Power supply system, control method and control device

Abstract

To realize a power-supply system capable of utilizing a solar battery without suppressing an output.SOLUTION: A power-supply system (1) comprises: a DC supply distribution system (10) for supplying power to a DC load (110); an AC supply distribution system (20) for supplying power to an AC load (120); and a power conversion device (40). The power conversion device is connected to a solar battery (11) included in the DC supply distribution system, and to the AC load, and converts DC power generated by the solar battery into AC power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply system, and a control method and a control device for controlling the power supply system. [Background technology]

[0002] With the recent expansion of renewable energy use, it is expected that DC power distribution systems that aim for efficient operation by supplying DC power to DC loads will become widespread. An example of such a DC power distribution system is disclosed in Patent Document 1. In this DC power distribution system, when the amount of power generated by a photovoltaic power generation device (solar cell) is greater than the power consumed by a load device, the surplus generated power is charged into a storage battery, and if there is any further surplus generated power, it is supplied to an AC grid and sold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5584763 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the DC power distribution system disclosed in Patent Document 1, if a contract for selling electricity has not been concluded in advance and if there is still surplus power generated by the solar cells even after charging the storage battery with the power generated by the solar cells, the output of the solar cells will be suppressed, which poses a problem of reduced power generation efficiency of the solar cells.

[0005] An object of one embodiment of the present invention is to provide a power supply system or the like that can utilize a solar cell without suppressing its output. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, one embodiment of the present invention provides a power supply system that can be connected to a commercial power source and can supply power to a DC load and an AC load, and includes a DC power supply / distribution system that supplies power to the DC load, an AC power supply / distribution system that supplies power to the AC load, and a power conversion device. The DC power supply / distribution system includes an AC (Alternating Current)-DC (Direct Current) converter to which the commercial power source is connected, a solar cell, a first DC-DC converter to which the solar cell is connected, a storage battery, a second DC-DC converter to which the storage battery is connected, and a DC bus that connects the AC-DC converter, the first DC-DC converter, and the second DC-DC converter to the DC load. The AC power supply / distribution system includes an AC bus that connects the commercial power source to the AC load. The power conversion device is connected to the solar cell and the AC load and converts DC power generated by the solar cell into AC power. [Effects of the Invention]

[0007] According to one embodiment of the present invention, it is possible to realize a power supply system or the like that can utilize a solar cell without suppressing its output. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of a main part of a power supply system according to an embodiment of the present invention; [Figure 2] 10 is a flowchart illustrating an example of a control method for a power supply system by a control device in a grid-connected mode. [Figure 3] 3 is a flowchart showing the "processing when connected to the grid and SOC>25%" in FIG. 2. [Figure 4] 4 is a flowchart showing the "processing when connected to the grid and SOC>75%" in FIG. 3. [Figure 5] 10 is a flowchart illustrating an example of a control method for a power supply system by a control device in a parallel-off mode. [Figure 6]6 is a flowchart showing the "processing when paralleled off and SOC≠0%" in FIG. 5. [Figure 7] 7 is a flowchart showing the "processing when parallel-off and SOC>90%" in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, one embodiment of the present invention will be described in detail.

[0010] (Configuration of power supply system 1) FIG. 1 is a diagram showing the configuration of a main part of a power supply system 1 according to this embodiment. The power supply system 1 can be interconnected with a commercial power source 100. The power supply system 1 can supply power to a DC load 110 and an AC load 120. As shown in FIG. 1, the power supply system 1 includes a DC power supply / distribution system 10, an AC power supply / distribution system 20, and a power conversion device 40. The DC power supply / distribution system 10 is connected to the commercial power source 100 via a circuit breaker 31 and supplies power to the DC load 110. The AC power supply / distribution system 20 is connected to the commercial power source 100 via a circuit breaker 32 and supplies power to the AC load 120. The circuit breakers 31 and 32 disconnect the power supply system 1 from the commercial power source 100 when the power supply system 1 is operated in an autonomous mode.

[0011] The DC power supply and distribution system 10 includes a solar cell 11, a first DC-DC converter 11a, a storage battery 12, a second DC-DC converter 12a, an AC-DC converter 14, a DC bus 15, and DC circuit breakers 11b and 12b.

[0012] The DC bus 15 connects the AC-DC converter 14, the first DC-DC converter 11a, and the second DC-DC converter 12a to the DC load 110. The DC bus 15 functions as a power line that supplies power from the solar cell 11, the storage battery 12, and / or the commercial power supply 100 to the DC load 110. For simplicity, a single load is shown as the DC load 110 in FIG. 1 . However, the DC load 110 may include two or more loads. The DC bus 15 also functions as a power line that supplies power from the solar cell 11 and / or the commercial power supply 100 to the storage battery 12.

[0013] The solar cell 11 generates DC power according to the amount of light received. The solar cell 11 is connected to a DC bus 15 via a first DC-DC converter 11a and a DC circuit breaker 11b. The DC-DC converter 11a converts the power supplied from the solar cell 11 to a DC load 110 into a voltage according to the rating of the DC load 110. The DC-DC converter 11a is a unidirectional converter. The DC circuit breaker 11b cuts off the supply of power from the solar cell 11 to the DC load 110 as necessary. The DC circuit breaker 11b is, for example, a semiconductor switch.

[0014] The storage battery 12 stores power as energy internally and supplies the stored energy as direct current to the DC bus 15 as needed. The storage battery 12 is connected to the DC bus 15 via a DC-DC converter 12a and a DC circuit breaker 12b. The DC-DC converter 12a converts the power supplied from the storage battery 12 to the DC load 110 into a voltage according to the rating of the DC load 110. The DC-DC converter 12a is a bidirectional converter. The DC circuit breaker 12b cuts off the supply of power from the storage battery 12 to the DC load 110 as needed. The DC circuit breaker 12b is, for example, a semiconductor switch.

[0015] AC-DC converter 14 converts AC power supplied from commercial power supply 100 into DC power of a voltage corresponding to the rating of DC load 110. In power supply system 1, AC-DC converter 14 converts power only in the direction from commercial power supply 100 to DC load 110. Power supply system 1 includes a diode (not shown) for blocking current flowing from DC load 110 to commercial power supply 100. In other words, the interconnection between power supply system 1 and commercial power supply 100 is a so-called unidirectional interconnection in which power supply system 1 only receives power from commercial power supply 100. Therefore, in power supply system 1, power is not supplied from solar cell 11 or storage battery 12 to AC load 120 via AC-DC converter 14.

[0016] The power supply system 1 is also configured so that the mobile storage battery 13 can be connected to a DC bus 15 via a third DC-DC converter 13a and a DC circuit breaker 13b. The mobile storage battery 13 stores power internally as energy and supplies the stored energy to the DC bus 15 as direct current as needed. The third DC-DC converter 13a converts the power supplied from the mobile storage battery 13 to the DC load 110 into a voltage according to the rating of the DC load 110. The third DC-DC converter 13a is a bidirectional converter. The DC circuit breaker 13b cuts off the supply of power from the storage battery 12 to the DC load 110 as needed. The DC circuit breaker 13b is, for example, a semiconductor switch.

[0017] In the power supply system 1, when power is supplied from the storage battery 12 to the DC load 110, power may also be supplied from the mobile storage battery 13 to the DC load 110. Furthermore, in the power supply system 1, when the storage battery 12 is charged, the mobile storage battery 13 may also be charged at the same time. The mobile storage battery 13 is, for example, a storage battery mounted on an electric vehicle. Therefore, the mobile storage battery 13, the third DC-DC converter 13a, and the DC circuit breaker 13b do not need to be considered as components of the power supply system 1.

[0018] The power conversion device 40 is connected to the solar cell 11 and the AC load 120. The power conversion device 40 converts DC power generated by the solar cell 11 into AC power. The solar cell 11 can switch between supplying power to the DC-DC converter 11a or the power conversion device 40. However, the solar cell 11 does not supply power to both the DC-DC converter 11a and the power conversion device 40 at the same time.

[0019] The AC power supply and distribution system 20 includes an AC bus 21 and an AC circuit breaker 22. The AC bus 21 connects a commercial power source 100, a power conversion device 40, and an AC load 120. In the power supply system 1, power is supplied from the commercial power source 100 and / or the power conversion device 40 to the AC load 120. The AC circuit breaker 22 is provided on the AC bus 21 between the power conversion device 40 and the AC load 120, and disconnects the power conversion device 40 from the AC load 120 as necessary. The AC circuit breaker 22 is, for example, an AC circuit breaker such as a so-called hybrid switch that combines a semiconductor switch and a mechanical switch.

[0020] The power consumption of the AC load 120 is assumed to be greater than the capacity of the solar cell 11. In other words, when the power generated by the solar cell 11 is supplied to the AC load 120 via the power conversion device 40, no surplus power is generated.

[0021] (Configuration of control device 50) The control device 50 controls the operation of the power supply system 1. The control device 50 is communicably connected to a storage device 60 that stores information necessary for controlling the power supply system 1. The control device 50 includes a SOC (State Of Charge) determination unit 51 (a charging rate determination unit), a charge control unit 52, a power generation amount determination unit 53, and a power supply control unit 54 (an AC load power supply control unit).

[0022] The control device 50 has two operation modes: a grid-connected mode and a disconnected mode. The grid-connected mode is an operation mode in which the power supply system 1 is connected to the commercial power source 100. The disconnected mode is an operation mode in which the power supply system 1 is disconnected from the commercial power source 100.

[0023] The control device 50 may be connected to a switch that receives a user's operation for switching the operation mode, for example. The control device 50 may also be capable of switching the operation mode in conjunction with the states of the circuit breakers 31 and 32.

[0024] The SOC determination unit 51 determines the SOC of the storage battery 12. The SOC determination unit 51 does not determine the SOC of the mobile storage battery 13. In the following description, the SOC of the storage battery 12 will be simply referred to as SOC.

[0025] In the grid-connected mode, the SOC determination unit 51 determines whether the SOC is equal to or lower than a predetermined charge-requiring threshold. The charge-requiring threshold is an upper limit of the SOC at which the storage battery 12 is charged with power from the commercial power source 100. The state in which the power supply system 1 is connected to the commercial power source 100 can be said to be the normal state for the power supply system 1. In this state, the storage battery 12 is charged so that the SOC is maintained higher than the charge-requiring threshold in order to extend its life. In other words, when the SOC is higher than the charge-requiring threshold, the storage battery 12 is not charged with power from the commercial power source 100. The charge-requiring threshold may be, for example, 10%, but is not limited to this and may be set as appropriate depending on the manufacturer of the storage battery 12, etc.

[0026] Furthermore, the SOC determination unit 51 determines whether the SOC is equal to or lower than a predetermined power supply stop threshold. The power supply stop threshold is an upper limit value of the SOC at which power supply from the storage battery 12 to the DC load 110 is stopped. In other words, when the SOC is higher than the power supply stop threshold, power may be supplied from the storage battery 12 to the DC load 110 depending on the amount of power generated by the solar cell 11 (described later). The power supply stop threshold in the grid-connected mode is preferably higher than the charge-required threshold, for example, 25%. The power supply stop threshold in the disconnection mode is preferably lower than the charge-required threshold, for example, 0%. However, the power supply stop threshold in each operation mode is not limited to this and may be set as appropriate depending on the manufacturer of the storage battery 12, etc.

[0027] As described above, the charge-requiring threshold is a lower limit of the SOC that is preferably maintained to extend the life of the storage battery 12. However, if power supply from the storage battery 12 is enabled when the SOC is higher than the charge-requiring threshold, charging and discharging of the storage battery 12 will be repeated while the SOC is close to the charge-requiring threshold, depending on the amount of power generated by the solar cell 11. Operating the storage battery 12 in this manner will shorten the life of the storage battery 12. For this reason, in the grid-connected mode, even if the SOC is higher than the charge-requiring threshold, the supply of power from the storage battery 12 to the DC load 110 is stopped if the SOC is equal to or lower than the power supply stop threshold. This makes it possible to stably maintain the SOC higher than the charge-requiring threshold.

[0028] On the other hand, a state in which the power supply system 1 is disconnected from the commercial power source 100 (during stand-alone operation) can be considered an emergency state for the power supply system 1. For this reason, in the disconnection mode, power may be supplied from the storage battery 12 to the DC load 110 as needed even if the SOC becomes equal to or lower than the charge requirement threshold, without considering the extension of the life of the storage battery 12 described above.

[0029] When the power supply interruption threshold in the grid-connected mode is set as described above, the SOC will not become equal to or lower than the charge-requiring threshold while the control device 50 is operating in the grid-connected mode. However, for example, if the control device 50 temporarily operates in the disconnected mode, and power is supplied from the storage battery 12 to the DC load 110 until the SOC becomes equal to or lower than the charge-requiring threshold, and then the control device 50 transitions to the grid-connected mode, the SOC will become equal to or lower than the charge-requiring threshold in the grid-connected mode.

[0030] Furthermore, the SOC determination unit 51 determines whether the SOC is equal to or lower than a predetermined upper charge threshold. The upper charge threshold is an upper limit value of the SOC at which, when the amount of power generated by the solar cell 11 is greater than the power consumed by the DC load 110, the power generated by the solar cell 11 is supplied to the DC load 110 and the surplus power is charged to the storage battery 12. In other words, when the SOC is greater than the upper charge threshold, the power generated by the solar cell 11 is not charged to the storage battery 12.

[0031] The upper charge threshold in the grid-connected mode and the upper charge threshold in the disconnected mode may be different from each other. Specifically, the upper charge threshold in the grid-connected mode is preferably smaller than the upper charge threshold in the disconnected mode. More specifically, the upper charge threshold in the grid-connected mode is, for example, 75%. Furthermore, the upper charge threshold in the disconnected mode is, for example, 90%. However, the upper charge thresholds in each operation mode are not limited to these and may be set appropriately depending on the manufacturer of the storage battery 12, etc.

[0032] From the viewpoint of stabilizing the supply of power to the DC load 110, it is preferable to keep the SOC high so that more power can be supplied from the storage battery 12 to the DC load 110 in preparation for a possibility that the amount of power generated by the solar cell 11 will decrease due to weather conditions or the like. On the other hand, from the viewpoint of extending the life of the storage battery, it is preferable not to make the SOC excessive. When the upper charge threshold takes the value described above, the storage battery 12 is not charged at a relatively low SOC in the grid-connected mode, which is the operating mode in a normal state for the power supply system 1. Therefore, the SOC does not become excessive, and the life of the storage battery 12 can be extended. Furthermore, in the disconnection mode, which is the operating mode in an emergency state for the power supply system 1, power is maintained in the storage battery 12 up to an SOC that is higher than that in the grid-connected mode. Therefore, it is possible to keep the SOC high in preparation for a possibility that the amount of power generated by the solar cell 11 will decrease due to weather conditions or the like.

[0033] The power generation amount determination unit 53 determines whether the amount of power generated by the solar cell 11 is greater than the power consumption of the DC load 110. For example, the DC load 110 includes a recording medium on which information indicating its own power consumption is recorded. In this case, the power generation amount determination unit 53 is connected to a reader (not shown) that reads information from the recording medium. The power generation amount determination unit 53 compares the power consumption of the DC load 110 indicated by the information read by the reader with the amount of power generated by the solar cell 11.

[0034] The charging control unit 52 controls the charging of the storage battery 12 by controlling the DC-DC converter 11a, the DC circuit breaker 11b, the DC-DC converter 12a, the DC circuit breaker 12b, and the AC-DC converter 14. When the SOC is equal to or lower than the charge-required threshold in the grid-connected mode, the charging control unit 52 charges the storage battery 12 with power from the commercial power source 100. Furthermore, when the SOC is equal to or lower than the charge upper limit threshold and the amount of power generated by the solar cell 11 is greater than the power consumption of the DC load 110, the charging control unit 52 charges the storage battery 12 with surplus power. Furthermore, the charging control unit 52 may further control the third DC-DC converter 13a and the DC circuit breaker 13b to control the charging of the mobile storage battery 13.

[0035] The power supply control unit 54 controls the DC-DC converter 11a, the DC circuit breaker 11b, the DC-DC converter 12a, the DC circuit breaker 12b, and / or the AC-DC converter 14 to control the supply of power from the solar cell 11, the storage battery 12, and / or the commercial power supply 100 to the DC load 110. The charging control unit 52 may further control the third DC-DC converter 13a and the DC circuit breaker 13b to control the supply of power from the mobile storage battery 13 to the DC load 110. The power supply control unit 54 also controls the power conversion device 40 to control the supply of power from the solar cell 11 to the AC load 120.

[0036] Specifically, when (i) the charging rate of the storage battery 12 is greater than the upper charge threshold, and (ii) the amount of power generated by the solar cell 11 is greater than the power consumption of the DC load 110, the power supply control unit 54 supplies the power generated by the solar cell 11 to the AC load 120 via the power conversion device 40 and the AC bus 21. In this case, the power supply control unit 54 supplies power from the storage battery 12 and / or the commercial power source 100 to the DC load 110.

[0037] In this case, the power supply control unit 54 stops supplying the power generated by the solar cell 11 to the DC load 110. Therefore, compared to when the power generated by the solar cell 11 is simultaneously supplied to both the DC load 110 and the AC load 120, there is no need to control the ratio of the power supplied to the DC load 110 and the AC load 120. This simplifies the control by the power supply control unit 54.

[0038] Furthermore, when the charging rate of the storage battery 12 is equal to or lower than the upper charge threshold, or when the amount of power generated by the solar cell 11 is equal to or lower than the power consumption of the DC load 110, the power supply control unit 54 supplies the power generated by the solar cell 11 to the DC load 110. In this case, the power supply control unit 54 also supplies power from the storage battery 12 and / or the commercial power source 100 to the DC load as necessary.

[0039] (Processing by the control device 50) Fig. 2 is a flowchart showing an example of a method for controlling the power supply system 1 by the control device 50 in the grid-connected mode. In the grid-connected mode, the control device 50 repeats the process shown in Fig. 2 at predetermined intervals, for example, at intervals of 10 seconds to 1 minute. In each control method, charging or power supply, which is performed according to the result of the determination, continues until the next process. If it is not determined in the next process that charging or power supply should be performed, charging or power supply is stopped at that point.

[0040] In the grid-connected mode, the SOC determination unit 51 determines whether the SOC is 25% or less (the power supply interruption threshold in the grid-connected mode) (S11). If the SOC is not 25% or less ("NO" in S11), the control device 50 executes the "processing when the grid is connected and the SOC is greater than 25%" (S2), which will be described later.

[0041] If the SOC is 25% or less ("YES" in S11), the SOC determination unit 51 determines whether the SOC is 10% or less (the charging threshold) (S12). If the SOC is 10% or less ("YES" in S12), the charge control unit 52 charges the storage battery 12 from the commercial power source 100 (S13). If the SOC is not 10% or less ("NO" in S12), the control device 50 skips step S13.

[0042] After step S13 or step S12, the power generation amount determination unit 53 determines the amount of power generated by the solar cell 11 (S14). If the amount of power generated by the solar cell 11 is 0 W (i.e., the solar cell 11 is not generating power) (“=0” in S14), the power supply control unit 54 supplies power from the commercial power supply 100 to the DC load 110 (S15). If the amount of power generated by the solar cell 11 is greater than 0 W and is equal to or less than the power consumption of the DC load 110 (“≦DC load” in S14), the power supply control unit 54 supplies power to the DC load 110 in the following order of priority: (1) the solar cell 11, and (2) the commercial power supply 100 (S16). That is, the power supply control unit 54 supplies the power generated by the solar cell 11 to the DC load 110. Furthermore, the power supply control unit 54 supplements the power that is insufficient in the power generated by the solar cell 11 with power from the commercial power supply 100.

[0043] If the amount of power generated by solar cell 11 is greater than the power consumption of the DC load (>DC load in S14), power supply control unit 54 supplies the power generated by solar cell 11 to DC load 110 (S17). In parallel with step S17, charging control unit 52 charges the storage battery 12 with surplus power generated by solar cell 11 that exceeds the power consumption of DC load 110 (S18). After step S15, step S16, or steps S17 and S18, control device 50 ends the series of processes.

[0044] 3 is a flowchart showing the "processing when connected to the grid and SOC>25%" in FIG. 2. In the "processing when connected to the grid and SOC>25%", the SOC determination unit 51 determines whether the SOC is 75% or less (the upper charge threshold in the grid-connected mode) (S21). Step S21 can also be expressed as a step of determining whether the SOC is greater than 75% (a charging rate determination step). If the SOC is not 75% or less ("NO" in S21), the control device 50 executes the "processing when connected to the grid and SOC>75%" (S3), which will be described later.

[0045] If the SOC is 75% or less ("YES" in S21), the power generation amount determination unit 53 determines the power generation amount of the solar cell 11 (S22). If the power generation amount of the solar cell 11 is 0 W ("=0" in S22), the power supply control unit 54 supplies power to the DC load in the following order of priority: (1) the storage battery 12, and (2) the commercial power source 100 (S23). That is, the power supply control unit 54 supplies power from the storage battery 12 to the DC load 110. Furthermore, if the power supplied from the storage battery 12 is insufficient for the power consumed by the DC load 110, the power supply control unit 54 supplies power from the commercial power source 100 to the DC load 110 to make up for the shortage.

[0046] If the power generation amount of the solar cell 11 is greater than 0 W and is equal to or less than the power consumption of the DC load 110 ("≦DC load" in S22), the power supply control unit 54 supplies power to the DC load in the following order of priority (1) solar cell 11, (2) storage battery 12, and (3) commercial power supply 100 (S24). That is, the power supply control unit 54 supplies the power generated by the solar cell 11 to the DC load 110. The power supply control unit 54 also compensates for a shortage of the power generated by the solar cell 11 relative to the power consumption of the DC load 110 by supplying power from the storage battery 12 to the DC load 110. Furthermore, if a shortage of power relative to the power consumption of the DC load 110 still occurs even when power is supplied from the storage battery 12 to the DC load 110, the power supply control unit 54 compensates for the shortage by supplying power from the commercial power supply 100 to the DC load 110.

[0047] If the amount of power generated by the solar cell 11 is greater than the power consumption of the DC load 110 (>DC load in S22), the power supply control unit 54 supplies the power generated by the solar cell 11 to the DC load 110 (S25). In parallel with step S25, the charging control unit 52 charges the surplus power to the storage battery 12 (S26). After step S23, step S24, or steps S25 and S26, the control device 50 ends the series of processes.

[0048] 4 is a flowchart showing the "processing when the system is interconnected and the SOC is greater than 75%" in FIG. 3. In the "processing when the system is interconnected and the SOC is greater than 75%," the power generation amount determination unit 53 determines the power generation amount of the solar cell 11 (S31, power generation amount determination step). If the power generation amount of the solar cell 11 is 0 W ("=0" in S31), the power supply control unit 54 supplies power to the DC load in the following order of priority (1) the storage battery 12, and (2) the commercial power source 100, as in step S23 (S32). If the power generation amount of the solar cell 11 is greater than 0 W and is equal to or less than the power consumption of the DC load 110 ("≦DC load" in S31), the power supply control unit 54 supplies power to the DC load in the following order of priority (1) the solar cell 11, (2) the storage battery 12, and (3) the commercial power source 100, as in step S24 (S33).

[0049] If the amount of power generated by the solar cell 11 is greater than the power consumption of the DC load 110 (>DC load in S31), the power supply control unit 54 supplies power to the DC load in the following order of priority: (1) the storage battery 12, and (2) the commercial power source 100 (S34), as in step S32. In parallel with step S34, the charging control unit 52 supplies the power generated by the solar cell 11 to the AC load 120 (S35, AC load power supply step). After step S32, step S33, or steps S34 and S35, the control device 50 ends the series of processes.

[0050] Fig. 5 is a flowchart showing an example of a method for controlling the power supply system 1 in the disconnection mode by the control device 50. In the disconnection mode, the control device 50 repeats the process shown in Fig. 5 at predetermined intervals, for example, at intervals of 10 seconds to 1 minute.

[0051] In the disconnection mode, the SOC determination unit 51 determines whether the SOC is 0% (less than the power supply stop threshold in the disconnection mode) (S41). If the SOC is not 0% ("NO" in S41), the control device 50 executes "processing when disconnected and SOC≠0%" (S5), which will be described later.

[0052] If the SOC is 0% ("YES" in S41), the power generation amount determination unit 53 determines the power generation amount of the solar cell 11 (S42). If the power generation amount of the solar cell 11 is 0 W ("=0" in S42), there is no power that can be supplied to the DC load 110, so the control device 50 stops the power supply system 1 (S43).

[0053] If the power generation amount of the solar cell 11 is greater than 0 W and is equal to or less than the power consumption of the DC load 110 ("≦DC load" in S42), the control device 50 cuts off the supply of power to the DC load 110 so that the power consumption of the DC load 110 is less than the power generation amount of the solar cell 11 (S44). To enable such power supply cutoff, the DC power supply and distribution system 10 includes a DC circuit breaker 16 that can be controlled by the control device 50. The DC circuit breaker 16 is a circuit breaker that can individually cut off multiple loads included in the DC load 110. The DC load 110 is connected to the DC bus 15 via the DC circuit breaker 16. Thereafter, the power supply control unit 54 supplies power from the solar cell 11 to the DC loads 110 that are not cut off by the DC circuit breaker 16 (S45). However, for example, when the DC load 110 is a single load, the control device 50 may stop the power supply system 1 in the same manner as in step S43, instead of executing steps S44 and S45.

[0054] If the amount of power generated by the solar cell 11 is greater than the power consumption of the DC load 110 (>DC load in S42), the power supply control unit 54 supplies the power generated by the solar cell 11 to the DC load 110 (S46). In parallel with step S45, the charging control unit 52 charges the surplus power to the storage battery 12 (S47). After step S43, step S45, or steps S46 and S47, the control device 50 ends the series of processes.

[0055] As described above, in the parallel-off mode, the control device 50 repeats the process shown in Fig. 5 at predetermined intervals. If the determination result in step S42 at one time is "≦DC load" and the power supply to part of the DC load 110 is cut off, the next and subsequent processes are performed with the power supply to that part of the DC load 110 cut off. In this case, if the power generation amount determination unit 53 determines ">DC load" in step S42, it may further determine whether or not it is possible to resume the power supply to the DC load 110 to which the power supply was cut off.

[0056] 6 is a flowchart showing the "processing when parallel-off and SOC≠0%" in FIG. 5. In the "processing when parallel-off and SOC≠0%, the SOC determination unit 51 determines whether the SOC is 90% or less (the upper charge threshold in parallel-off mode) (S51). Step S51 can also be expressed as a step of determining whether the SOC is greater than 90% (a charging rate determination step). If the SOC is not 90% or less ("NO" in S51), the control device 50 executes the "processing when parallel-off and SOC>90%" (S6), which will be described later.

[0057] If the SOC is 90% or less ("YES" in S51), the power generation amount determination unit 53 determines the power generation amount of the solar cell 11 (S52). If the power generation amount of the solar cell 11 is 0 W ("=0" in S52), the power supply control unit 54 supplies power from the storage battery 12 to the DC load 110 (S53). If the power generation amount of the solar cell 11 is greater than 0 W and less than or equal to the power consumption of the DC load 110 ("≦DC load" in S52), the power supply control unit 54 supplies power to the DC load 110 in the following order of priority (1) the solar cell 11, and (2) the storage battery 12 (S54). If the power generation amount of the solar cell 11 is greater than the power consumption of the DC load 110 (">DC load" in S52), the power supply control unit 54 supplies the power generated by the solar cell 11 to the DC load 110 (S55). In parallel with step S55, the charge control unit 52 charges the surplus power to the storage battery 12 (S56). After step S53, step S54, or steps S55 and S56, the control device 50 ends the series of processes.

[0058] 7 is a flowchart showing the "processing when parallel-off occurs and SOC>90%" in FIG. 6. In the "processing when parallel-off occurs and SOC>90%, the power generation amount determination unit 53 determines the power generation amount of the solar cell 11 (S61, power generation amount determination step). If the power generation amount of the solar cell 11 is 0 W ("=0" in S61), the power supply control unit 54 supplies power from the storage battery 12 to the DC load 110 (S62). If the power generation amount of the solar cell 11 is greater than 0 W and is equal to or less than the power consumption of the DC load 110 ("≦DC load" in S61), the power supply control unit 54 supplies power to the DC load 110 in the following order of priority (1) the solar cell 11, and (2) the storage battery 12 (S63). If the power generation amount of the solar cell 11 is greater than the power consumption of the DC load 110 (">DC load" in S61), the power supply control unit 54 supplies power from the storage battery 12 to the DC load 110 (S64). In parallel with step S64, the power supply control unit 54 supplies the power generated by the solar cell 11 to the AC load 120 (S65, AC load power supply step). After step S62, step S63, or steps S64 and S65, the control device 50 ends the series of processes.

[0059] As described above, in the power supply system 1, the power generated by the solar cell 11 is preferentially supplied to the DC load 110, and the surplus power is charged to the storage battery 12. If surplus power still remains even after the power generated by the solar cell 11 is supplied to the DC load 110 and the surplus power is charged to the storage battery 12, the power generated by the solar cell 11 is supplied to the AC load 120. This makes it unnecessary to suppress the output of the solar cell 11 even when surplus power is generated. Therefore, it is possible to prevent a decrease in power generation efficiency caused by suppressing the output of the solar cell 11.

[0060] Furthermore, in the power supply system 1, when power generated by the solar cell 11 is supplied to the AC load 120, it is supplied via the power conversion device 40. Therefore, compared to when, for example, a bidirectional AC-DC converter is used instead of the AC-DC converter 14 and power is supplied to the AC load 120 via the first DC-DC converter 11a and the bidirectional AC-DC converter, power loss in the power conversion process is reduced. Therefore, the efficiency of power supply from the solar cell 11 to the AC load 120 can be improved.

[0061] Furthermore, in the power supply system 1, the power generated by the solar cell 11 can be supplied to the DC load 110 or the AC load 120 depending on the SOC and the amount of power generated by the solar cell 11. In other words, the DC power supply / distribution system 10 and the AC power supply / distribution system 20 share the solar cell 11. Therefore, the number of pieces of equipment (i.e., costs) can be reduced compared to a system in which the DC power supply / distribution system 10 and the AC power supply / distribution system 20 each have their own solar cell.

[0062] As described above, power supply system 1 includes a diode for blocking current flowing from DC load 110 to commercial power supply 100, and is unidirectionally interconnected with commercial power supply 100. The cost of the diode is lower than the cost of configuring AC-DC converter 14 as a bidirectional converter. Therefore, with the above configuration, the cost of power supply system 1 can be reduced compared to when power supply system 1 is bidirectionally interconnected with commercial power supply 100.

[0063] Furthermore, in the power supply system 1, when the storage battery 12 has a small capacity, surplus power is more likely to occur than when the storage battery 12 has a large capacity. However, as described above, in the power supply system 1, when surplus power occurs, the power generated by the solar cell 11 can be supplied to the AC load 120. Therefore, even if surplus power occurs, the operation of the power supply system 1 is not hindered. Therefore, by using a storage battery 12 with a small capacity, the cost of the power supply system 1 can be reduced.

[0064] [Software implementation example] The functions of the control device 50 (hereinafter referred to as the "device") can be realized by a program that causes a computer to function as the device, and a program that causes a computer to function as each control block of the device (particularly each part included in the control device 50).

[0065] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program, thereby realizing the functions described in each of the above embodiments.

[0066] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0067] Furthermore, some or all of the functions of the control blocks can be realized by logic circuits. For example, an integrated circuit in which a logic circuit that functions as each of the control blocks is formed is also included in the scope of the present invention. In addition, the functions of the control blocks can also be realized by, for example, a quantum computer.

[0068] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0069] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0070] 1. Power supply system 10 DC power distribution system 11 Solar cells 11a First DC-DC converter 12 Storage battery 12a Second DC-DC Converter 14 AC-DC converter 15 DC bus 20 AC power distribution system 21 AC busbar 40 Power conversion device 50 Control device 51 SOC judgment section (charging rate judgment section) 53 Power generation amount determination unit 54 Power supply control unit (AC load power supply control unit)

Claims

1. A power supply system that can be connected to a commercial power source and can supply power to a DC load and an AC load, a DC power supply / distribution system that supplies power to the DC load, an AC power supply / distribution system that supplies power to the AC load, and a power conversion device; The DC power supply and distribution system comprises: an alternating current (AC)-direct current (DC) converter to which the commercial power supply is connected; A solar cell and a first DC-DC converter to which the solar cell is connected; A storage battery and a second DC-DC converter to which the storage battery is connected; a DC bus connecting the AC-DC converter, the first DC-DC converter, and the second DC-DC converter to the DC load; the AC power supply / distribution system includes an AC bus that connects the commercial power source to the AC load; the power conversion device is connected to the solar cell and the AC load, and converts DC power generated by the solar cell into AC power; When the charging rate of the storage battery is greater than a predetermined upper charge threshold and the amount of power generated by the solar cell is greater than the power consumption of the DC load, the power generated by the solar cell is supplied to the AC load via the power conversion device and the AC bus.

2. 2. The power supply system according to claim 1, wherein when the charging rate of the storage battery is greater than the upper charging threshold and the amount of power generated by the solar cell is greater than the power consumed by the DC load, the supply of power generated by the solar cell to the DC load is stopped.

3. 3. The power supply system according to claim 1, wherein when the charging rate of the storage battery is equal to or lower than the upper charging threshold, or when the amount of power generated by the solar cell is equal to or lower than the power consumption of the DC load, the power generated by the solar cell is supplied to the DC bus.

4. 4. The power supply system according to claim 1, wherein the upper limit charging threshold when the power supply system is connected to the commercial power source and the upper limit charging threshold when the power supply system is disconnected from the commercial power source are different from each other.

5. 5. The power supply system according to claim 4, wherein the upper limit charging threshold when the power supply system is interconnected with the commercial power source is lower than the upper limit charging threshold when the power supply system is disconnected from the commercial power source.

6. A power supply system that can be connected to a commercial power source and can supply power to a DC load and an AC load, a DC power supply / distribution system that supplies power to the DC load, an AC power supply / distribution system that supplies power to the AC load, and a power conversion device; The DC power supply and distribution system comprises: an alternating current (AC)-direct current (DC) converter to which the commercial power supply is connected; A solar cell and a first DC-DC converter to which the solar cell is connected; A storage battery and a second DC-DC converter to which the storage battery is connected; a DC bus connecting the AC-DC converter, the first DC-DC converter, and the second DC-DC converter to the DC load; the AC power supply / distribution system includes an AC bus that connects the commercial power source to the AC load; a control method for controlling a power supply system in which the power conversion device is connected to the solar cell and the AC load and converts DC power generated by the solar cell into AC power, the method comprising: a charging rate determination step of determining whether the charging rate of the storage battery is greater than a predetermined upper charging threshold; a power generation amount determination step of determining whether or not the amount of power generated by the solar cell is greater than the power consumption of the DC load; an AC load power supply step of supplying the power generated by the solar cell to the AC load via the power conversion device and the AC bus when it is determined in the charging rate determination step that the charging rate of the storage battery is equal to or higher than the upper charging threshold and when it is determined in the power generation amount determination step that the amount of power generated by the solar cell is greater than the power consumption of the DC load.

7. A power supply system that can be connected to a commercial power source and can supply power to a DC load and an AC load, comprising: a DC power supply / distribution system that supplies power to the DC load, an AC power supply / distribution system that supplies power to the AC load, and a power conversion device; The DC power supply and distribution system comprises: an alternating current (AC)-direct current (DC) converter to which the commercial power supply is connected; A solar cell and a first DC-DC converter to which the solar cell is connected; A storage battery and a second DC-DC converter to which the storage battery is connected; a DC bus connecting the AC-DC converter, the first DC-DC converter, and the second DC-DC converter to the DC load; the AC power supply / distribution system includes an AC bus that connects the commercial power source to the AC load; the power conversion device is a control device that is connected to the solar cell and the AC load and controls a power supply system that converts DC power generated by the solar cell into AC power, a charging rate determination unit that determines whether the charging rate of the storage battery is greater than a predetermined upper charging threshold; a power generation amount determination unit that determines whether the amount of power generated by the solar cell is greater than the power consumption of the DC load; and an AC load power supply control unit that supplies the power generated by the solar cell to the AC load via the power conversion device and the AC bus when the charging rate determination unit determines that the charging rate of the storage battery is higher than the upper charging threshold and the power generation amount determination unit determines that the amount of power generated by the solar cell is higher than the power consumption of the DC load.

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