Method of controlling charging and discharging

Abstract

To provide a power conditioner system including a charge / discharge stand of a vehicle, capable of stabilizing voltage of a DC link and appropriately executing power transfer between the vehicle and a storage battery.SOLUTION: A method includes a step of selecting a battery unit that executes charging / discharging operation for controlling voltage of a DC link 21, a step of charging all battery units 10 and a vehicle battery unit 71 when PV≥PL+PB+PC, and a step of discharging all the battery units 10 and the vehicle battery unit 71 when PV≤PL+PB+PC and PL≥PV.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a technique for controlling charging and discharging in a power conditioner system including a charging and discharging stand for a vehicle. [Background technology]

[0002] With the widespread use of distributed power sources such as solar power generation systems and wind power generation systems, power conditioner systems equipped with storage batteries are becoming increasingly popular for stabilizing the grid, adjusting supply and demand, and preparing for long-term power outages due to disasters. Furthermore, with the widespread use of electric vehicles, there is an increasing demand for power conditioner systems that include vehicle charging and discharging stations.

[0003] Patent Document 1 provides a charge / discharge control method for a power storage system for controlling the voltage of a DC link in a power conditioner system including a power storage system having multiple battery units. In this charge / discharge control method, at least one first battery unit is selected from the multiple battery units to perform a charge / discharge operation for controlling the voltage of the DC link. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-17295 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 does not describe a configuration in which the power conditioner system includes a vehicle charging / discharging stand. In a power conditioner system including a vehicle charging / discharging system, when operating autonomously during a power outage or other such event, the user may be able to select between V2B (vehicle to battery) mode and B2V (battery to vehicle) mode. In such a power conditioner system including a vehicle charging / discharging stand, it is required to stabilize the DC link voltage and to control the appropriate transfer of power between the vehicle and the battery.

[0006] The present invention aims to provide a method for stabilizing the voltage of a DC link and controlling charging and discharging so as to appropriately transfer power between a vehicle and a storage battery in a power conditioner system including a vehicle charging and discharging station. [Means for solving the problem]

[0007] An aspect of the present invention is a charge / discharge control method in a power conditioner system in which a distributed power source, at least one battery unit having a storage battery, and a charging / discharging stand for charging / discharging a vehicle battery unit are connected to a DC link, the method comprising the steps of selecting at least one first battery unit from the battery units and the vehicle battery units to perform charge / discharge operations to control the voltage of the DC link, where PV is the total power generated by the distributed power sources, PL is the load power consumption of the power conditioner system, PB is the charge / discharge power of the battery unit, which is positive when charging and negative when discharging, and PC is the charge / discharge power of the vehicle battery unit, which is positive when charging and negative when discharging, and selecting at least one first battery unit to perform charge / discharge operations to control the voltage of the DC link from among the battery units and the vehicle battery units, charging all of the battery units and the vehicle battery unit when PV≧PL+PB+PC, and discharging all of the battery units and the vehicle battery unit when PV≦PL+PB+PC and PL≧PV.

[0008] In the above aspect, when the vehicle battery unit is selected as the first battery unit, in the V2B mode for charging the battery unit from the vehicle battery unit, when PV < PL + PB, the vehicle battery unit discharges the shortage of PV (PV - PB - PL = PC), and the step of charging the battery unit; when the battery unit is selected as the first battery unit, in the B2V mode for charging the vehicle battery unit from the battery unit, when PV < PL + PC, the step of charging the vehicle battery unit and discharging the shortage of PV (PV - PC - PL = PB) from the battery unit may be provided.

[0009] Also, in the above aspect, when the vehicle battery unit is selected as the first battery unit, in the V2B mode for charging the battery unit from the vehicle battery unit, when PV ≤ PL + PB ≤ PV - PC, the vehicle battery unit discharges the shortage of PV (PV - PB - PL = PC), and the step of charging the battery unit; when PV < PL + PB and PL + PB > PV - PC, the vehicle battery unit discharges the shortage of PV (PV - PB - PL = PC), and the step of charging the battery unit so that PV - PC = PL + PB is achieved. When the battery unit is selected as the first battery unit, in the B2V mode for charging the vehicle battery unit from the battery unit, when PV ≤ PL + PC ≤ PV - PB, the battery unit discharges the shortage of PV (PV - PC - PL = PB), and the step of charging the vehicle battery unit; when PV < PL + PC and PL + PB > PV - PB, the battery unit discharges the shortage of PV (PV - PC - PL = PB), and the step of charging the vehicle battery unit so that PV - PB = PL + PC is achieved may be provided.

[0010] This makes it possible to stabilize the voltage of the DC link and to properly transfer power between the vehicle and the storage battery. [Effects of the Invention]

[0011] According to the present invention, in a power conditioner system including a vehicle charging / discharging stand, it is possible to stabilize the voltage of the DC link and to appropriately transfer power between the vehicle and the storage battery. [Brief explanation of the drawings]

[0012] [Figure 1] Overall configuration example of a power conditioner system in an embodiment [Figure 2] Cases of charge / discharge control according to the embodiment [Figure 3] 1 is a flowchart illustrating an example of a charge / discharge control method according to an embodiment. [Figure 4] 1 is a flowchart illustrating an example of a charge / discharge control method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its scope of application, or its uses.

[0014] (Embodiment) Fig. 1 shows an example of the overall configuration of a power conditioner system. In Fig. 1, the power storage system 1 includes n (n is a positive integer) battery units 10 that can be charged and discharged. Each battery unit 10 includes a storage battery 11 and a power converter 12.

[0015] The power conditioner 2 includes a DC link 21 connected to each battery unit 10 of the power storage system 1, an inverter 22 that converts DC power of the DC link 21 into AC power, and a controller 23 that controls the charge and discharge operations of the battery units 10 of the power storage system 1. The controller 23 is realized by, for example, a microcomputer equipped with a processor and a memory.

[0016] The power converter 12 of each battery unit 10 includes a bidirectional DC / DC converter, and charges and discharges the storage battery 11 in accordance with a signal transmitted from the controller 23 of the power conditioner 2. In addition, the power converter 12 of each battery unit 10 includes a voltage sensor that measures the voltage of the DC link 21.

[0017] The photovoltaic power generation system 4 is connected to a DC link 21 via a power converter 5 and outputs electric power. The photovoltaic power generation system is an example of a distributed power source, and may also be, for example, a hydroelectric power generation system, a wind power generation system, etc. The output power of the power conditioner 2 is supplied to a commercial power system and a load.

[0018] The V2H (Vehicle to Home) station 6 is connected to the DC link 21 and charges and discharges the battery unit 71 of the vehicle 7. The V2H station 6 also has the function of supplying electricity from the battery unit 71 of the vehicle 7 to the inside of the building. The V2H station 6 charges and discharges the battery unit 71 of the vehicle 7 in accordance with a signal sent from the controller 23 of the power conditioner 2.

[0019] Here, the inverter 22 of the power conditioner 2 performs control to stabilize the voltage of the DC link 21. However, for example, when a power limit command is received from the commercial power grid or when the power consumption of the load suddenly changes, it may become difficult to control the voltage of the DC link 21.

[0020] Therefore, in this embodiment, one of the battery units 10 included in the energy storage system 1 and the battery unit 71 included in the vehicle 7 is selected, and the selected battery unit controls the voltage of the DC link 21. The method described in Patent Document 1 is assumed for selecting the battery unit. The controller 23 of the power conditioner 2 transmits a CV command to the selected battery unit. Here, "CV" refers to CV control, i.e., constant voltage control, and refers to control to maintain the voltage of the DC link 21 constant. The selected battery unit performs a charging operation when the voltage of the DC link 21 is higher than a predetermined reference value, and performs a discharging operation when the voltage of the DC link 21 is lower than the predetermined reference value. This allows the voltage of the DC link 21 to be more stabilized even when the inverter 22 of the power conditioner 2 has difficulty in appropriately controlling the voltage of the DC link 21.

[0021] Here, we consider a case where the power conditioner system is not connected to the grid power and is operating independently, such as during a power outage. In such a case, it would be practically useful if the user could operate the V2B mode, i.e., a mode in which the vehicle charges the storage battery, or the B2V mode, i.e., a mode in which the storage battery charges the vehicle. For example, even if the commercial grid is affected by a power outage during a disaster and the power supply is cut off, the electric vehicle can be moved to a location where it can be charged and charged, and the power can be used to charge the storage battery and power the household loads. In addition, the electric vehicle can be operated by charging the power from the domestic storage battery to the electric vehicle.

[0022] In this embodiment, while executing CV control on one of the battery units, the V2B mode or B2V mode can be executed, enabling power interchange between the vehicle and the storage battery.

[0023] FIG. 2 shows examples of case-by-case charge / discharge control according to this embodiment. FIG. 2 assumes a configuration in which the number n of battery units 10 in the power storage system 1 of FIG. 1 is 2, i.e., the power storage system 1 includes two battery units 10. In FIG. 2, the two battery units 10 included in the power storage system 1 are referred to as "storage battery 1" and "storage battery 2," and are also collectively referred to as "storage battery." Furthermore, the battery unit 71 included in the vehicle 7 connected to the V2H stand 6 is referred to as the "vehicle." In the following explanation, to the extent that no misunderstanding occurs, the battery unit 10 of the power storage system 1 will be referred to simply as the "storage battery," and the battery unit 71 included in the vehicle 7 connected to the V2H stand 6 will be referred to simply as the "vehicle."

[0024] 2, "CV" refers to the above-mentioned CV control, i.e., constant voltage control, which indicates control to maintain a constant voltage of the DC link 21. "CC" refers to CC control, i.e., constant current control, which indicates control to charge and discharge a predetermined amount of power while the DC link 21 is at a constant voltage.

[0025] Pattern 1-4 in the upper part of Fig. 2 is a case where one of the two battery units 10 included in the power storage system 1 performs CV control. Note that in Fig. 2, storage battery 1 performs CV control, but similar control is performed even when storage battery 2 performs CV control. Furthermore, even when the number n of battery units 10 is 3 or more, similarly, one of the battery units 10 performs CV control, and the other (n-1) battery units 10 perform CC control.

[0026] Also, let the total power generation of the solar power generation system 4 be PV, and the load consumption power be PL. When the charge-discharge power of the storage battery 1 is PB1 with a positive value during charging and a negative value during discharging, and the charge-discharge power of the storage battery 2 is PB2 with a positive value during charging and a negative value during discharging, the charge-discharge power PB of the two battery units 10 of the power storage system 1, that is, the storage battery, is PB = PB1 + PB2. The charge-discharge power of the battery unit 71 provided in the vehicle 7, that is, the charge-discharge power PC is set to a positive value during charging of the vehicle and a negative value during discharging.

[0027] Pattern 1 is the case where PV ≥ PL + PB + PC holds. That is, it is the case where the total power generation of the solar power generation system 4 exceeds the sum of the load consumption power, the charging power of the storage battery, and the charging power of the vehicle. In this case, the storage battery and the vehicle perform charging. The vehicle charges according to the command value from the power conditioner 2, and the storage battery charges the surplus.

[0028] Pattern 2 is the case where PV ≤ PL + PC ≤ PV - PB holds. That is, it is the case where the total power generation of the solar power generation system 4 is less than the sum of the load consumption power and the charging power of the vehicle, but when the absolute value of the discharge power of the storage battery is added, it exceeds this. In this case, the vehicle charges, and the storage battery discharges the shortage (PV - PC - PL = PB).

[0029] Pattern 3 is the case where PV < PL + PC and PV - PB < PL + PC hold. That is, it is the case where the total power generation of the solar power generation system 4 is less than the sum of the load consumption power and the charging power of the vehicle, and even when the absolute value of the discharge power of the storage battery is added, it is still less than this. In this case, the storage battery discharges the shortage (PV - PC - PL = PB), and the power conditioner 2 reduces the charging power PC of the vehicle so that PV - PB (maximum discharge) = PL + PC.

[0030] Pattern 4 is the case where PL ≧ PV and PV ≦ PL + PB + PC hold. That is, it is the case where the total power generation of the solar power generation system 4 is less than the load consumption power. In this case, the storage battery and the vehicle discharge. The vehicle discharges according to the command value from the power conditioner 2, and the storage battery discharges the shortage.

[0031] Patterns 5 - 8 below FIG. 2 are the cases where the battery unit 71 of the vehicle 7 connected to the V2H stand 6 performs CV control.

[0032] Pattern 5 is the case where PV ≧ PL + PB + PC holds. That is, it is the case where the total power generation of the solar power generation system 4 exceeds the sum of the load consumption power, the charging power of the storage battery, and the charging power of the vehicle. In this case, the storage battery and the vehicle are charged. The storage battery is charged according to the command value from the power conditioner 2, and the vehicle is charged with the surplus.

[0033] Pattern 6 is the case where PV ≦ PL + PB ≦ PV - PC holds. That is, it is the case where the total power generation of the solar power generation system 4 is less than the sum of the load consumption power and the charging power of the storage battery, but exceeds this when the absolute value of the discharge power of the vehicle is added. In this case, the storage battery is charged, and the vehicle discharges the shortage (PV - PB - PL = PC).

[0034] Pattern 7 is the case where PV < PL + PB and PV - PC < PL + PB hold. That is, it is the case where the total power generation of the solar power generation system 4 is less than the sum of the load consumption power and the charging power of the storage battery, and still less even when the absolute value of the discharge power of the vehicle is added. In this case, the vehicle discharges the shortage (PV - PB - PL = PC), and the power conditioner 2 decreases the charging power PB of the storage battery so that PV - PC (maximum discharge) = PL + PB.

[0035] Pattern 8 is the case where PL≧PV and PV≦PL+PB+PC hold. That is, this is the case where the total power generated by the photovoltaic power generation system 4 is less than the load power consumption. In this case, the storage battery and the vehicle discharge. The storage battery discharges according to the command value from the power conditioner 2, and the vehicle discharges the shortfall.

[0036] 3 is a flowchart showing an example of the charge / discharge control method according to this embodiment, illustrating a case where the vehicle performs CV control, i.e., a case where the battery unit 71 of the vehicle performs control to maintain the voltage of the DC link 21 constant.

[0037] First, when PV≧PL+PB+PC (Yes in S11), that is, when the total power generated by the solar power generation system 4 exceeds the sum of the load power consumption, the charging power of the storage battery, and the charging power of the vehicle, the storage battery and the vehicle are charged. This corresponds to pattern 5 in Figure 2.

[0038] If the result in S11 is No, it is determined whether the user has operated the V2B mode (S12). If the mode is V2B (Yes in S12), and if PV≦PL+PB≦PV-PC (Yes in S13), that is, if the total power generated by the photovoltaic power generation system 4 is less than the sum of the load power consumption and the charging power of the storage battery, but exceeds this when the absolute value of the vehicle's discharge power is added, the storage battery is charged and the vehicle discharges the shortfall (PV-PB-PL=PC). This corresponds to pattern 6 in Figure 2.

[0039] If the answer in S13 is No and PL+PB>PV-PC and PL+PB>PV, that is, if the total power generated by the solar power generation system 4 is less than the sum of the load power consumption and the charging power of the storage battery, and the sum of the absolute value of the vehicle's discharge power and the total power generated by the solar power generation system 4 is still less than the sum of the load power consumption and the charging power of the storage battery, then PC becomes a negative value, that is, the vehicle discharges at maximum power, and the power conditioner 2 reduces the charging power PB of the storage battery. This corresponds to pattern 7 in Figure 2.

[0040] When not in V2B mode (No in S12), when PV ≤ PL + PB + PC and PL ≥ PV, that is, when the total power generation of the solar power generation system 4 is less than the load consumption power, and even when the charge-discharge power of the battery and the vehicle is added to the load consumption power, it still exceeds the total power generation of the solar power generation system 4, the battery and the vehicle discharge. The battery discharges according to the command value from the power conditioner 2, and the vehicle discharges the shortage. This corresponds to pattern 8 in FIG. 2.

[0041] In the flow of FIG. 3, when PV ≥ PL + PB + PC, all battery units 10 and the vehicle battery unit 71 are charged. When PV ≤ PL + PB + PC and PL ≥ PV, all battery units 10 and the vehicle battery unit 71 are discharged. When the vehicle battery unit 71 is selected as the battery unit that performs CV control to keep the voltage of the DC link 21 constant, in the V2B mode of charging from the vehicle to the battery, when PV < PL + PB, the vehicle battery unit 71 discharges the shortage of PV (PV - PB - PL = PC), and the battery unit 10 is charged.

[0042] FIG. 4 is a flowchart showing an example of the charge-discharge control method according to the present embodiment, showing the case where the battery performs CV control. That is, it is the case where one of the battery units 10 performs control to keep the voltage of the DC link 21 constant.

[0043] First, when PV ≥ PL + PB + PC (Yes in S21), that is, when the total power generation of the solar power generation system 4 exceeds the sum of the load consumption power, the battery charging power, and the vehicle charging power, the battery and the vehicle are charged. This corresponds to pattern 1 in FIG. 2.

[0044] If it is No in S21, it is determined whether it is in the B2V mode in the user operation (S22). In the case of the B2V mode (Yes in S22), when further PV ≤ PL + PC ≤ PV - PB (Yes in S23), that is, when the total power generation power of the photovoltaic power generation system 4 is less than the sum of the load consumption power and the charging power of the vehicle, but when the absolute value of the discharge power of the storage battery is added, it exceeds this, the vehicle charges and the storage battery discharges the shortage amount (PV - PC - PL = PB). This corresponds to Pattern 2 in FIG. 2.

[0045] If it is No in S23 and PL + PC > PV - PB and PV < PL + PC, that is, when the total power generation power of the photovoltaic power generation system 4 is less than the sum of the load consumption power and the charging power of the vehicle, and even when the absolute value of the discharge power of the storage battery is added to the total power generation power of the photovoltaic power generation system 4, it is less than the sum of the load consumption power and the charging power of the vehicle, PB is a negative value, that is, the storage battery discharges at the maximum power, and the power conditioner 2 reduces the charging power PC of the vehicle. This corresponds to Pattern 3 in FIG. 2.

[0046] When it is not in the B2V mode (No in S22), when PV ≥ PL + PB + PC and PL ≥ PV, that is, when the total power generation power of the photovoltaic power generation system 4 is less than the load consumption power, and even when the charge and discharge power of the storage battery and the vehicle is added to the load consumption power, it exceeds the total power generation power of the photovoltaic power generation system 4, the storage battery and the vehicle discharge. The vehicle discharges according to the command value from the power conditioner 2, and the storage battery discharges the shortage amount. This corresponds to Pattern 4 in FIG. 3.

[0047] In the flow of FIG. 4, when PV ≧ PL + PB + PC, all battery units 10 and the vehicle battery unit 71 are charged. When PV ≦ PL + PB + PC and PL ≧ PV, all battery units 10 and the vehicle battery unit 71 are discharged. When one of the battery units 10 is selected as the battery unit that performs CV control to keep the voltage of the DC link 21 constant, in the B2V mode of charging from the storage battery to the vehicle, when PV < PL + PC, the battery unit 10 discharges the shortage of PV (PV - PC - PL = PB), and the vehicle battery unit 71 of the vehicle 7 is charged.

[0048] As described above, according to the present embodiment, a battery unit that performs a charge / discharge operation for controlling the voltage of the DC link 21 is selected from the battery units 10 and the vehicle battery unit 71. When the vehicle battery unit 71 is selected, in the V2B mode of charging from the vehicle to the storage battery, when PV < PL + PB, the vehicle battery unit 71 discharges and the battery unit 10 is charged. On the other hand, when the battery unit 10 is selected, in the B2V mode of charging from the storage battery to the vehicle, when PV < PL + PC, the vehicle battery unit 71 is charged and the battery unit 10 discharges. Thereby, the voltage of the DC link 21 can be stabilized, and power transfer can be appropriately executed between the vehicle and the storage battery.

[0049] Also, in the present embodiment, power transfer is performed between the vehicle and the storage battery on the DC side. Therefore, for example, by disconnecting the system side from the power conditioner system and setting it to the self-driving state, the loss on the AC side can be reduced.

[0050] Furthermore, in this embodiment, it is easy to add a battery unit 10 to the power storage system 1. For example, in recent years, the input and output power of a vehicle has increased along with improvements in the performance of vehicle battery units, and it is conceivable that the input power of the vehicle may exceed the output power of the initially installed storage battery, making rated charging impossible. Even in such cases, it is possible to add a storage battery and charge the vehicle adequately. [Industrial Applicability]

[0051] The present invention is useful for stably operating a power conditioner system including a vehicle charging / discharging stand. [Explanation of symbols]

[0052] 1. Energy storage system 2 Power conditioner 4. Solar power generation system (distributed power source) 6 V2H Stand (Charging / Discharging Stand) 7 vehicles 10 Battery Unit 11 Storage battery 21 DC link 71 Vehicle battery unit

Claims

1. A charge / discharge control method in a power conditioner system in which a distributed power source, at least one battery unit having a storage battery, and a charging / discharging stand that charges and discharges a vehicle battery unit are connected to a DC link, comprising: Let PV be the total power generated by the distributed power sources, PL be the load power consumption of the power conditioner system, PB be the charge / discharge power of the battery unit, where the charge is positive and the discharge is negative, and PC be the charge / discharge power of the vehicle battery unit, where the charge is positive and the discharge is negative. selecting at least one first battery unit from among the battery units and the vehicle battery units to perform a charging / discharging operation to control a voltage of the DC link; When PV≧PL+PB+PC, charging all the battery units and the vehicle battery unit; and discharging all of the battery units and the vehicle battery unit when PV≦PL+PB+PC and PL≧PV. Charge and discharge control method.

2. 2. The charge / discharge control method according to claim 1, When the vehicle battery unit is selected as the first battery unit, in a V2B mode in which charging is performed from the vehicle battery unit, when PV<PL+PB, discharging the vehicle battery unit by an amount corresponding to a PV shortage (PV-PB-PL=PC) and charging the battery unit; and when the battery unit is selected as the first battery unit, in a B2V mode in which the battery unit charges the vehicle battery unit, when PV<PL+PC, charging the vehicle battery unit and discharging the battery unit by an amount corresponding to a PV shortage (PV-PC-PL=PB). Charge and discharge control method.

3. 2. The charge / discharge control method according to claim 1, When the vehicle battery unit is selected as the first battery unit, In a V2B mode in which the battery unit is charged from the vehicle battery unit, when PV≦PL+PB≦PV−PC, discharging the vehicle battery unit by an amount equal to the PV shortage (PV−PB−PL=PC) and charging the battery unit; When PV<PL+PB and PL+PB>PV-PC, discharge the vehicle battery unit to compensate for the PV shortage (PV-PB-PL=PC) and charge the battery unit so that PV-PC=PL+PB is satisfied; When the battery unit is selected as the first battery unit, In a B2V mode in which the battery unit charges the vehicle battery unit, when PV≦PL+PC≦PV−PB, discharging the battery unit by an amount corresponding to a PV shortage (PV−PC−PL=PB) and charging the vehicle battery unit; When PV<PL+PC and PL+PC>PV-PB, the battery unit is discharged to make up for the PV shortage (PV-PC-PL=PB), and the vehicle battery unit is charged so that PV-PB=PL+PC is satisfied. Charge and discharge control method.

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