Power supply system and control method thereof

Abstract

To provide a power supply system including a storage battery capable of flexibly coping with various system configurations.SOLUTION: A storage battery, a DC bus, a first DC / DC converter provided between the storage battery and the DC bus, a second DC / DC converter, an inverter connected to the DC bus, a first AC electric path connected from the inverter to a commercial power system, a second AC electric path for supplying power to a load, a current sensor provided on the first AC electric path, a switch provided on the first AC electric path, and a control unit, the control unit has a first control mode in which the first DC / DC converter, the second DC / DC converter, and the inverter are controlled, and a second control mode in which the second DC / DC converter is disabled in switching control and the first DC / DC converter and the inverter are controlled, and sets any one control mode in accordance with whether or not the photovoltaic panel is connected to the second DC / DC converter.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a power supply system and a control method thereof. [Background technology]

[0002] Solar power generation systems for homes are already widely used. Furthermore, in recent years, power supply systems that incorporate a storage battery-equipped power storage system alongside a solar power generation system have begun to become popular (see, for example, Patent Document 1). In such power supply systems, a hybrid power conditioner that combines a solar power generation system with a storage battery may be installed from the beginning, or a storage battery may be added later to a consumer that already has a solar power generation system installed. Furthermore, in such power supply systems, in the event of a power outage in the commercial power grid, the power generated by the solar power generation system can be used as an auxiliary input to the output of the storage battery (see, for example, Patent Document 2), or the AC output from the solar power generation system can be pseudo-connected to the AC output from the storage battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-035236 [Patent Document 2] Japanese Patent Application Publication No. 2018-011476 Summary of the Invention [Problem to be solved by the invention]

[0004] As the introduction of storage batteries into homes progresses, it is expected that there will be a wide variety of configurations for power supply systems that include storage batteries and power conditioners. Furthermore, there will be a demand for systems that can accommodate both a mode that prioritizes selling solar power and a mode that prioritizes self-consumption and reduces selling.

[0005] An object of the present disclosure is to provide a power supply system including a storage battery that can flexibly accommodate various system configurations. [Means for solving the problem]

[0006] The present disclosure includes the following inventions, which are defined by the claims.

[0007] The power supply system of the present disclosure comprises: A storage battery and DC bus and a first DC / DC converter provided between the storage battery and the DC bus; a second DC / DC converter for photovoltaic power generation capable of outputting to the DC bus; an inverter connected to the DC bus; a first AC circuit connecting an AC side end of the inverter to a commercial power system; a second AC current path that supplies power from the AC side end to a load; a current sensor for detecting reverse power provided in the first AC current path; a switch provided on the first AC circuit for connecting to or disconnecting from the commercial power grid; a control unit that receives a detection output from the current sensor and controls the switch, The control unit is a power supply system that selects one of a first control mode for switching control, in which the control unit controls the first DC / DC converter, the second DC / DC converter, and the inverter, and a second control mode in which the control unit disables the second DC / DC converter and controls the first DC / DC converter and the inverter. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a power supply system including a storage battery that can flexibly accommodate various system configurations. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a single-line diagram showing the configuration of a power supply system including a hybrid power storage system equipped with a storage battery. [Figure 2] FIG. 2 is a single-line diagram showing the configuration of a power supply system including an auxiliary input type power storage system equipped with a storage battery. [Figure 3] FIG. 3 is a single-line diagram showing the configuration of a power supply system including a pseudo-grid-connected power storage system equipped with a storage battery. [Figure 4] FIG. 4 is a single-line diagram showing the configuration of a power supply system including a combined power storage system equipped with a storage battery. [Figure 5] FIG. 5 is a connection diagram showing common hardware of the power storage system. [Figure 6] FIG. 6 is a diagram in which a photovoltaic power generation panel is connected to a DC / DC converter, a commercial power system is connected to the AC end, and a load is also connected to the AC end. [Figure 7] FIG. 7 is a diagram in which a photovoltaic power generation panel is not connected to the DC / DC converter, a commercial power system is connected to the AC side end, and a load is also connected to the AC side end. [Figure 8] FIG. 8 is a diagram in which a photovoltaic power generation panel is connected to a DC / DC converter, a commercial power system is connected to the AC end, and a load is also connected to the AC end. [Figure 9] FIG. 9 is a diagram showing an example of a circuit configuration of a power supply system including a power storage system, and is an example of a hybrid type. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Description of the embodiments of the present disclosure] The gist of the present disclosure includes at least the following.

[0011] (1) A power supply system according to the present disclosure includes: a storage battery; a DC bus; a first DC / DC converter provided between the storage battery and the DC bus; a second DC / DC converter for photovoltaic power generation capable of outputting power to the DC bus; an inverter connected to the DC bus; a first AC current circuit connecting an AC end of the inverter to a commercial power grid; a second AC current circuit supplying power from the AC end to a load; a current sensor provided on the first AC current circuit for detecting reverse power; a switch provided on the first AC current circuit for connecting to or disconnecting from the commercial power grid; and a control unit that receives a detection output from the current sensor and controls the switch, wherein the control unit has, with respect to switching control, a first control mode for controlling the first DC / DC converter, the second DC / DC converter, and the inverter; and a second control mode for disabling the second DC / DC converter and controlling the first DC / DC converter and the inverter, and the power supply system is configured to select one of the control modes.

[0012] In such a power supply system, while common hardware is installed, different system configurations can be easily realized by selecting a control mode using the control unit. By implementing the first control mode, a so-called hybrid power supply system that uses both solar power generation and a storage battery can be realized. By implementing the second control mode, a single-function power supply system that uses only a storage battery as a DC power source can be realized. In this way, a power supply system including a storage battery that can flexibly accommodate various system configurations can be provided.

[0013] (2) The power supply system of (1) may include a solar power generation panel connected to the second DC / DC converter, and the control unit may execute the first control mode. In this case, a hybrid power supply system can be configured that uses both photovoltaic power generation and a storage battery as a DC power supply.

[0014] (3) The power supply system of (1) may include an AC output power generating device connected to the second AC circuit, and a second current sensor that measures the generated output current supplied from the power generating device to the second AC circuit, and the control unit may receive the detection output from the second current sensor and execute the second control mode. In this case, a single-function power supply system can be configured using only the storage battery as a DC power source. Furthermore, the AC output of the power generation device can be connected to the second AC circuit to provide AC output. Furthermore, the load following control can also accommodate so-called single power generation mode, double power generation mode, and green mode.

[0015] (4) The power supply system of (1) may include a solar power generation panel connected to the second DC / DC converter, an AC output power generation device connected to the second AC circuit, and a second current sensor that measures the power generation output current supplied from the power generation device to the second AC circuit, and the control unit may receive the detection output from the second current sensor and execute the first control mode. In this case, a hybrid power supply system can be created that uses both solar power generation and a storage battery as a DC power source. Furthermore, the AC output of the power generation device can be connected to the second AC circuit to provide AC output. Furthermore, the load following control can also be used in single power generation mode, dual power generation mode, and green mode.

[0016] (5) From the viewpoint of a method, this is a control method for a power supply system including a storage battery, a DC bus, a first DC / DC converter provided between the storage battery and the DC bus, a second DC / DC converter for photovoltaic power generation capable of outputting to the DC bus, an inverter connected to the DC bus, a first AC current circuit connecting an AC side end of the inverter to a commercial power grid, and a second AC current circuit supplying power from the AC side end to a load, wherein, with regard to switching control, the method has a first control mode for controlling the first DC / DC converter, the second DC / DC converter, and the inverter, and a second control mode for disabling the second DC / DC converter and controlling the first DC / DC converter and the inverter, and selects one of the control modes.

[0017] By using this control method for a power supply system, different system configurations can be easily achieved by selecting a control mode using a control unit, even while using common hardware. By executing the first control mode, a so-called hybrid power supply system can be achieved, which uses both solar power generation and a storage battery. By executing the second control mode, a single-function power supply system can be achieved, which uses only a storage battery as a DC power source. In this way, a control method for a power supply system including a storage battery can be provided that can flexibly accommodate various system configurations.

[0018] [Details of the embodiments of the present disclosure] Example of system configuration First, various system configurations as power supply systems at consumers will be illustrated.

[0019] (hybrid type) Fig. 1 is a single-line connection diagram showing the configuration of a power supply system 100 including a hybrid power storage system 1 equipped with a storage battery. A photovoltaic power generation panel 2 is connected to a DC side input terminal P1 of the power storage system 1. An AC side terminal P2 of the power storage system 1 is connected to a single-phase three-wire commercial power system 3. The other AC side terminal P3 is connected to a single-phase three-wire load 4 of 200V or 100V.

[0020] The energy storage system 1 includes a storage battery 11, a DC bus 12, a first DC / DC converter 13 provided between the storage battery 11 and the DC bus 12, a second DC / DC converter 14 for photovoltaic power generation capable of outputting to the DC bus 12, an inverter 15 connected to the DC bus 12, a first AC circuit 16 connecting an AC end 15a of the inverter 15 to the commercial power grid 3, a second AC circuit 17 supplying power from the AC end 15a to the load 4, a current transformer (CT) 18 provided on the first AC circuit 16 as a current sensor for detecting reverse power, and a relay 19 provided on the first AC circuit 16 as a switch for connecting to or disconnecting from the commercial power grid 3. Note that the positions of the CT 18 and the relay 19 may be reversed (the same applies below).

[0021] The DC / DC converter 13 is capable of bidirectional conversion operations, and can charge the storage battery 11 with a voltage stepped down based on the voltage of the DC bus 12, and conversely, can step up the output voltage of the storage battery 11 and send it to the DC bus 12. The inverter 15 is also capable of bidirectional conversion operations, and can provide AC power based on the voltage of the DC bus 12, and conversely, can convert AC voltage into DC voltage and supply it to the DC bus 12.

[0022] There is a control unit (not shown) that controls the DC / DC converters 13, 14, inverter 15, and relay 19 and receives the detection output of CT 18. When the commercial power system 3 is normal, the relay 19 is closed, and the power supply system 100 is interconnected with the commercial power system 3.

[0023] The power generated by the solar panel 2 is MPPT (Maximum Power Point Tracking) controlled by a DC / DC converter 14, and a DC voltage is supplied to a DC bus 12. The voltage of the DC bus 12 is converted to single-phase three-wire AC power by an inverter 15 and supplied to a load 4, and can also be sold as reverse power flow to the commercial power grid 3. The storage battery 11 can also be charged from the DC bus 12 via a DC / DC converter 13.

[0024] When the solar power generation panel 2 is not generating power or the amount of power generation is insufficient, the storage battery 11 is discharged and output to the DC bus 12 via the DC / DC converter 13, and further, power can be supplied to the load 4 via the inverter 15. In this case, the power storage system 1 is controlled based on the detection output of the CT 18 so that the power from the storage battery does not become a reverse flow (reverse power) to the commercial power system 3. Also, power can be supplied from the commercial power system 3 to the load 4. The AC voltage of the commercial power system 3 can be inversely converted by the inverter 15 to supply power to the DC bus 12, and the storage battery 11 can be charged via the DC / DC converter 13.

[0025] In the event of a power outage in the commercial power grid 3, the relay 19 is opened and the power storage system 1 is disconnected from the commercial power grid 3. Even in this state, if solar power generation is in progress, power generated by the stand-alone output operation of the solar power generation system can be supplied to the load 4 at full load compatibility with single-phase three-wire 200V / 100V. When the solar power generation panel 2 is not generating power or the amount of power generation is insufficient, the storage battery 11 can be discharged to supply power to the load 4.

[0026] (Auxiliary input type) FIG. 2 is a single-wire diagram showing the configuration of a power supply system 100 including an auxiliary input-type power storage system 1 equipped with a storage battery. An AC end P2 of the power storage system 1 is connected to a single-phase three-wire commercial power grid 3 via a current transformer (CT) 5. Another AC end P4 is a single-phase two-wire 100V output end, to which a specific load 4b, to which power supply should be continued even during a power outage, is connected. An auxiliary input line 21 is connected to the auxiliary input P5 from a solar power generation panel 6 via a power conditioner 7. The auxiliary input line 21 provides an AC output (100V) as an auxiliary input. While the maximum auxiliary input is typically 1500W, some power conditioners can output 2000W. Furthermore, a normal output line 20 (single-phase three-wire, 200V / 100V) of the power conditioner 7 is connected to a system circuit 22 that connects the AC end P2 to the commercial power grid 3. A general load 4a is connected to the system circuit 22. The general load 4a is a load that does not need to be supplied with power in the event of a power outage.

[0027] The power storage system 1 includes a storage battery 11, a DC / DC converter 13 connected to the storage battery 11, an inverter 15 connected to the DC / DC converter 13, a first AC circuit 16 connecting an AC end 15a of the inverter 15 to the commercial power grid 3, a second AC circuit 17b supplying power from the AC end 15a to a specific load 4b, and an auxiliary input circuit 17c connecting the second AC circuit 17b to an auxiliary input terminal P5. The first AC circuit 16 is provided with a relay 19a as a switch, the second AC circuit 17b with a relay 19b, and the auxiliary input circuit 17c with a relay 19c.

[0028] The inverter 15 is capable of bidirectional conversion operations, and not only provides AC power based on the output voltage of the DC / DC converter 13, but also conversely converts AC voltage into DC voltage and supplies it to the DC / DC converter 13. The DC / DC converter 13 is also capable of bidirectional conversion operations, and not only charges the storage battery 11 with a voltage stepped down based on the DC output voltage of the inverter 15, but also conversely can step up the output voltage of the storage battery 11 and send it to the inverter 15.

[0029] It should be noted that there is a control section that controls the DC / DC converter 13, the inverter 15, and the relays 19a, 19b, and 19c, and receives the detection output from the external CT 5, but this is not shown here.

[0030] In the energy storage system 1 of FIG. 2 , normally (when the commercial power grid 3 is normal), relays 19a and 19b are closed and relay 19c is open. The power conditioner 7 during solar power generation is interconnected with the commercial power grid 3. The general load 4a and the specific load 4b can be supplied with solar power or power from the commercial power grid 3. Excess solar power can be sold as reverse power flow to the commercial power grid 3 or can be charged in the storage battery 11. The storage battery 11 can be charged with solar power or power from the commercial power grid 3.

[0031] When the solar power generation panel 2 is not generating power or the amount of power generation is insufficient, the storage battery 11 is discharged to supply power to the general load 4a and the specific load 4b via the DC / DC converter 13 and the inverter 15. In this case, the storage system 1 is controlled based on the detection output of the CT 5 so that the power from the storage battery does not flow reversely (reverse power) to the commercial power grid 3. It is also possible to supply power from the commercial power grid 3 to the general load 4a and the specific load 4b.

[0032] In the event of a power outage in the commercial power grid 3, relay 19a is opened, and the energy storage system 1 is disconnected from the commercial power grid 3. Relay 19b remains closed, and relay 19c, which was open, is closed. In this state, power is supplied from the storage battery 11 to the specific load 4b via the DC / DC converter 13 and the inverter 15 at single-phase two-wire 100V. In the event of a power outage in the commercial power grid 3, the power conditioner 7 cannot operate in grid-connected mode, but it can operate as an independent output. Therefore, if solar power generation is in progress, a single-phase two-wire 100V output is supplied from the power conditioner 7 to the auxiliary input terminal P5 via the auxiliary input line 21. This auxiliary input can be used to supply power to the specific load 4b, and if there is surplus power, it can also be used to charge the storage battery 11.

[0033] (pseudo-interconnected type) 3 is a single-line connection diagram showing the configuration of a power supply system 100 including a pseudo-grid-connected energy storage system 1 equipped with a storage battery. An AC end P2 of the energy storage system 1 is connected to a single-phase three-wire commercial power system 3. The other AC end P3 is a single-phase three-wire 200V / 100V output end, to which a load 4 and an AC output from a solar power generation panel 6 via a power conditioner 7 are connected.

[0034] The energy storage system 1 includes therein a storage battery 11, a DC / DC converter 13, an inverter 15 connected to the DC / DC converter 13, a first AC circuit 16 connecting an AC end 15a of the inverter 15 to the commercial power grid 3, a second AC circuit 17 supplying power from the AC end 15a to the load 4, a CT 18 provided on the first AC circuit 16 as a current sensor for detecting reverse power, and a relay 19 provided on the first AC circuit 16 as a switch for connecting to or disconnecting from the commercial power grid 3.

[0035] The inverter 15 is capable of bidirectional conversion operations, and not only provides AC power based on the output voltage of the DC / DC converter 13, but also conversely converts AC voltage into DC voltage and supplies it to the DC / DC converter 13. The DC / DC converter 13 is also capable of bidirectional conversion operations, and not only charges the storage battery 11 with a voltage stepped down based on the DC output voltage of the inverter 15, but also conversely can step up the output voltage of the storage battery 11 and send it to the inverter 15.

[0036] It should be noted that there is a control section that controls the DC / DC converter 13, the inverter 15, and the relay 19 and receives the detection output from the CT 19, but this is not shown here.

[0037] In the energy storage system 1 of FIG. 3 , the relay 19 is normally closed (when the commercial power grid 3 is normal). The power conditioner 7 is interconnected with the commercial power grid 3 during solar power generation. The load 4 can be supplied with solar power or power from the commercial power grid 3. Excess solar power can be sold as reverse power flow to the commercial power grid 3 or can be charged in the storage battery 11. The storage battery 11 can be charged with solar power or power from the commercial power grid 3.

[0038] When the solar power generation panel 2 is not generating power or the amount of power generation is insufficient, the storage battery 11 is discharged and power can be supplied to the load 4 via the DC / DC converter 13 and the inverter 15. In this case, the power storage system 1 is controlled based on the detection output of the CT 18 so that the power from the storage battery does not flow reversely (reverse power) to the commercial power grid 3. It is also possible to supply power from the commercial power grid 3 to the load 4.

[0039] During a power outage in the commercial power grid 3, the relay 19 is opened, and the power supply system 100 is disconnected from the commercial power grid 3. In this state, single-phase three-wire 200V / 100V power is supplied from the storage battery 11 to the load 4 via the DC / DC converter 13 and the inverter 15. During a power outage in the commercial power grid 3, the power conditioner 7 cannot operate in a grid-connected state. However, when an AC voltage appears at the AC end P3 due to the output of the inverter 15, the power conditioner can interpret it as if it were the AC voltage of the commercial power grid 3 and perform a pseudo-grid-connection (pseudo-grid-connection). Therefore, during solar power generation, the power conditioner 7 supplies a single-phase three-wire 200V / 100V power output to the load 4. In addition to supplying this generated power to the load 4, any surplus power can be used to charge the storage battery 11.

[0040] (Combination type) FIG. 4 is a single-line diagram showing the configuration of a power supply system 100 including a combined type energy storage system 1 equipped with a storage battery. The combined type is a combination of a hybrid type and a pseudo-grid-connected type. In FIG. 4, a photovoltaic power generation panel 2 is connected to a DC side input terminal P1 of the energy storage system 1. An AC side terminal P2 of the energy storage system 1 is connected to a single-phase three-wire commercial power grid 3. The other AC side terminal P3 is a single-phase three-wire 200V / 100V output terminal to which a load 4 and an AC output from a photovoltaic power generation panel 6 via a power conditioner 7 are connected.

[0041] The energy storage system 1 includes therein a storage battery 11, a DC bus 12, a first DC / DC converter 13 provided between the storage battery 11 and the DC bus 12, a second DC / DC converter 14 for solar power generation capable of outputting to the DC bus 12, an inverter 15 connected to the DC bus 12, a first AC circuit 16 connecting an AC side end 15a of the inverter 15 to the commercial power grid 3, a second AC circuit 17 supplying power from the AC side end 15a to the load 4, a CT 18 provided on the first AC circuit 16 as a current sensor for detecting reverse power, and a relay 19 provided on the first AC circuit 16 as a switch for connecting to or disconnecting from the commercial power grid 3.

[0042] The DC / DC converter 13 is capable of bidirectional conversion operations, and can charge the storage battery 11 with a voltage stepped down based on the voltage of the DC bus 12, and conversely, can step up the output voltage of the storage battery 11 and send it to the DC bus 12. The inverter 15 is also capable of bidirectional conversion operations, and can provide AC power based on the voltage of the DC bus 12, and conversely, can convert AC voltage into DC voltage and supply it to the DC bus 12.

[0043] There is a control unit (not shown) that controls the DC / DC converters 13, 14, inverter 15, and relay 19 and receives the detection output of CT 18. When the commercial power grid 3 is normal, the relay 19 is closed, and the energy storage system 1 is interconnected with the commercial power grid 3.

[0044] The power generated by the solar panel 2 is MPPT controlled by a DC / DC converter 14, and a DC voltage is supplied to a DC bus 12. The voltage of the DC bus 12 is converted into single-phase three-wire AC power by an inverter 15 and supplied to a load 4, and can also be sold as a reverse power flow to the commercial power grid 3. The storage battery 11 can also be charged from the DC bus 12 via a DC / DC converter 13.

[0045] Furthermore, the power conditioner 7, which is generating solar power, is also interconnected with the commercial power grid 3. The load 4 can be supplied with solar power generated based on the power generated by the solar power generation panel 6 or with power from the commercial power grid 3. Excess solar power can be sold as reverse power flow to the commercial power grid 3 or can be charged into the storage battery 11. In this way, the storage battery 11 can be charged with power based on the power generated by the solar power generation panels 2, 6 or with power from the commercial power grid 3.

[0046] When the solar power generation panels 2 and 6 are not generating power or the amount of power generation is insufficient, the storage battery 11 is discharged and output to the DC bus 12 via the DC / DC converter 13, and further, power can be supplied to the load 4 via the inverter 15. In this case, the storage system 1 is controlled based on the detection output of the CT 18 so that the power from the storage battery does not become a reverse flow (reverse power) to the commercial power system 3.

[0047] In the event of a power outage in the commercial power grid 3, the relay 19 is opened, and the power storage system 1 is disconnected from the commercial power grid 3. Even in this state, as long as solar power generation is in progress, AC power based on the power generated by the solar power generation panel 2 can be supplied to the load 4 at full load compatibility with single-phase three-wire 200V / 100V. Also, AC power based on the power generated by the solar power generation panel 6 can be supplied to the load 4 at full load compatibility with single-phase three-wire 200V / 100V. When neither the solar power generation panels 2, 6 is generating power or the amount of power generation is insufficient, the storage battery 11 can be discharged to supply power to the load 4.

[0048] The above describes variations in the system configuration of power supply system 100, but there are also known ways of managing (or contracting for) generated power, such as single power generation, double power generation, and green mode (described in detail below).

[0049] Common hardware for energy storage systems Of the system configurations in Figures 1 to 4, Figure 2 tends to deviate from the industry development trend. Therefore, common hardware is considered for Figures 1, 3, and 4. Figure 5 is a connection diagram showing common hardware for energy storage systems as an example. In Figure 5, the internal hardware configuration of the energy storage system 1 is the same as that of Figures 1 and 4. An optional external accessory part is the power generation CT 8, which serves as a current sensor for measuring the generated current. By providing users with such a configuration as standard equipment, it becomes possible to apply it to various system configurations simply by changing the control mode.

[0050] 6 is a diagram in which a photovoltaic power generation panel 2 is connected to a DC / DC converter 14, a commercial power system 3 is connected to an AC side end P2, and a load 4 is connected to an AC side end P3. There is no need to connect a power generation CT 8. This system configuration is the hybrid type power storage system 1 and power supply system 100 in FIG. In this case, the DC / DC converter 14 is enabled as a control target by the control unit 10 (FIG. 7), and performs MPPT control switching operations to always extract maximum power from the solar power generation panel 2. It is also possible to realize a protection function for the solar power generation panel 2 and remote output control with the power transmission and distribution company.

[0051] FIG. 7 shows a diagram in which the photovoltaic power generation panel 2 is not connected to the DC / DC converter 14, the commercial power grid 3 is connected to the AC side end P2, and the load 4 is connected to the AC side end P3. In FIG. 7, the DC / DC converter 14 is disabled in terms of switching control, and the photovoltaic power generation panel is not connected. This is the same as if the DC / DC converter 14 does not exist. The AC side end P3 is supplied with the load 4 and an AC output obtained by converting the power output of the photovoltaic power generation panel 6 by the power conditioner 7. The current output by the power conditioner 7 is detected by the power generation CT 8, and the detected output is sent to a control unit (not shown) of the energy storage system 1. FIG. 7 is the same as the pseudo-grid-connected system configuration in FIG. 3.

[0052] 8 is a diagram in which a photovoltaic power generation panel 2 is connected to a DC / DC converter 14, a commercial power system 3 is connected to an AC side end P2, and a load 4 is connected to an AC side end P3. An AC output obtained by converting the power output of a photovoltaic power generation panel 6 by a power conditioner 7 is also supplied to the AC side end P3. The current output by the power conditioner 7 is detected by a power generation CT 8, and the detected output is sent to a control unit (not shown) of the power storage system 1. FIG. 8 is the same as the combined system configuration in FIG. 4. In this case, the DC / DC converter 14 is enabled as a control target by the control unit 10 (FIG. 7), and performs MPPT control switching operations to always extract maximum power from the solar power generation panel 2. It is also possible to realize a protection function for the solar power generation panel 2 and remote output control with the power transmission and distribution company.

[0053] Summary of the disclosure so far As shown in Figures 6, 7, and 8, the power storage system 1 of the power supply system 100 includes: a storage battery 11; a DC bus 12; a first DC / DC converter 13 provided between the storage battery 11 and the DC bus 12; a second DC / DC converter 14 for solar power generation capable of outputting to the DC bus 12; an inverter 15 connected to the DC bus 12; a first AC circuit 16 connecting an AC side end 15a of the inverter 15 to the commercial power grid 3; a second AC circuit 17 supplying power from the AC side end 15a to the load 4; a current sensor (CT 18) for detecting reverse power provided on the first AC circuit 16; a switch (relay 19) provided on the first AC circuit 16 for connecting to or disconnecting from the commercial power grid 3; and a control unit 10 (Figure 9) that receives the detection output from the current sensor (CT 18) and controls the switch (relay 19).

[0054] With regard to switching control, the control unit 10 has a first control mode in which the first DC / DC converter 13, the second DC / DC converter 14, and the inverter 15 are controlled, and a second control mode in which the second DC / DC converter 14 is disabled and the first DC / DC converter 13 and the inverter 15 are controlled, and the control unit 10 can select either control mode.

[0055] In the power storage system 1 in such a power supply system 100, although common hardware is installed, different system configurations can be easily realized by selecting a control mode by the control unit 10. By executing the first control mode, a so-called hybrid power supply system can be realized, which uses both solar power generation and the storage battery 11. By executing the second control mode, a single-function power supply system can be realized, which uses only the storage battery 11 as a DC power source.

[0056] The power supply system 100 can include a solar power generation panel 2 connected to a second DC / DC converter 14 (FIG. 6), and in this case the control unit 10 executes the first control mode. In this case, a hybrid power supply system can be configured that uses both photovoltaic power generation and a storage battery as a DC power supply.

[0057] The power supply system 100 can also include an AC output power generating device (6, 7) connected to the second AC circuit 17, and a second current sensor (8) that measures the power generating output current supplied from the power generating device (6, 7) to the second AC circuit 17 (FIG. 7), and in this case the control unit 10 executes the second control mode. In this case, a single-function power supply system can be configured in which only the storage battery 11 is used as a DC power supply. Furthermore, AC output from the power generation device (6, 7) can be interconnected to the second AC circuit to provide AC output. Note that the power generation device is not limited to solar power generation, and may be a power generation device using other renewable energy such as wind power, a fuel cell power generation device, or a V2H (Vehicle to Home) power generation device using an on-board storage battery.

[0058] Furthermore, the power supply system 100 can include a solar power generation panel 2 connected to a second DC / DC converter 14, an AC output power generation device (6, 7) connected to a second AC circuit 17, and a second current sensor that measures the power generation output current supplied from the power generation device (6, 7) to the second AC circuit 17 (FIG. 8), and in this case the control unit 10 executes the first control mode. In this case, a hybrid power supply system can be configured in which both solar power generation and the storage battery 11 are used as DC power sources. Furthermore, a combined system configuration can be configured in which the AC output of the power generation device (6, 7) is interconnected with the second AC circuit 17 to provide AC output.

[0059] <<Example of circuit configuration of power storage system>> FIG. 9 is a diagram showing an example of the circuit configuration of a power supply system 100 including a power storage system 1. This is an example of a hybrid type. A solar power generation panel 2 is generally configured with multiple strings. In this example, four strings of solar power generation panels 2a, 2b, 2c, and 2d together constitute one solar power generation panel 2. It should be noted that the circuit configuration of FIG. 9 is merely an example for explaining the load following control described later, and the circuit configuration is not limited to this.

[0060] A capacitor C1 is connected in parallel to the solar power generation panel 2a, and a boosted voltage is sent between the two wires of the DC bus 12 (12p, 12n) via a DC / DC converter 14a. A capacitor C2 is connected in parallel to the solar power generation panel 2b, and a boosted voltage is sent between the two wires of the DC bus 12 via a DC / DC converter 14b. A capacitor C3 is connected in parallel to the solar power generation panel 2c, and a boosted voltage is sent between the two wires of the DC bus 12 via a DC / DC converter 14c. A capacitor C4 is connected in parallel to the solar power generation panel 2d, and a boosted voltage is sent between the two wires of the DC bus 12 via a DC / DC converter 14d. The output lines of the four DC / DC converters 14a, 14b, 14c, and 14d are connected in parallel to form the two wires of the DC bus 12. A capacitor C5 is connected between the two wires of the DC bus 12.

[0061] DC / DC converter 14a includes a DC reactor L1, a switching element Q1, a diode D1, a current sensor A1, and a voltage sensor V1. Current sensor A1 detects the current flowing through DC reactor L1 and sends the detected output to control unit 10. Voltage sensor V1 detects the input voltage to DC / DC converter 14a and sends the detected output to control unit 10. Based on the detected outputs of current sensor A1 and voltage sensor V1, control unit 10 can determine the power generation power Pa of solar power generation panel 2a.

[0062] DC / DC converter 14b includes a DC reactor L2, a switching element Q2, a diode D2, a current sensor A2, and a voltage sensor V2. Current sensor A2 detects the current flowing through DC reactor L2 and sends the detected output to control unit 10. Voltage sensor V2 detects the input voltage to DC / DC converter 14b and sends the detected output to control unit 10. Based on the detected outputs of current sensor A2 and voltage sensor V2, control unit 10 can determine the power generation power Pb of solar power generation panel 2b.

[0063] DC / DC converter 14c includes a DC reactor L3, a switching element Q3, a diode D3, a current sensor A3, and a voltage sensor V3. Current sensor A3 detects the current flowing through DC reactor L3 and sends the detected output to control unit 10. Voltage sensor V3 detects the input voltage to DC / DC converter 14c and sends the detected output to control unit 10. Based on the detected outputs of current sensor A3 and voltage sensor V3, control unit 10 can determine the power generation power Pc of solar power generation panel 2c.

[0064] DC / DC converter 14d includes a DC reactor L4, a switching element Q4, a diode D4, a current sensor A4, and a voltage sensor V4. Current sensor A4 detects the current flowing through DC reactor L4 and sends the detected output to control unit 10. Voltage sensor V4 detects the input voltage to DC / DC converter 14d and sends the detected output to control unit 10. Based on the detected outputs of current sensor A4 and voltage sensor V4, control unit 10 can calculate the power generation power Pd of solar power generation panel 2d.

[0065] The control unit 10 can add up the generated powers Pa, Pb, Pc, and Pd to obtain the total photovoltaic generated power Ppv.

[0066] A capacitor C6 is connected in parallel to the storage battery 11. A DC / DC converter 13 capable of bidirectional power conversion is provided between the storage battery 11 and the DC bus 12. The DC / DC converter 13 includes a DC reactor L6, switching elements Q6 and Q7, a current sensor A6, and a voltage sensor V6. The current sensor A6 detects the current flowing through the DC reactor L1 and sends the detected output to the control unit 10. The voltage sensor V6 detects the voltage across the capacitor C6 and sends the detected output to the control unit 10. Based on the detected outputs of the current sensor A6 and the voltage sensor V6, the control unit 10 can calculate the charge / discharge power (charge power or discharge power) Pbat of the storage battery 11.

[0067] An inverter 15 capable of bidirectional power conversion is connected to the DC bus 12. The inverter 15 includes switching elements Qi1, Qi2, Qi3, Qi4, Qi5, and Qi6 that form a three-leg full-bridge circuit of single-phase three wires (U wire, O wire, and W wire) and AC reactors Lu, Lo, and Lw. The inverter 15 outputs 200V / 100V in a single-phase three-wire system to voltage lines U and W and a neutral line O, which have opposite polarities. On the AC side of the inverter 15, three capacitors C7 are connected between the three wires (U wire, O wire, and W wire).

[0068] Although not shown, sensors are provided at various locations to acquire information on voltage or current values ​​required for control, and the information is sent to the control unit 10. For example, voltage sensors are provided to detect the DC side voltage of the inverter 15 (the voltage of the DC bus 12) and the AC side voltage of the single-phase three-wire system, and the control unit 10 keeps track of these detected values.

[0069] Furthermore, a relay 19 is provided on the AC side of the inverter 15, and a CT 18 is provided on the U and W lines. The CT 18 can detect reverse power flow, and based on the detection output, the control unit 10 can calculate the reverse power Prev.

[0070] The relay 19 is composed of a three-pole output relay 191, a single-pole grounding relay 192, and a three-pole grid-connection relay 193. A commercial power system 3 is connected to the upstream side (commercial power system side) of the grid-connection relay 193, outside the power storage system 1, via a main breaker 23 and an electricity meter 24. An electric circuit connecting the grid-connection relay 193 and the output relay 191 is connected to a distribution board 25. A load 4 is connected to the distribution board 25. A CT 18L is provided in the electric circuit leading to the distribution board 25. The CT 18L detects the load current, and the control unit 10 can calculate the power consumption PL based on the detected output.

[0071] When the power storage system 1 performs grid-connected operation, the output relay 191 and the grid-connection relay 193 are both closed, and the grounding relay 192 is open. When the power storage system 1 performs stand-alone operation, the output relay 191 and the grounding relay 192 are closed. The grid-connection relay 193 is open, and the power storage system 1 is disconnected from the commercial power grid 3.

[0072] The switching of the illustrated switching elements constituting the DC / DC converters 13, 14a, 14b, 14c, and 14d and the inverter 15 is controlled by the control unit 10. The opening and closing of the relays 19 (191, 192, and 193) is also controlled by the control unit 10. The control unit 10 includes, for example, a microcomputer, which executes software (computer programs) to realize the necessary control functions. The software is stored in a storage device (not shown) of the control unit 10. The control unit 10 may be configured as another device having the same functions as a microcomputer.

[0073] The control unit 10 is connected to a remote control device 30 that is external to the power storage system 1. The power storage system 1 is usually installed outdoors (including on a balcony, etc.) in a user's home, and the remote control device 30 is installed in an easily visible location indoors, such as in the living room.

[0074] Regarding load following control As described above, the power storage system 1 can calculate the generated power Ppv, the charge / discharge power Pbat, the reverse power Prev, and the consumed power PL, and can perform control according to the operation mode based on these. The operation modes include, for example, a green mode in which generated power is used with priority given to self-consumption and the aim is to neither buy nor sell power to the commercial power grid, a single power generation mode in which surplus power from solar power generation for self-consumption is sold to the commercial power grid, and a double power generation mode in which all power generated by solar power generation is sold and self-consumption power is met by discharging the storage battery.

[0075] Here, load following control based on the operation mode will be described for each of the system configurations shown in Figs. 6, 7, and 8 to which the power storage system 1 of the present disclosure is to be applied. The operation mode can be set using a remote control device 30 (Fig. 9). However, the setting may also be performed on the main body of the power storage system 1.

[0076] First, consider the system configuration of Fig. 6. In this case, the generated power Ppv is found based on a detected value in DC / DC converter 14. In the green mode, the power storage system 1 controls the charge / discharge power Pbat so that the reverse power Prev becomes approximately 0. "Approximately 0" strictly speaking means that the forward power flow (purchased power) is offset by a small predetermined amount.

[0077] In the single power generation mode, when the generated power Ppv is greater than the consumed power PL, the power storage system 1 does not discharge the storage battery 11. When the generated power Ppv is less than the consumed power PL, the power storage system 1 controls the charging and discharging power Pbat so that the reverse power Prev becomes approximately zero. "Approximately zero" strictly speaking means that the forward power flow (purchased power) is offset by a small, predetermined amount. The storage battery 11 is charged only at predetermined times, for example, by setting a timer.

[0078] In the double power generation mode, the power storage system 1 controls the charging and discharging power so that the reverse power Prev roughly matches the generated power Ppv. "Roughly matches the generated power Ppv" means that the forward power flow (purchased power) is offset by a small, predetermined amount.

[0079] Next, consider the system configuration in Fig. 7. In this case, the generated power Ppv is calculated based on the detected value of the power generation CT8. In the green mode, the power storage system 1 controls the charge / discharge power Pbat so that the reverse power Prev becomes approximately 0. "Approximately 0" strictly speaking means that the forward power flow (purchased power) is offset by a small predetermined amount.

[0080] In the single power generation mode, when the generated power Ppv is greater than the consumed power PL, the power storage system 1 does not discharge the storage battery 11. When the generated power Ppv is less than the consumed power PL, the power storage system 1 controls the charging and discharging power Pbat so that the reverse power Prev becomes approximately zero. "Approximately zero" strictly speaking means that the forward power flow (purchased power) is offset by a small, predetermined amount. The storage battery 11 is charged only at predetermined times, for example, by setting a timer.

[0081] In the double power generation mode, the power storage system 1 controls the charging and discharging power so that the reverse power Prev roughly matches the generated power Ppv. "Roughly matches the generated power Ppv" means that the forward power flow (purchased power) is offset by a small, predetermined amount.

[0082] Next, consider the system configuration of Fig. 8. In this case, the generated power Ppv is calculated based on both the detected value in DC / DC converter 14 and the detected value of power generation CT8 (total). In the green mode, the power storage system 1 controls the charge / discharge power Pbat so that the reverse power Prev becomes approximately 0. "Approximately 0" strictly speaking means that the forward power flow (purchased power) is offset by a small predetermined amount.

[0083] In the single power generation mode, when the generated power Ppv is greater than the consumed power PL, the power storage system 1 does not discharge the storage battery 11. When the generated power Ppv is less than the consumed power PL, the power storage system 1 controls the charging and discharging power Pbat so that the reverse power Prev becomes approximately zero. "Approximately zero" strictly speaking means that the forward power flow (purchased power) is offset by a small, predetermined amount. The storage battery 11 is charged only at predetermined times, for example, by setting a timer.

[0084] In the double power generation mode, the power storage system 1 controls the charging and discharging power so that the reverse power Prev roughly matches the generated power Ppv. "Roughly matches the generated power Ppv" means that the forward power flow (purchased power) is offset by a small, predetermined amount.

[0085] As described above, in any of the system configurations shown in Figs. 6, 7 and 8, appropriate load following control can be performed according to the operation mode.

[0086] 《Addendum》 The present invention is intended to cover a wide range of applications, including those related to the present invention, including those related to the present invention. [Explanation of symbols]

[0087] 1. Energy storage system 2. Solar panels 3 Commercial power system 4. Load 4a General load 4b Specific load 5CT 6. Solar panels 7 Power Conditioner 8 Power generation current transformer 10 Control Unit 11 Storage battery 12, 12p, 12n DC bus 13 (First) DC / DC Converter 14 (Second) DC / DC Converter 15 Inverter 15a AC side end 16 1st AC line 17,17b 2nd AC line 17c Auxiliary input circuit 18 CT (current sensor) 18L CT 19, 19a, 19b, 19c Relay (switch) 20 Normal output line 21 Auxiliary input line 22 Grid line 23 Main breaker 24 Energy meter 25 Distribution board 30 Remote control device 100 Power System 191 Output Relay 192 Ground relay 193 Interconnection Relay A1, A2, A3, A4, A6 current sensors C1, C2, C3, C4, C5, C6, C7 capacitors D1, D2, D3, D4 diodes L1, L2, L3, L4, L6 DC reactor Lu, Lo, Lw AC reactor P1 DC input terminal P2 AC side end P3,P4 AC side end P5 Auxiliary input terminal Q1, Q2, Q3, Q4, Q6, Q7, Qi1, Qi2, Qi3, Qi4, Qi5, Qi6 switching elements

Claims

1. A storage battery and DC bus and a first DC / DC converter provided between the storage battery and the DC bus; a second DC / DC converter for photovoltaic power generation that can output to the DC bus; an inverter connected to the DC bus; a first AC circuit connecting an AC side end of the inverter to a commercial power system; a second AC current path that supplies power from the AC side end to a load; a current sensor for detecting reverse power provided in the first AC current path; a switch provided in the first AC current circuit and configured to connect to or disconnect from the commercial power grid; a control unit that receives a detection output from the current sensor and controls the switch, The control unit has, with regard to switching control, a first control mode in which it controls the first DC / DC converter, the second DC / DC converter, and the inverter, and a second control mode in which it controls the first DC / DC converter and the inverter by disabling the second DC / DC converter in switching control, and sets one of the control modes depending on whether a solar power generation panel is connected to the second DC / DC converter.

2. a solar power generation panel connected to the second DC / DC converter; The power supply system according to claim 1 , wherein the control unit executes the first control mode.

3. a power generating device for AC output connected to the second AC current path; a second current sensor that measures a generated output current supplied from the power generation device to the second AC current path, 2. The power supply system according to claim 1, wherein the control unit receives a detection output from the second current sensor and executes the second control mode.

4. a solar panel connected to the second DC / DC converter; a power generating device for AC output connected to the second AC current path; a second current sensor that measures a generated output current supplied from the power generation device to the second AC current path, The power supply system according to claim 1 , wherein the control unit receives a detection output from the second current sensor and executes the first control mode.

5. A control method for a power supply system in a case where the power supply system includes a storage battery, a DC bus, a first DC / DC converter provided between the storage battery and the DC bus, a second DC / DC converter for photovoltaic power generation capable of outputting to the DC bus, an inverter connected to the DC bus, a first AC current path connecting an AC side end of the inverter to a commercial power system, and a second AC current path supplying power from the AC side end to a load, the method comprising: Regarding switching control, a first control mode for controlling the first DC / DC converter, the second DC / DC converter, and the inverter; a second control mode in which the second DC / DC converter is disabled in terms of switching control to control the first DC / DC converter and the inverter, A control method for a power supply system, wherein one of the control modes is set depending on whether a solar power generation panel is connected to the second DC / DC converter.

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