Connection unit, battery unit, power generation system, and method of operating power generation system

Abstract

To provide a connection unit, a battery unit, a power generation system, and a method of operating the power generation system, which can prevent waste of generated power and flexibly cope with changes in facilities after the start of operation.SOLUTION: A power generation system includes a battery unit 30 that stores surplus power not transmitted by a power conditioner 20 out of the power generated by a power generation unit 10, and a connection unit 40 that connects the power generation unit 10, the power conditioner 20, and the battery unit 30 to each other. A controller 33 of the battery unit 30 controls a bidirectional DC / DC converter 32 to charge a storage battery 31 with surplus power out of the generated power output from the MPPT control DC / DC converter 41 of the connection unit 40, or discharges electric power stored in the storage battery 31 to the power conditioner 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a connection unit, a battery unit, a power generation system, and an operation method of the power generation system.

Background Art

[0002] As a power generation system for transmitting power generated by renewable energy to the grid, for example, there is a solar power generation system provided with a power conditioner for efficiently transmitting power generated by sunlight to the grid. The power conditioner of the solar power generation system usually has a maximum power point tracking (MPPT) control function, and control is performed to extract the generated power at the maximum point.

[0003] Some such power generation systems include a system equipped with a storage battery (for example, Patent Documents 1 and 2). The power generation systems described in Patent Documents 1 and 2 charge the generated power into the storage battery, and transmit the power stored in the storage battery to the grid via a grid-connected type power conditioner.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The power generation output of solar power generation, which is one of renewable energies, depends on the weather. For this reason, an operator of a solar power generation system that has entered into a power sales contract may introduce power generation facilities having a power generation capacity greater than the contract power generation amount so that power can be sold close to the contract power generation amount even on cloudy days.

[0006] However, many of the existing solar power generation systems currently in operation do not have a battery, and the power generated on sunny days that exceeds the contracted power generation amount becomes surplus power and has not been effectively utilized.

[0007] On the other hand, adding a battery to a solar power generation system after operation starts requires changes to the equipment specifications of the solar power generation system, change applications, and significant renovations, which poses a problem that it is difficult to introduce.

[0008] In addition, for a power generation system equipped with a battery, when replacing the battery unit due to changes in equipment specifications or performance degradation of the battery, there is also a problem that the entire equipment needs to be replaced or significantly renovated.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a connection unit, a battery unit, a power generation system, and an operation method of a power generation system that can prevent waste of generated power and flexibly respond to equipment after the start of operation.

Means for Solving the Problems

[0010] To achieve the above object, a connection unit according to a first aspect of the present disclosure is a connection unit that connects a power generation unit, a power conditioner that transmits the power generated by the power generation unit to the grid, and a battery unit to each other, a first MPPT control DC (Direct Current) / DC converter that performs MPPT (Maximum Power Point Tracking) control on the power generated by the power generation unit, a main power transmission path that connects the first MPPT control DC / DC converter and the power conditioner, a charge and discharge path that connects the main power transmission path and the battery unit, and By controlling a bidirectional DC / DC converter inserted between the charge / discharge circuit and the storage battery of the battery unit, surplus power generated by the power generation unit that the power conditioner does not transmit is charged to the storage battery, or power stored in the storage battery is discharged to the power conditioner.

[0011] A battery unit according to a second aspect of the present disclosure is a battery unit connected to a power generation unit via a connection unit and connected to a power conditioner that transmits power generated by the power generation unit to the grid via the connection unit, wherein the connection unit has a first MPPT control DC / DC converter that performs MPPT control on power generated by the power generation unit between the power generation unit and the battery unit, the battery unit includes a storage battery that stores surplus power generated by the power generation unit that the power conditioner does not transmit, a bidirectional DC / DC converter inserted between the first MPPT control DC / DC converter and the storage battery, and a controller that controls the bidirectional DC / DC converter to charge the storage battery with the surplus power or discharge power stored in the storage battery to the power conditioner.

[0012] A power generation system according to a third aspect of the present disclosure is a power generation system having a power generation unit and a power conditioner that transmits power generated by the power generation unit to the grid, wherein a battery unit having a storage battery that stores surplus power generated by the power generation unit that the power conditioner does not transmit, a bidirectional DC / DC converter that switches charging and discharging of the storage battery, and a controller that controls the storage battery and the bidirectional DC / DC converter is provided. A connection unit that connects the power generation unit, the power conditioner, and the battery unit to each other and has a first MPPT control DC / DC converter that performs MPPT control on the power generated by the power generation unit. The controller of the battery unit is characterized in that by controlling the bidirectional DC / DC converter, the surplus power is charged into the storage battery, or the power stored in the storage battery is discharged to the power conditioner.

[0013] The operation method of the power generation system according to the fourth aspect of the present disclosure is as follows. An operation method of a power generation system having a power generation unit and a power conditioner that transmits the power generated by the power generation unit to the grid. The power generation system includes a battery unit having a storage battery that stores surplus power that the power conditioner does not transmit among the power generated by the power generation unit, and a bidirectional DC / DC converter that switches the charge and discharge of the storage battery; a connection unit that connects the power generation unit, the power conditioner, and the battery unit to each other and has a first MPPT control DC / DC converter that performs MPPT control on the power generated by the power generation unit. A charging step of setting the high-voltage DC side voltage of the bidirectional DC / DC converter to be lower than the high-voltage DC side voltage of the first MPPT control DC / DC converter to charge the surplus power into the storage battery. A discharging step of setting the high-voltage DC side voltage of the bidirectional DC / DC converter to be higher than the high-voltage DC side voltage of the first MPPT control DC / DC converter to discharge the power stored in the storage battery. It is characterized by having the above steps.

Advantages of the Invention

[0014] According to the present invention, charging and discharging are performed using the storage battery of the battery unit connected via the connection unit, thereby preventing waste of generated power and enabling flexible response to facilities after the start of operation.

Brief Description of Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0016] (Embodiment) Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals. The power generation system 1 according to the present embodiment is a power generation system that stores the power generated by the power generation unit 10 and transmits the power to the grid. In the present embodiment, the case where the power generation unit 10 performs solar power generation using a solar panel will be described.

[0017] FIG. 1 is a block diagram showing the hardware configuration of the power generation system 1 according to the present embodiment. As shown in FIG. 1, the power generation system 1 includes a power generation unit 10, a power conditioner (Power Conditioning System: denoted as PCS in the figure) 20 that transmits the power generated by the power generation unit 10 to the grid, a battery unit 30 that stores surplus power that the power conditioner 20 does not transmit among the power generated by the power generation unit 10, and a connection unit 40 that connects the power generation unit 10, the power conditioner 20, and the battery unit 30 to each other.

[0018] The power generation unit 10 is a unit that converts solar energy into electric power by a solar panel and generates electricity. The power conditioner 20 has a well-known configuration including a maximum power point tracking (MPPT) control DC (Direct Current) / DC converter and a DC / AC (Alternating Current) inverter, and transmits power to the grid while being connected to the grid.

[0019] The power generation unit 10 and the power conditioner 20 may be existing facilities having a conventional configuration, or may be those included in the power generation system after the start of operation. That is, the power generation unit 10 and the power conditioner 20 that were directly connected to each other by the old wiring shown by the dashed arrow in FIG. 1 may be used. When the power generation unit 10 and the power conditioner 20 are existing facilities, the power generation system 1 realizes a power generation system with a storage battery by retrofitting the battery unit 30 and the connection unit 40 by changing the wiring.

[0020] The connection unit 40 includes an MPPT control DC / DC converter 41, a main power transmission line 42 that connects the MPPT control DC / DC converter 41 and the power conditioner 20, a charge / discharge line 43 that connects the main power transmission line 42 and the battery unit 30, and a voltage fluctuation absorption unit 44 inserted into the main power transmission line 42.

[0021] The MPPT control DC / DC converter 41 (the first MPPT control DC / DC converter) performs MPPT control on the output of the power generation unit 10. The MPPT control DC / DC converter 41 has the same function as the MPPT control DC / DC converter (the second MPPT control DC / DC converter) included in the power conditioner 20.

[0022] The voltage fluctuation absorption unit 44 is a unit that absorbs voltage fluctuations generated by the interference between the MPPT control DC / DC converter 41 and the MPPT control DC / DC converter of the power conditioner 20, and is composed of, for example, a filter. By absorbing the voltage fluctuations caused by this interference, the voltage fluctuation absorption unit 44 can suppress the adverse effects on the charging and discharging operations of the bidirectional DC / DC converter 32 included in the battery unit 30.

[0023] Figure 2 is a graph showing the difference in output voltage depending on the presence or absence of the voltage fluctuation absorption unit 44. It can be seen that the minute voltage fluctuations observed in the output voltage when there is no voltage fluctuation absorption unit 44 on the left are suppressed in the output voltage when there is a voltage fluctuation absorption unit 44 on the right.

[0024] The connection unit 40 further includes an input connection terminal for connecting the power generation unit 10 to the MPPT control DC / DC converter 41 and an output connection terminal for connecting the main power transmission line 42 to the power conditioner 20. The number of output connection terminals is the number corresponding to the number of circuits of the MPPT control DC / DC converter of the power conditioner 20, and the output connection terminals are arranged on a terminal block. The terminal block may be equipped with a reverse current prevention diode connected to each output connection terminal.

[0025] By having the configuration as described above, the connection unit 40 transmits the power generated by the power generation unit 10 to the power conditioner 20 via the MPPT control DC / DC converter 41 and the voltage fluctuation absorption unit 44.

[0026] The battery unit 30 includes a storage battery 31, a bidirectional DC / DC converter 32 connected between the charge / discharge path 43 of the connection unit 40 and the storage battery 31, and a controller 33 that controls the storage battery 31 and the bidirectional DC / DC converter 32.

[0027] Here, the power conditioner 20, the battery unit 30, and the connection unit 40 can operate independently of each other, and there is no need for transmission and reception of control signals. Therefore, when the battery unit 30 is additionally installed in the existing power generation unit 10 and power conditioner 20, or when the power conditioner 20 is replaced or changes occur in the control content related to the power conditioner 20, etc., there is no need for transmission and reception of signals between the power conditioner 20, the battery unit 30, and the connection unit 40.

[0028] The storage battery 31 of the battery unit 30 can be any battery capable of monitoring the stored power, for example, a redox flow battery (hereinafter referred to as RFB). Since the RFB is easy to control, has excellent environmental resistance, and a long lifespan, it is suitable for the power generation system 1. In this embodiment, the case where the storage battery 31 is an RFB will be described.

[0029] When the storage battery 31 is an RFB, as shown in FIG. 1, the storage battery 31 includes an RFB stack 311, a positive electrode electrolyte tank section 312 and a pump 313 to which an electrolyte pipe is connected to the RFB stack 311, and a negative electrode electrolyte tank section 314 and a pump 315. The electrolyte tank sections 312 and 314 can increase or decrease the number of electrolyte tanks even when the power generation system 1 is newly installed or after operation, and thereby the storage capacity can be easily increased or decreased.

[0030] Furthermore, the storage battery 31 includes a monitor cell 316 that measures the open circuit voltage (hereinafter referred to as OCV) of the electrolyte. By measuring the OCV with the monitor cell 316, the stored power of the entire storage battery 31 can be obtained.

[0031] The bidirectional DC / DC converter 32 is a DC / DC converter that controls the charging and discharging of the storage battery 31, and switches between the charging operation and the discharging operation by switching the high-voltage direct current (hereinafter referred to as HVDC) side voltage.

[0032] The controller 33 controls the storage battery 31 and the bidirectional DC / DC converter 32. The controller 33 has a function of overall controlling the entire battery unit 30 including the charge and discharge control command and the flow rate control command of the electrolyte for the storage battery 31 and the bidirectional DC / DC converter 32.

[0033] The charge and discharge control of the battery unit 30 by the controller 33 will be described along the flowchart of FIG. 3. FIG. 3 is a flowchart showing the processing of the controller 33 of the battery unit 30.

[0034] When the power generation unit 10 generates power and the output voltage of the power generation unit 10 reaches within the tracking voltage range of the MPPT control DC / DC converter 41, the HVDC side voltage V of the MPPT control DC / DC converter 41 D maintains a preset voltage V1.

[0035] When the controller 33 starts the charge and discharge control, first, it monitors the generated power of the power generation unit 10, and determines whether the generated power P of the power generation unit 10 A is equal to or less than the rated power P of the power conditioner (PCS) 20 B (step S101).

[0036] If the generated power P of the power generation unit 10 A exceeds the rated power P of the power conditioner (PCS) 20 B (step S101: No), the controller 33 sets the HVDC side voltage V of the bidirectional DC / DC converter 32 E to the HVDC side voltage V of the MPPT control DC / DC converter 41 DSet it to a lower value of V2 (step S102), and set the battery unit 30 to the charging mode (step S103). As a result, the generated power P of the power generation unit 10 A Among them, the rated power P of the power conditioner (PCS) 20 B Exceeding the surplus power (P A -P B ) will be charged to the storage battery 31 (charging step).

[0037] On the other hand, if the generated power P of the power generation unit 10 A Is less than or equal to the rated power P of the power conditioner (PCS) 20 B And it is not nighttime (step S104: No), the controller 33 sets the HVDC side voltage V of the bidirectional DC / DC converter 32 E To the same value of V1 as the HVDC side voltage V of the MPPT control DC / DC converter 41 D And set the battery unit 30 to the charging mode (step S105). At this time, the generated power P of the power generation unit 10 A Is less than or equal to the rated power P of the power conditioner 20 B Therefore, all of the generated power P A Is transmitted to the grid by the power conditioner 20. The battery unit 30 is in the charging mode but is not charged.

[0038] If the generated power P of the power generation unit 10 A Is less than or equal to the rated power P of the power conditioner (PCS) 20 B And it is nighttime (step S104: Yes), the controller 33 sets the HVDC side voltage V of the bidirectional DC / DC converter 32 E To the value of V2 (step S107). In this case, since it is nighttime, the generated power P of the power generation unit 10 A Is 0 kW, and the HVDC side voltage V of the MPPT control DC / DC converter 41 D Is 0 V.

[0039] Next, the controller 33 monitors the OCV measured by the monitor cell 316. When the OCV is equal to or lower than a predetermined threshold (step S108: Yes), since the power storage amount of the storage battery 31 is insufficient, the charge and discharge of the storage battery 31 are stopped (step S109). When the OCV is higher than the predetermined threshold (step S108: No), the controller 33 sets the battery unit 30 to the discharge mode (step S110), and the power stored in the storage battery 31 is discharged to the connection unit 40 via the bidirectional DC / DC converter 32 (discharge step). The discharged power is transmitted to the grid by the power conditioner 20.

[0040] Thereafter, when an administrator or the like of the power generation system 1 performs an operation to end the charge and discharge control (step S111: Yes), the controller 33 ends the process. On the other hand, when the charge and discharge control is not ended (step S111: No), the process returns to step S101, and the monitoring of the generated power is continued.

[0041] The operation of the power generation system 1 configured as described above will be described with reference to the flowcharts of FIGS. 4 and 5. FIG. 4 is a flowchart showing the operation of the power generation system 1 during the day, and FIG. 5 is a flowchart showing the operation of the power generation system 1 at night.

[0042] When the solar panel of the power generation unit 10 receives solar radiation in the morning, it automatically starts generating power (step S201). When the output voltage of the solar panel reaches within the tracking voltage range of the MPPT control DC / DC converter 41, the HVDC side voltage V D of the MPPT control DC / DC converter 41 maintains a preset voltage V1 (step S202).

[0043] The controller 33 monitors the generated power P A and determines whether the generated power P A is equal to or lower than the rated output P B of the power conditioner (PCS) 20 (step S203). Whether the generated power P A is equal to or lower than the rated output P of the power conditioner 20B When the following conditions are met (step S203: Yes), the generated power P of the power generation unit 10 A is all transmitted to the grid via the power conditioner 20 (step S204).

[0044] At this time, the controller 33 sets the battery unit 30 to the charging mode, but since the HVDC side voltage V of the bidirectional DC / DC converter 32 E is set to the same voltage V1 as the HVDC side voltage V of the MPPT control DC / DC converter 41 D , V E ≥ V D and it is not charged (step S205).

[0045] When the generated power P of the power generation unit 10 A becomes large and exceeds the rated power P B of the power conditioner 20 (step S203: No), the rated power P A among the generated power P B is transmitted to the grid by the power conditioner 20 (step S206), and (P A - P B ) becomes surplus power.

[0046] At this time, the controller 33 continues the charging mode as the operation mode of the battery unit 30, and sets the HVDC side voltage V of the bidirectional DC / DC converter 32 E to a voltage V2 lower than the HVDC side voltage V of the MPPT control DC / DC converter 41 D . As a result, V E < V D and the surplus power is charged to the storage battery 31 via the bidirectional DC / DC converter 32 (step S207).

[0047] Next, when night falls, as shown in FIG. 5, the power generation of the power generation unit 10 stops (step S301), and the generated power P A becomes 0 kW. At this time, since the MPPT control DC / DC converter 41 is below the follow-up voltage range, its operation stops and the HVDC side voltage V Dbecomes 0V (step S302).

[0048] When the setting is not to perform night-time power transmission, or when the time zone for performing night-time power transmission is set and it is a time outside that time zone, so night-time power transmission is not performed (step S303: No), since there is no power generation by the power generation unit 10 and no discharge from the storage battery 31, power transmission is stopped (step S304). The controller 33 sets the HVDC side voltage V of the bidirectional DC / DC converter 32 to V1 and sets the battery unit 30 to the charging mode to prepare for resumption of power generation. However, since V E is such that V E ≥ V D charging is not performed (step S305).

[0049] When the setting is to perform night-time power transmission, or when the time zone for performing night-time power transmission is set and it is a time within that time zone, so night-time power transmission is performed (step S303: Yes), the OCV is measured by the monitor cell 316. When the OCV is greater than a predetermined threshold voltage V th (step S306: Yes), the controller 33 sets the HVDC side voltage V of the bidirectional DC / DC converter 32 to V2 and sets the battery unit 30 to the discharge mode (step S307). E At this time, since V

[0050] V E > V D the power discharged from the bidirectional DC / DC converter 32 is transmitted to the power grid by the power conditioner 20 via the connection unit 40 (step S308).

[0051] When the discharge of the storage battery 31 continues and the OCV of the monitor cell becomes less than or equal to the predetermined threshold (step S306: No), the charging and discharging of the battery unit 30 is stopped with the HVDC side voltage V of the bidirectional DC / DC converter 32 set to V2 (step S309). For this reason, power transmission from the power conditioner 20 to the power grid is stopped (step S310). E

[0052] ​ In this way, at night, while measuring the OCV of the monitor cell 316 of the electrolytic solution of the RFB which is the storage battery 31 to monitor the stored power amount, it is possible to easily and surely perform charge and discharge control of the entire battery unit 30.

[0053] Note that in the power generation system 1 of the present embodiment, the charge and discharge path 43 of the connection unit 40 and the battery unit 30 can be arbitrarily attached and detached. That is, it is possible to switch between an operating state in which the charge and discharge path 43 and the battery unit 30 are connected and charge and discharge are possible, and an operating state in which the charge and discharge path 43 and the battery unit 30 are disconnected and charge and discharge are stopped.

[0054] Since the battery unit 30 has a configuration that can be attached and detached, while continuing the operation of directly transmitting the power generated by the power generation unit 10 to the grid via the connection unit 40 and the power conditioner 20, the battery unit 30 can be temporarily disconnected from the power generation system 1 to perform maintenance inspection, increase or decrease the electrolytic solution tank, etc.

[0055] Also, when newly connecting the connection unit 40 and the battery unit 30 to the existing power generation unit 10 and power conditioner 20, first connect the wiring from the existing power generation unit 10 to the input connection terminal of the connection unit 40, and connect the output connection terminal of the connection unit 40 to the input end of the existing power conditioner 20.

[0056] By independently enabling only the main power transmission path 42 of the connection unit 40 in this state, after the start of solar power generation during the day, the existing power generation unit 10 and power conditioner 20 can be operated as usual. Next, after connecting the connection unit 40 and the battery unit 30 and completing the trial operation of the battery unit 30, the existing power generation system can be started to operate as the power generation system 1 with a battery.

[0057] As described above, the power generation system 1 according to the present embodiment includes a battery unit 30 that stores surplus power that the power conditioner 20 does not transmit among the power generated by the power generation unit 10, and a connection unit 40 that connects the power generation unit 10, the power conditioner 20, and the battery unit 30 to each other. The battery unit 30 includes a storage battery 31, a bidirectional DC / DC converter 32 that switches the charge and discharge of the storage battery 31, and a controller 33 that controls the storage battery 31 and the bidirectional DC / DC converter 32. The connection unit 40 includes an MPPT control DC / DC converter 41 that performs MPPT control on the power generated by the power generation unit 10. The controller 33 of the battery unit 30 controls the bidirectional DC / DC converter 32 to charge the battery unit 30 with the surplus power among the power output by the MPPT control DC / DC converter 41, or to discharge the power stored in the battery unit 30 to the power conditioner 20. Thereby, since a power storage function can be added to the existing power generation unit 10 with a simple configuration, it is possible to prevent waste of generated power and to flexibly respond to the equipment after the start of operation. That is, it is possible to easily construct the power generation system 1 having a power storage function only by changing the wiring without modifying the equipment specifications of the existing power generation unit 10 and the power conditioner 20.

[0058] Further, in the power generation system 1 according to the present embodiment, the battery unit 30 includes a redox flow battery, monitors the OCV of the redox flow battery, and stops discharging when the OCV is equal to or lower than a predetermined threshold value. Thereby, the power storage amount of the entire storage battery 31 can be easily and surely grasped in real time by measuring the OCV of the electrolytic solution of the redox flow that is the storage battery 31, and appropriate charge and discharge control of the battery unit 30 can be performed by using the measured value.

[0059] Also, in the power generation system 1 according to the present embodiment, the power conditioner 20 includes a second MPPT control DC / DC converter, and a voltage fluctuation absorption unit 44 is inserted into the main power transmission path of the connection unit 40. Thereby, it is possible to absorb voltage fluctuations caused by interference between the MPPT control DC / DC converter 41 (first MPPT control DC / DC converter) and the MPPT control DC / DC converter (second MPPT control DC / DC converter) of the power conditioner 20, and it is possible to suppress adverse effects on the charge / discharge operation of the bidirectional DC / DC converter 32 of the battery unit 30.

[0060] Also, the power generation unit 10 according to the present embodiment is a solar power generation unit, and the discharge from the battery unit 30 via the main power transmission path 42 of the connection unit 40 is performed at night. Thereby, when the power generation unit 10 generates a large amount of power on a sunny day during the day and the generated power exceeds the rated power of the power conditioner 20, while transmitting the upper limit amount to the power grid, the surplus of the generated power is charged in the battery unit 30 via the connection unit 40. Then, when the power generation unit 10 is not generating power, such as at night, the stored power is transmitted to the power conditioner 20, so that waste of the generated power can be reduced.

[0061] (Example) Regarding an example of the power generation system 1 having the configuration shown in the embodiment, the measured data of the generated power and the surplus power are shown in FIG. 6. As shown in FIG. 6, the generated power P A from the solar panel which is the power generation unit 10 is drawn at the maximum power point by the MPPT control DC / DC converter 41 of the connection unit 40.

[0062] Of the generated power P A , the portion exceeding the rated power P B of the power conditioner 20 is the surplus power (P A -P B) is charged to the storage battery 31 of the battery unit 30. Then, the power stored in the storage battery 31 can be discharged to the power conditioner 20 via the bidirectional DC / DC converter 32 and the voltage fluctuation absorption unit 44 during a predetermined time period at night after power generation stops due to sunset.

[0063] As described above, the embodiments of the present disclosure have been explained. However, these embodiments are merely examples, and the scope of application of the present disclosure is not limited thereto. That is, various changes or applications can be made without departing from the gist of the present disclosure.

[0064] Hereinafter, aspects of the present disclosure will be collectively described as appendices.

[0065] (Appendix 1) A connection unit that connects a power generation unit, a power conditioner that transmits the power generated by the power generation unit to the grid, and a battery unit to each other, A first MPPT control DC (Direct Current) / DC converter that performs MPPT (Maximum Power Point Tracking) control on the power generated by the power generation unit, A main power transmission path that connects the first MPPT control DC / DC converter and the power conditioner, A charge / discharge path that connects the main power transmission path and the battery unit, and By controlling a bidirectional DC / DC converter inserted between the charge / discharge path and the storage battery of the battery unit, surplus power that the power conditioner does not transmit among the power generated by the power generation unit is charged to the storage battery, or the power stored in the storage battery is discharged to the power conditioner. Connection unit.

[0066] (Appendix 2) The battery unit includes a redox flow battery, When the power storage amount of the redox flow battery is equal to or less than a predetermined threshold value, discharge is stopped. The connection unit according to Appendix 1.

[0067] (Appendix 3) When charging the storage battery of the battery unit with the electric power generated by the power generation unit, the high-voltage DC side voltage of the bidirectional DC / DC converter inserted between the charge and discharge path and the storage battery of the battery unit is set lower than the high-voltage DC side voltage of the first MPPT control DC / DC converter. When discharging the electric power stored in the storage battery to the power conditioner, the high-voltage DC side voltage of the bidirectional DC / DC converter is set higher than the high-voltage DC side voltage of the first MPPT control DC / DC converter. The connection unit according to Appendix 1 or 2.

[0068] (Appendix 4) The power conditioner includes a second MPPT control DC / DC converter. A voltage fluctuation absorption unit is inserted into the main power transmission path. The connection unit according to any one of Appendices 1 to 3.

[0069] (Appendix 5) The power generation unit is a solar power generation unit. The discharge from the battery unit via the main power transmission path of the connection unit is performed at night. The connection unit according to any one of Appendices 1 to 4.

[0070] (Appendix 6) An input connection terminal for connecting to the existing power generation unit, and an output connection terminal for connecting to the existing power conditioner. The connection unit according to any one of Appendices 1 to 5.

[0071] (Appendix 7) The charge and discharge path and the battery unit are detachably connected. The connection unit according to any one of Appendices 1 to 6.

[0072] (Appendix 8) The connection unit according to appended note 7, which is capable of switching between an operating state in which the charge / discharge circuit and the battery unit are connected and charge / discharge is possible, and an operating state in which the charge / discharge circuit and the battery unit are disconnected and charge / discharge is stopped.

[0073] (Appended note 9) A battery unit connected to a power generation unit via a connection unit and connected to a power conditioner that transmits the power generated by the power generation unit to the grid via the connection unit, The connection unit has a first MPPT control DC / DC converter that performs MPPT control on the power generated by the power generation unit between the power generation unit and the battery unit, The battery unit A storage battery that stores surplus power that the power conditioner does not transmit among the power generated by the power generation unit, A bidirectional DC / DC converter inserted between the first MPPT control DC / DC converter and the storage battery, A controller that charges the storage battery with the surplus power or discharges the power stored in the storage battery to the power conditioner by controlling the bidirectional DC / DC converter. Battery unit.

[0074] (Appended note 10) A power generation system having a power generation unit and a power conditioner that transmits the power generated by the power generation unit to the grid, A battery unit having a storage battery that stores surplus power that the power conditioner does not transmit among the power generated by the power generation unit, a bidirectional DC / DC converter that switches the charge and discharge of the storage battery, and a controller that controls the storage battery and the bidirectional DC / DC converter, A connection unit that connects the power generation unit, the power conditioner, and the battery unit to each other and has a first MPPT control DC / DC converter that performs MPPT control on the power generated by the power generation unit. The controller of the battery unit controls the bidirectional DC / DC converter to charge the surplus power to the storage battery, or discharge the power stored in the storage battery to the power conditioner. Power generation system.

[0075] (Appendix 11) An operation method of a power generation system including a power generation unit and a power conditioner that transmits the power generated by the power generation unit to the grid, The power generation system includes: a battery unit including a storage battery that stores surplus power that the power conditioner does not transmit among the power generated by the power generation unit, and a bidirectional DC / DC converter that switches charging and discharging of the storage battery; a connection unit that connects the power generation unit, the power conditioner, and the battery unit to each other and includes a first MPPT control DC / DC converter that performs MPPT control on the power generated by the power generation unit; a charging step of setting the high-voltage DC side voltage of the bidirectional DC / DC converter to be lower than the high-voltage DC side voltage of the first MPPT control DC / DC converter to charge the surplus power to the storage battery; a discharging step of setting the high-voltage DC side voltage of the bidirectional DC / DC converter to be higher than the high-voltage DC side voltage of the first MPPT control DC / DC converter to discharge the power stored in the storage battery; An operation method of a power generation system having the above steps.

Description of Reference Numerals

[0076] 1 Power generation system, 10 Power generation unit, 20 Power conditioner (PCS), 30 Battery unit, 31 Storage battery, 32 Bidirectional DC / DC converter, 33 Controller, 40 Connection unit, 41 MPPT control DC / DC converter (first MPPT DC / DC converter), 42 Main power transmission line, 43 Charge / discharge path, 44 Voltage fluctuation absorption unit, 311 RFB stack, 312, 314 Electrolyte tank section, 313, 315 Pump, 316 Monitor cell.

Claims

1. A connection unit that connects a power generation unit, a power conditioner that transmits power generated by the power generation unit to a grid, and a battery unit to each other, a first MPPT control DC (Direct Current) / DC converter that performs MPPT (Maximum Power Point Tracking) control of the power generated by the power generation unit; a main transmission line connecting the first MPPT control DC / DC converter and the power conditioner; a charge / discharge path connecting the main power transmission path and the battery unit; By controlling a bidirectional DC / DC converter inserted between the charge / discharge path and the storage battery of the battery unit, surplus power generated by the power generation unit that is not transmitted by the power conditioner is charged to the storage battery, or power stored in the storage battery is discharged to the power conditioner. Connection unit.

2. the battery unit includes a redox flow battery; When the amount of stored electricity in the redox flow battery is equal to or less than a predetermined threshold, discharging is stopped. The connection unit according to claim 1 .

3. when charging the storage battery of the battery unit with power generated by the power generation unit, a high-voltage DC side voltage of the bidirectional DC / DC converter inserted between the charge / discharge path and the storage battery of the battery unit is set lower than a high-voltage DC side voltage of the first MPPT control DC / DC converter, and when discharging the power stored in the storage battery to the power conditioner, the high-voltage DC side voltage of the bidirectional DC / DC converter is set higher than the high-voltage DC side voltage of the first MPPT control DC / DC converter. A connection unit according to claim 1 or 2.

4. The power conditioner includes a second MPPT controlled DC / DC converter, A voltage fluctuation absorption unit is inserted in the main transmission line. A connection unit according to any one of claims 1 to 3.

5. the power generating unit is a solar power generating unit; Discharge from the battery unit through the main power transmission line of the connection unit is performed at night. A connection unit according to any one of claims 1 to 4.

6. an input connection terminal for connecting to the existing power generating unit; Further comprising an output connection terminal for connecting to the existing power conditioner; A connection unit according to any one of claims 1 to 5.

7. The charging / discharging path and the battery unit are detachably connected. A connection unit according to any one of claims 1 to 6.

8. The connection unit according to claim 7 , which is switchable between an operating state in which the charge / discharge path and the battery unit are connected to enable charging and discharging, and an operating state in which the charge / discharge path and the battery unit are disconnected to stop charging and discharging.

9. A battery unit connected to a power generation unit via a connection unit and connected to a power conditioner via the connection unit, the power conditioner transmitting power generated by the power generation unit to a power grid, the connection unit has a first MPPT control DC / DC converter between the power generation unit and the battery unit, the first MPPT control DC / DC converter performing MPPT control of the electric power generated by the power generation unit, The battery unit includes: A storage battery that stores surplus power that is not transmitted by the power conditioner out of the power generated by the power generation unit; a bidirectional DC / DC converter inserted between the first MPPT control DC / DC converter and the storage battery; and a controller that controls the bidirectional DC / DC converter to charge the surplus power to the storage battery or discharge the power stored in the storage battery to the power conditioner. Battery unit.

10. A power generation system having a power generation unit and a power conditioner that transmits power generated by the power generation unit to a power grid, a battery unit including a storage battery that stores surplus power generated by the power generation unit and not transmitted by the power conditioner, a bidirectional DC / DC converter that switches between charging and discharging the storage battery, and a controller that controls the storage battery and the bidirectional DC / DC converter; a connection unit that connects the power generation unit, the power conditioner, and the battery unit to each other and has a first MPPT control DC / DC converter that performs MPPT control of the power generated by the power generation unit; The controller of the battery unit controls the bidirectional DC / DC converter to charge the surplus power to the storage battery or to discharge the power stored in the storage battery to the power conditioner. Power generation system.

11. A method for operating a power generation system having a power generation unit and a power conditioner that transmits power generated by the power generation unit to a power grid, comprising: The power generation system includes: A battery unit including a storage battery that stores surplus power generated by the power generation unit and not transmitted by the power conditioner, and a bidirectional DC / DC converter that switches between charging and discharging the storage battery; a connection unit that connects the power generation unit, the power conditioner, and the battery unit to each other and has a first MPPT control DC / DC converter that performs MPPT control of the power generated by the power generation unit; a charging step of setting a high-voltage DC side voltage of the bidirectional DC / DC converter lower than a high-voltage DC side voltage of the first MPPT control DC / DC converter and charging the storage battery with the surplus power; a discharging step of discharging the power stored in the storage battery by setting a high-voltage DC side voltage of the bidirectional DC / DC converter higher than a high-voltage DC side voltage of the first MPPT control DC / DC converter; A method for operating a power generation system having the above structure.

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