JP2021005978A - Autonomous power supply system and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both stable charging and stable power supply between a self-sustaining output end of a renewable energy source and a load. An independent power supply system 100 that supplies electric power to a load is provided between a renewable energy source and the load, has a first storage battery 30, and converts an independent output into DC electric power to provide a first. Between the renewable energy source and the load, the first power storage device 3 having a power storage function for charging the storage battery and a power supply function for converting the DC power of the first storage battery into AC power to supply the power required for the load. It has a second storage battery 40, and is required for the load by converting the self-sustaining output into DC power to charge the second storage battery and converting the DC power of the second storage battery into AC power. One of the second power storage device 4 and the first power storage device and the second power storage device, which have a power supply function for supplying electric power, executes only the power storage function, and the other executes only the power supply function. The control unit 5 is provided to control the execution subject to change with the progress of the above. [Selection diagram] Fig. 1

Description

The present disclosure relates to an independent power supply system and a control method thereof.

The power output of the photovoltaic power generation panel can be interconnected to the commercial power system via a power conditioner (power conversion device). Further, a power storage system in which a grid-connected power storage device equipped with a storage battery is added to such a photovoltaic power generation device has also been proposed (see, for example, Patent Document 1). The storage battery is charged by the power of the commercial power system.

In the event of a power outage in the commercial power system, the power storage device can continue to supply power to the load (important load) in the consumer. Further, when the self-sustaining output of the power conditioner can be obtained, the self-sustaining output can continue to supply power to the load in the consumer. If surplus power is generated even when power is supplied to the load, the storage battery can be charged by independent output.

Japanese Unexamined Patent Publication No. 2018-11476

As described above, when the photovoltaic power generation panel generates power and the power conditioner provides the self-sustaining output, the photovoltaic power generation supplies power to the load and charges the storage battery if there is surplus power. In this state, for example, when the load is a non-linear load including a rectifier, the voltage of the self-supporting output is distorted. Therefore, the power storage device may detect a voltage abnormality and stop charging. In addition, the power conditioner may detect a voltage abnormality and stop the output. As described above, in the case of self-sustaining output, the power supply to the load and the charging from the power conditioner to the storage battery are not stable. Furthermore, the power supply to the load based on photovoltaic power generation changes due to the influence of the weather, so stable supply is difficult.

In view of such problems, it is an object of the present invention to realize both stable charging and stable power supply between the self-sustaining output end of a renewable energy source represented by a photovoltaic power generation device and a load.

The present disclosure includes the following inventions. However, the present invention is defined by the scope of claims.

The self-sustaining power supply system of the present disclosure is a self-sustaining power supply system that can receive a self-sustaining output from a renewable energy source in a state of system disconnection and supplies power to a load.
A storage function provided between the renewable energy source and the load, having a first storage battery, converting the self-sustaining output into DC power to charge the first storage battery, and the first storage battery. A first power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
A storage function provided between the renewable energy source and the load, having a second storage battery, converting the self-sustaining output into DC power to charge the second storage battery, and the second storage battery. A second power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
One of the first power storage device and the second power storage device executes only the power storage function, the other executes only the power supply function, and the executing entity changes with the passage of time. The control unit to control and
It is a self-sustaining power supply system equipped with.

Further, the self-sustaining power supply system of the present disclosure is a self-sustaining power supply system that supplies power to a load in a state of system disconnection.
Solar power generation equipment that can provide self-sustaining output,
A storage function provided between the solar power generation device and the load, having a first storage battery, converting the self-sustaining output into DC power to charge the first storage battery, and the first storage battery. A first power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
A storage function provided between the solar power generation device and the load, having a second storage battery, converting the self-sustaining output into DC power to charge the second storage battery, and the second storage battery. A second power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
One of the first power storage device and the second power storage device executes only the power storage function, the other executes only the power supply function, and the executing entity changes with the passage of time. The control unit to control and
It is a self-sustaining power supply system equipped with.

On the other hand, the present disclosure is a self-sustaining power supply system in a self-sustaining power supply system in which a first power storage device and a second power storage device are interposed in parallel between an output end that provides a self-sustaining output from a renewable energy source and a load. It is a control method of
The self-sustaining output is converted into DC power to charge the first storage battery of the first power storage device, and the DC power of the second storage battery of the second power storage device is converted into AC power to be used as the load. Supply the required power,
The roles of the first power storage device and the second power storage device are switched with each other over time.
This is a control method for an independent power supply system.

According to the present disclosure, both stable charging and stable power feeding can be realized between the self-sustaining output end of the renewable energy source and the load.

FIG. 1 is a single-line connection diagram of an independent power supply system. FIG. 2 is a single-line connection diagram of an independent power supply system when the commercial power system has a normal voltage. FIG. 3 is a single-line connection diagram (charging on the left side, discharging on the right side) that clearly shows the switch open / closed state of the self-sustaining power supply system at the time of power failure of the commercial power system during photovoltaic power generation. FIG. 4 is a single-line connection diagram (discharging on the left side and charging on the right side) that clearly shows the switch open / closed state of the self-sustaining power supply system 100 at the time of power failure of the commercial power system 6 during photovoltaic power generation. FIG. 5 is an example of a flowchart executed by the control unit (remote control device) when the independent output is started. FIG. 6 is an example of a flowchart (1/2) executed by the control unit when the independent output is started. FIG. 7 is an example of a flowchart (2/2) executed by the control unit when the independent output is started.

[Explanation of Embodiments of the present disclosure]
The embodiments of the present disclosure include at least the following as the gist of the superordinate concept.

(1) The disclosure is a self-sustaining power supply system capable of receiving a self-sustaining output supply from a rechargeable energy source and supplying electric power to a load in a state of system disconnection, and the rechargeable energy A storage function provided between the source and the load, having a first storage battery, converting the self-sustaining output into DC power to charge the first storage battery, and DC power of the first storage battery. A first power storage device having a power supply function of converting the power into AC power to supply the power required for the load, and a second storage battery provided between the renewable energy source and the load. A power storage function that converts the self-sustaining output into DC power to charge the second storage battery, and a power supply function that converts the DC power of the second storage battery into AC power to supply the power required for the load. One of the second power storage device, the first power storage device, and the second power storage device has only the power storage function, and the other executes only the power supply function, and over time. It is provided with a control unit that controls the execution subject to change accordingly.

According to such a self-sustaining power supply system, the self-sustaining output of the renewable energy source is used only for charging one of the power storage devices, and the renewable energy source does not directly supply power to the load. Power is always supplied to the load from either power storage device. Therefore, even when the non-linear load is fed, the independent output of the renewable energy source is not affected by it. Therefore, the alternating current output from the renewable energy source always has a sinusoidal current with small distortion, and stable charging can be performed. On the other hand, since power is supplied to the load by the self-sustaining output of the power storage device, stable power can be supplied to the load without being affected by the weather even if the renewable energy source is a photovoltaic power generation device. ..
In this way, both stable charging and stable power supply can be realized between the self-sustaining output end of the renewable energy source and the load.

(2) In the self-sustaining power supply system of (1), for example, the first power storage device and the second power storage device are connected in parallel to each other, and each of them is on the input side from the renewable energy source. It has an auxiliary input switch that can be opened and closed, a self-supporting output switch that can be opened and closed on the load side, a voltage sensor connected to the input side, and a voltage sensor connected to the load side.
In this case, the power storage device can be charged by closing the auxiliary input switch and opening the self-supporting output switch. Further, the power storage device can be discharged by opening the auxiliary input switch and closing the self-supporting output switch. As a result, the two sets of power storage devices are electrically separated from each other. Moreover, since the input / output voltages of the other two sets of power storage devices can be detected by the voltage sensor, they can be easily synchronized with each other.

(3) In the self-sustaining power supply system of (2), for example, the control unit detects the phase based on the AC voltage currently being output, and switches the execution subject at the timing of zero cross.
In this case, even if the supply source changes due to the change, it is possible to continue supplying power to the load by the AC voltage synchronized with each other before and after the change.

(4) In the self-sustaining power supply system according to any one of (1) to (3), for example, of the first storage battery and the second storage battery, the charged storage battery has reached the upper limit of charging. In some cases, the executing entity changes.
In this case, the discharge by the storage battery that has reached the upper limit of charging can be started immediately, and the charging can be continued by another storage battery.

(5) In the self-sustaining power supply system according to any one of (1) to (3), for example, of the first storage battery and the second storage battery, the discharging battery has reached the discharge limit value. In some cases, the executing entity changes.
In this case, in order to stop further discharge by the storage battery that has reached the discharge limit value, discharge by another storage battery can be started, and charging of the stopped storage battery can be started.

(6) In the self-sustaining power supply system according to any one of (1) to (5), specifically, for example, the control unit is a first control unit provided in the first power storage device and the second power storage. It is composed of a second control unit provided in the device, and a common remote controller device connected to both the first power storage device and the second power storage device.
In this case, charging / discharging of the storage battery can be performed by the first control unit and the second control unit provided in each power storage device. The remote control device can instruct the first control unit and the second control unit to switch between charging and discharging based on the information on the charging / discharging state obtained from the first control unit and the second control unit.

(7) Further, this is an independent power supply system that supplies electric power to a load in a state of system disconnection, and is a solar power generation device capable of providing independent output, and the solar power generation device and the load. It has a first storage battery provided between them, and has a storage function that converts the self-sustaining output into DC power to charge the first storage battery, and converts the DC power of the first storage battery into AC power. A first power storage device having a power supply function for supplying the power required for the load, a second storage battery provided between the solar power generation device and the load, and the self-sustaining output being DC power. A second storage device having a power storage function for charging the second storage battery and a power supply function for converting the DC power of the second storage battery into AC power to supply the power required for the load. And, one of the first power storage device and the second power storage device executes only the power storage function, the other executes only the power supply function, and the executing entity changes with the passage of time. It is provided with a control unit that controls the operation.

According to such an independent power supply system, the independent output of the photovoltaic power generation device is used only for charging one of the power storage devices, and the photovoltaic power generation device does not directly supply power to the load. Power is always supplied to the load from either power storage device. Therefore, even when the non-linear load is fed, the self-sustaining output of the photovoltaic power generation device is not affected by it. Therefore, the alternating current output from the photovoltaic power generation device always flows a sine wave current with small distortion, and stable charging can be performed. On the other hand, since power is supplied to the load by the self-sustaining output of the power storage device, stable power can be supplied to the load without being affected by the weather even if the photovoltaic power generation device is a photovoltaic power generation device. ..
In this way, both stable charging and stable power supply can be realized between the photovoltaic power generation device and the load.

(8) On the other hand, from the viewpoint of the method, in a self-sustaining power supply system in which a first power storage device and a second power storage device are interposed in parallel between an output end that provides a self-sustaining output from a renewable energy source and a load. It is a control method of the self-sustaining power supply system, in which the self-sustaining output is converted into DC power to charge the first storage battery of the first power storage device and the second storage battery of the second power storage device. A self-sustaining power supply system that converts DC power into AC power to supply the power required for the load, and alternates the roles of the first power storage device and the second power storage device with the passage of time. It is a control method.

According to such a control method of the self-sustaining power supply system, the self-sustaining output of the renewable energy source is used only for charging one of the power storage devices, and the renewable energy source does not directly supply power to the load. Power is always supplied to the load from either power storage device. Therefore, even when the non-linear load is fed, the independent output of the renewable energy source is not affected by it. Therefore, the alternating current output from the renewable energy source always has a sinusoidal current with small distortion, and stable charging can be performed. On the other hand, since power is supplied to the load by the self-sustaining output of the power storage device, stable power can be supplied to the load without being affected by the weather even if the renewable energy source is a photovoltaic power generation device. ..
In this way, both stable charging and stable power supply can be realized between the self-sustaining output end of the renewable energy source and the load.

[Details of Embodiments of the present disclosure]
<< Circuit configuration including independent power supply system >>
Hereinafter, specific examples of the self-sustaining power supply system (including the control method) of the present disclosure will be described with reference to the drawings.
FIG. 1 is a single-line connection diagram of the self-sustaining power supply system 100. In the figure, the self-sustaining power supply system 100 includes a photovoltaic power generation panel 1, a power conversion device 2, two sets of power storage devices 3 and 4, and a control unit 5 as main components. It should be noted that only the two sets of power storage devices 3 and 4 and the control unit 5 can be considered as the self-sustaining power supply system 100. Both of the two sets of power storage devices 3 and 4 are provided between the self-sustaining output terminal 2t of the power conversion device 2 and the load 8 via the important load distribution board 7. Further, the two sets of power storage devices 3 and 4 are in a parallel relationship with each other with respect to the independent output of the power conversion device 2.

The power conversion device 2 connected to the photovoltaic power generation panel 1 includes an inverter circuit 21, a grid interconnection switch 22, and an independent output switch 23. These switches 22 and 23 are generally relay contacts, but semiconductor switches can also be used (the same shall apply hereinafter). When the grid interconnection switch 22 is closed, the power conversion device 2 can be grid-connected to the commercial power grid 6. The photovoltaic power generation device 10 is composed of the photovoltaic power generation panel 1 and the power conversion device 2.

The power storage device 3 includes a storage battery 30, a converter circuit 31 connected to the storage battery 30 for bidirectional conversion of AC / DC, a grid interconnection switch 32, an independent output switch 33, an auxiliary input switch 34, and a control unit. 35 and voltage sensors 36 and 37 are provided. The control unit 35 controls the switching operation of the converter circuit 31, and also controls the opening and closing of each of the grid interconnection switch 32, the self-supporting output switch 33, and the auxiliary input switch 34. The voltage sensor 36 detects the input voltage to the power storage device 3 and sends the detected output to the control unit 35. The voltage sensor 37 detects the output voltage of the power storage device 3 or the output voltage of the power storage device 4, and sends the detected output to the control unit 35.

The power storage device 4 includes a storage battery 40, a converter circuit 41 connected to the storage battery 40 for bidirectional conversion of AC / DC, a grid interconnection switch 42, an independent output switch 43, an auxiliary input switch 44, and a control unit. 45 and voltage sensors 46 and 47 are provided. The control unit 45 controls the switching operation of the converter circuit 41, and also controls the opening and closing of each of the grid interconnection switch 42, the independent output switch 43, and the auxiliary input switch 44. The voltage sensor 46 detects the input voltage to the power storage device 4 and sends the detected output to the control unit 45. The voltage sensor 47 detects the output voltage of the power storage device 4 or the output voltage of the power storage device 3, and sends the detected output to the control unit 45.

The control units 35 and 45 include, for example, a computer, and the computer executes software (computer program) to realize necessary control functions. The software is stored in a storage device (not shown) in the control units 35 and 45. The control units 35 and 45 also periodically obtain information on the remaining amount (SOC: State of Charge) from the storage batteries 30 and 40, respectively, and transmit the obtained information to the common control unit 5.

The control unit 5 common to the two sets of power storage devices 3 and 4 is typically a remote control device having a monitor function and an operation function. The control unit 5 includes, for example, a computer, and the computer executes software (computer program) to realize necessary control functions. The software is stored in a storage device (not shown) in the control unit 5. The control unit 5 is daisy-chained with the control units 35 and 45 of the power storage devices 3 and 4, and can communicate with each other by, for example, RS485.

The important load distribution board 7 is a distribution board for an important load 8 whose power supply is to be maintained even during a power failure of the commercial power system 6. A changeover switch 71 and a circuit breaker 72 are provided in the important load distribution board 7. The changeover switch 71 may be one that detects the presence or absence of voltage and automatically selects the one to which the voltage is applied, or may be one that manually switches. The circuit breaker 72 is actually provided in parallel by the number of wiring systems of the load. The load 8 is connected to the commercial power system 6 or the self-sustaining power supply system 100 via the critical load distribution board 7.

FIG. 2 is a single-line connection diagram of the self-sustaining power supply system 100 when the commercial power system 6 has a normal voltage. In FIG. 2, the grid interconnection switches 22, 32, and 42 are all closed, and the power conversion device 2 and the power storage devices 3 and 4 are grid-connected. The commercial power system 6 is a single-phase three-wire system, and the voltage of the system interconnection is 200 V. The changeover switch 71 of the critical load distribution board 7 is connected to the commercial power system 6 and draws 100V from the single-phase three-wire system.

On the other hand, the self-supporting output switches 23, 33, 43 and the auxiliary input switches 34, 44 are all open. In this state, the power conversion device 2 can supply power to the load 8, power to the power storage devices 3 and 4, and reverse tide to the commercial power system. The power storage devices 3 and 4 can charge the storage batteries 30 and 40, or supply power to the load 8.

<< Operation of independent power supply system >>
Next, the operation by the self-sustaining power supply system 100 at the time of a power failure of the commercial power system 6, which is the main content of the present disclosure, will be described.

(Introduction)
One of the power storage devices 3 and 4 of the self-sustaining power supply system 100 outputs 100 V independently, and the other charges the 100 V self-sustaining output of photovoltaic power generation. When the remaining amount (SOC) of the self-supporting storage battery reaches the discharge limit value or the remaining amount of the charged storage battery reaches the charge upper limit value, the two power storage devices 3 and 4 are discharged and charged. Is switched virtually without interruption.

3 and 4 are single-line connection diagrams in which the switch open / closed state of the self-sustaining power supply system 100 at the time of a power failure of the commercial power system 6 during photovoltaic power generation is also specified. Since the commercial power system 6 has a power failure, it is represented by a dotted line. During a power failure of the commercial power system 6, all the grid interconnection switches 22, 32, and 42 are open, and the self-sustaining power supply system 100 is in a state of being disconnected from the commercial power system 6. The thick lines in FIGS. 3 and 4 indicate the direction of electric power movement.

First, in FIG. 3, the independent output switch 23 of the power conversion device 2 and the auxiliary input switch 34 of the power storage device 3 are closed, and the independent output switch 33 of the power storage device 3 is open. The inverter circuit 21 of the power conversion device 2 converts DC to AC, and the converter circuit 31 of the power storage device 3 converts AC to DC to charge the storage battery 30.

On the other hand, the auxiliary input switch 44 of the power storage device 4 is open, and the self-supporting output switch 43 is closed. The changeover switch 71 of the critical load distribution board 7 is connected to the self-sustaining power supply system 100 side. The converter circuit 41 of the power storage device 4 discharges the storage battery 40, converts it from direct current to alternating current, and supplies power to the load 8.

Next, in FIG. 4, the independent output switch 23 of the power conversion device 2 and the auxiliary input switch 44 of the power storage device 4 are closed, and the independent output switch 43 of the power storage device 4 is open. The inverter circuit 21 of the power conversion device 2 converts DC to AC, and the converter circuit 41 of the power storage device 4 converts AC to DC to charge the storage battery 40.

On the other hand, the auxiliary input switch 34 of the power storage device 3 is open, and the self-supporting output switch 33 is closed. The changeover switch 71 of the critical load distribution board 7 is connected to the self-sustaining power supply system 100 side. The converter circuit 31 of the power storage device 3 discharges the storage battery 30, converts direct current to alternating current, and supplies power to the load 8.

When the storage battery 30 reaches the charge upper limit value or the storage battery 40 reaches the discharge limit value in the state of FIG. 3, the state is switched to the state of FIG. When the storage battery 40 reaches the charge upper limit value or the storage battery 30 reaches the discharge limit value in the state of FIG. 4, the state is switched to the state of FIG. By using the two sets of power storage devices 3 and 4 while switching their roles at any time, the power that can be supplied to the load is, for example, a maximum of 1.5 kW at 100 V, and the amount of power that can be used for charging / discharging is a maximum of about 6 kWh. Assuming that there is only one power storage device on the premise that power is supplied from the storage battery to the load, the instantaneous power supply is the same. However, if the same power is continuously supplied, the power cannot be supplied when the discharge limit is reached. However, by using the two sets of power storage devices 3 and 4 while switching their roles at any time, it is possible to continuously supply power from the storage battery to the load.

Now, there is something to be careful about when changing the power storage device that supplies power to the load. This is because the charging circuit and the discharging circuit are electrically separated from each other by the self-sustaining output switch of one power storage device and the auxiliary input switch of the other power storage device, so that if the voltage phases of both power lines are reversed. , AC200V voltage is applied to both ends of these switches.

In order to minimize the voltage applied to both ends of the switch, it is necessary to match the voltage phase of the independent output of the power storage device on the discharge side with the independent output of the power converter 2 based on the detection outputs of the voltage sensors 36 and 46. Is. Further, when the charging / discharging of the power storage devices 3 and 4 is changed, the power storage device that is about to start discharging is set to the phase of the self-sustaining output voltage of the power storage device currently being discharged based on the detection output of the voltage sensors 37 and 47. Match the phase and prevent the phase jump due to the change.

<< Example of flowchart >>
Hereinafter, a flowchart regarding the change of charge / discharge will be described as an example. The flowchart is an example of a concrete idea, and is not limited to this.

(Control unit 5)
FIG. 5 is an example of a flowchart executed by the control unit 5 (remote control device) when the independent output is started. When the power conversion device 2 starts the self-sustaining output at AC100V due to a power failure of the commercial power system 6, the voltage is detected by the voltage sensors 36 and 46, and this is detected via the control units 35 and 45 of the power storage devices 3 and 4. , It is also transmitted to the control unit 5. Therefore, the control unit 5 instructs the power storage devices 3 and 4 to discharge one and charge the other (step S1).

Next, the control unit 5 determines whether or not the charging storage battery has reached the upper limit of charging (step S2). In the case of "NO", the control unit 5 determines whether or not the discharging storage battery has reached the discharge limit value (step S3). If "NO" is used here as well, steps S2, S3, and S8 are repeated unless the self-sustaining output is completed (step S8). If the commercial power system recovers power and the self-sustaining output ends during this repeating period, the processing of this flowchart ends.

If "YES" is obtained in either step S2 or S3, the control unit 5 transmits a shift preparation command to the power storage devices 3 and 4 (step S4). The change preparation command is to adjust the open / closed state of the auxiliary input switches 34 and 44 and the independent output switches 33 and 43 prior to the change of charge / discharge. After that, the control unit 5 waits for receiving the discharge preparation completion signal (step S5), and when it receives the signal, transmits a charge / discharge change command (step S6). Then, the control unit 5 confirms the charge / discharge change (step S7), and returns to step S2. Hereinafter, the control unit 5 repeats the processes after step S2.

(Control unit 35, Control unit 45)
6 and 7 are examples of flowcharts executed by the control units 35 and 45 when the independent output is started. The two control units 35 and 45 execute the same flowchart with different movements. Here, FIGS. 6 and 7 are two flowcharts, and C, F, E, and D at the lower end of FIG. 6 are connected to C, F, E, and D at the upper end of FIG. 7, respectively. Note that C, F, E, and D each use characters that suggest meaning in the flowchart as shown below.

C: Flow from discharge to charge (Charge) F: State where the upper limit of charge (Full) is reached E: State where the lower limit of discharge (Empty) is reached D: Flow from charge to discharge (Discharge)

First, the control unit 35 will be described. In FIG. 6, when the self-sustaining output is started, the control unit 35 receives an instruction for initial charging / discharging from the control unit 5 (step S11). If a charging instruction is received (charging in step S12), the control unit 35 prepares for charging (step S13). Specifically, the control unit 35 opens the self-supporting output switch 33 and closes the auxiliary input switch 34.

Subsequently, the control unit 35 operates the converter 31 to charge the storage battery 30 (step S14). After that, charging can be performed until the upper limit of charging is reached (step S17), but if the self-sustaining output ends (step S15) during that time, the process ends. If the charge upper limit value is reached before the replacement preparation command (step S16) comes (“YES” in step S17), the control unit 35 sends a charge completion flag to the control unit 5 to notify (step S18). ), Go to step S19 of FIG. If a replacement preparation command is received before reaching the upper limit of charging (“YES” in step S16), the control unit 35 goes to step S19 in FIG. 7 without notifying.

In FIG. 7, the control unit 35 stops charging (step S19) and prepares for discharge (step S20). Specifically, the discharge preparation is to open the auxiliary input switch 34 and close the self-sustaining output switch 33. When the discharge preparation is completed, the control unit 35 transmits a discharge preparation completion signal to the control unit 5 (step S21). After transmitting the signal, it waits for receiving the charge / discharge change command from the control unit 5 (step S22), and when it receives the signal, the converter 31 starts operating in the discharge direction at the next zero cross (step S23).
As a result, the role of the power storage device 3 changes from charging to discharging, and then the process starts from step S25.

Here, the control unit 45 will be described from a different point of view. In FIG. 6, when the self-sustaining output is started, the control unit 45 receives an instruction for initial charging / discharging from the control unit 5 (step S11). Assuming that the control unit 35 receives the charge instruction as described above, the instruction to the control unit 45 is discharge (discharge in step S12), and the control unit 45 prepares for discharge (step S24). Specifically, the control unit 45 opens the auxiliary input switch 44 and closes the self-supporting output switch 43.

Subsequently, the control unit 45 operates the converter 41 to discharge the storage battery 40 (step S25). After that, the discharge can be performed until the discharge limit value is reached (step S28), but the process ends when the self-sustaining output ends (step S26) during that time. If the discharge limit value is reached before the replacement preparation command (step S27) comes (“YES” in step S28), the control unit 45 sends a discharge limit flag to the control unit 5 to notify (step S29). ), Go to step S30 of FIG. If a replacement preparation command is received before reaching the discharge limit value (“YES” in step S27), the control unit 45 goes to step S30 in FIG. 7 without notifying.

In FIG. 7, the control unit 45 waits for receiving the charge / discharge change command from the control unit 5 (step S30), and when it receives it, stops the converter 41 at the next zero cross (step S31). The timing at which the control unit 35 receives the charge / discharge change command and the timing at which the control unit 45 receives the charge / discharge change command are the same. Therefore, step S23 by the control unit 35 and step S31 by the control unit 45 Are done at the same time as each other. In this way, the phase of newly starting the discharge and the phase of stopping the discharge are synchronized, and the main body of the discharge is smoothly changed without causing a phase jump.

Next, the control unit 45 prepares for charging (step S32). Specifically, the self-supporting output switch 43 is opened and the auxiliary input switch 44 is closed. Then, the converter 41 is charged (step S33). As a result, the role of the power storage device 4 changes from discharging to charging, and thereafter, the process proceeds from step S14.

<< Summary of Disclosure >>
As described above, the self-sustaining power supply system 100 of the present disclosure can first receive the self-sustaining output from the renewable energy source such as the photovoltaic power generation panel 1 in the state of system disconnection, and the load 8 It supplies power to the.
The self-sustaining power supply system 100 has a first storage battery 30, a storage function that converts the self-sustaining output into DC power to charge the first storage battery 30, and AC power for the DC power of the first storage battery 30. It has a first power storage device 3 having a power supply function to supply the power required for the load 8 and a second storage battery 40, and converts the self-sustaining output into DC power to charge the second storage battery 40. A second power storage device 4 having a power storage function and a power supply function of converting the DC power of the second storage battery 40 into AC power to supply the power required for the load 8, the first power storage device 3 and the first With control units 5, 35, 45, one of the power storage devices 4 of 2 executes only the power storage function, the other executes only the power supply function, and controls the execution subject to change with the passage of time. , Is equipped.

According to such an independent power supply system 100, the independent output of the renewable energy source is used only for charging one of the power storage devices 3 or 4, and the renewable energy source does not directly supply power to the load 8. Power is always supplied to the load 8 from any of the power storage devices 4 or 3. Therefore, even when the non-linear load is fed, the independent output of the renewable energy source is not affected by it. Therefore, the alternating current output from the renewable energy source always has a sinusoidal current with small distortion, and stable charging can be performed. On the other hand, since power is supplied to the load 8 by the self-sustaining output of the power storage device, stable power can be supplied to the load without being affected by the weather even if the renewable energy source is the photovoltaic power generation device 10. Can be done.
In this way, both stable charging and stable power supply can be realized between the self-sustaining output end of the renewable energy source and the load.

《Others》
Although the photovoltaic power generation panel 1 is shown in the above embodiment, such a self-sustaining power supply system can also be applied to other renewable energy sources.

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It should be noted that the embodiments disclosed this time are examples in all respects and are not restrictive. The scope of the present invention is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Solar power generation panel 2 Power conversion device 2t Independent output terminal 3, 4 Power storage device 5 Control unit 6 Commercial power system 7 Important load distribution board 8 Load 10 Solar power generation device 21 Inverter circuit 22 System interconnection switch 23 Independent output switch 30 Storage battery 31 Converter circuit 32 Grid interconnection switch 33 Independent output switch 34 Auxiliary input switch 35 Control unit 36,37 Voltage sensor 40 Storage battery 41 Converter circuit 42 Grid interconnection switch 43 Independent output switch 44 Auxiliary input switch 45 Control unit 46,47 Voltage sensor 71 Changeover switch 72 Circuit breaker 100 Independent power supply system

Claims (8)

It is a self-sustaining power supply system that can receive a self-sustaining output from a renewable energy source and supplies power to a load in a system-unconnected state.
A storage function provided between the renewable energy source and the load, having a first storage battery, converting the self-sustaining output into DC power to charge the first storage battery, and the first storage battery. A first power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
A storage function provided between the renewable energy source and the load, having a second storage battery, converting the self-sustaining output into DC power to charge the second storage battery, and the second storage battery. A second power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
One of the first power storage device and the second power storage device executes only the power storage function, the other executes only the power supply function, and the executing entity changes with the passage of time. The control unit to control and
Independent power supply system equipped with. The first power storage device and the second power storage device are connected in parallel with each other, and each of them has an auxiliary input switch that can be opened and closed on the input side from the renewable energy source and a self-supporting device that can be opened and closed on the load side. The self-sustaining power supply system according to claim 1, further comprising an output switch, a voltage sensor connected to the input side, and a voltage sensor connected to the load side. The self-sustaining power supply system according to claim 2, wherein the control unit detects a phase based on an AC voltage currently being output, and alternates the execution subject at the timing of zero crossing. The item according to any one of claims 1 to 3, wherein when the charged storage battery of the first storage battery and the second storage battery reaches the upper limit of charging, the executing entity is replaced. The self-sustaining power supply system described. According to any one of claims 1 to 3, the executing entity is replaced when the discharging battery of the first storage battery and the second storage battery reaches the discharge limit value. Described self-sustaining power supply system. The control unit is used in both the first control unit provided in the first power storage device, the second control unit provided in the second power storage device, and the first power storage device and the second power storage device. The self-sustaining power supply system according to any one of claims 1 to 5, which comprises a common remote control device connected. It is an independent power supply system that supplies power to the load in a disconnected state.
Solar power generation equipment that can provide self-sustaining output,
A storage function provided between the solar power generation device and the load, having a first storage battery, converting the self-sustaining output into DC power to charge the first storage battery, and the first storage battery. A first power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
A storage function provided between the solar power generation device and the load, having a second storage battery, converting the self-sustaining output into DC power to charge the second storage battery, and the second storage battery. A second power storage device having a power supply function that converts the DC power of the storage battery into AC power and supplies the power required for the load.
One of the first power storage device and the second power storage device executes only the power storage function, the other executes only the power supply function, and the executing entity changes with the passage of time. The control unit to control and
Independent power supply system equipped with. A method for controlling a self-sustaining power supply system in a self-sustaining power supply system in which a first power storage device and a second power storage device are interposed in parallel between an output end that provides a self-sustaining output from a renewable energy source and a load. ,
The self-sustaining output is converted into DC power to charge the first storage battery of the first power storage device, and the DC power of the second storage battery of the second power storage device is converted into AC power to be used as the load. Supply the required power,
The roles of the first power storage device and the second power storage device are switched with each other over time.
How to control an independent power supply system.

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