PID repair circuit and PID repair method for photovoltaic system

Abstract

The present invention relates to a PID repair circuit and PID repair method for a photovoltaic system. The photovoltaic system comprises a solar cell module, an energy storage module, a DC-DC boost circuit and an inverter circuit. The PID repair circuit comprises a direct-current power source and an isolation circuit. After the direct-current power source is processed by the isolation circuit, one end of the isolation circuit is connected to a positive terminal PV+ or a negative terminal PV- of the solar cell module, and the other end of the isolation circuit is connected to a ground terminal PE. A first switch is provided on a connection path between the solar cell module and the energy storage module. The direct-current power source applies a negative voltage to the positive terminal PV+ of the solar cell module or applies a positive voltage to the negative terminal PV- of the solar cell module, so as to perform PID repair on the solar cell module, and when the PID repair is performed, a connection path between the solar cell module and the inverter circuit is disconnected. The present application can ensure that when PID repair is performed, no internal short circuit is produced due to an inverter circuit, thereby effectively ensuring the operating safety of a photovoltaic system.

Description

PID repair circuit and PID repair method for photovoltaic system Technical Field

[0001] The present invention relates to the technical field of photovoltaic control, and in particular to a PID repair circuit and a PID repair method for a photovoltaic system. Background Art

[0002] Potential Induced Degradation (PID), also known as cell-induced degradation, occurs when photovoltaic solar panels are subjected to high voltage for extended periods, leading to leakage current between the glass substrate and the encapsulation material. This causes a large amount of charge to accumulate on the panel surface, deteriorating the cell surface passivation and causing a decrease in the overall output power of the photovoltaic module. To suppress panel power degradation, the industry typically applies a positive voltage to the PV- terminal on the PE side of the panel, or a negative voltage to the PV+ terminal on the PE side.

[0003] The above PID repair work is usually performed at night because the photovoltaic panels are not working at night and the AC relay is not closed and is in the disconnected state. Therefore, the above PID repair work can be performed without forming a closed short-circuit path. However, for photovoltaic systems with energy storage modules, since the energy storage module supplies power at night, the AC relay is in the closed state. When the neutral line of the photovoltaic system's inverter circuit is grounded, performing the above PID repair work will cause a short circuit between the power supply and the inverter circuit in the PID repair circuit. This may cause device damage or trigger the inverter's RCD residual current protection, causing the inverter to malfunction. Not only will the PID repair be impossible, but it may also cause the photovoltaic system to malfunction and even damage the equipment. Therefore, it is necessary to disconnect the energy storage module when performing the PID repair.

[0004] Therefore, how to keep the photovoltaic power generation system safe and stable during PID repair is a technical problem that needs to be solved in this application.

[0005] Summary of the Invention

[0006] A main purpose of the present invention is to overcome at least one of the above-mentioned defects, and to provide a PID repair circuit and a PID repair method for a photovoltaic system, which can ensure safe and efficient PID nighttime repair with good stability.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The present invention provides a PID repair circuit for a photovoltaic system. The photovoltaic system includes a solar cell module, an energy storage module, a DC-DC boost circuit, and an inverter circuit. The DC output of the solar cell module is connected to the inverter circuit through the DC-DC boost circuit to form an AC output. The energy storage module is connected to the inverter circuit to form an AC output. The PID repair circuit includes a DC power supply and an isolation circuit. After being processed by the isolation circuit, one end of the DC power supply is connected to the positive terminal PV+ or the negative terminal PV- of the solar cell module. The other end of the isolation circuit is connected to a ground terminal PE. A first switch is provided on the connection path between the DC-DC boost circuit and the energy storage module.

[0009] The output side of the PID repair circuit is connected to the positive terminal PV+ or the negative terminal PV- of the solar cell module, and the connected connection point is recorded as the repair access point of the PID repair circuit. The first switch is set on the first connection path between the repair access point and the energy storage module.

[0010] According to one embodiment of the present invention, the photovoltaic system includes at least one solar cell module, each of the solar cell modules includes one solar cell module or at least two solar cell modules connected in series or in parallel, each of the solar cell modules is connected to the DCDC boost circuit via a DC bus, and the repair access point is located on a second connection path between the solar cell module and the energy storage module.

[0011] According to one embodiment of the present invention, the photovoltaic system includes at least one DC-DC boost circuit, each solar cell module is connected to the DC-DC boost circuit respectively and then connected in parallel to a DC bus, which is further connected to the energy storage module. The output side of the PID repair circuit is connected to each solar cell module respectively, and includes a plurality of repair access points, each of which is located on the second connection path between the solar cell module and the energy storage module.

[0012] According to one embodiment of the present invention, a plurality of PID repair circuits are included, each of the repair access points is connected to at least one PID repair circuit, and the first switch is arranged on a third connection path defined between a connection point between a DC conversion circuit and a DC bus and the repair access point.

[0013] According to one embodiment of the present invention, a discharge circuit is provided in parallel with the first switch, for discharging the voltage across the first switch after the PID repair is completed.

[0014] According to one embodiment of the present invention, the discharge circuit includes at least one discharge element, and each of the discharge elements is connected in series and then in parallel with the first switch;

[0015] Alternatively, a discharge switch is connected in series in the connection link formed by the discharge resistors connected in series.

[0016] According to one embodiment of the present invention, the discharge circuit includes at least two discharge elements, one end of a first discharge branch formed by at least one discharge element connected in series is connected to one end of the first switch, and the other end of the first discharge branch is grounded; one end of a second discharge branch formed by at least one discharge element connected in series is connected to the other end of the first switch, and the other end of the second discharge branch is grounded;

[0017] Alternatively, a discharge switch is connected in series in the first discharge branch or the second discharge branch.

[0018] According to one embodiment of the present invention, the discharge circuit absorbs the voltage across the first switch through the inductor in the DCDC boost circuit and discharges the energy to the bus capacitor.

[0019] According to one embodiment of the present invention, the first switch is a unidirectional conducting device, configured to conduct the second connection path unidirectionally along a direction from the solar cell module to the energy storage module.

[0020] According to one embodiment of the present invention, the first switch is an electromagnetic relay, a DC contactor, an AC contactor, a semiconductor device IGBT or a MOSFET.

[0021] According to one embodiment of the present invention, the first switch is a single-pole double-throw switch, including a static contact and two moving contacts, wherein the static contact is connected to the solar cell module, one moving contact serves as the repair access point, and the other moving contact is connected to the energy storage module.

[0022] According to one embodiment of the present invention, the positive electrode of the DC power supply is connected to the negative terminal PV- of the solar cell module, and the negative electrode is connected to the ground terminal PE.

[0023] According to one embodiment of the present invention, the first switch is either connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the energy storage module, or is connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the DCDC boost circuit.

[0024] According to one embodiment of the present invention, the negative electrode of the DC power supply is connected to the positive terminal PV+ of the solar cell module, and the positive electrode is connected to the ground terminal PE.

[0025] According to one embodiment of the present invention, the first switch is either connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the energy storage module, or is connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the DCDC boost circuit.

[0026] According to one embodiment of the present invention, the first switch is an electromagnetic relay, a DC contactor, an AC contactor, a semiconductor device IGBT or a MOSFET.

[0027] According to one embodiment of the present invention, the DC power supply is connected to the positive and negative electrodes of the solar cell module via a connecting branch, and a second switch and a third switch for controlling the on and off of the connecting branch are provided on the connecting branch.

[0028] According to one embodiment of the present invention, the DC power supply is a UPS or a battery, or the DC power supply is a power supply obtained by DC bus conversion, or the DC power supply is a power supply obtained by grid inversion and DC conversion.

[0029] According to one embodiment of the present invention, the photovoltaic system further includes an RCD circuit, which is arranged at the output line of the inverter circuit to provide leakage protection for the circuit.

[0030] In particular, the present invention also provides a PID repair method for a photovoltaic system, which performs PID repair on the solar cell module by applying a negative voltage to the positive terminal PV+ of the solar cell module or applying a positive voltage to the negative terminal PV- of the solar cell module through a DC power supply, and disconnects the connection path between the solar cell module and the inverter circuit when performing the PID repair.

[0031] According to one embodiment of the present invention, the method specifically includes the following steps:

[0032] Based on the control instruction of starting PID repair, the first switch is turned off;

[0033] The PID repair circuit detects the output voltage in real time during operation, increases the output voltage until it reaches a target voltage value, and maintains the output voltage at this time to perform PID repair on the solar cell module;

[0034] After determining that the PID repair is completed, the discharge circuit is started, and after determining that the discharge is completed, the isolation switch is closed.

[0035] According to one embodiment of the present invention, the PID repair circuit maintains detection of the output voltage during operation, and compares the output voltage with an output reference voltage. If the difference between the output voltage and the output reference voltage is within a voltage threshold range, the output reference voltage is increased by a preset voltage step until the output voltage reaches a target voltage value.

[0036] According to one embodiment of the present invention, the process of the output voltage following the output reference voltage is detected. If the difference between the output voltage and the output reference voltage exceeds the voltage threshold, PID voltage following timing is started. If the PID voltage following timing time reaches a preset following time threshold, a fault instruction is issued and the PID repair process is stopped. If the PID voltage following timing time does not reach the preset following time threshold, the output voltage continues to follow the increase of the output reference voltage.

[0037] According to one embodiment of the present invention, the condition for judging that the PID repair is completed is to count the working time of the PID repair circuit after the output voltage or the output reference voltage reaches the target voltage value until the repair time reaches a preset maintenance time threshold.

[0038] According to one embodiment of the present invention, the energy storage module maintains connectivity with the inverter circuit when performing PID repair.

[0039] Compared with the prior art, the advantages and beneficial effects of the PID repair circuit and PID repair method for photovoltaic systems disclosed in the present invention are:

[0040] The PID repair circuit for a photovoltaic system of the present application has a simple circuit structure and can physically cut off the connection between the photovoltaic component and the inverter circuit when performing PID repair. This ensures that no internal short circuit will be generated by the inverter circuit when performing PID repair, thereby effectively ensuring the working safety of the photovoltaic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0042] FIG1 is a schematic structural diagram of a PID repair circuit for a photovoltaic system according to an embodiment of the present invention;

[0043] FIG2 is a schematic structural diagram of a PID repair circuit for a photovoltaic system according to another embodiment of the present invention;

[0044] FIG3 is a schematic structural diagram of a PID repair circuit for a photovoltaic system according to an embodiment of the present invention, which improves the circuit diagram of the isolation circuit;

[0045] FIG4 is a schematic structural diagram of a PID repair circuit for a photovoltaic system according to an embodiment of the present invention, which improves the circuit diagram of a DCDC boost circuit;

[0046] FIG5 is a schematic structural diagram of a PID repair circuit for a photovoltaic system according to an embodiment of the present invention;

[0047] FIG6 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 7 of the present invention;

[0048] FIG7 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 8 of the present invention;

[0049] FIG8 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 9 of the present invention;

[0050] FIG9 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 10 of the present invention;

[0051] FIG10 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 11 of the present invention;

[0052] FIG11 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 12 of the present invention;

[0053] FIG12 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 13 of the present invention;

[0054] FIG13 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 14 of the present invention;

[0055] FIG14 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 15 of the present invention;

[0056] FIG15 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 16 of the present invention;

[0057] FIG16 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 17 of the present invention;

[0058] FIG17 is a schematic structural diagram of a photovoltaic system PID repair device according to Example 18 of the present invention;

[0059] FIG18 is a schematic diagram of the circuit structure of the photovoltaic system PID repair device after repair is completed according to Example 19 of the present invention, with common-mode capacitors;

[0060] FIG19 is a schematic diagram of a circuit structure for discharging a first switch according to Embodiment 19 of the present invention;

[0061] FIG20 is a schematic diagram of another circuit structure for discharging the first switch according to Embodiment 19 of the present invention;

[0062] FIG21 is a schematic diagram of another circuit structure for discharging the first switch according to Embodiment 19 of the present invention;

[0063] FIG22 is a schematic diagram showing a principle of controlling the current of the inductor L1 when the first switch is discharged through the inductor in the DC conversion circuit according to Embodiment 19 of the present invention;

[0064] 23 is another schematic diagram showing another principle of controlling the current of the inductor L1 when the first switch is discharged through the inductor in the DC conversion circuit according to Embodiment 19 of the present invention;

[0065] FIG24 is a schematic diagram of the workflow of the photovoltaic system PID repair method according to Example 20 of the present invention.

[0066] The reference numerals are as follows: 1. Solar cell module, 2. Energy storage module, 3. DCDC boost circuit, 4. Inverter circuit, 5. DC power supply, 6. Isolation circuit. DETAILED DESCRIPTION

[0067] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0068] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0069] Example 1:

[0070] This embodiment describes a PID repair circuit for a photovoltaic system. As shown in Figure 1, the photovoltaic system includes a solar cell module 1, an energy storage module 2, a DC-DC boost circuit 3, and an inverter circuit 4. The DC output of the solar cell module 1 is connected to the inverter circuit 4 through the DC-DC boost circuit 3 to form an AC output. The energy storage module 2 is connected to the inverter circuit 4 to form an AC output. The positive terminal BUS+ of the energy storage module 2 corresponds to the positive terminal PV+ of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1. The negative terminal BUS- of the energy storage module 2 corresponds to the negative terminal PV- of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1. The output line of the inverter circuit 4 is connected to an RCD protection circuit for leakage protection of the circuit. The N line of the AC output is connected to the ground terminal PE.

[0071] The PID repair circuit includes a DC power supply 5 and an isolation circuit 6. After being processed by the isolation circuit 6, the positive terminal GV+ of the DC power supply 5, which is connected to the positive electrode of the DC power supply 5, is connected to the negative terminal PV- of the solar cell module 1, and the negative terminal GV-, which is connected to the negative electrode of the DC power supply 5, is connected to the ground terminal PE. Furthermore, a first switch K1 is provided in the connection path between the solar cell module 1 and the energy storage module 2. In this embodiment, the first switch K1 is provided in series with the DC output bus between the negative terminal PV- of the solar cell module 1 and the negative terminal BUS- of the energy storage module 2.

[0072] In this embodiment, to safely and efficiently extract the charge from the solar cell panel, a capacitor C1 is connected between the positive terminal GV+ and the negative terminal GV-. For ease of control and safety, a switch K2, a switch K3, and a resistor R1 are also provided. Specifically, the positive terminal GV+ is connected to the first end of the switch K2 and the first end of the capacitor C1, the negative terminal GV- is connected to the second end of the capacitor C1 and the first end of the switch K3, the second end of the switch K2 is connected to the negative terminal PV- of the solar cell module 1, the second end of the switch K3 is connected to the first end of the resistor R1, and the second end of the resistor R1 is connected to the ground terminal PE.

[0073] In addition, a bus capacitor C2 may be connected between the two DC output busbars. The first plate of the bus capacitor C2 is electrically connected to the positive terminal BUS+ of the energy storage module 2, and the second plate of the bus capacitor C2 is connected to the first end of the first switch K1. The first end of the first switch K1 is also connected to the negative terminal PV- of the solar panel, and the second end of the first switch K1 is electrically connected to the negative terminal BUS- of the energy storage module 2.

[0074] When performing PID repair on the solar cell module 1 of the photovoltaic system, the switches K2 and K3 are controlled to be closed, and the first switch K1 is opened. In this way, a path is formed from the positive terminal GV+ connected to the positive electrode of the DC power supply 5 to the negative terminal PV- of the solar cell module 1, and a path is formed from the capacitor C1 to the ground terminal PE, thereby forming a PID repair circuit for the solar cell module 1. The resistor R1 serves as a safety protection.

[0075] During the repair process, the first switch K1 remains in the off state, thereby disconnecting the connection path between the solar cell module 1 and the energy storage module 2 and the inverter circuit 4, preventing a short circuit inside the PID repair circuit due to grounding. Even if an AC output is generated due to the DC-to-AC conversion of the energy storage module 2, it will not affect the operation of the PID repair circuit, effectively protecting the operating safety of the PID repair circuit.

[0076] Example 2:

[0077] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Embodiment 1, the main difference lies in the difference in the terminal polarity of the connection end between the PID repair circuit and the solar cell module 1 .

[0078] Specifically, as shown in Figure 2, the photovoltaic system includes a solar cell module 1, an energy storage module 2, a DC-DC boost circuit 3, and an inverter circuit 4. The DC output of the solar cell module 1 is connected to the inverter circuit 4 through the DCDC boost circuit 3 to form an AC output. The energy storage module 2 is connected to the inverter circuit 4 to form an AC output. The positive terminal BUS+ of the energy storage module 2 corresponds to the positive terminal PV+ of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1. The negative terminal BUS- of the energy storage module 2 corresponds to the negative terminal PV- of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1. The output line of the inverter circuit 4 is connected to an RCD protection circuit for leakage protection of the circuit. The N line of the AC output is connected to the ground terminal PE.

[0079] The PID repair circuit includes a DC power supply 5 and an isolation circuit 6. After being processed by the isolation circuit 6, the negative terminal GV- of the DC power supply 5, which is connected to the negative terminal of the DC power supply 5, is connected to the positive terminal PV+ of the solar cell module 1, and the positive terminal GV+, which is connected to the positive terminal of the DC power supply 5, is connected to the ground terminal PE. Furthermore, a first switch K1 is provided in the connection path between the solar cell module 1 and the energy storage module 2. In this embodiment, the first switch K1 is provided in series with the DC output bus between the positive terminal PV+ of the solar cell module 1 and the positive terminal BUS+ of the energy storage module 2.

[0080] In this embodiment, to safely and efficiently extract the charge from the solar cell panel, a capacitor C1 is connected between the negative terminal GV- and the positive terminal GV+. For ease of control and safety, a switch K2, a switch K3, and a resistor R1 are also provided. Specifically, the negative terminal GV- is connected to the first end of the switch K2 and the first end of the capacitor C1, the positive terminal GV+ is connected to the second end of the capacitor C1 and the first end of the switch K3, the second end of the switch K2 is connected to the positive terminal PV+ of the solar cell module 1, the second end of the switch K3 is connected to the first end of the resistor R1, and the second end of the resistor R1 is connected to the ground terminal PE.

[0081] In addition, a bus capacitor C2 may be connected between the two DC output busbars. The first plate of the bus capacitor C2 is electrically connected to the negative terminal BUS- of the energy storage module 2, and the second plate of the bus capacitor C2 is connected to the first end of the first switch K1. The first end of the first switch K1 is also connected to the positive terminal PV+ of the solar panel, and the second end of the first switch K1 is electrically connected to the positive terminal BUS+ of the energy storage module 2.

[0082] When performing PID repair on the solar cell module 1 of the photovoltaic system, the switches K2 and K3 are controlled to be closed, and the first switch K1 is opened. In this way, a path is formed from the negative terminal GV- connected to the negative electrode of the DC power supply 5 to the positive terminal PV+ of the solar cell module 1, and a path is formed from the capacitor C1 to the ground terminal PE, thereby forming a PID repair loop for the solar cell module 1. The resistor R1 serves as a safety protection.

[0083] During the repair process, the first switch K1 remains in the off state, thereby disconnecting the connection path between the solar cell module 1 and the energy storage module 2 and the inverter circuit 4, preventing a short circuit inside the PID repair circuit due to grounding. Even if an AC output is generated due to the DC-to-AC conversion of the energy storage module 2, it will not affect the operation of the PID repair circuit, effectively protecting the operating safety of the PID repair circuit.

[0084] Example 3:

[0085] The isolation circuit 6 can be a half-wave isolation circuit 6, a full-wave isolation circuit 6, a full-wave bridge isolation circuit 6, or a voltage doubler isolation circuit 6. In this embodiment, a half-wave isolation circuit 6 is taken as an example.

[0086] The PID repair circuit for photovoltaic systems in this embodiment has the same main architecture as that of Example 1. The isolation circuit 6 is a half-wave isolation circuit 6, as shown in Figure 3. The half-wave isolation circuit 6 includes a filter capacitor C3, a conversion coil L1, an IGBT (Insulated Gate Bipolar Transistor), and a diode D1. The positive electrode of the DC power supply 5 is electrically connected to the first plate of the filter capacitor C3 and the opposite-pole terminal of the primary coil of the conversion coil L1. The negative electrode of the DC power supply 5 is electrically connected to the second plate of the filter capacitor C3 and the emitter of the IGBT. The collector of the IGBT is electrically connected to the same-pole terminal of the primary coil of the conversion coil L1. The gate of the IGBT receives a control signal and turns on in response during operation. The same-pole terminal of the secondary coil of the conversion coil L1 is electrically connected to the anode of the diode. The cathode of the diode D1 is the positive terminal GV+, and the opposite-pole terminal of the secondary coil of the conversion coil L1 is the negative terminal GV-.

[0087] Example 4:

[0088] The DCDC boost circuit 3 can effectively suppress electromagnetic interference between power supplies, reduce or eliminate interference between AC and DC voltages, prevent overvoltage damage, heat loss, and damage to low-voltage components, and effectively protect electrical equipment and personnel from damage to low-voltage components caused by operating voltages. It can also avoid overvoltage damage, heat loss, and damage to low-voltage components. It is understood that any circuit that can achieve isolation between power supplies is protected by this application. This embodiment uses a relatively typical circuit structure as an example.

[0089] The PID repair circuit for a photovoltaic system in this embodiment has the same main architecture as that of Example 1. As shown in Figure 4, the DCDC boost circuit 3 includes a capacitor C4, an inductor Gm, a switch P1, and a diode M1. The first plate of the first capacitor C4 and the first end of the inductor Gm are both electrically connected to the positive terminal PV+ of the solar cell module 1. The positive terminal of the diode M1 and the first end of the switch P1 are both electrically connected to the second end of the inductor Gm. The negative terminal of the diode M1 is electrically connected to the positive terminal BUS+ of the energy storage module 2. The second plate of the capacitor C4 and the second end of the switch P1 are both electrically connected to the negative terminal PV- of the solar cell module 1.

[0090] Optionally, the switch tube P1 provided in this embodiment may be an IGBT switch tube, and the gate of each switch tube is electrically connected to a corresponding control signal to be controlled to be on or off during operation.

[0091] Example 5:

[0092] The PID repair circuit for a photovoltaic system in this embodiment has the same main architecture as that of Example 1, except that two connecting branches are added for charging the bus capacitor via a DC power supply 5. If necessary, the DC power supply 5 can also be charged via the solar cell module 1 or the energy storage module 2 to ensure that the DC power supply 5 has sufficient power for PID repair.

[0093] Specifically, as shown in FIG5 , the positive terminal GV+ of the isolation circuit 6 is connected to the first end of the second switch K6, the second end of the second switch K6 is connected to the positive terminal BUS+ of the energy storage module 2, the negative terminal GV- of the isolation circuit 6 is connected to the first end of the third switch K7, the second end of the third switch K7 is connected to the first end of the first switch K1, and the second end of the first switch K1 is connected to the negative terminal BUS- of the energy storage module 2. Therefore, when the switch K2 is opened and the second switch K6 and the third switch K7 are closed, the bus capacitor C2 can be charged through the DC power supply 5.

[0094] Optionally, the DC power supply 5 is a UPS or a battery, which can be charged by the solar cell module 1 or the energy storage module 2. Alternatively, the DC power supply is a power source obtained by converting the DC bus to DC, or a power source obtained by inverting and converting the grid to DC.

[0095] In addition, the electricity generated by the solar cell module 1 is direct current, while the electricity required for household or industrial use is alternating current. The function of the inverter circuit 4 is to convert the DC output of the solar cell module 1 or the energy storage module 2 into an alternating current output, so that the electricity generated by the solar cell module 1 can be used for household or industrial use. Common inverter circuits 4 include half-bridge inverter circuits 4 and full-bridge inverter circuits 4. This section does not involve the core protection of this application, and the conventional inverter circuit 4 structure can be used. Please be aware that this section is not described in detail here.

[0096] Optionally, the first switch is an electromagnetic relay, a DC contactor, an AC contactor, an IGBT, or a MOSFET. The remaining switches may also be any of the electromagnetic relays, DC contactors, AC contactors, IGBTs, or MOSFETs, as long as they can be controlled to open or close.

[0097] Example 6:

[0098] This embodiment also provides a PID repair method for a photovoltaic system, which performs PID repair on the solar cell module 1 by applying a negative voltage to the positive terminal PV+ of the solar cell module 1 or applying a positive voltage to the negative terminal PV- of the solar cell module 1 through a DC power supply 5, and disconnects the connection path between the solar cell module 1 and the inverter circuit 4 when performing the PID repair.

[0099] When performing PID repair, the energy storage module 2 maintains connectivity with the inverter circuit 4. Since the connection path between the solar cell module 1 and the inverter circuit 4 is disconnected, there is no need to worry about internal short circuit caused by grounding of the neutral line of the inverter module.

[0100] Example 7:

[0101] This embodiment describes a PID repair circuit for a photovoltaic system. As shown in FIG6 , the photovoltaic system includes a solar cell module 1, an energy storage module 2, a DC conversion circuit 3, and an inverter circuit 4. The inverter circuit 4 is a non-isolated circuit. The DC output of the solar cell module 1 is connected to the inverter circuit 4 via the DC conversion circuit 3 to form an AC output. The energy storage module 2 is connected to the inverter circuit 4 to form an AC output. The positive terminal BUS+ of the energy storage module 2 corresponds to the positive terminal PV+ of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1. The negative terminal BUS- of the energy storage module 2 corresponds to the negative terminal PV- of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1. The output line of the inverter circuit 4 is connected to an RCD protection circuit for leakage protection. The N line of the AC output is connected to the ground terminal PE.

[0102] The PID repair circuit includes a DC power supply 5 and an isolation circuit 6. After being processed by the isolation circuit 6, the positive terminal GV+ of the DC power supply 5, which is connected to the positive electrode of the DC power supply 5, is connected to the negative terminal PV- of the solar cell module 1, and the negative terminal GV-, which is connected to the negative electrode of the DC power supply 5, is connected to the ground terminal PE. The connection point between the positive terminal GV+ and the negative terminal PV- is recorded as the repair access point of the PID repair circuit. A first switch is provided in the connection path between the solar cell module 1 and the inverter circuit 4. In this embodiment, due to the presence of the energy storage module 2, the first switch is provided in series in the first connection path between the repair access point of the solar cell module 1 and the energy storage module 2.

[0103] In this embodiment, a plurality of solar cell modules 1 are provided. Each of the solar cell modules 1 is connected in parallel to form a solar cell module 11. The solar cell module 11 is connected to the DC-DC boost circuit 3 via a DC bus. The repair access point is located on the second connection path between the solar cell module 11 and the inverter circuit 4. In this embodiment, the repair access point is located on the DC bus between the negative terminal PV- of the solar cell module 11 and the DC conversion circuit 3.

[0104] In this embodiment, the first switch includes at least one switch, and the isolator can be installed at any of the switches K11, K12, and K13 shown in Figure 6 . Specifically, switch K11 is installed between the repair access point and the DC converter circuit 3, switch K12 is installed between the DC converter circuit 3 and the bus capacitor C2, and switch K13 is installed between the bus capacitor C2 and the energy storage module 2. Disconnecting the first switch at any of the three switch positions, K11, K12, and K13, can disconnect the repair access point from the energy storage module 2 and the inverter circuit 4.

[0105] In this embodiment, to safely and efficiently extract the charge from the solar cell panel, a capacitor C1 is connected between the positive terminal GV+ and the negative terminal GV-. For ease of control and safety, a switch K2, a switch K3, and a resistor R1 are also provided. Specifically, the positive terminal GV+ is connected to the first end of the switch K2 and the first end of the capacitor C1, the negative terminal GV- is connected to the second end of the capacitor C1 and the first end of the switch K3, the second end of the switch K2 is connected to the negative terminal PV- of the solar cell module 1, the second end of the switch K3 is connected to the first end of the resistor R1, and the second end of the resistor R1 is connected to the ground terminal PE.

[0106] In addition, bus capacitors C2 and C3 may be connected between the two DC output busbars. Bus capacitors C2 and C3 are connected in parallel to the positive and negative DC output busbars, respectively. Bus capacitor C2 is positioned near the DC conversion circuit 3 and between the DC conversion circuit 3 and the energy storage module 2, stabilizing the output voltage of the DC conversion circuit 3. Bus capacitor C3 is positioned near the inverter circuit 4 and between the energy storage module 2 and the inverter circuit 4, primarily stabilizing the DC side voltage of the inverter circuit 4. Furthermore, bus capacitors C2 and C3 are generally configured as low-capacitance bus capacitors and high-capacitance bus capacitors, respectively. Alternatively, bus capacitors C2 and C3 may be combined and configured at position C2 or C3 in the circuit.

[0107] When the energy storage module 2 performs PID repair on the solar cell module 1 of the photovoltaic system, it controls the switches K2 and K3 to be closed and the first switch to be opened. In this way, a path is formed from the positive terminal GV+ connected to the positive electrode of the DC power supply 5 to the negative terminal PV- of the solar cell module 1, and a path is formed from the capacitor C1 to the ground terminal PE, thereby forming a PID repair circuit for the solar cell module 1. The resistor R1 plays a role in safety protection.

[0108] During the repair process, the first switch remains in the off state, thereby disconnecting the connection path between the solar cell module 1 and the energy storage module 2 and the inverter circuit 4, preventing a short circuit inside the PID repair circuit due to grounding. Even if an AC output is generated due to the DC-to-AC conversion of the inverter circuit 4, it will not affect the operation of the PID repair circuit, effectively protecting the operating safety of the PID repair circuit.

[0109] Example 8:

[0110] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Embodiment 7, the main difference lies in the difference in the terminal polarity of the connection end between the PID repair circuit and the solar cell module 1 .

[0111] Specifically, as shown in Figure 7, the photovoltaic system includes a solar cell module 1, an energy storage module 2, a DC conversion circuit 3 and an inverter circuit 4. The DC output of the solar cell module 1 is connected to the inverter circuit 4 through the DC conversion circuit 3 to form an AC output, and the energy storage module 2 is connected to the inverter circuit 4 to form an AC output. The positive terminal BUS+ of the energy storage module 2 corresponds to the positive terminal PV+ of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1, and the negative terminal BUS- of the energy storage module 2 corresponds to the negative terminal PV- of the solar cell module 1 and is connected to the DC output bus of the solar cell module 1; the output line of the inverter circuit 4 is connected to an RCD protection circuit for providing leakage protection for the circuit, and the N line of the AC output is connected to the ground terminal PE.

[0112] The PID repair circuit includes a DC power supply 5 and an isolation circuit 6. After being processed by the isolation circuit 6, the negative terminal GV- of the DC power supply 5, which is connected to the negative terminal of the DC power supply 5, is connected to the positive terminal PV+ of the solar cell module 1. The positive terminal GV+, which is connected to the positive terminal of the DC power supply 5, is connected to the ground terminal PE. The connection point between the negative terminal GV- and the positive terminal PV+ is marked as the repair access point of the PID repair circuit. A first switch is provided in the connection path between the solar cell module 1 and the inverter circuit 4. In this embodiment, the first switch is provided in series in the first connection path between the repair access point and the inverter circuit 4.

[0113] In this embodiment, to safely and efficiently extract the charge from the solar cell panel, a capacitor C1 is connected between the negative terminal GV- and the positive terminal GV+. For ease of control and safety, a switch K2, a switch K3, and a resistor R1 are also provided. Specifically, the negative terminal GV- is connected to the first end of the switch K2 and the first end of the capacitor C1, the positive terminal GV+ is connected to the second end of the capacitor C1 and the first end of the switch K3, the second end of the switch K2 is connected to the positive terminal PV+ of the solar cell module 1, the second end of the switch K3 is connected to the first end of the resistor R1, and the second end of the resistor R1 is connected to the ground terminal PE.

[0114] When the energy storage module 2 performs PID repair on the solar cell module 1 of the photovoltaic system, it controls the switches K2 and K3 to be closed and the first switch to be opened. In this way, a path is formed from the negative terminal GV- connected to the negative electrode of the DC power supply 5 to the positive terminal PV+ of the solar cell module 1, and a path is formed from the capacitor C1 to the ground terminal PE, thereby forming a PID repair circuit for the solar cell module 1. The resistor R1 plays a role in safety protection.

[0115] During the repair process, the first switch remains in the off state, thereby disconnecting the connection path between the solar cell module 1 and the energy storage module 2 and the inverter circuit 4, preventing a short circuit inside the PID repair circuit due to grounding. Even if an AC output is generated due to the DC-to-AC conversion of the inverter circuit 4, it will not affect the operation of the PID repair circuit, effectively protecting the operating safety of the PID repair circuit.

[0116] Example 9:

[0117] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 7, the main differences are: the location of the repair access point is different, and the switches included in the first switch and the setting position are different.

[0118] Specifically, as shown in FIG8 , the repair access point is located on the DC bus between the output side of the DC conversion circuit 3 and the bus capacitor C2, and the first connection path is located between the repair access point and the energy storage module 2. Accordingly, the position of the switch K11 in Example 1 no longer meets the requirements. In this embodiment, the first switch can be set at the position of the switch K12 or the switch K13, wherein the switch K12 is set between the DC conversion circuit 3 and the bus capacitor C2, and the switch K13 is set between the bus capacitor C2 and the energy storage module 2. As long as the first switch is set in either the switch K12 or the switch K13 position, disconnecting the first switch can disconnect the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0119] Example 10:

[0120] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 7, the main differences are: the location of the repair access point is different, and the switches included in the first switch and the setting position are different.

[0121] Specifically, as shown in FIG9 , the repair access point is located on the DC bus between the bus capacitor C2 and the energy storage module 2, and the first connection path is located between the repair access point and the energy storage module 2. Accordingly, the solution of providing the first switch at the position of switches K11 and K12 in Example 1 no longer meets the requirements. In this embodiment, the first switch is only located at the position of switch K13, which is located between the bus capacitor C2 and the energy storage module 2. Disconnecting the first switch at the position of switch K13 can disconnect the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0122] Example 11:

[0123] This embodiment describes a PID repair circuit for a photovoltaic system. Compared to Example 7, the circuit differs primarily in that it comprises multiple DC conversion circuits 3, each composed of one or more solar cell modules 1 connected in parallel or in series to form a solar cell module 11. Each solar cell module 11 is connected to a DC conversion circuit 3 and then in parallel to a DC bus, which is in turn connected to the inverter circuit 4. Furthermore, a bus capacitor C2 is provided at the rear end of each DC conversion circuit 3, before the energy storage module 2.

[0124] As shown in Figure 10, the output side of the PID repair circuit is connected to each of the solar cell modules 11. This requires that the second connection path between each solar cell module 11 and the inverter circuit 4 must be disconnected during repair. Therefore, the PID repair circuit for a photovoltaic system in this embodiment includes multiple repair access points, each of which is located on the second connection path between the solar cell module 11 and the inverter circuit 4. The first switch is provided on the first connection path between each repair access point and the inverter circuit 4.

[0125] In this embodiment, each of the first switches includes at least one switch, which can be set as the first switch in any of the positions of switch K11, switch K12, and switch K13 in Figure 10. Switch K11 is set between the repair access point and the DC converter circuit 3, switch K12 is set between the DC converter circuit 3 and the bus capacitor C2, and switch K13 is set between the bus capacitor C2 and the energy storage module 2. Simply disconnecting the first switch set in any of the three switch positions, switch K11, switch K12, or switch K13, can disconnect the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0126] Example 12:

[0127] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 11, the main differences are: the location of the repair access point is different, and the switches included in the first switch and the setting position are different.

[0128] Specifically, as shown in FIG11 , the repair access point is located on the DC bus between the output side of each DC converter circuit 3 and the connected bus capacitor C2, and the first connection path is located between the repair access point and the energy storage module 2. Accordingly, the switch K11 in Example 5 no longer meets the requirements. In this embodiment, the first switch is only located at the position of switch K12 or switch K13. Switch K12 is located between the DC converter circuit 3 and the bus capacitor C2, and switch K13 is located between the bus capacitor C2 and the energy storage module 2. Disconnecting the first switch located at either switch K12 or switch K13 disconnects the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0129] Example 13:

[0130] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 11, the main differences are: the location of the repair access point is different, and the switches included in the first switch and the setting position are different.

[0131] Specifically, as shown in FIG12 , the repair access point is located on the DC bus between each bus capacitor C2 and the energy storage module 2 in the main circuit, and the first connection path is located between the repair access point and the energy storage module 2. Accordingly, the switches K11 and K12 in Example 5 no longer meet the requirements. In this embodiment, the first switch is located at the position of switch K13, where switch K13 is located between the bus capacitor C2 and the energy storage module 2. Disconnecting the first switch at the position of switch K13 can disconnect the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0132] Example 14:

[0133] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 11, the main difference is that it includes multiple PID repair circuits, each of the repair access points is connected to at least one PID repair circuit, and the first switch is arranged on a third connection path defined between the connection point between the DC conversion circuit 3 and the DC bus and the repair access point.

[0134] In this embodiment, in order to enable each solar cell module 11 to independently perform PID repair, no switch serving as the first switch is provided in the main circuit, that is, the solution of providing the first switch at the switch K13 in embodiment 5 is eliminated.

[0135] As shown in Figure 13, each of the first switches in this embodiment includes at least one switch, which can be located at the position of switch K11 or switch K12. Switch K11 is located between the repair access point and the DC converter circuit 3, and switch K12 is located between the DC converter circuit 3 and the bus capacitor C2. Disconnecting the first switch located at either switch K11 or switch K12 disconnects the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0136] Example 15:

[0137] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 14, the main differences are: the location of the repair access point is different, and the switches included in the first switch and the setting position are different.

[0138] Specifically, as shown in Figure 14, each of the first switches in this embodiment is located at the position of switch K12, wherein switch K12 is located between the DC converter circuit 3 and the bus capacitor C2. Simply disconnecting the first switch located at switch K12 disconnects the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0139] In the above embodiments, the switch used as the first switch can be any one of an electromagnetic relay, a DC contactor, an AC contactor, a semiconductor device IGBT or a MOSFET, and can receive an external control signal to cut off the second connection path, so as to disconnect the connection between the repair access point and the energy storage module 2 and the inverter circuit 4.

[0140] Example 16:

[0141] [Corrected 07.11.2024 according to Rule 91] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 7, the main difference is that: the type of the first switch is different. This embodiment selects a diode. As shown in Figure 15, a unidirectional diode is set at any of the three positions of switch K11, switch K12, and switch K13 in Example 1. The diode is used to unidirectionally conduct the second connection path from the solar cell module 11 to the inverter circuit 4.

[0142] Specifically, as shown in FIG15 , the cathode of the diode is connected to the repair access point (connected to the negative terminal PV− of the solar cell module 1 ), and the anode is connected to the inverter circuit 4 .

[0143] Example 17:

[0144] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 7, the main difference is that the type of the first switch is different. The switch selected as the first switch in this embodiment is a single-pole double-throw switch.

[0145] [Corrected 07.11.2024 in accordance with Rule 91] As shown in Figure 16, each single-pole double-throw switch includes one stationary contact and two movable contacts. The stationary contact is connected to the solar cell module 1, one movable contact serves as the repair access point, and the other movable contact is connected to the inverter circuit 4. By switching the single-pole double-throw switches, when performing PID repair, only one of the switches in Figure 16 needs to be switched from the movable contact connected to the inverter circuit 4 to the repair access point. This completes the connection to the PID repair circuit and simultaneously disconnects the inverter circuit 4.

[0146] However, it is understandable that when changing the connection contacts of one of the switches, the remaining switches on the connection path connecting the switch to the solar cell module 1 must remain in their original states to ensure that the PID repair circuit is connected to the solar cell module 1 during repair, thereby ensuring that the PID repair work is carried out.

[0147] Example 18:

[0148] This embodiment describes a PID repair circuit for a photovoltaic system. Compared with Example 13, the main difference is that the type of the first switch is different. The switch selected as the first switch in this embodiment is a single-pole double-throw switch.

[0149] [Corrected 07.11.2024 in accordance with Rule 91] As shown in Figure 17, each single-pole double-throw switch includes one stationary contact and two movable contacts. The stationary contact is connected to the solar cell module 1, one movable contact serves as the repair access point, and the other movable contact is connected to the inverter circuit 4. By switching the single-pole double-throw switch, when performing PID repair, it is only necessary to switch switch K13 in Figure 17 from the movable contact connected to the inverter circuit 4 to the repair access point. This completes the connection to the PID repair circuit and simultaneously disconnects the inverter circuit 4.

[0150] Example 19:

[0151] This embodiment is a PID repair circuit for a photovoltaic system, which is improved and optimized compared with Example 7. The improvement is that: a discharge circuit is provided in parallel with the first switch to discharge the voltage across the first switch after the PID repair is completed.

[0152] As shown in Figure 18, after the PID repair circuit for a photovoltaic system completes its PID repair, residual voltage remains across the common-mode capacitor CY1 between the negative terminal PV- of the solar cell module 1 and ground, resulting in a high voltage across the first switch K1. Closing the first switch K1 while this high voltage is present can damage the contacts of the first switch K1, increasing contact impedance and potentially damaging the switch, reducing overall system reliability. Therefore, the voltage across the first switch K1 must be reduced to a low level before closing.

[0153] In one embodiment, as shown in FIG19 , the discharge circuit includes a discharge element and a discharge switch, wherein the discharge element is connected in series with the discharge switch and then connected in parallel with the first switch. D / C Closed, the common mode capacitor CY1 is connected to the resistor R as a discharge element D / C Discharge. Discharge switch K D / C The operating logic can be one of the following three: ① After a preset time threshold, the discharge switch K D / C Disconnect; ② After the voltage across the first switch K1 is lower than the preset voltage threshold, the discharge switch K D / C Disconnect; ③ Discharge switch K D / C Closed until the first switch K1 is closed, K D / C Disconnect. Discharge switch K D / CIt is a low-current switch with high voltage resistance, which can be an electromagnetic relay, a solid-state relay, a DC / AC contactor, a semiconductor device (such as IGBT, MOSFET, thyristor, etc.) or a combination of the above switch types.

[0154] In another embodiment, as shown in FIG20 , a discharge circuit is connected between the first switch K1 and the ground PE. Specifically, the discharge circuit includes two discharge elements and two discharge switches, a resistor R as the discharge element, and a discharge circuit PE. D / C1 In conjunction with a bleeder switch K D / C1 One end of the first discharge branch formed in series is connected to one end of the first switch, and the other end of the first discharge branch is grounded; another resistor R D / C2 In conjunction with another bleeder switch K D / C2 One end of the second discharge branch formed in series is connected to the other end of the first switch, and the other end of the first discharge branch is grounded. D / C1 and discharge switch K D / C1 Closed, the common mode capacitor CY1 is connected to the resistor R as a discharge element D / C1 and resistor R D / C2 Discharge. Discharge switch K D / C1 and discharge switch K D / C2 The operation logic can be one of the following three: ① After a preset time threshold, the discharge switch K D / C1 and discharge switch K D / C2 Disconnect; ② After the voltage across the first switch K1 is lower than the preset voltage threshold, the discharge switch K D / C1 and discharge switch K D / C2 Disconnect; ③ Discharge switch K D / C1 and discharge switch K D / C2 Close until the first switch K1 is closed and the discharge switch K D / C1 and discharge switch K D / C2 Just disconnected.

[0155] The discharge element in the above two embodiments is a resistor. Other loads or components capable of consuming residual voltage can also be used. The representative discharge element is a resistor. The discharge switch is a low-current switch with high voltage resistance. It can be an electromagnetic relay, a solid-state relay, a DC / AC contactor, a semiconductor device (such as IGBT, MOSFET, thyristor, etc.) and a combination of the above switch types. In addition, the discharge switch can be omitted, that is, the discharge switch is short-circuited, and only the discharge resistor R is used. D / C Discharge the voltage across the first switch K1.

[0156] In another embodiment, the bleeder circuit absorbs the voltage across the first switch through the inductor in the DC converter circuit 3, discharging the energy to the bus capacitor. As shown in FIG21 , using the Boost circuit in the DC converter circuit 3 as an example, the energy of the common-mode capacitors CY1 and CY2 is transferred to the bus capacitor C2. When the switch Q1 in the Boost circuit is closed, the common-mode capacitors CY1 and CY2 transfer the energy to the inductor L1. When the switch Q1 is opened, the energy in the inductor L1 is transferred to the bus capacitor C2.

[0157] During this process, the current of the inductor L1 is detected, and the voltage across the first switch K1 is slowly released by monitoring and controlling between the upper preset threshold and the lower preset threshold, thereby realizing closed-loop current control. As shown in Figure 22, when the current of the inductor L1 does not reach the preset threshold 1, the switch Q1 is closed; when the L1 current increases to the preset threshold 1, the switch Q1 is disconnected; when the L1 current decreases to the preset threshold 2, the switch Q1 is closed; and this cycle repeats until the current drops to a smaller value and the switch Q1 is disconnected, or after the discharge time reaches the time threshold, the switch Q1 is disconnected. During operation, as time goes by, the energy transferred to the bus capacitor C2 gradually increases, and the transfer speed gradually slows down. This closed-loop current control method fully utilizes the energy transfer capability of the inductor L1 through closed-loop control, which can effectively improve the energy transfer speed in the later stage.

[0158] In addition, the above preset threshold 1 and preset threshold 2 can also change with time and change accordingly according to the preset curve, as shown in Figure 23, which can make the discharge process smoother and at the same time improve the charging speed of the bus capacitor C2.

[0159] Example 20:

[0160] This embodiment describes a photovoltaic system PID repair method, which is based on the PID repair circuit for a photovoltaic system as described in any of the above embodiments and includes the following steps:

[0161] Based on the control instruction of starting PID repair, the first switch is turned off;

[0162] Detect the output voltage in real time, increase the output voltage until it reaches the target voltage value, and maintain the output voltage at this time to perform PID repair on the solar cell module 1;

[0163] The discharge circuit is started after it is determined that the PID repair is completed, and the first switch is closed after it is determined that the discharge is completed.

[0164] The aforementioned control instruction for starting PID repair can be triggered by current detection and comparison on the first switch K1 or a component connected in series therewith, or by detection and comparison of the output voltage or DC bus voltage of the solar cell module 1. PID repair is then started, the first switch K1 is disconnected, and subsequent work processes are executed. Specifically, the following situations may occur:

[0165] ① Detect whether the current on the first switch K1 is zero or less than a certain threshold. If so, execute the next step;

[0166] ② Detect whether the current in series with the first switch K1 is zero or less than a certain threshold. If so, execute the next step;

[0167] ③ Whether the voltage of the solar photovoltaic module is lower than the DC bus voltage and the DC conversion circuit 3 stops working, if so, execute the next step;

[0168] ④ Whether the DC bus voltage is lower than a certain threshold, if so, execute the next step.

[0169] If any of the above four situations exists, the control instruction for starting PID repair is issued.

[0170] The PID repair circuit maintains detection of the output voltage during operation, compares the output voltage with an output reference voltage, and increases the output reference voltage by a preset voltage step if the difference between the output voltage and the output reference voltage is within a voltage threshold range until the output voltage reaches a target voltage value.

[0171] In addition, the process of the output voltage following the output reference voltage is timed. If the process of the output voltage following the output reference voltage reaches a preset following time threshold, that is, the output voltage still fails to reach the preset target voltage value after the predetermined following time is reached, a fault instruction is issued and the PID repair process is stopped.

[0172] The condition for judging that the PID repair is completed is that after the output voltage or the output reference voltage reaches the target voltage value, the working time of the PID repair circuit is counted until the repair time reaches a preset maintenance time threshold.

[0173] As shown in FIG24 , after the first switch K1 is disconnected, the switches K2 and K3 in the PID repair circuit are closed, and the isolation circuit 6 of the PID repair circuit starts to operate. By slowly increasing the output reference voltage V PIDref , determine the output reference voltage V PIDref Whether the target value is reached.

[0174] If the output reference voltage V PIDrefWhen the target value is reached, the PID voltage maintenance timer starts working to maintain the output voltage of the PID repair circuit for repair. At the same time, the PID voltage limit timer keeps timing and determines whether the PID voltage limit timer reaches the threshold. If the timing time of the PID voltage limit timer reaches the threshold, the isolation circuit 6 stops working, and then opens the switch K2 and the switch K3 to discharge the voltage across the first switch K1, and finally closes the first switch K1.

[0175] If the output reference voltage V PIDref If the target value is not reached, the output voltage V of the PID repair circuit will be determined. PID Can it follow the output reference voltage V PIDref and the difference between the two and the voltage threshold ΔV PIDlimit Compare. If the output voltage V PID With the output reference voltage V PIDref The difference is greater than the voltage threshold ΔV PIDlimit , the PID voltage follower timer starts working and determines whether the PID voltage limit timer reaches the threshold. If the threshold is reached, the fault is reported to the controller and the isolation circuit 6 is stopped. Otherwise, the output voltage of the isolation circuit 6 is slowly increased, and the output reference voltage V is increased at the same time. PIDref , so that the output voltage V PID Following the output reference voltage V PIDref .

[0176] The operating logic of the photovoltaic system PID repair method of this embodiment can realize the soft start of the PID repair circuit and reduce the impact on the DC conversion circuit 3. On the other hand, it can detect the abnormal output voltage of the PID repair circuit to achieve fault detection and protection. In summary, the PID repair circuit and PID repair method for the photovoltaic system of the present application have a simple circuit structure. When performing PID repair, the connection between the solar cell module 1 and the inverter circuit 4 can be cut off by physical means. In this way, it can be ensured that no internal short circuit will be generated due to the inverter circuit 4 when performing PID repair, effectively ensuring the working safety of the photovoltaic system.

[0177] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A PID repair circuit for a photovoltaic system, the photovoltaic system comprising a solar cell module, an energy storage module, an isolation circuit and an inverter circuit, the DC output of the solar cell module is connected to the inverter circuit through the DCDC boost circuit to form an AC output, and the energy storage module is connected to the inverter circuit to form an AC output, characterized in that: The PID repair circuit includes a DC power supply and an isolation circuit. After being processed by the isolation circuit, one end of the DC power supply is connected to the positive terminal PV+ or the negative terminal PV- of the solar cell module, and the other end of the isolation circuit is connected to the ground terminal PE. A first switch is provided on the connection path between the DCDC boost circuit and the energy storage module.

2. The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The output side of the PID repair circuit is connected to the positive terminal PV+ or the negative terminal PV- of the solar cell module, and the connected connection point is recorded as the repair access point of the PID repair circuit. The first switch is set on the first connection path between the repair access point and the energy storage module.

3. The PID repair circuit for a photovoltaic system according to claim 2, characterized in that: The photovoltaic system includes at least one solar cell module, each of the solar cell modules includes one solar cell module or at least two solar cell modules connected in series or in parallel, each of the solar cell modules is connected to the DCDC boost circuit via a DC bus, and the repair access point is located on a second connection path between the solar cell module and the energy storage module.

4. The PID repair circuit for a photovoltaic system according to claim 3, characterized in that: The photovoltaic system includes at least one DCDC boost circuit, each of the solar cell modules is respectively connected to the DCDC boost circuit and then connected in parallel to a DC bus, the DC bus is then connected to the energy storage module, the output side of the PID repair circuit is respectively connected to each of the solar cell modules, including a plurality of repair access points, each of which is located on a second connection path between the solar cell module and the energy storage module.

5. The PID repair circuit for a photovoltaic system according to claim 4, characterized in that: It comprises a plurality of PID repair circuits, each of the repair access points is connected to at least one PID repair circuit, and the first switch is arranged on a third connection path defined between a connection point between a DC conversion circuit and a DC bus and the repair access point.

6. The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The first switch is provided with a discharge circuit in parallel, which is used to discharge the voltage across the first switch after the PID repair is completed.

7. The PID repair circuit for a photovoltaic system according to claim 6, characterized in that: The discharge circuit includes at least one discharge element, and each of the discharge elements is connected in series and then in parallel with the first switch; Alternatively, a discharge switch is connected in series in the connection link formed by the discharge resistors connected in series.

8. The PID repair circuit for a photovoltaic system according to claim 6, characterized in that: The discharge circuit includes at least two discharge elements, one end of a first discharge branch formed by at least one discharge element connected in series is connected to one end of the first switch, the other end of the first discharge branch is grounded, one end of a second discharge branch formed by at least one discharge element connected in series is connected to the other end of the first switch, the other end of the second discharge branch is grounded; Alternatively, a discharge switch is connected in series in the first discharge branch or the second discharge branch.

9. The PID repair circuit for a photovoltaic system according to claim 6, characterized in that: The discharge circuit absorbs the voltage across the first switch through the inductor in the DCDC boost circuit, and discharges energy to the bus capacitor.

10. The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The first switch is a unidirectional conducting device, and is used for unidirectionally conducting the second connection path along the direction from the solar cell module to the energy storage module.

11. The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The first switch is an electromagnetic relay, a DC contactor, an AC contactor, a semiconductor device IGBT or a MOSFET.

12. [Corrected 06.11.2024 according to Rule 26] The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The first switch is a single-pole double-throw switch, including a static contact and two moving contacts, wherein the static contact is connected to the solar cell module, one moving contact serves as the repair access point, and the other moving contact is connected to the energy storage module.

13. [Corrected 06.11.2024 according to Rule 26] The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The positive electrode of the DC power supply is connected to the negative terminal PV- of the solar cell module, and the negative electrode is connected to the ground terminal PE.

14. The PID repair circuit for a photovoltaic system according to claim 13, characterized in that: The first switch is either connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the energy storage module, or is connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the DCDC boost circuit.

15. The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The negative electrode of the DC power supply is connected to the positive terminal PV+ of the solar cell module, and the positive electrode of the DC power supply is connected to the ground terminal PE.

16. The PID repair circuit for a photovoltaic system according to claim 15, characterized in that: The first switch is either connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the energy storage module, or is connected in series to a DC bus connecting the positive terminal PV+ or the negative terminal PV- of the solar cell module and the DCDC boost circuit.

17. The PID repair circuit for a photovoltaic system according to claim 1, characterized in that: The DC power source is connected to the positive and negative electrodes of the solar cell module through a connecting branch, and a second switch and a third switch for controlling the on and off of the connecting branch are arranged on the connecting branch.

18. A PID repair method for a photovoltaic system, characterized in that: A negative voltage is applied to the positive terminal PV+ of the solar cell module or a positive voltage is applied to the negative terminal PV- of the solar cell module through a DC power supply to perform PID repair on the solar cell module, and a connection path between the solar cell module and the inverter circuit is disconnected when performing PID repair.

19. The PID repair method for a photovoltaic system according to claim 18, characterized in that: The following steps are included: Based on the control instruction of starting PID repair, disconnecting the first switch; The PID repair circuit detects its output voltage in real time when working, increases the output voltage until it reaches the target voltage value, and maintains the output voltage at this time to perform PID repair on the solar cell module; The discharge circuit is started after it is determined that the PID repair is completed, and the isolation switch is closed after it is determined that the discharge is completed.

20. The photovoltaic system PID repair method according to claim 19, characterized in that: The PID repair circuit maintains detection of the output voltage during operation, and compares the output voltage with an output reference voltage. If the difference between the output voltage and the output reference voltage is within a voltage threshold range, the output reference voltage is increased according to a preset voltage step until the output voltage reaches a target voltage value.

21. The photovoltaic system PID repair method according to claim 20, characterized in that: The process of the output voltage following the output reference voltage is detected. If the difference between the output voltage and the output reference voltage exceeds the voltage threshold, the PID voltage following timing is started. If the PID voltage following timing time reaches a preset following time threshold, a fault instruction is issued and the PID repair process is stopped. If the PID voltage following timing time does not reach the preset following time threshold, the output voltage continues to follow the increase of the output reference voltage.

22. The photovoltaic system PID repair method according to claim 19, characterized in that: The condition for judging that the PID repair is completed is that after the output voltage or the output reference voltage reaches the target voltage value, the working time of the PID repair circuit is timed until the repair time reaches a preset maintenance time threshold.

23. The PID repair method for a photovoltaic system according to claim 18, characterized in that: When performing PID repair, the energy storage module maintains connectivity with the inverter circuit.

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