Power conditioner equipment and power supply systems

Abstract

To provide a power conditioner device capable of protecting a regenerative diode of an ARCP circuit from overvoltage.SOLUTION: Disclosed is a power conditioner device 10 having independent output ends T2 (U), T2 (O), T2 (W) of a single-phase three wire system which includes: an invertor circuit 13; a bidirectional DC / DC converter circuit 14; and a control part 15. The bidirectional DC / DC converter circuit 14 includes a main circuit and an ARCP circuit. When the overvoltage exceeding a predetermined threshold is applied to the independent output ends T2 (U), T2 (O), and T2 (W), the control part 15 performs a stop process to stop the operation of the ARCP circuit so as to prevent a voltage value of the voltage applied to a regeneration diode of the ARCP circuit from exceeding a predetermined permissible voltage value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power conditioner device and a power supply system including the power conditioner device. [Background technology]

[0002] Generally, a power supply system is known that includes a first power conditioner device that performs charging and discharging operations on a storage battery, and a second power conditioner device that controls power generated by a solar panel.

[0003] A known first power conditioner device has a single-phase three-wire isolated output terminal and further includes an inverter circuit and a bidirectional DC / DC converter circuit with an ARCP (Auxiliary Resonant Commutated Pole) circuit. The circuit configuration of the ARCP circuit is as described in Patent Document 1, for example.

[0004] If the isolated output terminal of the first power conditioner device is a single-phase two-wire type, the second power conditioner device can only be connected upstream of the first power conditioner device, but if the isolated output terminal is a single-phase three-wire type as described above, the second power conditioner device can be connected to the isolated output terminal of the first power conditioner device.

[0005] In a power supply system in which a second power conditioner is connected to the isolated output terminal of a first power conditioner, the second power conditioner performs grid-connected operation with respect to the grid power of the power grid when the power grid is energized, and performs grid-connected operation (pseudo-grid-connected operation) with respect to the isolated output power of the first power conditioner when the power grid is in a power outage. This makes it possible to charge a storage battery using power generated by solar panels even during a power outage, and to supply the generated power together with the discharged power of the storage battery to a load (e.g., home appliances) connected to the isolated output terminal.

[0006] However, if the power generated by the second power conditioner is greater than the power consumed by the load or the power available to charge the storage battery, the second power conditioner will continue to supply the generated power even though there is nowhere for the surplus power to go, causing the output voltage of the second power conditioner to continue rising, resulting in an overvoltage being applied to the isolated output terminal of the first power conditioner.

[0007] In order to stop the power supply from the second power conditioner, the first power conditioner changes the frequency of the applied voltage at the isolated output terminal to detect that an abnormality has occurred in the second power conditioner. However, it takes time for the second power conditioner to stop the power supply after detecting the abnormality, and an overvoltage continues to be applied to the isolated output terminal of the first power conditioner for a certain period of time.

[0008] The ARCP circuit of the bidirectional DC / DC converter circuit of the first power conditioner device includes a resonant switch, a resonant reactor, a resonant capacitor, a regenerative transformer, and a regenerative diode. The regenerative transformer typically has a larger number of turns in the regenerative winding than in the main winding; for example, the ratio of the number of turns in the regenerative winding to the number of turns in the main winding is 2:1. In this case, the voltage generated in the regenerative winding is twice the voltage applied to the main winding.

[0009] Therefore, the voltage applied to the regenerative diode via the regenerative winding is twice the voltage applied to the main winding plus the overshoot voltage when the resonant switch is switched, which is a very high voltage.If an overvoltage is applied to the independent output terminal in this state, the voltage applied to the regenerative diode will be even higher, which creates the problem that relatively inexpensive general-purpose diodes (for example, diodes with a voltage rating of 1200V) cannot be used as regenerative diodes. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent Publication No. 2021-19396 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power conditioner device and a power supply system that can protect the regenerative diode of an ARCP circuit from overvoltage. [Means for solving the problem]

[0012] In order to solve the above problem, a power conditioner device according to the present invention comprises: A power conditioner device having a single-phase three-wire independent output terminal, an inverter circuit connected to the independent output terminal; a DC / DC converter circuit connected to the inverter circuit; a control unit that controls the inverter circuit and the DC / DC converter circuit; Equipped with The DC / DC converter circuit a main circuit including a main switch; an ARCP circuit including a resonant switch, a regenerative transformer, and a regenerative diode; The control unit When an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a stop process is performed to stop the operation of the ARCP circuit, and the voltage value applied to the regenerative diode via the regenerative transformer does not exceed a predetermined allowable voltage value.

[0013] According to this configuration, when an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a shutdown process is performed to stop the operation of the ARCP circuit, and the voltage value applied to the regenerative diode does not exceed a predetermined allowable voltage value, thereby protecting the regenerative diode from overvoltage.

[0014] In the power conditioner device, The DC / DC converter circuit connected to the inverter circuit via a capacitor, The inverter circuit When an overvoltage is applied to the independent output terminal, a voltage is supplied to the capacitor to absorb the overvoltage; The control unit The device may be configured to determine whether or not to perform the stop process based on the voltage across the capacitor.

[0015] In the power conditioner device, The control unit When the stopping process is performed, the resonance switch can be kept in a continuous off state, while the main switch can be turned on / off by PWM control.

[0016] In order to solve the above problems, the power supply system according to the present invention comprises: A storage battery and A first power conditioner device having a single-phase three-wire isolated output terminal having the features of the power conditioner device; a second power conditioner device connected to the isolated output terminal; Including, The first power conditioner device is characterized by performing charging and discharging operations on the storage battery.

[0017] In the power supply system, The second power conditioner device is performing a grid-connected operation on the AC power output from the independent output terminal; The first power conditioner device is When an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a grid-connected operation stop process for stopping the grid-connected operation of the second power conditioner device can be performed. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a power conditioner device and a power supply system that can protect the regenerative diode of the ARCP circuit from an overvoltage. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram of a power supply system according to the present invention. [Figure 2] 1 is a block diagram of a power conditioner device according to the present invention. [Figure 3] FIG. 2 is a circuit diagram of an inverter circuit of the power conditioner device according to the present invention. [Figure 4] 1 is a circuit diagram of a bidirectional DC / DC converter circuit of a power conditioner device according to the present invention. [Figure 5] 1A and 1B are waveform diagrams showing various waveforms during operation of the ARCP circuit according to the present invention, in which (A) is a waveform diagram of the gate voltages of switching elements Q8 and Q10, (B) is a waveform diagram of the reactor current and the resonant current, and (C) is a waveform diagram of the drain current and the drain-source voltage of switching element Q8. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a power conditioner device and a power supply system according to the present invention will be described with reference to the accompanying drawings.

[0021] 1 shows a power supply system 1 according to one embodiment of the present invention. The power supply system 1 includes a first power conditioner device 10 (corresponding to the "power conditioner device" of the present invention), a second power conditioner device 20, a changeover switch SW, a storage battery BT, and a solar panel PV.

[0022] The first power conditioner device 10 includes a single-phase three-wire first terminal T1, a single-phase three-wire second terminal (independent output terminal) T2, and a third terminal T3 connected to a storage battery BT. The first terminal T1 is connected to a power grid 2 and is also connected to a load 3 (e.g., a home appliance) via a selector switch SW. The second terminal (independent output terminal) T2 is connected to the load 3 via a selector switch SW.

[0023] The changeover switch SW is configured by, for example, a relay, and connects a first terminal T1 to the load 3 when the power grid 2 is energized (hereinafter referred to as energized), and connects a second terminal (independent output terminal) T2 to the load 3 when the power grid 2 is in a power outage (hereinafter referred to as power outage). In other words, the first power conditioner device 10 can supply a voltage of AC 200 [V] to the load 3 even during a power outage.

[0024] The second power conditioner device 20 has a fourth terminal T4 connected to the load 3 and a fifth terminal T5 connected to the solar panel PV. The fourth terminal T4 is connected to the power grid 2 when energized, and is connected to the second terminal (independent output terminal) T2 of the first power conditioner device 10 when a power outage occurs. The second power conditioner device 20 performs grid-connected operation with respect to the system power of the power grid 2 when energized, and performs grid-connected operation (pseudo-grid-connected operation) with respect to the independent output power of the first power conditioner device 10 when a power outage occurs.

[0025] 2 shows a block diagram of the first power conditioner device 10. The first power conditioner device 10 includes a relay circuit 11, a noise filter 12, an inverter circuit 13, a bidirectional DC / DC converter circuit 14 (corresponding to the "DC / DC converter circuit" of the present invention), a control unit 15, and various detection circuits (not shown).

[0026] The relay circuit 11 includes relays S1 to S9 that are turned on / off under the control of the control unit 15. Relays S1 to S3 are provided in the wiring that connects the first terminals T1(U), T1(O), and T1(W) of the U, O, and W phases, respectively, to the noise filter 12. Relays S4 to S6 are provided in the wiring that connects the first terminals T1(U), T1(O), and T1(W) to the independent output terminals T2(U), T2(O), and T2(W) of the U, O, and W phases, respectively. Relays S7 to S9 are provided in the wiring that connects the independent output terminals T2(U), T2(O), and T2(W) to the noise filter 12, respectively.

[0027] The noise filter 12 is provided between the relay circuit 11 and the inverter circuit 13. The noise filter 12 is composed of, for example, a capacitor and a coil, and cuts out noise propagating through the wiring connecting the relay circuit 11 and the inverter circuit 13.

[0028] The inverter circuit 13 is connected to the first terminals T1(U), T1(O), and T1(W) and the independent output terminals T2(U), T2(O), and T2(W) via the noise filter 12 and the relay circuit 11. As shown in Fig. 3, the inverter circuit 13 includes a filter section made up of capacitors C1 to C3 and coils L1 to L3, and three arm sections made up of switching elements Q1 to Q6 and diodes D1 to D6. The switching elements Q1 to Q6 are turned on / off under the control of the control unit 15.

[0029] The switching elements Q1 to Q6 are, for example, metal-oxide semiconductor field-effect transistors (MOSFETs). The diodes D1 to D6 are connected in parallel in the reverse direction to the current paths (drain-source) of the switching elements Q1 to Q6. The diodes D1 to D6 may be parasitic diodes of the switching elements Q1 to Q6, or external diodes independent of the switching elements Q1 to Q6, or both.

[0030] The bidirectional DC / DC converter circuit 14 is connected to the inverter circuit 13. As shown in Fig. 4, the bidirectional DC / DC converter circuit 14 includes a main circuit 14A, an ARCP circuit 14B, and input / output terminals Ta to Td. The input / output terminals Ta and Tb are connected to the inverter circuit 13, and the input / output terminals Tc and Td are connected to the third terminals T3(+) and T3(-), i.e., the storage battery BT.

[0031] The main circuit 14A includes switching elements Q7, Q8 and diodes D7, D8 that constitute a main switch, a DC reactor L4, and capacitors C4, C5. The ARCP circuit 14B includes switching elements Q9, Q10 and diodes D9, D10 that constitute a resonant switch, a resonant reactor L5, resonant capacitors C6, C7, a regenerative transformer TR1 that includes a main winding N1 and a regenerative winding N2, and regenerative diodes D11, D12.

[0032] Switching elements Q7-Q10 may be, for example, MOSFETs. Diodes D7-D10 are connected in parallel in the reverse direction to the current paths (drain-source) of switching elements Q7-Q10. Diodes D7-D10 may be parasitic diodes of switching elements Q7-Q10, or external diodes independent of switching elements Q7-Q10, or both.

[0033] Switching elements Q7 and Q8 are connected in series with each other, with one end of the series-connected current path connected to input / output terminal Ta and the other end connected to input / output terminals Tb and Td. A connection point X1 between switching element Q7 and switching element Q8 is connected to input / output terminal Tc via a DC reactor L4. Capacitor C4 is connected between input / output terminals Ta and Tb, closer to input / output terminals Ta and Tb than switching elements Q7 and Q8. Capacitor C5 is connected between input / output terminals Tc and Td, closer to input / output terminals Tc and Td than DC reactor L4.

[0034] Switching elements Q9 and Q10 are connected in series between switching elements Q7 and Q8 and capacitor C4, and are connected in parallel to switching elements Q7 and Q8. A junction point X2 between switching elements Q9 and Q10 is connected to junction point X1 via a main winding N1 of regenerative transformer TR1 and resonant reactor L5. Resonant capacitor C6 is connected in parallel between the drain and source of switching element Q7, and resonant capacitor C7 is connected in parallel between the drain and source of switching element Q8.

[0035] One end and the other end of the regenerative winding N2 of the regenerative transformer TR1 are connected to the input / output terminal Ta via regenerative diodes D11 and D12, respectively. The regenerative winding N2 has a center tap that is connected to the input / output terminal Tb. In this embodiment, the turns ratio between the main winding N1 and the regenerative winding N2 is N1:N2=1:2. In this embodiment, relatively inexpensive, general-purpose diodes (e.g., diodes with a withstand voltage of 1200V) can be used as the regenerative diodes D11 and D12.

[0036] Control unit 15 includes a relay control circuit for controlling relay circuit 11, drive circuits for switching elements Q1 to Q10 for turning on / off switching elements Q1 to Q10, and a control circuit for sending control signals to each drive circuit. Control unit 15 may be configured with an analog circuit, a digital circuit using a microcontroller or the like, or a circuit that combines an analog circuit and a digital circuit.

[0037] Regarding the control of the inverter circuit 13, the control unit 15 causes the inverter circuit 13 to perform an AC / DC conversion operation of converting an AC voltage input via the noise filter 12 into a DC voltage and outputting the DC voltage to the bidirectional DC / DC converter circuit 14 side, and a DC / AC conversion operation of converting a DC voltage input from the bidirectional DC / DC converter circuit 14 into an AC voltage and outputting the AC voltage to the noise filter 12 side.

[0038] Regarding the control of the bidirectional DC / DC converter circuit 14, the control unit 15 causes the bidirectional DC / DC converter circuit 14 to perform a power conversion operation (step-up operation) from the input / output terminals Tc, Td side (storage battery BT) to the input / output terminals Ta, Tb side (inverter circuit 13 side), and a power conversion operation (step-down operation) from the input / output terminals Ta, Tb side (inverter circuit 13 side) to the input / output terminals Tc, Td side (storage battery BT). The control unit 15 performs PWM control on the switching elements Q7, Q8 of the main switch.

[0039] 5(A) to 5(C) show various waveforms during the boost operation and the operation of the ARCP circuit 14B. FIG. 5(A) shows the gate voltage Vgs of the switching elements Q8 and Q10, and FIG. 5(B) shows the reactor current I flowing through the DC reactor L4. L4 and the resonant current I flowing through the resonant reactor L5 L5 FIG. 5C is a waveform diagram of the drain current Id and the drain-source voltage Vds of the switching element Q8.

[0040] At time t1, when the control unit 15 turns on the switching element Q10, the current flowing through the diode D7 is commutated to the resonant reactor L5, and the resonant reactor L5 acts to extract charge from the resonant capacitor C7, causing the resonant reactor L5, the leakage inductance of the regenerative transformer TR1, and the resonant capacitor C7 to resonate. As a result, a resonant current I L5 flows, and the drain-source voltage Vds of the switching element Q8 decreases.

[0041] At time t2, the resonant current I L5 Current waveform at the falling edge of and reactor current I L4When control unit 15 turns on switching element Q8 at the timing when this current waveform intersects with switching element Q10, switching element Q10 is on, so the drain-source voltage Vds of switching element Q8 becomes approximately 0 V and the drain current Id of switching element Q10 rises from 0 A. As a result, zero-voltage switching and zero-current switching are achieved, and switching loss when switching element Q8 is turned on is reduced.

[0042] The charge extracted from the resonant capacitor C7 is the resonant current I L5 When this current flows through the main winding N1 of the regenerative transformer TR1, a voltage is induced in the regenerative winding N2 of the regenerative transformer TR1. The voltage induced in the regenerative winding N2 is regenerated in the capacitor C4 via the regenerative diodes D11 and D12.

[0043] At time t3, the resonant current I L5 After the current reaches 0 [A], the control unit 15 turns off the switching element Q10 at time t4, and then turns off the switching element Q8 in accordance with the duty of the PWM control (time t5).

[0044] At time t5, when control unit 15 turns off switching element Q8, the current flowing through switching element Q8 is commutated to resonant capacitor C7, which is then charged. Because the drain current Id of switching element Q8 decreases relatively quickly while the drain-source voltage Vds of switching element Q8 increases slowly, the overlapping region between the falling edge of drain current Id and the rising edge of drain-source voltage Vds decreases. As a result, zero-voltage switching is achieved, reducing switching loss when switching element Q8 is turned off.

[0045] In the bidirectional DC / DC converter circuit 14, the step-up operation and the step-down operation are based on the same operating principle, and therefore, during the step-down operation, the control unit 15 controls the switching element Q7 of the main switch and the switching element Q9 of the resonant switch in the same manner as described above.

[0046] Next, a stop process in which the control unit 15 stops the operation of the ARCP circuit 14B will be described.

[0047] In the power supply system 1 according to this embodiment, if the generated power output from the fourth terminal T4 of the second power conditioner 20 during a power outage in the power grid 2 is greater than the power consumed by the load 3 or the power that can be charged to the storage battery BT, the second power conditioner 20 will continue to supply the generated power even though there is nowhere for the surplus power to go, causing the output voltage of the second power conditioner 20 to rise. As a result, an overvoltage is applied to the isolated output terminal T2 of the first power conditioner 10.

[0048] When an overvoltage is applied to the isolated output terminal T2 of the first power conditioner device 10, the inverter circuit 13 of the first power conditioner device 10 operates to supply voltage to the capacitor C4 of the bidirectional DC / DC converter circuit 14 in order to absorb the overvoltage. As a result, the voltage across the capacitor C4 rises.

[0049] The bidirectional DC / DC converter circuit 14 is provided with a voltage detection sensor (not shown) for detecting the voltage across the capacitor C4.

[0050] The control unit 15 determines whether or not to perform the stop process based on the voltage across the capacitor C4 (the voltage value detected by the voltage detection sensor), and performs the stop process so that the voltage value applied to the regenerative diodes D11 and D12 does not exceed a predetermined allowable voltage value (e.g., 1200 [V]).

[0051] For example, if the voltage across capacitor C4 during normal operation (when no overvoltage is applied to independent output terminal T2) is 360 to 380 [V], when the voltage across capacitor C4 reaches 400 [V], control unit 15 determines that an overvoltage exceeding a predetermined threshold has been applied to independent output terminal T2 and executes a shutdown process.

[0052] During the stop processing, the control unit 15 keeps the switching elements Q9 and Q10 of the resonance switches in a continuous off state and turns the switching elements Q7 and Q8 of the main switch on and off by PWM control, thereby stopping the operation of the ARCP circuit 14B of the bidirectional DC / DC converter circuit 14 and switching it to a simple PWM-controlled bidirectional chopper operation.

[0053] When the operation of the ARCP circuit 14B stops, voltage is no longer applied to the regenerative diodes D11 and D12, so that the regenerative diodes D11 and D12 can be protected from overvoltage. That is, in the first power conditioner device 10 and the power supply system 1 according to this embodiment, relatively inexpensive general-purpose diodes (for example, diodes with a withstand voltage of 1200 V) can be used as the regenerative diodes D11 and D12.

[0054] The control unit 15 may stop the operation of the ARCP circuit 14B and may also perform a grid-connected operation stop process to stop the grid-connected operation (pseudo-grid-connected operation) of the second power conditioner apparatus 20. During the grid-connected operation stop process, the control unit 15 changes the frequency of the voltage applied to the isolated output terminal T2, etc., to detect that an abnormality has occurred in the second power conditioner apparatus 20. Furthermore, when the voltage across the capacitor C4 returns to the voltage during normal operation, the control unit 15 may resume the operation of the ARCP circuit 14B.

[0055] The control unit 15 defines the period during which the resonant current flows in the ARCP circuit 14B as a PWM control-disabled period (for example, times t1 to t3 in FIG. 5), and performs PWM control by varying the duty of the switching elements Q7 and Q8 during the PWM control-enabled period during which the resonant current does not flow (for example, times t3 to t6 in FIG. 5).

[0056] However, when the ON time of the switching elements Q7 and Q8 becomes so short that the PWM control disabled period cannot be secured (when the input / output voltage difference is small and the load is light) or when the OFF time of the switching elements Q7 and Q8 becomes so short (when the input / output voltage difference is large and the load is heavy), operating the ARCP circuit 14B actually increases the switching loss. Therefore, when the load is light or heavy as described above, the control unit 15 stops the operation of the ARCP circuit 14B and switches the operation of the bidirectional DC / DC converter circuit 14 to PWM-controlled bidirectional chopper operation.

[0057] Although the embodiments of the power conditioner device and the power supply system according to the present invention have been described above, the present invention is not limited to the above-described embodiments.

[0058] The power conditioner device of the present invention is a power conditioner device having a single-phase three-wire isolated output terminal, and comprises an inverter circuit connected to the isolated output terminal, a DC / DC converter circuit connected to the inverter circuit, and a control unit that controls the inverter circuit and the DC / DC converter circuit, wherein the DC / DC converter circuit comprises a main circuit including a main switch, and an ARCP circuit including a resonant switch, a regenerative transformer, and a regenerative diode, and the control unit performs a stop process to stop the operation of the ARCP circuit when an overvoltage exceeding a predetermined threshold is applied to the isolated output terminal, and the configuration can be changed as appropriate as long as the voltage value of the voltage applied to the regenerative diode via the regenerative transformer does not exceed a predetermined allowable voltage value.

[0059] For example, the control unit 15 in the above embodiment determines whether an overvoltage exceeding a predetermined threshold has been applied to the independent output terminal T2 based on the voltage across the capacitor C4, but it may also directly detect the applied voltage at the independent output terminal T2 to determine whether an overvoltage has occurred.

[0060] As the switching element of the main switch and / or the resonant switch, a switching element other than a MOSFET (for example, an IGBT) can be used.

[0061] The power supply system of the present invention includes a storage battery, a power conditioner device (first power conditioner device) of the present invention having a single-phase three-wire independent output terminal, and a second power conditioner device connected to the independent output terminal, and the configuration can be changed as appropriate as long as the power conditioner device performs charging and discharging operations on the storage battery. [Explanation of symbols]

[0062] 1 Power System 2 Power system 3. Load 10. First power conditioner device 11 Relay Circuit 12 Noise Filter 13 Inverter circuit 14 Bidirectional DC / DC converter circuit 14A main circuit 14B ARCP circuit 15 Control Unit 20 Second power conditioner device

Claims

1. A power conditioner device having a single-phase three-wire first terminal connected to a power grid and a single-phase three-wire independent output terminal, an inverter circuit connected to the independent output terminal; a DC / DC converter circuit connected to the inverter circuit; a control unit that controls the inverter circuit and the DC / DC converter circuit; Equipped with The DC / DC converter circuit connected to the inverter circuit via a capacitor, a main circuit including a main switch; an ARCP circuit including a resonance switch, a regenerative transformer, and a regenerative diode, wherein a voltage induced in the regenerative transformer by a resonance current flowing through the regenerative transformer is regenerated in the capacitor via the regenerative diode; The control unit When an overvoltage exceeding a predetermined threshold is applied to the independent output terminal, a stop process is performed to stop the operation of the ARCP circuit, and the voltage value of the voltage applied to the regenerative diode via the regenerative transformer does not exceed a predetermined allowable voltage value; When the stop process is performed, the resonance switch is kept in a continuous off state, while the main switch is turned on / off by PWM control. A power conditioner device characterized by the above.

2. The inverter circuit When an overvoltage is applied to the independent output terminal, a voltage is supplied to the capacitor to absorb the overvoltage; The control unit Whether or not to perform the stop process is determined based on the voltage across the capacitor. The power conditioner device according to claim 1 .

3. A storage battery and A first power conditioner device having the first terminal and the independent output end, the first power conditioner device having the features of the power conditioner device according to claim 1 or 2; a second power conditioner device connected to the isolated output terminal; Including, The first power conditioner device performs a charging operation and a discharging operation for the storage battery. A power supply system characterized by:

4. The second power conditioner device is performing a grid-connected operation on the AC power output from the independent output terminal; The first power conditioner device is When an overvoltage exceeding a predetermined threshold is applied to the isolated output terminal, a grid-connected operation stop process is performed to stop the grid-connected operation of the second power conditioner device.

4. The power supply system according to claim 3.

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