Power system and centralized management device

Abstract

To provide a power system of which the operation can be continued by an autonomous distributed cooperative control system using an induction index even during independent operation, and a centralized management device.SOLUTION: A power system F1 comprises: a power conditioner B to which a storage battery 29 is connected; a plurality of power conditioners C and D; and a centralized management device A which controls the power conditioners. The centralized management device A includes an index calculation section 13 which calculates a common induction index pr for controlling output power with respect to the plurality of power conditioners B, C and D based on a charging rate soc of the storage battery 29, and transmits the induction index pr to the plurality of power conditioners B, C and D. Each of the plurality of power conditioners B, C and D includes: a target power calculation section 21 for calculating individual target power Pref on the basis of the induction index pr and a preset optimization problem; and an output control section 22 which performs control so that the output power of the own device becomes the individual target power Pref.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power system and a centralized control device used in the power system. [Background technology]

[0002] In recent years, power systems that manage a plurality of power devices connected to a power system and control power transmitted and received between the power system are becoming widespread. For example, Patent Document 1 discloses an example of a power system that includes a centralized management device and a plurality of power devices and controls output power by an autonomous distributed cooperative control method. The centralized management device calculates a guide index for controlling the output power of the entire power system to a target power. The plurality of power devices calculates a target value of the output power of the device itself based on an optimization problem set for each device using the common guide index calculated by the centralized management device. Then, the output power of the device itself is controlled so that the output power becomes the target value. Each power device autonomously controls the output power based on the guide index, so that the output power of the entire power system is controlled to the target power. The centralized management device only calculates and transmits the guide index without grasping the state of each power device, so that the burden of calculation and communication is small. Therefore, a high-performance and expensive centralized management device is not required, and the initial introduction cost can be reduced. In addition, when the power system is expanded, no major modification of the centralized management device is required. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-148627 A Summary of the Invention [Problem to be solved by the invention]

[0004] Some power systems operate autonomously when disconnected from the power grid, supplying power to loads. In this case, a storage battery system included in the power system acts in place of the power grid, and other power devices are connected to the storage battery system to supply power to the loads. If each power device freely charges and discharges during autonomous operation, the storage battery system's storage battery may become fully charged or insufficiently charged, causing the storage battery system to stop. The storage battery system may also stop due to hardware abnormalities such as overcurrent. If the storage battery system stops, the other power devices will have nowhere to connect to, causing the entire power system to stop.

[0005] The present invention has been devised in light of the above-mentioned circumstances, and aims to provide a power system that can continue to operate using an autonomous decentralized cooperative control method that uses induction indexes even during independent operation, and a centralized management device for use in the power system. [Means for solving the problem]

[0006] A power system provided by a first aspect of the present invention is a power system comprising a plurality of power conditioners and a centralized management device that manages the plurality of power conditioners, wherein the plurality of power conditioners include a first power conditioner connected to a storage battery and a plurality of second power conditioners, and the centralized management device comprises a first index calculation unit that calculates a common first index for causing the plurality of second power conditioners to control their output power based on a charging rate of the storage battery, and transmits the first index to each of the plurality of second power conditioners, and each of the plurality of second power conditioners comprises a target power calculation unit that calculates an individual target power for the output power of the respective device based on the first index received from the centralized management device and an optimization problem set for each of the second power conditioners, and an output control unit that controls the output power of the respective device so that it becomes the individual target power.

[0007] In a preferred embodiment of the present invention, the centralized management device further includes a detection unit that detects interconnection point power at the interconnection point between the multiple power conditioners and a power grid, a second index calculation unit that calculates a common second index for causing the multiple power conditioners to control their output power so that the interconnection point power becomes a target power, and a switching unit that switches between a first state in which the first index is transmitted to each of the multiple second power conditioners and a second state in which the second index is transmitted to each of the multiple power conditioners, wherein the switching unit switches to the second state when the power system is interconnected to the power grid and to the first state when the power system is disconnected from the power grid.

[0008] In a preferred embodiment of the present invention, the first index calculation unit calculates the first index so that it has a minimum value when the charging rate is less than a predetermined value, and so that when the charging rate is equal to or greater than the predetermined value, it increases from the minimum value in proportion to the charging rate.

[0009] In a preferred embodiment of the present invention, the first index calculation unit calculates the first index so as to control the output power of the first power conditioner to an output target value calculated based on the charging rate.

[0010] A centralized management device provided by a second aspect of the present invention is a centralized management device that manages a plurality of power conditioners, the plurality of power conditioners including a first power conditioner connected to a storage battery and a plurality of second power conditioners, and includes an index calculation unit that calculates a common index for causing the plurality of second power conditioners to control output power based on the charging rate of the storage battery, and transmits the index to each of the plurality of second power conditioners, and each of the plurality of second power conditioners calculates an individual target power for its own output power based on the index received from the centralized management device and an optimization problem set for each, and controls the output power of the own device so that it becomes the individual target power. Effect of the Invention

[0011] According to the present invention, a centralized management device calculates a first index based on the charging rate of the storage battery, and transmits a common first index to each of the multiple power conditioners. Each of the multiple power conditioners controls its output power based on the received first index and an optimization problem set for each. By setting an appropriate optimization problem for each power conditioner, the charging rate of the storage battery is appropriately controlled. As a result, the power system of the present invention can continue to operate by an autonomous distributed cooperative control method using the first index even during independent operation. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing an overall configuration of a power system according to a first embodiment. [Diagram 2] FIG. 11 is a diagram illustrating an example of a correspondence relationship between a charging rate and a guidance index. [Diagram 3] FIG. 13 is a characteristic diagram showing a change characteristic of an individual target power with respect to an induction index. [Figure 4] FIG. 11 is a block diagram showing the overall configuration of a power system according to a second embodiment. [Diagram 5] FIG. 4 is a diagram showing an example of a correspondence relationship between a charging rate and an output target value. [Figure 6] FIG. 11 is a block diagram showing an overall configuration of a modified example of a power system according to the second embodiment. [Figure 7] FIG. 13 is a diagram showing an example of operation in the case where three electric vehicles are connected at once and start discharging one by one with a time lag. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0014] FIG. 1 is a block diagram showing the overall configuration of a power system F1 according to a first embodiment. The power system F1 is connected to a power system G and can transmit and receive power from the power system G. The power system F1 performs grid-connected operation while it is connected to the power system G. In grid-connected operation, the power system F1 controls output power by an autonomous distributed cooperative control method so that the power at the connection point between the power system F1 and the power system G (hereinafter referred to as "connection point power") becomes a target power. In the following description, the power value of the power flowing toward the power system G is taken as a positive value, and the power value of the power flowing in the opposite direction is taken as a negative value.

[0015] Furthermore, when an abnormality in the power system G (such as a ground fault, a short circuit, or a power outage) is detected, the power system F1 is separated from the power system G by the circuit breaker H. In this case, the power system F1 performs an independent operation and supplies power to the load E. Even during the independent operation, the power system F1 performs control using the autonomous distributed cooperative control method. However, during the independent operation, the power system F1 does not control the connection point power to a target power, but rather controls the storage battery 29 described below so that it does not become fully charged or become insufficiently charged.

[0016] The power system F1 includes a centralized control device A, a power conditioner B, a plurality of power conditioners C, a plurality of power conditioners D, and a load E.

[0017] The centralized control device A manages the entire power system F1. The centralized control device A calculates the induction index pr and transmits the calculated induction index pr to each power conditioner B, C, D. Each power conditioner B, C, D controls its output power based on the common induction index pr received from the centralized control device A. When a power outage occurs, the centralized control device A opens the circuit breaker H to isolate the power system F1 from the power grid G. Note that the centralized control device A does not need to have the function of opening and closing the circuit breaker H. In this case, the centralized control device A acquires the status of the circuit breaker H from a device that opens the circuit breaker H when a power outage occurs.

[0018] During interconnected operation in which the power system F1 is interconnected with the power system G, the centralized control device A monitors the connection point power and calculates a guide index pr for instantaneously controlling the connection point power to the target power. In this embodiment, the centralized control device A uses the power value detected at the connection point between the power system F1 and the power system G as the connection point power P(t). The centralized control device A may also receive detection values ​​of the output power detected by each of the power conditioners B, C, D and the load E, and use the total value calculated from these detection values ​​as the connection point power P(t). The centralized control device A calculates the connection point power P(t) based on the set target power P c and the connection point power P(t), and transmits a common guideline pr to each of the power conditioners B, C, and D. The communication method is not limited, and may be wired communication or wireless communication.

[0019] During independent operation in which the power system F1 is disconnected from the power grid G, the centralized control device A monitors the charging rate of the storage battery 29 and calculates a guide index pr based on the charging rate. The charging rate is also called SOC (State Of Charge), and is an index indicating the charging state, and indicates the ratio of the remaining charge to the capacity at full charge, expressed as a percentage. The centralized control device A also outputs an operation determination signal X indicating whether the power conditioners are in grid-connected operation or independent operation to each of the power conditioners B, C, and D. The centralized control device A includes a target setting unit 11, an index calculation unit 12, an index calculation unit 13, and a switching unit 14.

[0020] The target setting unit 11 and the index calculation unit 12 are components for calculating the induction index pr during grid-connected operation. The target setting unit 11 calculates a target power P c The target setting unit 11 acquires and sets the target power P c The target setting unit 11 acquires the target power P c Alternatively, the administrator may obtain the target power P c Alternatively, the target power P may be manually input. cInstead of directly acquiring the output suppression rate [%], the target power P is calculated by using the output suppression rate [%] and the rated output of the power system F1. c The target setting unit 11 may acquire the acquired target power P c to the index calculation unit 12.

[0021] The index calculation unit 12 calculates the connection point power P(t) as the target power P c The index calculation unit 12 calculates a guide index pr for controlling the power consumption at the connection point P(t) to the target power P(t) input from the target setting unit 11. c From the above, the guide index pr is calculated based on the following formulas (1) and (2), where ε is a gradient coefficient. Note that the formula for calculating the guide index pr by the index calculation unit 12 is not limited to this.

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[0022] The index calculation unit 13 is configured to calculate the guide index pr during independent operation. The index calculation unit 13 calculates the guide index pr based on the charging rate soc of the storage battery 29 acquired from the power conditioner B. The index calculation unit 13 stores a correspondence relationship between the charging rate soc and the guide index pr. FIG. 2 is a diagram showing an example of the correspondence relationship between the charging rate soc and the guide index pr. In the correspondence relationship shown in FIG. 2, the guide index pr is set to a minimum value "-Pr lim When the charging rate soc is 80% or more, lim " in proportion to the charging rate soc, and becomes "0" when the charging rate soc is 100%. In reality, the power conditioner B stops when the charging rate soc exceeds a predetermined range, so the charging rate soc never becomes 0% or 100%. The index calculation unit 13 calculates the induction index pr based on, for example, the following equations (3) and (4) which represent the correspondence shown in FIG. 2. The calculation equation for the induction index pr by the index calculation unit 13 is not limited to this. The correspondence shown in FIG. 2 is only an example, and the correspondence between the charging rate soc and the induction index pr stored in the index calculation unit 13 is not limited.

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[0023] The switching unit 14 is configured to switch the operation of the power system F1 between grid-connected operation and independent operation. The switching unit 14 switches between the guide index pr calculated by the index calculation unit 12 and the guide index pr calculated by the index calculation unit 13, and transmits the guide index pr to each of the power conditioners B, C, and D. When the circuit breaker H is closed and the power system F1 is connected to the power system G, the switching unit 14 transmits the guide index pr calculated by the index calculation unit 12 to perform grid-connected operation. On the other hand, when the circuit breaker H is opened and the power system F1 is separated from the power system G, the switching unit 14 transmits the guide index pr calculated by the index calculation unit 13 to perform independent operation. The switching unit 14 also transmits an operation discrimination signal X indicating whether the power system F1 is in grid-connected operation or independent operation.

[0024] A storage battery 29 is connected to the power conditioner B. The number of storage batteries 29 connected to the power conditioner B is not limited. The power conditioner B converts DC power discharged from the storage battery 29 into AC power and outputs it. The power conditioner B also converts AC power into DC power and charges the storage battery 29. In other words, the power conditioner B controls the charging and discharging of the storage battery 29 by controlling the output power of its own device (the power that the power conditioner B outputs to the power system G side). The power value of the output power of the power conditioner B is a positive value when the storage battery 29 is discharging, and is a negative value when the storage battery 29 is charging.

[0025] The power conditioner B includes a target power calculation unit 21, an output control unit 22, and a charging rate detection unit 23. The target power calculation unit 21 uses the guidance indicator pr received from the centralized management device A to calculate an individual target power P refIn the target power calculation unit 21, an optimization problem suitable for charging and discharging a storage battery or a calculation formula calculated from the optimization problem is set in advance. For example, the target power calculation unit 21 calculates an individual target power P ref In this embodiment, the target power calculation unit 21 is set with a calculation formula for the case where the power system F1 is in grid-connected operation. During independent operation, the storage battery 29 and the power conditioner B act as a voltage source similar to an emergency generator, and control the output voltage to a predetermined voltage. Therefore, the input / output power of the power conditioner B is determined based on the individual target power P ref Regardless of the above, the power consumption is determined according to the input / output power of the power conditioners C and D and the power consumption of the load E. Whether the power system F1 is in grid-connected operation or independent operation is determined based on an operation determination signal X input from the centralized control device A.

[0026] During grid-connected operation, the target power calculation unit 21 uses a calculation formula as shown by the characteristic line in Fig. 3(a). In Fig. 3(a), the horizontal axis indicates the induction index pr, and the vertical axis indicates the individual target power P ref It shows that. lmt is the maximum value of the induction index pr, and -pr lmt is the minimum value of the induction index pr. The same applies to the other figures in FIG. 3 shown below. On the other hand, during the independent operation, the target power calculation unit 21 calculates the individual target power P ref The characteristic line shown in FIG. 3(a) is an example, and the individual target power P ref The change characteristic of the individual target power P ref When the voltage is positive, the battery 29 is discharged, and when the voltage is negative, the battery 29 is charged.

[0027] The output control unit 22 calculates the individual target power P ref Specifically, the output control unit 22 controls the output power based on a detection value of the output power of the power conditioner B detected by a sensor and an individual target power P refBased on the difference between the individual target power P and the output power of the power conditioner B, the switching of the inverter circuit (not shown) is adjusted to the individual target power P ref to control.

[0028] The charging rate detection unit 23 estimates the charging rate soc of the storage battery 29 connected to the power conditioner B (when multiple storage batteries 29 are connected, the charging rate of all the connected storage batteries 29). The charging rate detection unit 23 estimates the charging rate soc using a well-known method such as a current integration method or an OCV method. The method of estimating the charging rate soc by the charging rate detection unit 23 is not limited. The charging rate detection unit 23 outputs the estimated charging rate soc to the centralized management device A. The charging rate soc is used by the index calculation unit 13 to calculate the induction index pr during independent operation.

[0029] Each power conditioner C is connected to a solar cell 39, and converts DC power generated by the solar cell 39 into AC power and outputs it. Each power conditioner C controls the power generation of the solar cell 39 by controlling the output power of its own device (the power that the power conditioner C outputs to the power grid G). The power value of the output power of each power conditioner C is a positive value.

[0030] Each power conditioner C includes a target power calculation unit 31 and an output control unit 32. The target power calculation unit 31 calculates an individual target power P, which is a target value of the output power of the power conditioner C, based on a preset optimization problem, using the guidance indicator pr received from the centralized management device A. ref In the target power calculation unit 31, an optimization problem suitable for power generation by a solar cell or a calculation formula calculated from the optimization problem is set in advance. For example, the target power calculation unit 31 calculates an individual target power P ref In this embodiment, a different arithmetic expression is set in the target power calculation unit 31 depending on whether the power system F1 is in grid-connected operation or in independent operation. Whether the power system F1 is in grid-connected operation or in independent operation is determined based on an operation determination signal X input from the centralized management device A.

[0031] During grid-connected operation, the target power calculation unit 31 uses an arithmetic expression as shown by the characteristic line in Fig. 3(b). During isolated operation, the target power calculation unit 31 uses an arithmetic expression as shown by the characteristic line in Fig. 3(c). Note that the characteristic lines shown in Figs. 3(b) and (c) are merely examples, and the individual target power P ref The change characteristic of the individual target power P ref is a positive value, and as it becomes smaller, the output power of the solar cell 39 is suppressed.

[0032] The output control unit 32 calculates the individual target power P ref Specifically, the output control unit 32 controls the output power based on a detection value of the output power of the power conditioner C detected by a sensor and an individual target power P ref Based on the difference between the output power of the power conditioner C and the individual target power P, the switching of the inverter circuit (not shown) is adjusted. ref The number of power conditioners C included in the power system F1 is not limited, and may be one.

[0033] Each power conditioner D is a device that charges and discharges the connected electric vehicle 5, and is a so-called EV charger and discharger. The electric vehicle 5 is a vehicle that can run using an electric motor as a power source, and includes vehicles equipped with an internal combustion engine (for example, a plug-in hybrid vehicle). The electric vehicle 5 is equipped with a storage battery 51. The power conditioner D charges and discharges the storage battery 51 installed in the electric vehicle 5 connected to it by a charging cable 52. The electric motor of the electric vehicle 5 runs on the power stored in the storage battery 51.

[0034] Each power conditioner D includes a target power calculation unit 41 and an output control unit 42. The target power calculation unit 41 calculates an individual target power P, which is a target value of the output power of the power conditioner D, based on a preset optimization problem, using the guidance indicator pr received from the centralized management device A.ref In the target power calculation unit 41, an optimization problem suitable for charging and discharging the electric vehicle 5 or a calculation formula calculated from the optimization problem is set in advance. For example, the target power calculation unit 41 calculates an individual target power P ref In this embodiment, a different arithmetic expression is set in the target power calculation unit 41 depending on whether the power system F1 is in grid-connected operation or in independent operation. Whether the power system F1 is in grid-connected operation or in independent operation is determined based on an operation determination signal X input from the centralized management device A.

[0035] During grid-connected operation, the target power calculation unit 41 uses an arithmetic expression as shown by the characteristic line in Fig. 3(d). During isolated operation, the target power calculation unit 41 uses an arithmetic expression as shown by the characteristic line in Fig. 3(e). Note that the characteristic lines shown in Figs. 3(d) and (e) are merely examples, and the individual target power P ref The change characteristic of the individual target power P ref When the value is positive, the electric vehicle 5 is discharged, and when the value is negative, the electric vehicle 5 is charged.

[0036] The output control unit 42 calculates the individual target power P ref Specifically, the output control unit 42 controls the output power based on a detection value of the output power of the power conditioner D detected by a sensor and an individual target power P ref Based on the difference between the output power of the power conditioner D and the individual target power P, the switching of the inverter circuit (not shown) is adjusted. ref The number of power conditioners D included in the power system F1 is not limited, and may be one.

[0037] Each of the power conditioners B, C, and D autonomously controls the output power based on the common induction index pr received from the centralized control device A. When the power system F1 is in grid-connected operation, the centralized control device A transmits the induction index pr calculated by the index calculation unit 12 to each of the power conditioners B, C, and D. In this embodiment, the connection point power P(t) is set to the target power P c When the power P(t) is larger than the target power P, the induction index pr becomes larger. c When the induction index pr is smaller, the induction index pr becomes smaller. Each of the power conditioners B, C, and D operates to reduce the connection point power P(t) as the induction index pr becomes larger, and operates to increase the connection point power P(t) as the induction index pr becomes smaller.

[0038] The power conditioner B calculates the individual target power P for the received induction index pr using the calculation formula shown by the characteristic line in Figure 3(a). ref Calculate the individual target power P ref The output power is controlled based on the above. Therefore, when the guide index pr is a positive value, the power value of the output power of the power conditioner B is a negative value, so the power conditioner charges the storage battery 29, and the larger the guide index pr, the larger the amount of charge. On the other hand, when the guide index pr is a negative value, the power value of the output power is a positive value, so the power conditioner discharges the storage battery 29, and the smaller the guide index pr, the larger the amount of discharge.

[0039] Each power conditioner C calculates the individual target power P for the received induction index pr using the calculation formula shown by the characteristic line in Figure 3(b). ref Calculate the individual target power P ref Therefore, when the induction index pr is a negative value, the output power of each power conditioner C is maximized. On the other hand, when the induction index pr is a positive value, the output power is suppressed as the induction index pr is larger.

[0040] Each power conditioner D calculates the individual target power P for the received induction index pr using the calculation formula shown by the characteristic line in Figure 3(d). refCalculate the individual target power P ref Therefore, each power conditioner D discharges the storage battery 51 of the electric vehicle 5 when the induction index pr is less than a negative predetermined value, and charges the storage battery 51 when the induction index pr is equal to or greater than the negative predetermined value.

[0041] Each of the power conditioners B, C, and D autonomously controls the output power as described above based on the common induction index pr received from the centralized control device A. As a result, the connection point power P(t) of the power system F1 is equal to the target power P c is controlled by.

[0042] When the power system F1 is in an independent operation, the centralized control device A transmits the guide index pr calculated by the index calculation unit 13 to each of the power conditioners B, C, and D. The power conditioner B performs constant voltage control regardless of the guide index pr. The centralized control device A does not need to transmit the guide index pr to the power conditioner B. In this embodiment, as shown in the correspondence relationship between the charging rate soc and the guide index pr in FIG. 2, when the charging rate soc of the storage battery 29 is less than 80%, the guide index pr is set to the minimum value "-Pr lim In this case, the power value of the output power of each power conditioner C becomes the maximum value, as shown by the characteristic line in FIG. 3(c). Also, the power value of the output power of each power conditioner D becomes the maximum value (positive value), as shown by the characteristic line in FIG. 3(e), so that the storage battery 51 of the electric vehicle 5 is discharged to the maximum. As a result, the storage battery 29 is charged by the output power of each solar cell 39 and the discharged power from the storage battery 51 of each electric vehicle 5.

[0043] In addition, when the charging rate SOC of the storage battery 29 is 80% or more, the induction index pr becomes "-pr lim" in proportion to the charging rate soc, and becomes "0" when the charging rate soc is 100%. In this case, as shown by the characteristic line in FIG. 3(c), each power conditioner C suppresses the output power when the induction index pr becomes equal to or greater than a predetermined value. Also, as shown by the characteristic line in FIG. 3(e), each power conditioner D switches from discharging to charging when the induction index pr becomes equal to or greater than a predetermined value. As a result, when the charging rate soc of the storage battery 29 becomes equal to or greater than 80%, the charging amount of the storage battery 29 is suppressed, and the storage battery 51 of each electric vehicle 5 is discharged before being fully charged. Also, the output power of each solar cell 39 is suppressed according to the charging rate soc of the storage battery 29, and the charging and discharging of the storage battery 51 of each electric vehicle 5 is also controlled. Note that each power conditioner C may stop the output power by disconnecting when the induction index pr becomes equal to or greater than a predetermined value.

[0044] Each of the power conditioners C, D autonomously controls the output power as described above based on the common induction index pr received from the centralized control device A, so that the charging rate soc of the storage battery 29 is controlled to be within as appropriate a range as possible.

[0045] Next, the operation and effects of the centralized control device A and the power system F1 according to this embodiment will be described.

[0046] According to this embodiment, when the power system F1 is in an independent operation, the centralized control device A calculates the induction index pr based on the charging rate soc of the storage battery 29, and transmits the common induction index pr to each of the power conditioners B, C, and D. Each of the power conditioners C and D calculates the individual target power P based on the received induction index pr and an arithmetic expression calculated from the optimization problem set for each of them. ref The output power of the device is calculated to be the individual target power P refEach power conditioner C, D controls the output power according to a set calculation formula, so that the charging rate SOC of the storage battery 29 is appropriately controlled. For example, when the charging rate SOC is less than 80%, the storage battery 29 is charged by the output power of each solar cell 39 and the discharged power from the storage battery 51 of each electric vehicle 5, so that the charging rate SOC is prevented from becoming too small. Also, when the charging rate SOC is 80% or more, the charging amount of the storage battery 29 is restricted, and the battery 29 is discharged before being fully charged. As a result, the power system F1 can continue to operate by the autonomous distributed cooperative control method using the induction index pr even during autonomous operation.

[0047] According to the present embodiment, when the power system F1 is in grid-connected operation, the centralized control device A sets the connection point power P(t) to the target power P c The power conditioner calculates a guide index pr for instantaneous value control and transmits a common guide index pr to each of the power conditioners B, C, and D. Each of the power conditioners B, C, and D calculates an individual target power P based on the received guide index pr and an arithmetic expression calculated from the optimization problem set for each. ref The output power of the device is calculated to be the individual target power P ref Each power conditioner B, C, and D controls its output power according to the set formula, so that the connection point power P(t) is equal to the target power P c is controlled by.

[0048] According to the present embodiment, when the power system F1 is connected to the power system G, the switching unit 14 of the centralized management device A transmits the induction index pr calculated by the index calculation unit 12 for performing the interconnected operation. On the other hand, when the power system F1 is disconnected from the power system G, the switching unit 14 transmits the induction index pr calculated by the index calculation unit 13 for performing the independent operation. The switching unit 14 also transmits an operation discrimination signal X indicating whether the power system F1 is in the interconnected operation or the independent operation in accordance with the operation discrimination signal X, and performs control based on the received induction index pr. Therefore, the power system F1 can be operated by appropriately switching between the interconnected operation and the independent operation.

[0049] In the present embodiment, the case has been described in which the arithmetic expressions (characteristic diagrams) used in each of the power conditioners C and D differ depending on whether they are in grid-connected operation or independent operation, but this is not limited thereto. Each of the power conditioners C and D may be set with an arithmetic expression (characteristic diagram) that can be commonly used in both grid-connected operation and independent operation.

[0050] In addition, in the present embodiment, the case has been described in which the power system F1 includes the power conditioner B connected to the storage battery 29, the power conditioner C connected to the solar cell 39, and the power conditioner D connected to the electric vehicle 5, but this is not limiting. The power system F1 does not have to include the power conditioner C or the power conditioner D. Furthermore, the power system F1 may include other power devices, and the centralized management device A may include the other power devices in the objects to be managed.

[0051] Fig. 4 is a block diagram showing the overall configuration of a power system F2 according to the second embodiment. In Fig. 4, elements that are the same as or similar to those in the power system F1 according to the first embodiment are given the same reference numerals, and duplicated explanations are omitted. The power system F2 according to this embodiment differs from the power system F1 according to the first embodiment in the method of calculating the induction index pr during independent operation.

[0052] The power conditioner B according to the second embodiment further includes an output power detection unit 24. The output power detection unit 24 detects the output power of the power conditioner B, and transmits the detected output power value Pb to the centralized management device A.

[0053] The centralized control device A according to the second embodiment further includes a target setting unit 15. The target setting unit 15 sets an output target value P c The target setting unit 15 calculates the charging rate soc and the output target value P c b. Figure 5 shows the relationship between the charging rate soc and the output target value P c 5 is a diagram showing an example of a correspondence relationship between the output target value P c b is "-5kW" when the charging rate soc is less than 60%, and increases from "-5kW" in proportion to the charging rate soc when the charging rate soc is 60% or more, and becomes "0kW" when the charging rate soc is 100%. In reality, the power conditioner B stops when the charging rate soc exceeds a predetermined range, so the charging rate soc never becomes 0% or 100%. The target setting unit 15 determines the output target value P c b is calculated. Note that the output target value P c The calculation formula for b is not limited to this. The correspondence relationship shown in FIG. 5 is only an example, and the relationship between the charging rate soc stored in the target setting unit 15 and the output target value P c The correspondence relationship with the calculated output target value P c b is output to the index calculation unit 13.

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[0054] The index calculation unit 13 according to the second embodiment calculates the output power value Pb as the output target value P cThe index calculation unit 13 calculates a guide index pr for controlling the power conditioner B to be in the range of 100 to 1500 kWh based on the output power value Pb received from the output power detection unit 24 of the power conditioner B and the output target value P c The induction index pr is calculated from b based on the following expressions (7) and (8), where εb is a gradient coefficient. Note that the calculation expression for the induction index pr by the index calculation unit 12 is not limited to this.

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[0055] In this embodiment, the target power calculation unit 31 of the power conditioner C uses an arithmetic expression as shown by the characteristic line in Fig. 3(b) during the independent operation as well as during the grid-connected operation. Also, the target power calculation unit 41 of the power conditioner D uses an arithmetic expression as shown by the characteristic line in Fig. 3(d) during the independent operation as well as during the grid-connected operation. Note that the arithmetic expression used by the target power calculation units 31, 41 during the independent operation is not limited.

[0056] According to this embodiment, when the power system F2 is in an independent operation, the centralized control device A transmits the induction index pr calculated by the index calculation unit 13 to each of the power conditioners B, C, and D. Each of the power conditioners C and D autonomously controls the output power based on the common induction index pr received from the centralized control device A, so that the output power of the power conditioner B reaches the output target value P c The output target value P c b is calculated by the target setting unit 15 based on the charging rate soc of the storage battery 29. c b is set so that when the charging rate soc is less than 60%, the power conditioner B charges at 5 kW. This prevents the charging rate soc from becoming too small. In addition, the output target value P cb is set so that the amount of charge of the power conditioner B is suppressed when the charging rate soc is 60% or more. Therefore, the charging rate soc is prevented from becoming too large. This allows the power system F2 to continue operating by the autonomous decentralized cooperative control method using the induction index pr even during independent operation.

[0057] Also in this embodiment, when the power system F2 is in grid-connected operation, the connection point power P(t) is set to the target power P c In addition, the power system F2 can be operated by appropriately switching between grid-connected operation and isolated operation.

[0058] FIG. 6 is a block diagram showing the overall configuration of a modified example of the power system F2 according to the second embodiment. In FIG. 6, elements that are the same as or similar to those in the power system F2 according to the second embodiment are given the same reference numerals, and duplicated explanations are omitted. When an electric vehicle 5 is connected to each power conditioner D at once during the independent operation of the power system F2 according to the second embodiment, the update of the induction index pr may not be in time, and an overcurrent may be detected in the power conditioner B. Similarly, when the output of the solar cell 39 connected to each power conditioner C increases suddenly, an overcurrent may be detected. The power system F2 according to this modified example is provided with a countermeasure for preventing an overcurrent from being detected when the update of the induction index pr is not in time.

[0059] The power conditioner C according to this modification further includes an output power detection unit 34. The output power detection unit 34 detects the output power of the power conditioner C, and transmits the detected output power value to the centralized management device A.

[0060] The power conditioner D according to this modification further includes a connection detection unit 43. The connection detection unit 43 detects that the electric vehicle 5 is connected to the power conditioner D, and transmits a detection signal to the centralized management device A.

[0061] The centralized control device A according to this modification receives the output power value from each of the output power detection units 34 of the power conditioners C, and when the total power value becomes equal to or greater than a predetermined power value, stops one of the power conditioners C. The method of stopping the power conditioner C is not limited, and the switching of the inverter circuit of the power conditioner C may be stopped, or the power conditioner C may be disconnected. The centralized control device A may also stop a plurality of power conditioners C according to the total power value. When the output of each solar cell 39 increases suddenly and the induction index pr cannot be updated in time, one of the power conditioners C is stopped to suppress the output. This allows the centralized control device A to prevent an overcurrent from being detected in the power conditioner B.

[0062] In addition, the centralized management device A according to this modification receives a detection signal from the connection detection unit 43 of each power conditioner D, and when a large number of electric vehicles 5 are connected at the same time, the centralized management device A does not start discharging from all electric vehicles 5 at once, but starts discharging one by one with a time lag. The number of vehicles that start discharging is not limited to one, and may be two or more. Even when electric vehicles 5 are connected to each power conditioner D at the same time, by starting discharging one by one with a time lag, it is possible to suppress a sudden increase in the discharge amount. In addition, the induction index pr is updated until the start of discharging of the next power conditioner D. This allows the centralized management device A to prevent an overcurrent from being detected in the power conditioner B.

[0063] FIG. 7 is a diagram showing an example of operation in the case where three electric vehicles 5 are connected at once and start discharging one by one with a time lag. The load E consumes 5 kW of power. Each of the power conditioners B and D changes the output power according to the induction index pr. Note that in each diagram in FIG. 7, the power conditioner D and the electric vehicles 5 that are not discharging are omitted. Before the three electric vehicles 5 are connected, the charging rate soc of the storage battery 29 is less than 60%, and the output target value Pcb is "-5 kW" (see FIG. 5).

[0064] In FIG. 7(a), one electric vehicle 5 starts discharging, and one power conditioner D outputs power. lim Power conditioner D is discharging at 10 kW, which is the maximum output (see Figure 3(d)). Power conditioner B is charging at 5 kW, excluding the 5 kW consumed by load E.

[0065] In FIG. 7(b), the second electric vehicle 5 starts discharging, and the two power conditioners D output power. lim " and each power conditioner D is discharging its maximum output of 10 kW. Since the power consumed by load E is 5 kW, power conditioner B is charged with 15 kW. Therefore, the output power value Pb (-15 kW) and the output target value P c Due to the difference with b (-5kW), the induction index pr becomes larger. As a result, the output of power conditioner D decreases (see Fig. 3(d)), discharging to 5kW, and power conditioner B is restricted to charging to 5kW.

[0066] In FIG. 7(c), the third electric vehicle 5 starts discharging, and the three power conditioners D are outputting power. Since the induction index pr is large, each power conditioner D is discharging 5 kW. Since the power consumed by the load E is 5 kW, 10 kW is charged to the power conditioner B. Therefore, the output power value Pb (-10 kW) and the output target value P c The difference with b (-5kW) causes the induction index pr to become even larger. As a result, the output of power conditioner D decreases to 3.3kW discharging, and power conditioner B is restricted to charging at 5kW.

[0067] As described above, even if electric vehicles 5 are connected to each power conditioner D at the same time, the centralized control device A starts discharging one by one with a time lag, so that a sudden increase in the discharge amount can be suppressed. In addition, the induction index pr is updated until the next power conditioner D starts discharging. This allows the centralized control device A to prevent an overcurrent from being detected in the power conditioner B.

[0068] The power system F2 according to the second embodiment may employ another overcurrent prevention method in addition to or instead of the overcurrent prevention method according to the above-described modified example. For example, a discharge-side C rate, which is a characteristic value for limiting the output power during discharging, may be set for each power conditioner D. In this case, the output power of each power conditioner D is limited according to the C rate, so that an overcurrent is prevented in the power conditioner B.

[0069] The power system and the centralized control device according to the present invention are not limited to the above-described embodiment. The specific configurations of the components of the power system and the centralized control device according to the present invention can be freely designed in various ways. [Explanation of symbols]

[0070] A: centralized control device, 12, 13: index calculation unit, 14: switching unit, B, C, D: power conditioners, 21, 31, 41: target power calculation unit, 22, 32, 42: output control unit, 29: storage battery, F1, F2: power system, G: power grid

Claims

1. A power system including a plurality of power conditioners and a centralized management device that manages the plurality of power conditioners, The plurality of power conditioners include a first power conditioner connected to a storage battery and a plurality of second power conditioners, the centralized management device includes a first index calculation unit that calculates a common first index for causing the plurality of second power conditioners to control output power based on a charging rate of the storage battery, and transmits the first index to each of the plurality of second power conditioners; Each of the plurality of second power conditioners includes: a target power calculation unit that calculates an individual target power of an output power of the device itself based on the first index received from the centralized management device and an optimization problem set for each of the first indexes; an output control unit that controls an output power of the device itself so as to become the individual target power; Equipped with Power system.

2. The centralized management device A detection unit that detects interconnection point power at an interconnection point between the plurality of power conditioners and a power grid; a second index calculation unit that calculates a common second index for causing the plurality of power conditioners to control output power so that the interconnection point power becomes a target power; A switching unit that switches between a first state in which the first indicator is transmitted to each of the plurality of second power conditioners and a second state in which the second indicator is transmitted to each of the plurality of power conditioners; Further equipped with the switching unit sets the power system to the second state when the power system is connected to the power grid, and sets the power system to the first state when the power system is disconnected from the power grid. The power system of claim 1 .

3. The first index calculation unit calculates the first index so that the first index has a minimum value when the charging rate is less than a predetermined value, and has a value that increases from the minimum value in proportion to the charging rate when the charging rate is equal to or greater than the predetermined value. The power system of claim 1 .

4. The first index calculation unit calculates the first index so as to control the output power of the first power conditioner to an output target value calculated based on the charging rate. The power system of claim 1 .

5. A centralized management device that manages a plurality of power conditioners, The plurality of power conditioners include a first power conditioner connected to a storage battery and a plurality of second power conditioners, An index calculation unit that calculates a common index for causing the plurality of second power conditioners to control output power based on the charging rate of the storage battery, and transmits the index to each of the plurality of second power conditioners; Each of the second power conditioners calculates an individual target power of the output power of the own device based on the index received from the centralized management device and the optimization problem set for each of the second power conditioners, and controls the output power of the own device to become the individual target power. Centralized management device.

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