Hybrid energy storage system

Abstract

To provide a hybrid power storage system which can suppress increase in the quantity of relays for a measure against PID.SOLUTION: A hybrid power storage system includes a plurality of DC / DC converters 10 (10-1 and 10-2), a bidirectional DC / DC converter 20, a DC / AC inverter 30, a first relay RL1 interposed in a first power line L1, a relay drive part 60A, and a power source part 50A, wherein in the plurality of DC / DC converters 10 (10-1 and 10-2), cathodes of diodes 16 on an output end side are connected to each other, in the power source part 50A, a supply path of a power source voltage supplied to each of the DC / DC converters 10 (10-1 and 10-2) and a supply path of a power source voltage supplied to the bidirectional DC / DC converter 20 and the DC / AC inverter 30 are insulated and separated from each other, and the relay drive part 60A turns the first relay RL1 to be OFF state, when power generation power output from power generation devices PV1 and PV2 is equal to or less than a predetermined threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hybrid power storage system that is used by connecting to a power generation device such as a solar cell and a storage battery. [Background technology]

[0002] In transformerless (non-insulated) solar power generation systems designed for high efficiency, when the solar power generation system's power conditioner operates in grid-connected mode during the day, a large potential difference occurs between the solar cell's internal circuitry and the solar cell's frame ground (FG). If this large potential difference continues for a long period of time, some solar cells will experience a PID (Potential Induced Degradation) phenomenon, in which their power generation capacity rapidly deteriorates. However, by disconnecting the solar cell from the commercial power grid (hereinafter referred to as the grid) at night when the solar cell is not generating power, the potential difference between the solar cell's internal circuitry and the solar cell's frame ground (FG) is eliminated, and the PID phenomenon can be suppressed.

[0003] On the other hand, in hybrid energy storage systems, the solar cells are not disconnected from the grid at night (the solar cells are connected to the grid 24 hours a day), so it is not possible to prevent the occurrence of PID. However, there are solar cells that are less susceptible to PID, so PID countermeasures are not necessarily required.

[0004] Therefore, in the hybrid energy storage system 1C shown in Figure 3, when solar cells PV1 and PV2 that may be susceptible to the PID phenomenon are used, the solar cells PV1 and PV2 are connected to the power conditioner 3 via a connection box 2 for PID prevention.

[0005] The connection box 2 includes relays RL11 and RL12, a control circuit 2a, a control power supply 2b, a voltage detection unit 2c, and bridge diodes D1 and D2 for preventing reverse current.

[0006] The relay RL11 is provided on the positive and negative power lines connecting the solar cell PV1 and the DC / DC converter 4 (4-1) of the power conditioner 3. Similarly, the relay RL12 is provided on the positive and negative power lines connecting the solar cell PV2 and the DC / DC converter 4 (4-2) of the power conditioner 3.

[0007] The control circuit 2a is activated by the power supply voltage supplied from the control power supply 2b, and controls the on / off of the relays RL11 and RL12 according to the voltage value detected by the voltage detection unit 2c (the voltage value of the generated voltage input from the solar cells PV1 and PV2).

[0008] Specifically, the control circuit 2a turns off the relays RL11 and RL12 when the solar cells PV1 and PV2 are not generating power (for example, at night). When the relays RL11 and RL12 are off, even if the power conditioner 3 is operating in a grid-connected state, no potential difference occurs between the internal circuits of the solar cells PV1 and PV2 and the frame ground (FG) of the solar cells PV1 and PV2, thereby suppressing the occurrence of the PID phenomenon. Configurations like this, in which a junction box is used to disconnect the solar cells from the grid when they are not generating power, are also disclosed in, for example, Patent Documents 1 to 3.

[0009] 4 shows a hybrid power storage system 1D having a built-in junction box function for PID countermeasures. The hybrid power storage system 1D includes a DC / DC converter 10 (10-1, 10-2), a bidirectional DC / DC converter 20 connected to a storage battery BT, a DC / AC inverter 30, a relay circuit 40, and a power supply unit 50D.

[0010] The hybrid energy storage system 1D also includes terminals T1 to T5. Terminals T1 to T3 are connected to the U, O, and W phases of the grid, and terminals T4 and T5 are connected to the voltage line and neutral line of a single-phase two-wire system. An independent load (a household load such as an electrical appliance that should continue to operate even during a grid power outage) is connected between the voltage line and neutral line of the single-phase two-wire system.

[0011] Relays RL21 and RL22 are installed on the positive and negative power lines connecting the solar cells PV1 and PV2 to the DC / DC converter 10 (10-1 and 10-2). The relays RL21 and RL22 function as connection boxes for PID countermeasures, and disconnect the solar cells PV1 and PV2 from the grid when they are not generating power.

[0012] The power supply unit 50D includes an insulating transformer 51, an auxiliary power supply 52 and a drive power supply 53 provided on the primary side of the insulating transformer 51, and a secondary power supply (not shown) provided on the secondary side of the insulating transformer 51.

[0013] The auxiliary power supply 52 supplies power supply voltage to each detection unit including the voltage detection unit 11 in the DC / DC converter 10, and also supplies power supply voltage to each detection unit including the voltage detection unit 21 in the bidirectional DC / DC converter 20, each detection unit in the DC / AC inverter 30, and an intermediate voltage detection unit 11′ that detects the voltage across the capacitor C1.

[0014] The drive power supply 53 supplies a power supply voltage to the drive circuits of the switching elements of the DC / DC converter 10 , and also to the drive circuits in the bidirectional DC / DC converter 20 and the DC / AC inverter 30 .

[0015] For example, if relays RL21 and RL22 are placed between voltage detection unit 11 and current detection unit CT, auxiliary power supply 52 supplies power supply voltage to voltage detection unit 11 and intermediate voltage detection unit 11', so the negative side contacts of relays RL21 and RL22 are short-circuited by the ground (GND) line of auxiliary power supply 52, and the negative sides of solar cells PV1 and PV2 cannot be disconnected from the system. As a result, relays RL21 and RL22 are limited to the positions shown in Figure 4.

[0016] In Figure 4, two solar cells PV1 and PV2 are connected, so two relays RL21 and RL22 are used as relays for PID countermeasures to disconnect the solar cells from the grid, but as the number of solar cells increases, the number of relays for PID countermeasures also needs to increase. In other words, in the hybrid energy storage system 1D with a built-in junction box function for PID countermeasures, an increase in the number of relays for PID countermeasures leads to a problem of an increase in the cost of the entire system.

[0017] Furthermore, in the hybrid energy storage system 1D, the detection signal of the voltage detection unit 11 cannot be used to control the on-state of the relays RL21 and RL22, so it is necessary to set in advance the time at which the solar cells PV1 and PV2 start generating electricity and turn on the relays RL21 and RL22. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-169436 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-169434 [Patent Document 3] Japanese Patent Application Publication No. 2019-103209 Summary of the Invention [Problem to be solved by the invention]

[0019] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hybrid power storage system that can suppress an increase in the number of relays used as countermeasures against PID. [Means for solving the problem]

[0020] In order to solve the above problems, the hybrid type power storage system according to the present invention comprises: a plurality of DC / DC converters connected to a power generation device; a bidirectional DC / DC converter connected to a storage battery; a DC / AC inverter connected to the plurality of DC / DC converters and the bidirectional DC / DC converter; A hybrid power storage system comprising: a first relay interposed in a first power line connecting the plurality of DC / DC converters to the bidirectional DC / DC converter and the DC / AC inverter; a relay driver that switches the first relay between an on state and an off state; a power supply unit that supplies a power supply voltage to the plurality of DC / DC converters, the bidirectional DC / DC converter, and the DC / AC inverter; Equipped with each of the plurality of DC / DC converters includes a diode on the output end side, and the cathodes of the diodes of the DC / DC converters are connected to each other; the power supply unit has a supply path of a power supply voltage supplied to each of the DC / DC converters and a supply path of a power supply voltage supplied to the bidirectional DC / DC converter and the DC / AC inverter, which are insulated and separated from each other; The relay driving unit turns the first relay to the off state when the generated power output from the power generation device is equal to or less than a predetermined threshold value.

[0021] According to this configuration, the first relay for PID countermeasures is installed in the first power line connecting the multiple DC / DC converters with the bidirectional DC / DC converter and the DC / AC inverter, so the number of power generation devices and DC / DC converters can be increased without increasing the number of first relays.In other words, according to this configuration, it is possible to suppress an increase in the number of first relays for PID countermeasures.

[0022] The hybrid power storage system includes: a control unit that controls the DC / DC converters, the bidirectional DC / DC converter, and the DC / AC inverter; a first detection unit in each of the DC / DC converters that detects a voltage and / or a current input from the power generation device and outputs a first detection signal; a second detection unit that detects a voltage and / or a current input / output between the bidirectional DC / DC converter and the storage battery, or detects a voltage and / or a current input / output to / from the DC / AC inverter, and outputs a second detection signal; Equipped with It is preferable that the first detection unit and the control unit are insulated and separated, and that the first detection unit and the second detection unit are also insulated and separated.

[0023] In the hybrid power storage system, The power supply unit a first auxiliary power supply that supplies a power supply voltage to the first detection unit; a first drive power supply that supplies a power supply voltage to a drive circuit of a switching element included in each of the DC / DC converters; a second auxiliary power supply that supplies a power supply voltage to the second detection unit; a second drive power supply that supplies a power supply voltage to a drive circuit of a switching element included in the bidirectional DC / DC converter and a drive circuit of a switching element included in the DC / AC inverter, the first auxiliary power supply and the second auxiliary power supply are insulated and separated from each other; The first driving power source and the second driving power source can also be configured to be insulated and separated.

[0024] In the hybrid power storage system, The power supply unit an auxiliary power supply that supplies a power supply voltage to the first detection unit and the second detection unit; a drive power supply that supplies a power supply voltage to a first drive circuit that drives a switching element included in each of the DC / DC converters, and a second drive circuit that drives a switching element included in the bidirectional DC / DC converter or a switching element included in the DC / AC inverter, the auxiliary power supply is connected to the first detection unit by a second power line having a second relay interposed therein, and is also connected to the second detection unit by a power line separate from the second power line; the drive power supply is connected to the first drive circuit by a third power line having a third relay interposed therein, and is connected to the second drive circuit by a power line separate from the third power line; The second relay and the third relay can be configured to switch between an on state and an off state in conjunction with the first relay.

[0025] The hybrid power storage system includes: Further comprising a lightning detection circuit, When the lightning detection circuit detects lightning, the relay driving unit can be configured to turn the first relay to the off state regardless of the magnitude of the generated power. [Effects of the Invention]

[0026] According to the present invention, it is possible to provide a hybrid power storage system that can suppress an increase in the number of relays used as a countermeasure against PID. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram showing a hybrid power storage system according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a diagram showing a hybrid power storage system according to a second embodiment of the present invention. [Figure 3] FIG. 1 is a diagram showing a conventional hybrid power storage system equipped with a junction box for PID countermeasures. [Figure 4] FIG. 1 is a diagram showing a conventional hybrid power storage system having a built-in junction box function for PID countermeasures. DETAILED DESCRIPTION OF THE INVENTION

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a hybrid power storage system according to the present invention will be described with reference to the accompanying drawings.

[0029] [First embodiment] 1 shows a hybrid power storage system 1A according to a first embodiment of the present invention. The hybrid power storage system 1A is a system incorporating the function of a junction box for PID countermeasures, and includes DC / DC converters 10 (10-1, 10-2) connected to solar cells PV1, PV2 (corresponding to the "power generation device" of the present invention), a bidirectional DC / DC converter 20 connected to a storage battery BT, a DC / AC inverter 30, a relay circuit 40, terminals T1 to T5, a power supply unit 50A, a relay driver 60A, and a control unit 70.

[0030] One end of the DC / DC converter 10 (10-1) is connected to the solar cell PV1, and the other end is connected to the bidirectional DC / DC converter 20 and the DC / AC inverter 30 via a first power line L1. The DC / DC converter 10 (10-1) boosts the DC generated voltage input from the solar cell PV1 and outputs it to the first power line L1. Similarly, one end of the DC / DC converter 10 (10-2) is connected to the solar cell PV2, and the other end is connected to the bidirectional DC / DC converter 20 and the DC / AC inverter 30 via the first power line L1. The DC / DC converter 10 (10-2) boosts the DC generated voltage input from the solar cell PV2 and outputs it to the first power line L1.

[0031] The DC / DC converter 10 includes a voltage detection unit 11 that detects the generated voltage, a current detection unit 12 (a current transformer in this embodiment) that detects the DC generated current input from the solar cells PV1 and PV2, a step-up chopper circuit including a capacitor 13, a coil 14, a switching element 15, and a diode 16, and a drive circuit (not shown) that turns the switching element 15 on and off under the control of a control unit 70. The cathodes of the diode 16 of the DC / DC converter 10 (10-1) and the diode 16 of the DC / DC converter 10 (10-2) are connected to each other to form an OR circuit.

[0032] The DC / DC converter 10 may include various detection units other than the voltage detection unit 11 and the current detection unit 12. The various detection units may include not only a voltage detection unit and a current detection unit, but also any detection unit that detects physical quantities necessary for controlling the DC / DC converter 10. The bidirectional DC / DC converter 20 and the DC / AC inverter 30 may also include various detection units.

[0033] The voltage detection unit 11, the current detection unit 12, and the various detection units of the DC / DC converter 10 correspond to the "first detection unit" of the present invention. The voltage detection signal output from the voltage detection unit 11, the current detection signal output from the current detection unit 12, and the detection signals output from the various detection units correspond to the "first detection signal" of the present invention. The first detection signal is transmitted to the control unit 70. The first detection unit and the control unit 70 are insulated and separated. In this embodiment, the first detection signal is transmitted to the control unit 70 using an insulating amplifier (e.g., a photocoupler) not shown.

[0034] A first relay RL1 is interposed between the positive and negative lines of the first power line L1. The first relay RL1 functions as a connection box for PID countermeasures, and disconnects the solar cells PV1 and PV2 from the commercial power grid (hereinafter referred to as the grid) when the solar cells PV1 and PV2 are not generating power. A capacitor C1 is provided between the positive and negative lines of the first power line L1, closer to the DC / AC inverter 30 than the first relay RL1.

[0035] One end of the bidirectional DC / DC converter 20 is connected to the storage battery BT, and the other end is connected to the first power line L1 on the DC / AC inverter 30 side of the first relay RL1. The bidirectional DC / DC converter 20 performs charging and discharging operations on the storage battery BT. The storage battery BT may be, for example, a lithium-ion battery.

[0036] The bidirectional DC / DC converter 20 includes a voltage detection unit 21, a current detection unit 22 (a current transformer in this embodiment), a bidirectional chopper circuit including a capacitor 23, a coil 24, and switching elements 25 a and 25 b, and a drive circuit (not shown) that turns on and off the switching elements 25 a and 25 b under the control of a control unit 70.

[0037] The voltage detection unit 21 detects the DC charging voltage supplied to the storage battery BT and the DC discharging voltage supplied from the storage battery BT. The current detection unit 22 detects the DC charging current supplied to the storage battery BT and the DC discharging current supplied from the storage battery BT.

[0038] The voltage detection unit 21, the current detection unit 22, and the various detection units of the bidirectional DC / DC converter 20 correspond to the "second detection unit" of the present invention. The voltage detection signal output from the voltage detection unit 21, the current detection signal output from the current detection unit 22, and the detection signals output from the various detection units correspond to the "second detection signal" of the present invention. The second detection signal is transmitted to the control unit 70. The second detection unit and the control unit 70 are insulated and separated. Furthermore, the transmission path of the second detection signal is insulated and separated from the transmission path of the first detection signal.

[0039] The DC end of the DC / AC inverter 30 is connected to the DC / DC converter 10 and the bidirectional DC / DC converter 20, and the AC end is connected to terminals T1 to T5 via the relay circuit 40. The DC / AC inverter 30 converts the AC voltage supplied from the AC end side into a DC voltage and supplies it to the DC / DC converter 10 and the bidirectional DC / DC converter 20, and converts the DC voltage supplied from the DC end side into an AC voltage and supplies it to the relay circuit 40 side.

[0040] Although not shown, the DC / AC inverter 30 includes various detection units corresponding to the "second detection unit" of the present invention, a power conversion unit including multiple switching elements to convert the power to direct current and alternating current, and a drive circuit that turns the multiple switching elements on and off under the control of the control unit 70.

[0041] The relay circuit 40 includes relays S1 to S6. Of the power lines connecting the DC / AC inverter 30 to the terminals T1 to T5, relays S1, S2, S5, and S6 are installed on the power lines connecting the DC / AC inverter 30 to the terminals T1, T3, T4, and T5, respectively. Terminals T2 and T5 are connected by a power line on which relay S3 is installed. Terminals T3 and T4 are connected by a power line on which relay S4 is installed.

[0042] Terminals T1 to T3 are connected to the U, O, and W phases of the grid, and terminals T4 and T5 are connected to the voltage and neutral wires of the single-phase, two-wire system. An independent load (a household load such as an electrical appliance that should continue to operate even during a grid power outage) is connected between the voltage and neutral wires of the single-phase, two-wire system.

[0043] The power supply unit 50A includes an isolation transformer 51, a first auxiliary power supply 52a, a second auxiliary power supply 52b, a first drive power supply 53a, a second drive power supply 53b, and a secondary power supply 54. The first auxiliary power supply 52a, the second auxiliary power supply 52b, the first drive power supply 53a, and the second drive power supply 53b are insulated and separated from one another.

[0044] The isolation transformer 51 includes a primary winding (not shown), primary auxiliary windings N1 to N4, and a secondary winding N5. The primary winding is connected to the power lines connecting the DC / AC inverter 30 and the terminals T1 and T3, for example, and receives power from the system.

[0045] The first auxiliary power supply 52a is configured to generate a power supply voltage and supplies it to the first detectors that require the power supply voltage (in this embodiment, the voltage detector 11 and various detectors (not shown) that are provided closer to the solar cells PV1 and PV2 than the first relay RL1). The first auxiliary power supply 52a includes, for example, a constant voltage circuit for generating the power supply voltage, is connected to the auxiliary winding N1, and generates the power supply voltage based on the voltage induced in the auxiliary winding N1. A diode and a capacitor are provided between the first auxiliary power supply 52a and the auxiliary winding N1, but the diode and capacitor may be included in the first auxiliary power supply 52a.

[0046] The second auxiliary power supply 52b is configured to generate a power supply voltage and supplies it to the detection units of the second detection units that require the power supply voltage (in this embodiment, the voltage detection unit 21 and various detection units (not shown) provided on the opposite side of the first relay RL1 from the solar cells PV1 and PV2). The various detection units provided on the opposite side of the first relay RL1 from the solar cells PV1 and PV2 include various detection units provided between the first relay RL1 and the terminals T1 to T5 and various detection units provided between the first relay RL1 and one end of the bidirectional DC / DC converter 20 (the terminal connected to the storage battery BT).

[0047] The second auxiliary power supply 52b includes, for example, a constant voltage circuit for generating a power supply voltage, is connected to the auxiliary winding N2, and generates the power supply voltage based on the voltage induced in the auxiliary winding N2. A diode and a capacitor are provided between the second auxiliary power supply 52b and the auxiliary winding N2, but the diode and capacitor may be included in the second auxiliary power supply 52b.

[0048] The first drive power supply 53a is configured to generate a power supply voltage to be supplied to a drive circuit for the switching element 15 of the DC / DC converter 10. The first drive power supply 53a includes, for example, a constant voltage circuit for generating the power supply voltage, is connected to the auxiliary winding N3, and generates the power supply voltage based on the voltage induced in the auxiliary winding N3. A diode and a capacitor are provided between the first drive power supply 53a and the auxiliary winding N3, but the diode and capacitor may also be included in the first drive power supply 53a.

[0049] The second drive power supply 53b is configured to generate a power supply voltage to be supplied to the drive circuits for the switching elements 25a, 25b of the bidirectional DC / DC converter 20 and the drive circuits for the switching elements of the DC / AC inverter 30. The second drive power supply 53b includes, for example, a constant voltage circuit for generating the power supply voltage, is connected to the auxiliary winding N4, and generates the power supply voltage based on the voltage induced in the auxiliary winding N4. A diode and a capacitor are provided between the second drive power supply 53b and the auxiliary winding N4, but the diode and capacitor may be included in the second drive power supply 53b.

[0050] The secondary power supply 54 is configured to generate a power supply voltage to be supplied to the relay driving unit 60A and the control unit 70. The secondary power supply 54 includes, for example, a constant voltage circuit for generating the power supply voltage, is connected to the secondary winding N5, and generates the power supply voltage based on the voltage induced in the secondary winding N5.

[0051] The relay driver 60A is configured to switch the first relay RL1 between an ON state and an OFF state under the control of the controller 70. The relay driver 60A includes, for example, a drive coil for the first relay RL1. When the power generated by the solar cells PV1 and PV2 detected by the voltage detector 11 exceeds a predetermined threshold, the relay driver 60A passes current through the drive coil of the first relay RL1 to turn the first relay RL1 ON. When the power generated by the solar cells PV1 and PV2 is equal to or lower than the predetermined threshold, the relay driver 60A cuts off the current flowing through the drive coil of the first relay RL1 to turn the first relay RL1 OFF. In this embodiment, the threshold is set to zero or a value close to zero, so that the first relay RL1 is turned ON when the solar cells PV1 and PV2 are generating power, and is turned OFF when the solar cells PV1 and PV2 are not generating power, such as at night, thereby suppressing the occurrence of the PID phenomenon.

[0052] The relay driving unit 60A is configured to switch the relays S1 to S6 of the relay circuit 40 between an on state and an off state under the control of the control unit 70. The relay driving unit 60A includes, for example, drive coils for the relays S1 to S6, and when the grid is energized, it puts the relays S1 to S4 into an on state and the relays S5 and S6 into an off state, and when the grid is powered down, it puts the relays S1 to S4 into an off state and the relays S5 and S6 into an on state.

[0053] The control unit 70 outputs control signals (e.g., PWM signals) to the drive circuit for the switching element 15 of the DC / DC converter 10, the drive circuit for the switching elements 25a and 25b of the bidirectional DC / DC converter 20, and the drive circuit for the switching element of the DC / AC inverter 30 to control each drive circuit, and also controls the relay drive unit 60A. The control unit 70 is configured, for example, by a control IC such as a microcomputer or an FPGA (Field-Programmable Gate Array).

[0054] In the hybrid energy storage system 1A according to this embodiment, when the solar cells PV1 and PV2 are not generating electricity, such as at night, the relay driving unit 60A turns off the first relay RL1 to disconnect the solar cells PV1 and PV2 from the grid, thereby suppressing the occurrence of the PID phenomenon.

[0055] Furthermore, in the hybrid energy storage system 1A according to this embodiment, the first auxiliary power source 52a, the second auxiliary power source 52b, the first drive power source 53a, and the second drive power source 53b are insulated and separated from one another, so that it is possible to avoid a short circuit between the negative side contacts of the first relay RL1 when the first relay RL1 is in the off state.

[0056] Furthermore, in the hybrid energy storage system 1A according to this embodiment, the voltage detection signal of the voltage detection unit 11 can be used to control the on state of the first relay RL1, so there is no need to preset the time at which the solar cells PV1 and PV2 start generating electricity in order to control the on state of the first relay RL1.

[0057] Furthermore, in the hybrid power storage system 1A according to this embodiment, even if the number of solar cells increases, there is no need to increase the number of first relays RL1, so it is possible to suppress an increase in the number of relays used as a countermeasure against PID. Note that, compared to the conventional hybrid power storage system 1D shown in Fig. 4, the hybrid power storage system 1A according to this embodiment has an additional first auxiliary power supply 52a and a first drive power supply 53a, but the first auxiliary power supply 52a and the first drive power supply 53a are less expensive than the relay (first relay RL1) used as a countermeasure against PID, so the cost of the entire system can be reduced.

[0058] [Second embodiment] 2 shows a hybrid power storage system 1B according to a second embodiment of the present invention. The hybrid power storage system 1B has the same configuration as the hybrid power storage system 1A of the first embodiment, except that the hybrid power storage system 1B includes a power supply unit 50B instead of the power supply unit 50A, and a relay driving unit 60B instead of the relay driving unit 60A.

[0059] The power supply unit 50B includes an isolation transformer 51′, an auxiliary power supply 52, a drive power supply 53, and a secondary power supply 54. The secondary power supply 54 has the same configuration as in the first embodiment. The auxiliary power supply 52 and the drive power supply 53 are insulated and separated from each other.

[0060] The isolation transformer 51' includes a primary winding (not shown), primary auxiliary windings N1 and N2, and a secondary winding N5. The primary winding is connected to the power lines connecting the DC / AC inverter 30 to the terminals T1 and T3, for example, and receives power from the power grid.

[0061] The auxiliary power supply 52 includes, for example, a constant voltage circuit for generating a power supply voltage, is connected to the auxiliary winding N1, and generates the power supply voltage based on the voltage induced in the auxiliary winding N1. A diode and a capacitor are provided between the auxiliary power supply 52 and the auxiliary winding N1, but the diode and capacitor may also be included in the auxiliary power supply 52.

[0062] The auxiliary power supply 52 supplies a power supply voltage via a second power line L2 having a second relay RL2 interposed therebetween and a fourth power line L4 separate from the second power line. The second power line L2 is connected to the first detectors that require the power supply voltage (in this embodiment, a voltage detector 11 and various detectors (not shown) that are provided on the solar cells PV1 and PV2 side of the first relay RL1). The fourth power line L4 is connected to the second detectors that require the power supply voltage (in this embodiment, a voltage detector 21 and various detectors (not shown) that are provided on the opposite side of the first relay RL1 from the solar cells PV1 and PV2). The second power line L2 and the fourth power line L4 are insulated and separated from each other. The second relay RL2 is switched between an ON state and an OFF state in conjunction with the first relay RL1.

[0063] The driving power supply 53 includes, for example, a constant voltage circuit for generating a power supply voltage, is connected to the auxiliary winding N2, and generates the power supply voltage based on the voltage induced in the auxiliary winding N2. A diode and a capacitor are provided between the driving power supply 53 and the auxiliary winding N2, but the diode and capacitor may also be included in the driving power supply 53.

[0064] The drive power supply 53 supplies a power supply voltage via a third power line L3 having a third relay RL3 interposed therein and a fifth power line L5 separate from the third power line L3. The third power line L3 is connected to a drive circuit for the switching element 15 of the DC / DC converter 10. The fifth power line L5 is connected to a drive circuit for the switching elements 25a and 25b of the bidirectional DC / DC converter 20 and a drive circuit for the switching elements of the DC / AC inverter 30. The third power line L3 and the fifth power line L5 are insulated and separated from each other. The third relay RL3 switches between an ON state and an OFF state in conjunction with the first relay RL1.

[0065] The relay driving unit 60B has the same configuration as the relay driving unit 60A of the first embodiment, but also has a configuration that switches the second relay RL2 and the third relay RL3 between the on state and the off state in conjunction with the first relay RL1. That is, the relay driving unit 60B includes drive coils for the first relay RL1, the second relay RL2, and the third relay RL3, and turns the first relay RL1, the second relay RL2, and the third relay RL3 on when the solar cells PV1 and PV2 are generating power, and turns the first relay RL1, the second relay RL2, and the third relay RL3 off when the solar cells PV1 and PV2 are not generating power, such as at night.

[0066] In the hybrid energy storage system 1B according to this embodiment, similarly to the first embodiment, it is possible to suppress the occurrence of the PID phenomenon, to avoid a short circuit between the negative side contacts of the first relay RL1 when the first relay RL1 is in the off state, and to suppress an increase in the number of relays used as a countermeasure against PID.

[0067] Furthermore, compared to the first embodiment, the hybrid power storage system 1B according to this embodiment has an additional second relay RL2 and a third relay RL3, but is configured to include an auxiliary power source 52 that shares the first auxiliary power source 52a and the second auxiliary power source 52b, and a drive power source 53 that shares the first drive power source 53a and the second drive power source 53b. Since the second relay RL2 and the third relay RL3 can be small relays that are less expensive than the first auxiliary power source 52a and the first drive power source 53a, the overall system can be made less expensive than the first embodiment.

[0068] [Variations] Although the embodiment of the hybrid power storage system according to the present invention has been described above, the present invention is not limited to the above embodiment.

[0069] The hybrid power storage system 1A according to the first embodiment may further include a lightning detection circuit configured to detect lightning.

[0070] The lightning detection circuit is configured to detect lightning by detecting at least one of the following: electromagnetic waves emitted from a thundercloud when lightning occurs, an increase in current or voltage within the lightning detection circuit, the intensity of lightning or sound volume, etc. Upon detecting lightning, the lightning detection circuit outputs a lightning detection signal to the control unit 70. Upon receiving the lightning detection signal, the control unit 70 controls the relay driving unit 60A to turn off the first relay RL1 regardless of the magnitude of the generated power.

[0071] The lightning detection circuit may determine the risk of a lightning surge when it detects lightning. For example, the lightning detection circuit may be configured to classify the risk of a lightning surge in advance into an unoccurred stage (undetected), a caution stage, an alert stage, and a danger stage in order of increasing risk, and to determine the current risk stage when it detects lightning, and output a lightning detection signal to the control unit 70 if the current risk has reached a preset stage (for example, the danger stage).

[0072] In this modification, by turning off the first relay RL1 when lightning is detected, the circuits related to the solar cells PV1 and PV2 (the circuits on the solar cells PV1 and PV2 side of the first relay RL1, the first auxiliary power supply 52a and the first drive power supply 53a) are insulated and separated from the other circuits. As a result, in this modification, when lightning strikes the solar cells PV1 and PV2, it is possible to reduce the risk of damage due to a lightning surge to the other circuits (circuits other than the circuits related to the solar cells PV1 and PV2).

[0073] Furthermore, in this modified example, the first relay RL1 is turned off only when the risk of a lightning surge reaches a predetermined level, thereby minimizing the number of times the first relay RL1 operates and reducing the risk of damage due to a lightning surge to circuits other than those related to the solar cells PV1 and PV2.

[0074] In this modification, the hybrid power storage system 1A according to the first embodiment is described as being equipped with a lightning detection circuit, but the hybrid power storage system 1B according to the second embodiment may be equipped with a lightning detection circuit, or the hybrid power storage system according to the present invention described later may be equipped with a lightning detection circuit.

[0075] [Other variations] a first relay interposed in a first power line connecting the plurality of DC / DC converters to the bidirectional DC / DC converter and the DC / AC inverter; a relay drive unit that switches the first relay between an on state and an off state; and a power supply unit that supplies power supply voltage to the plurality of DC / DC converters, the bidirectional DC / DC converter and the DC / AC inverter, wherein each of the plurality of DC / DC converters has a diode on its output end side and the cathodes of the diodes of the DC / DC converters are connected to each other; the power supply unit insulates and separates the supply path of the power supply voltage supplied to each DC / DC converter from the supply path of the power supply voltage supplied to the bidirectional DC / DC converter and the DC / AC inverter; and the configuration of the relay drive unit can be modified as appropriate as long as it switches the first relay to an off state when the generated power output from the power generation device is equal to or lower than a predetermined threshold.

[0076] For example, in the first embodiment, if the first auxiliary power supply 52a and the first drive power supply 53a can be combined into a single first power supply, they may be combined. Furthermore, if the second auxiliary power supply 52b and the second drive power supply 53ba can be combined into a single second power supply, they may be combined. However, the first power supply and the second power supply must be insulated and separated. When the first power supply and the second power supply are combined into a single power supply, it is necessary to use a relay, as in the second embodiment, to insulate and separate the supply path of the power supply voltage to the circuits related to the solar cells PV1 and PV2 from the supply path of the power supply voltage to other circuits.

[0077] The circuit configurations of the DC / DC converter 10, the bidirectional DC / DC converter 20, and the DC / AC inverter 30 of the above-described embodiments can be modified as appropriate.

[0078] The second relay RL2 and the third relay RL3 in the second embodiment may use switching means such as semiconductor switches. However, since it is necessary to insulate and separate the drive circuit of the switching means corresponding to the second relay RL2 from the drive circuit of the switching means corresponding to the third relay RL3, it is more cost-effective to use relays as in the second embodiment. [Explanation of symbols]

[0079] 1A, 1B Hybrid Energy Storage System 10 DC / DC converter 11 Voltage detection section 12 Current detection section 13 Capacitor 14 coils 15 Switching element 16 Diodes 20 Bidirectional DC / DC Converter 21 Voltage detection section 22 Current detection section 23 Capacitor 24 coils 25a, 25b Switching elements 30 DC / AC inverter 40 Relay Circuit 50A,50B power supply section 51 Isolation transformer 52 Auxiliary power supply 52a 1st auxiliary power supply 52b 2nd auxiliary power supply 53 Drive power supply 53a First drive power supply 53b Second drive power supply 54 Secondary power supply 60A, 60B relay driver 70 Control Unit

Claims

1. a plurality of DC / DC converters connected to a power generation device; a bidirectional DC / DC converter connected to the storage battery; a DC / AC inverter connected to the plurality of DC / DC converters and the bidirectional DC / DC converter; A hybrid power storage system comprising: a first relay interposed in a first power line connecting the plurality of DC / DC converters to the bidirectional DC / DC converter and the DC / AC inverter; a relay driver that switches the first relay between an on state and an off state; a power supply unit that supplies a power supply voltage to the plurality of DC / DC converters, the bidirectional DC / DC converter, and the DC / AC inverter; Equipped with each of the plurality of DC / DC converters includes a diode on an output end side, and cathodes of the diodes of the DC / DC converters are connected to each other; the power supply unit has a supply path of a power supply voltage supplied to each of the DC / DC converters and a supply path of a power supply voltage supplied to the bidirectional DC / DC converter and the DC / AC inverter, which are insulated and separated from each other; The relay driver turns the first relay to the off state when the generated power output from the power generation device is equal to or less than a predetermined threshold. A hybrid energy storage system characterized by:

2. a control unit that controls the DC / DC converters, the bidirectional DC / DC converter, and the DC / AC inverter; a first detection unit in each of the DC / DC converters that detects a voltage and / or a current input from the power generation device and outputs a first detection signal; a second detection unit that detects a voltage and / or a current input / output between the bidirectional DC / DC converter and the storage battery, or that detects a voltage and / or a current input / output to / from the DC / AC inverter, and outputs a second detection signal; Equipped with The first detection unit and the control unit are insulated and separated, and the first detection unit and the second detection unit are also insulated and separated. The hybrid power storage system according to claim 1 .

3. The power supply unit a first auxiliary power supply that supplies a power supply voltage to the first detection unit; a first drive power supply that supplies a power supply voltage to a drive circuit of a switching element included in each of the DC / DC converters; a second auxiliary power supply that supplies a power supply voltage to the second detection unit; a second drive power supply that supplies a power supply voltage to a drive circuit of a switching element included in the bidirectional DC / DC converter and a drive circuit of a switching element included in the DC / AC inverter, the first auxiliary power supply and the second auxiliary power supply are insulated and separated from each other; The first driving power supply and the second driving power supply are also insulated and separated. The hybrid power storage system according to claim 2 .

4. The power supply unit an auxiliary power supply that supplies a power supply voltage to the first detection unit and the second detection unit; a drive power supply that supplies a power supply voltage to a first drive circuit that drives a switching element included in each of the DC / DC converters, and a second drive circuit that drives a switching element included in the bidirectional DC / DC converter or a switching element included in the DC / AC inverter, the auxiliary power supply is connected to the first detector by a second power line having a second relay interposed therein, and is connected to the second detector by a power line separate from the second power line; the drive power supply is connected to the first drive circuit by a third power line having a third relay interposed therein, and is connected to the second drive circuit by a power line separate from the third power line; The second relay and the third relay are switched between an on state and an off state in conjunction with the first relay. The hybrid power storage system according to claim 2 .

5. Further comprising a lightning detection circuit, When the lightning detection circuit detects lightning, the relay driving unit turns the first relay to the off state regardless of the magnitude of the generated power. The hybrid power storage system according to any one of claims 1 to 4.

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