Power supply system

Abstract

To be able to perform deterioration diagnosis without stopping the operation of an entire power supply system.SOLUTION: A power supply system 1 includes multiple storage batteries for charging the power generated by a solar battery 13 through a main circuit, which is an electrical circuit for supplying electricity to a load 12 and a storage battery 11, a power conditioner 61 which is capable of converting direct current to alternating current and performing voltage adjustment and phase adjustment in the main circuit and supplies and discharges power of the storage battery, a discharger 31 for discharging the power charged in the storage battery to outside the main circuit, and a switching unit 17 used for switching connection destination of each storage battery to the power conditioner and the discharger. The power supply system 1 controls the storage battery for which deterioration diagnosis is to be performed to be connected to the discharger and controls the storage battery for which deterioration diagnosis is not to be performed to be connected to the power conditioner.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power supply system.

Background Art

[0002] As described in Patent Document 1, in a power supply system using photovoltaic power generation, the power generated by a solar cell is used for consumption by a load or charging of a storage battery. On the other hand, when the storage battery is continuously used, deterioration occurs and the amount that can be charged decreases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] By the way, in order to diagnose the deterioration of a storage battery, there is a method of discharging at a constant charging rate until the charge amount reaches a specified value from a fully charged state and measuring the discharge amount until the specified value is reached. This method is, in theory, a method that can be implemented regardless of whether the storage battery is used as a load. However, since the power consumption by the load changes every moment, the discharge rate from the storage battery does not become constant, and it is difficult to accurately diagnose the deterioration of the storage battery in the actual operation state. To avoid this and perform the diagnosis, it is conceivable to perform the diagnosis without using the storage battery as a load. However, conventionally, when a single power supply system includes a plurality of storage batteries, even when diagnosing the deterioration of one of the storage batteries, it is necessary to prevent the storage batteries of the entire power supply system from being used as a load, and the demerits due to the deterioration diagnosis were large. In particular, for a storage battery with a large capacity, several hours to several days were required to diagnose one storage battery, and since the other storage batteries could not be used during that time, the loss due to diagnosing the storage battery was large.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors of this invention have attempted to solve this problem by diligently considering it. The problem that this invention aims to solve is to enable degradation diagnosis without interrupting the operation of the entire power supply system. [Means for solving the problem]

[0006] To solve the above problems, the power supply system comprises a solar cell that supplies generated electricity to a storage battery, multiple storage batteries that are charged via a main circuit which is an electrical circuit that supplies electricity to loads and storage batteries using the electricity generated by the solar cell, an operational power conditioner that converts DC to AC in the main circuit and is capable of voltage adjustment and phase adjustment and supplies power to the storage batteries, a diagnostic power conditioner used for diagnosing the storage batteries, and a switching unit that can switch the connection destination of each storage battery between the operational power conditioner and the diagnostic power conditioner, wherein the storage battery to be diagnosed is connected to the diagnostic power conditioner and the storage battery not to be diagnosed is connected to the operational power conditioner.

[0007] Furthermore, it is preferable to select one battery from among those connected to the operational power conditioner to undergo degradation diagnosis, use a switching unit to switch the connection so that the selected battery is connected to the diagnostic power conditioner, keep the other batteries connected to the operational power conditioner, and after the degradation diagnosis is completed, switch the switching unit to connect one of the other batteries to the diagnostic power conditioner, and also switch the switching unit so that the battery for which the degradation diagnosis has been completed is connected to the operational power conditioner.

[0008] Furthermore, it is preferable to configure the system so that, after the degradation diagnosis of one battery is completed and the voltage of all batteries is within the specified range, the switching unit is switched to connect one of the other batteries to the diagnostic power conditioner, and the switching unit is also switched to connect the battery for which the degradation diagnosis has been completed to the operational power conditioner.

[0009] Furthermore, it is preferable to have a power supply system that includes multiple batteries that are charged with electricity generated by solar cells via a main circuit, which is an electrical circuit that supplies electricity to loads and batteries; a power conditioner that converts DC to AC in the main circuit and is capable of voltage and phase adjustment, and that supplies and discharges power to the batteries; a discharger that discharges the electricity stored in the batteries to the outside of the main circuit; and a switching unit used to switch the connection destination of each battery between the power conditioner and the discharger, and controls the system so that batteries to be subjected to degradation diagnosis are connected to the discharger and batteries not subjected to degradation diagnosis are connected to the power conditioner. [Effects of the Invention]

[0010] This invention makes it possible to perform degradation diagnosis without interrupting the operation of the entire power supply system. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of an example power supply system. However, it represents a normal operating state where all batteries are connected to the power conditioner. [Figure 2] This figure shows an example of the power supply system shown in Figure 1, where one battery is connected to the discharger. [Figure 3] This figure shows an example of the power supply system shown in Figure 1, but with a different battery connected to the discharger than the one shown in Figure 2. [Figure 4] This is a schematic diagram of an example of a power supply system different from Figure 1. [Figure 5] This is a schematic diagram illustrating an example of performing degradation diagnosis on a string-by-string basis in a power supply system. [Modes for carrying out the invention]

[0012] The following describes embodiments for carrying out the invention. The power supply system 1 shown in Figures 1 to 3 comprises a plurality of batteries 11 that are charged with power generated by a solar cell 13 via a main circuit, which is an electrical circuit that supplies electricity to a load 12 and a storage battery 11; a power conditioner 61 that converts DC to AC in the main circuit and is capable of voltage adjustment and phase adjustment, and is used to supply and discharge power to the storage batteries 11; a discharger 31 that discharges the power charged in the storage batteries 11 to the outside of the main circuit; and a switching unit 17 used to switch the connection destination of each storage battery 11 between the power conditioner 61 and the discharger 31. The power supply system 1 controls the storage battery 11 to be subjected to degradation diagnosis to be connected to the discharger 31, and the storage battery 11 that is not subjected to degradation diagnosis to be connected to the power conditioner 61. As a result, degradation diagnosis can be performed without stopping the operation of the entire power supply system 1.

[0013] Here, we will describe an example of the configuration of the power supply system 1 of the embodiment. In the example shown in Figure 1, power can be supplied to the load 12 from the commercial power supply 14, the solar cell 13, and the storage battery 11. Furthermore, a line that branches off from the line connecting the load 12 and the commercial power supply 14 is further branched so that power can be supplied to the load 12 from the solar cell 13 and the storage battery 11. A power conditioner 61 is provided between the storage battery 11 and the load 12, and multiple storage batteries 11 can be connected to the power conditioner 61.

[0014] Furthermore, a switching unit 17 is interposed between the battery 11 and the power conditioner 61. This switching unit 17 can switch between the state in which the battery 11 is connected to the power conditioner 61 and the state in which it is connected to the discharger 31, and each battery 11 is provided with its own unique switching unit 17.

[0015] The switching unit 17 shown in Figure 1 switches between two contacts, and the battery 11 is configured to be connected to either the power conditioner 61 or the discharger 31. Under normal operation, the battery 11 is connected to the power conditioner 61, but it is connected to the discharger 31 when degradation diagnosis is required.

[0016] When a degradation diagnosis is to be performed, one battery 11 is selected from among several batteries 11, and the degradation diagnosis is performed on that battery 11. To do this, the switching unit 17 linked to the selected battery 11 is activated so that the battery 11 is connected to the discharger 31 (see Figures 1, 2, and 3). The switching units 17 linked to the other batteries 11 are kept in their state, maintaining their connection to the power conditioner 61. By switching only some of the multiple switching units 17 in this way, some batteries 11 can be diagnosed while others are used for the normal operation of the power supply system 1.

[0017] In the example shown in Figure 1, when the switching unit 17 is moved to connect the battery 11 and the discharger 31, the power stored in the battery 11 is consumed by the discharger 31. Since the power consumption in the discharger 31 is constant, the degradation status of the battery 11 can be checked by connecting a fully charged battery 11 to the discharger 31 and observing the time required for the battery 11 to consume power until it reaches a predetermined state. The discharger 31 can be anything that has resistance and consumes power at a constant rate. For example, a resistor that consumes power by generating heat can be used. Furthermore, when diagnosing multiple batteries 11 simultaneously, it is preferable to individually link the discharger 31 and the diagnostic unit 32 to each battery 11.

[0018] In the embodiment, such confirmation is performed by the diagnostic unit 32, and the diagnostic unit 32 can output the diagnostic result externally. In the example shown in FIG. 1, the diagnostic unit 32 is connected between the discharger 31 and the storage battery 11, but it is not necessary to be limited to such a configuration. For example, the diagnostic unit 32 may be provided inside the discharger 31 or inside the storage battery 11. In the embodiment, the deterioration state of the storage battery 11 is diagnosed by comparing the discharge amount from the initial full charge to the specified value of the storage battery 11 with the discharge amount from the full charge at the time of diagnosis to the specified value, but diagnosis may be performed by other methods.

[0019] When diagnosing the deterioration of the storage battery 11 one by one, when the deterioration diagnosis of one storage battery 11 is completed, the switching unit 17 linked to the storage battery 11 for which the deterioration diagnosis has been performed is operated, and the connection destination of the storage battery 11 is switched from the discharger 31 to the power conditioner 61. Also, the switching unit 17 linked to the storage battery 11 for which deterioration diagnosis is to be performed next is operated, and the connection destination of the storage battery 11 is switched from the power conditioner 61 to the discharger 31 (see FIGS. 2 and 3).

[0020] One storage battery 11 for which deterioration diagnosis is to be performed is selected from the storage batteries 11 connected to the power conditioner 61, the connection is switched using the switching unit 17 so that the storage battery 11 is connected to the discharger 31, and the other storage batteries 11 are maintained in a state of being connected to the power conditioner 61. After the deterioration diagnosis is completed, the switching unit 17 is switched so that one of the other storage batteries 11 is connected to the discharger 31, and the switching unit 17 is switched so that the storage battery 11 for which the deterioration diagnosis has been completed is connected to the power conditioner 61. By doing so, the deterioration of the storage battery 11 can be diagnosed one by one, and thus the deterioration of a plurality of storage batteries 11 can be diagnosed while reducing the storage batteries 11 separated from operation.

[0021] Incidentally, there may be a significant voltage difference between the battery 11 after the deterioration diagnosis is completed and the battery 11 during normal operation. When there is a voltage difference between the batteries 11, there is a possibility that an overcurrent may flow from the battery 11 during normal operation to the battery 11 after the deterioration diagnosis is completed by switching the switching unit 17. In order to suppress the occurrence of this phenomenon, after the deterioration diagnosis of one battery 11 is completed, when the voltages of all the batteries 11 are within the specified range, the switching unit 17 is switched so that one of the other batteries 11 is connected to the discharger 31, and at the same time, the switching unit 17 is switched so that the battery 11 for which the deterioration diagnosis has been completed is connected to the power conditioner 61.

[0022] In the example shown in FIG. 1, a charging device 51 capable of charging the battery 11 after the deterioration diagnosis is completed is provided. This charging device 51 can pass a current from the commercial power supply 14 or the solar cell 13 to the battery 11, and can be connected to the battery 11 while maintaining the switched state when the switching unit 17 is connected to the discharger 31. Since this charging device 51 passes a current to the battery 11 after the deterioration diagnosis is completed, the current is unidirectional. In the example shown in FIG. 1, the current is configured to be unidirectional from right to left.

[0023] By passing a current from the charging device 51 to the battery 11, the voltage difference between the batteries 11 can be actively eliminated. When passing a current from the charging device 51 to the battery 11, it is preferable to prevent the current from flowing through the discharger 31. When a current is flowing from the battery 11 to the discharger 31 for the deterioration diagnosis, the current is not allowed to flow from the charging device 51 to the battery 11 side.

[0024] By the way, in the example above, the discharger 31 consumes the power stored in the battery 11, but the power consumption does not have to be done by the discharger 31. In the example shown in Figure 4, the power is consumed by the load 12. However, since the power consumption at load 12 fluctuates greatly, the current flowing from the battery 11 to load 12 during diagnosis is set to a constant value that is below the minimum power consumed by load 12. To make this possible, a diagnostic power conditioner 64 is provided, which is used to supply current from the battery 11 to load 12 during degradation diagnosis. By including the diagnostic power conditioner 64, the power used for diagnosis can be used for load 12, enabling efficient use of power.

[0025] Therefore, it is preferable to have a power supply system 1 comprising: a solar cell 13 that supplies generated power to a storage battery 11; multiple storage batteries 11 that are charged via a main circuit, which is an electrical circuit that supplies power to a load 12 and storage batteries 11 using the power generated by the solar cell 13; an operational power conditioner 66 that converts DC to AC in the main circuit and is capable of voltage and phase adjustment, and is used to supply power to the storage batteries 11; a diagnostic power conditioner 64 used for diagnosing the storage batteries 11; and a switching unit 17 that can switch the connection destination of each storage battery 11 between the operational power conditioner 66 and the diagnostic power conditioner 64, wherein the storage battery 11 to be diagnosed is connected to the diagnostic power conditioner 64, and the storage battery 11 that is not to be diagnosed is connected to the operational power conditioner 66. With such a configuration, it is possible to perform degradation diagnosis without stopping the operation of the entire power supply system 1.

[0026] Furthermore, it is preferable to select one battery 11 from among the batteries 11 connected to the operational power conditioner 66 to be subjected to degradation diagnosis, and use the switching unit 17 to switch the connection so that the selected battery 11 is connected to the diagnostic power conditioner 64, while the other batteries 11 remain connected to the operational power conditioner 66. After the degradation diagnosis is completed, the switching unit 17 is switched to connect one of the other batteries 11 to the diagnostic power conditioner 64, and the switching unit 17 is switched so that the battery 11 whose degradation diagnosis has been completed is connected to the operational power conditioner 66. This configuration allows for the degradation of each battery 11 to be diagnosed one by one, making it possible to diagnose the degradation of multiple batteries 11 while reducing the number of batteries 11 that are disconnected from operation.

[0027] Furthermore, it is preferable to configure the system so that, after the degradation diagnosis of one battery 11 is completed, when the voltage of all batteries 11 is within the specified range, the switching unit 17 is switched to connect one of the other batteries 11 to the diagnostic power conditioner 64, and the switching unit 17 is switched to connect the battery 11 for which the degradation diagnosis has been completed to the operation power conditioner 66. In this way, it is possible to suppress the phenomenon in which an overcurrent flows from a battery 11 that is in normal operation to a battery 11 for which the degradation diagnosis has been completed.

[0028] Furthermore, the diagnostic power conditioner 64 only needs to be capable of supplying a constant low current from one battery 11, and therefore can be simpler than the operational power conditioner 66.

[0029] In the example shown in Figure 4, the diagnostic unit 32 is provided so as to branch off from the line connecting the diagnostic power conditioner 64 and the battery 11, but the placement of the diagnostic unit 32 does not have to be this way. In the example shown in Figure 4, an operational power conditioner 66 used for normal operation is also provided, so this system 1 uses two types of power conditioners 61. Note that both the operational power conditioner 66 and the diagnostic power conditioner 64 may be housed in a single enclosure, or they may be housed in separate enclosures.

[0030] When using the diagnostic power conditioner 64, any power insufficient from the battery 11 during the diagnosis is supplied from the commercial power supply 14, the solar cells 13, or other batteries 11 that are not being diagnosed. For this reason, the example shown in Figure 4 includes a power consumption control unit 69 that controls the power supply from the commercial power supply 14 and the solar cells 13 so that a certain amount of discharge from the battery 11 being diagnosed can be consumed by the load 12.

[0031] Incidentally, it is preferable to be able to monitor the degradation of the solar cell 13 in addition to the degradation of the storage battery 11. In the example shown in Figure 5, a monitoring device 81 is provided on the main circuit on the load 12 side of the solar cell 13. Furthermore, the configuration includes a switching part 71 that switches from the main circuit to the monitoring circuit. In the example shown in Figure 5, two strings, which are DC circuits formed by connecting multiple solar cells 13 to each other, are shown, but there are not limited to two strings; there may be three or more. In the example shown in Figure 5, a monitoring device 81 is provided for each of the multiple strings, and the switching part 71 of a specific monitoring device 81 can be operated when there is a power surplus. By switching the switching part 71 to the monitoring device 81 side, a closed circuit is formed connecting the solar cell 13 or string and the monitoring device 81, and the degradation of the solar cell 13 can be monitored by examining the current and voltage characteristics with the monitoring device 81.

[0032] In the example shown in Figure 5, once the degradation monitoring of one string is complete, the switching part 71 of that string is switched to connect to the main circuit, and the switching part 71 of another string is switched from its main circuit to the monitoring device 81 and connected. In this way, the degradation status of some strings can be checked while other strings can continue to perform functions such as power generation.

[0033] Although the present invention has been described above with reference to the embodiments described, the present invention is not limited to the above embodiments and can be implemented in various forms. [Explanation of symbols]

[0034] 1. Power supply system 11. Storage batteries 12 loads 13 Solar Cells 14 Commercial power supply 17 Switching section 31 Discharger 61 Power Conditioner 64 Diagnostic Power Conditioner 66 Power conditioner for operation

Claims

1. A solar panel that supplies the generated electricity to a storage battery, Multiple batteries are charged via a main circuit, which is an electrical circuit that supplies electricity generated by solar cells to the load and the batteries, An operational power conditioner that converts DC to AC in the main circuit, and is capable of voltage and phase adjustment, and supplies power to the storage battery, A diagnostic power conditioner used for diagnosing battery storage systems, A switching unit that allows switching between the operational power conditioner and the diagnostic power conditioner to connect to each battery, Equipped with, A power supply system in which a battery used for diagnosis is connected to a diagnostic power conditioner, and a battery not used for diagnosis is connected to an operational power conditioner.

2. Select one battery from among those connected to the operational power conditioner to undergo degradation diagnosis, and use a switch to switch the connection so that this battery is connected to the diagnostic power conditioner, while the other batteries remain connected to the operational power conditioner. After the deterioration diagnosis is complete, The battery degradation diagnosis system according to claim 1, which switches the switching unit to connect one of the other batteries to a diagnostic power conditioner, and also switches the switching unit to connect the battery for which degradation diagnosis has been completed to an operational power conditioner.

3. After the degradation diagnosis of one battery is completed, if the voltage of all batteries is within the specified range, The power supply system according to claim 2, wherein the switching unit is switched to connect one of the other storage batteries to a diagnostic power conditioner, and the switching unit is switched to connect the storage battery for which degradation diagnosis has been completed to the operational power conditioner.

4. Multiple batteries are charged with electricity generated by solar cells via a main circuit, which is an electrical circuit that supplies electricity to the load and the batteries. A power conditioner that converts DC to AC in the main circuit, and is capable of voltage and phase adjustment, and is used to supply and discharge power to a storage battery, A discharger that discharges the power stored in the battery to the outside of the main circuit, A switching unit used to switch the connection destination of each battery between the power conditioner and the discharger, Equipped with, A power supply system that controls the system so that a battery undergoing degradation diagnosis is connected to a discharger, and a battery not undergoing degradation diagnosis is connected to a power conditioner, characterized in that, after the degradation diagnosis of one battery is completed, when the voltage of all batteries falls within a specified range, the switching unit is switched to connect one of the other batteries to the discharger, and the switching unit is also switched so that the battery for which the degradation diagnosis has been completed is connected to the power conditioner.

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