalized within a predetermined power storage amount range. .

1: AC line 2: Self-connection line 2a: 1st self-connection line 2b: 2nd self-connection line 3: Interconnection line 4: Power storage device 5: Self-supporting inverter device 6: Power consumption device 7: Power generation device 9: Linked inverter Device 10: Self-system 10A: Self-system 10B: Self-system C: Control device D: Power consumer fA: Frequency fB: Frequency

Claims (5)

A plurality of self-systems including an AC line to which a plurality of power consumers are connected, a power storage device, and a self-standing inverter device that connects the power storage device and the AC line using a self-connection line,
An interconnection line is used between the power storage device of one self system and the AC line of the other self system so that a plurality of the self systems are electrically connected in series. A power supply system comprising a connected inverter device to be connected between the self systems,
Power control is performed on the self-supporting inverter device, and a control device is provided that performs power interchange control on the connected inverter device,
The controller is
As the power quality control, with respect to the independent inverter device included in one self-system, in the one self-system, the power voltage in the AC line becomes a target voltage and the power in the AC line. Power is supplied to the AC line so that the frequency becomes a target frequency determined according to the amount of power stored in the power storage device, and
As the power interchange control, when power is interchanged from one self system to another self system using the interconnect line, the first interconnect line and the second interconnect constituting the interconnect line are used. Relative to the connected inverter device provided between the power line and the power supply amount of the power storage device based on the target frequency on the AC line in each of the one self system and the other self system. Power from a large self-system to a self-system with a relatively small amount of electricity stored in the power storage device,
In each of the plurality of self-systems,
The self-supporting inverter device determines the target frequency according to the power storage amount of the power storage device according to a relational expression between the power storage amount of the power storage device and the target frequency,
In the relational expression between the power storage amount of the power storage device and the target frequency, the target frequency is equal to or higher than a lower limit target frequency set from the viewpoint of frequency quality of power on the AC line, and an upper limit target frequency. Limited to
The reference change in which the absolute value of the rate of change of the target frequency with respect to the change of the storage amount of the power storage device is set relatively large in the relational expression between the storage amount of the power storage device and the target frequency A rate region is set, and the target frequency with respect to the change in the storage amount of the power storage device is set on the small storage amount side and the large storage amount side of the storage amount range of the power storage device corresponding to the reference change rate region. A first small change rate region and a second small change rate region are set in which the absolute value of the change rate is relatively smaller than the absolute value of the change rate of the target frequency in the reference change rate region. Power supply system. The relational expression, the target frequency, converges to the upper limit target frequency with an increase of the storage amount of the electrical storage device with large storage amount side, the following decrease of the storage amount of the electrical storage device with a small storage amount side or a relational expression converges to the lower limit target frequency, or the target frequency, converges to the lower limit target frequency with an increase of the storage amount of the electrical storage device with large storage amount side, the electric storage a small storage amount side The power supply system according to claim 1, wherein the power supply system is a relational expression that converges to the upper limit target frequency according to a decrease in the amount of electricity stored in the apparatus . The target operation area related to the storage amount of the power storage device determined in consideration of the life of the power storage device is defined as a region between the target lower limit storage amount and a target upper limit storage amount larger than the target lower limit storage amount And
The power supply system according to claim 1 or 2, wherein a region between the target lower limit charged amount and the target upper limit charged amount related to the charged amount of the power storage device corresponds to the reference change rate region.   In the relational expression between the power storage amount of the power storage device and the target frequency, the target frequency is a frequency fluctuation value determined by a function of the power storage amount of the power storage device with respect to a reference frequency of the AC line. The power supply system according to any one of claims 1 to 3, which is derived by addition.   The range between the upper limit target frequency and the lower limit target frequency set from the viewpoint of the frequency quality of the power on the AC line is set for normal operation of the device connected to the AC line. It is a range, The electric power supply system as described in any one of Claims 1-4.

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