Potential-induced degradation repairing device and photovoltaic power generation system

Abstract

The utility model provides a potential induced degradation repairing device and a photovoltaic power generation system. The device is connected with the alternating current end of an inverter in the photovoltaic power generation system. The device comprises a rectification unit, a positive DC bus, a negative DC bus, a virtual neutral point, a first capacitor, a second capacitor, a third capacitor, a bus selection unit, a voltage regulation unit and a control unit. The control unit is connected with the rectification unit, the bus selection unit and the voltage regulation unit. The potential between the bus and the functional ground is increased through the voltage regulating unit and the bus selection unit, so that the potential to ground of the middle point BUSN or the alternating current end of the inverter is changed, and the potential to ground of the negative electrode or the positive electrode of the photovoltaic module is indirectly increased; the compatibility and reliability of the system are improved, the cost of the system is not increased, and centralized management and maintenance are facilitated.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a potential-induced degradation repair device and a photovoltaic power generation system. Background Technology

[0002] In order to reduce the cost of photovoltaic power generation systems and increase their power generation, the voltage configuration of photovoltaic units in photovoltaic power generation systems is getting higher and higher, and high-voltage photovoltaic power generation systems (such as 1500V high-voltage photovoltaic power generation systems) are gradually becoming the mainstream in the market.

[0003] Increased voltage in a photovoltaic power generation system can cause photovoltaic cells to experience higher forward or negative bias voltages to the ground. Especially under special conditions such as high temperature and high humidity, photovoltaic cells, such as photovoltaic modules, will experience severe PID (Potential Induced Degradation) effects, leading to a decrease in open-circuit voltage, short-circuit current, and fill factor of the photovoltaic cells, resulting in a gradual reduction in the power generation of the photovoltaic power generation system.

[0004] To correct the PID effect, such as Figure 1 As shown, a PID power supply is generally used to positively raise the potential of the negative terminal PV- of the photovoltaic unit to ground, thereby correcting the PID effect of the photovoltaic unit. However, this method can only be applied to photovoltaic power generation systems using P-type photovoltaic modules, not N-type photovoltaic modules, thus exhibiting poor compatibility with photovoltaic power generation systems. Furthermore, connecting a PID power supply to each inverter or module would increase costs, resulting in wasted system resources and hindering centralized management and maintenance. Utility Model Content

[0005] This application provides a potential-induced degradation repair device and a photovoltaic power generation system to solve the problems of poor compatibility and high cost of existing potential-induced degradation repair devices.

[0006] This application provides a potential-induced degradation repair device, which is connected to the AC terminal of the inverter in a photovoltaic power generation system; the device includes a rectifier unit, a positive DC bus, a negative DC bus, a virtual neutral point, a first capacitor, a second capacitor, a third capacitor, a bus selection unit, a voltage regulation unit, and a control unit;

[0007] The input terminal of the rectifier unit is connected to the AC terminal of the inverter. The positive output terminal of the rectifier unit is connected to the positive input terminal of the voltage regulator unit through the positive DC bus. The negative output terminal of the rectifier unit is connected to the negative input terminal of the voltage regulator unit through the negative DC bus.

[0008] One end of the first capacitor is connected to the positive DC bus, and the other end of the first capacitor is connected to the virtual neutral point. One end of the second capacitor is connected to the negative DC bus, and the other end of the second capacitor is connected to the virtual neutral point. One end of the third capacitor is connected to the input terminal of the rectifier unit or the AC terminal of the inverter, and the other end of the third capacitor is connected to the virtual neutral point.

[0009] The first input terminal of the bus selection unit is connected to the positive DC bus, the second input terminal of the bus selection unit is connected to the negative DC bus, the output terminal of the bus selection unit is connected to the output terminal of the voltage regulating unit, and the grounding terminal of the voltage regulating unit is connected to ground.

[0010] The control unit is connected to the rectifier unit, the bus selection unit, and the voltage regulation unit.

[0011] In some examples, the voltage regulating unit includes a first DC / DC unit, a first polarity switching unit, and a bidirectional lifting unit;

[0012] The positive input terminal of the first DC / DC unit is the positive input terminal of the voltage regulating unit, the negative input terminal of the first DC / DC unit is the negative input terminal of the voltage regulating unit, the output terminal of the first DC / DC unit is connected to the bidirectional lifting unit through the first polarity switching unit, the first output terminal of the bidirectional lifting unit is the output terminal of the voltage regulating unit, and the second output terminal of the bidirectional lifting unit is the ground terminal of the voltage regulating unit.

[0013] In some examples, the bidirectional lifting unit includes a first set of switching transistors, a second set of switching transistors, a third set of switching transistors, a fourth set of switching transistors, a first resistor, a third capacitor, a second resistor, and a fourth capacitor;

[0014] One end of the first set of switching transistors is the first input terminal of the bidirectional lifting unit, the other end of the first set of switching transistors is connected to one end of the third set of switching transistors and one end of the first resistor, and the other end of the third set of switching transistors is the first output terminal of the bidirectional lifting unit.

[0015] One end of the second set of switching transistors is the second input terminal of the bidirectional lifting unit, and the other end of the second set of switching transistors is connected to one end of the fourth set of switching transistors and one end of the third capacitor. The other end of the fourth set of switching transistors is the second output terminal of the bidirectional lifting unit.

[0016] The other end of the first resistor is connected to the other end of the third capacitor, one end of the second resistor is connected to the other end of the third group of switching transistors, the other end of the second resistor is connected to one end of the fourth capacitor, and the other end of the fourth capacitor is connected to the other end of the fourth group of switching transistors.

[0017] In some examples, any one of the first group of switches, the second group of switches, the third group of switches, and the fourth group of switches includes switches connected in series.

[0018] In some examples, the voltage regulating unit includes a second DC / DC unit, a second polarity switching unit, and a unidirectional lifting unit;

[0019] The positive input terminal of the second DC / DC unit is the positive input terminal of the voltage regulating unit, the negative input terminal of the second DC / DC unit is the negative input terminal of the voltage regulating unit, the output terminal of the second DC / DC unit is connected to the second polarity switching unit through the unidirectional lifting unit, the first output terminal of the second polarity switching unit is the output terminal of the voltage regulating unit, and the second output terminal of the second polarity switching unit is the ground terminal of the voltage regulating unit.

[0020] In some examples, the unidirectional lifting unit includes a first switch, a second switch, a third switch, a fourth switch, a third resistor, a fifth capacitor, a fourth resistor, and a sixth capacitor;

[0021] One end of the first switching transistor is the first input terminal of the unidirectional lifting unit, and the other end of the first switching transistor is connected to one end of the third switching transistor and one end of the third resistor. The other end of the third switching transistor is the first output terminal of the unidirectional lifting unit.

[0022] One end of the second switch is the second input terminal of the unidirectional lifting unit, and the other end of the second switch is connected to one end of the fourth switch and one end of the fifth capacitor. The other end of the fourth switch is the second output terminal of the unidirectional lifting unit.

[0023] The other end of the third resistor is connected to the other end of the fifth capacitor, one end of the fourth resistor is connected to the other end of the third switch, the other end of the fourth resistor is connected to one end of the sixth capacitor, and the other end of the sixth capacitor is connected to the other end of the fourth switch.

[0024] In some examples, the first polarity switching unit includes a first switching circuit and a second switching circuit connected in parallel;

[0025] The first switching circuit includes a fifth and a sixth switching transistor connected in series, and the connection point between the fifth and the sixth switching transistors is the first output terminal of the polarity switching unit; the second switching circuit includes a seventh and an eighth switching transistor connected in series, and the connection point between the seventh and the eighth switching transistors is the second output terminal of the polarity switching unit.

[0026] In some examples, the second polarity switching unit includes a first switching circuit and a second switching circuit connected in parallel;

[0027] The first switching circuit includes a fifth and a sixth switching transistor connected in series, and the connection point between the fifth and the sixth switching transistors is the first output terminal of the polarity switching unit; the second switching circuit includes a seventh and an eighth switching transistor connected in series, and the connection point between the seventh and the eighth switching transistors is the second output terminal of the polarity switching unit.

[0028] In some examples, the bus selection unit includes a ninth switch and a tenth switch. One end of the ninth switch is the first input terminal of the bus selection unit, and one end of the tenth switch is the second input terminal of the bus selection unit. The other end of the ninth switch and the other end of the tenth switch are connected to form the output terminal of the bus selection unit.

[0029] This application also provides a photovoltaic power generation system, including the aforementioned potential-induced degradation repair device, photovoltaic module, and inverter;

[0030] The photovoltaic module is connected to the DC terminal of the inverter, and the AC terminal of the inverter is connected to the power grid or load.

[0031] In some examples, the photovoltaic power generation system also includes a grid-connected transformer, through which the AC terminal of the inverter is connected to the power grid or load.

[0032] The potential-induced degradation repair device and photovoltaic power generation system provided in this application raise the potential between the bus and the functional ground through the voltage regulation unit and the bus selection unit, thereby changing the potential of the neutral point BUS_N or the AC terminal of the inverter relative to ground, thus indirectly raising the potential of the negative or positive electrode of the photovoltaic module relative to ground; improving the compatibility and reliability of the system, without increasing the cost of the system, and facilitating centralized management and maintenance. Attached Figure Description

[0033] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0034] Figure 1 This is a schematic diagram of an existing photovoltaic power generation system;

[0035] Figure 2 This is a schematic diagram of a photovoltaic power generation system provided in the embodiments of this application;

[0036] Figure 3 This is a schematic diagram of a photovoltaic power generation system provided in the embodiments of this application;

[0037] Figure 4 This is another specific circuit diagram of the photovoltaic power generation system provided in the embodiments of this application;

[0038] Figure 5 This is a schematic diagram of the polarity switching unit provided in the embodiments of this application;

[0039] Figure 6 This is a schematic diagram of the bidirectional lifting unit provided in the embodiments of this application;

[0040] Figure 7 This is a schematic diagram of a unidirectional lifting unit provided in the embodiments of this application. Detailed Implementation

[0041] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0042] This application provides a photovoltaic power generation system, including a photovoltaic module, an inverter, and a grid-connected transformer. The photovoltaic module is connected to the DC terminal of the inverter, the AC terminal of the inverter is connected to the input terminal of the grid-connected transformer, and the output terminal of the grid-connected transformer is connected to the power grid or a load.

[0043] by Figure 2 For example, the DC terminal of the inverter is connected to the corresponding photovoltaic array, which consists of one or more photovoltaic modules (or one or more photovoltaic strings) assembled together mechanically and electrically in a certain way. The AC terminal of the inverter is connected to the input terminal of the grid-connected transformer (shown as P in the figure), and the output terminal of the grid-connected transformer (shown as S in the figure) is connected to the power grid.

[0044] Furthermore, the photovoltaic power generation system also includes a potential-induced degradation repair device (such as a voltage-induced degradation repair device) connected between the AC terminal of the inverter and the grid-connected transformer.Figure 2 (As shown in the dashed box). The potential-induced degradation repair device can be integrated inside the inverter cabinet or installed as a separate module on the low-voltage side (input side) of the grid-connected transformer.

[0045] like Figure 2 As shown, in one example, the potential-induced decay repair device includes a rectifier unit, a positive DC bus BUS+, a negative DC bus BUS-, a virtual neutral point BUS_N, a first capacitor C1, a second capacitor C2, a third capacitor (C6, C7, and C8 in the figure), a bus selection unit, a voltage regulation unit, and a control unit.

[0046] The input terminal of the rectifier unit is connected to the AC terminal of the inverter. The positive output terminal of the rectifier unit is connected to the positive input terminal VIN+ of the voltage regulator unit through the positive DC bus BUS+. The negative output terminal of the rectifier unit is connected to the negative input terminal VIN- of the voltage regulator unit through the negative DC bus BUS-.

[0047] One end of the first capacitor C1 is connected to the positive DC bus BUS+, and the other end of the first capacitor C1 is connected to the virtual neutral point BUS_N. One end of the second capacitor C2 is connected to the negative DC bus BUS-, and the other end of the second capacitor C2 is connected to the virtual neutral point BUS_N. One end of the third capacitor is connected to the input terminal of the rectifier unit or the AC terminal of the inverter, and the other end of the third capacitor is connected to the virtual neutral point BUS_N.

[0048] The first input terminal of the bus selection unit is connected to the positive DC bus BUS+, the second input terminal of the bus selection unit is connected to the negative DC bus BUS-, the output terminal of the bus selection unit is connected to the output terminal VO of the voltage regulation unit, and the grounding terminal FE of the voltage regulation unit is connected to ground (as shown by the functional ground FE in the figure).

[0049] The control unit is connected to the rectifier unit, the bus selection unit, and the voltage regulation unit.

[0050] In one example, the rectifier unit includes a three-phase two-level controlled rectifier unit for converting alternating current (AC) to direct current (DC). The three-phase two-level controlled rectifier unit converts three-phase AC (phases A, B, and C in the diagram) into DC and outputs a constant DC voltage.

[0051] like Figure 3 , Figure 6 As shown, in one example, the voltage regulation unit includes a DC / DC unit, a polarity switching unit, and a bidirectional lifting unit;

[0052] The positive input terminal of the DC / DC unit is the positive input terminal VIN+ of the voltage regulation unit, and the negative input terminal of the DC / DC unit is the negative input terminal VIN- of the voltage regulation unit. The output terminal of the DC / DC unit is connected to the bidirectional lifting unit through the polarity switching unit. The first output terminal of the bidirectional lifting unit is the output terminal VO of the voltage regulation unit, and the second output terminal of the bidirectional lifting unit is the ground terminal of the voltage regulation unit.

[0053] The bidirectional lifting unit includes a first set of switching transistors (two Q5s in the figure), a second set of switching transistors (two Q6s in the figure), a third set of switching transistors (two Q7s in the figure), a fourth set of switching transistors (two Q8s in the figure), a resistor R1, a capacitor C4, a resistor R2, and a capacitor C5.

[0054] One end of the first set of switching transistors is the first input terminal of the bidirectional lifting unit, the other end of the first set of switching transistors is connected to one end of the third set of switching transistors and one end of the resistor R1, and the other end of the third set of switching transistors is the first output terminal of the bidirectional lifting unit.

[0055] One end of the second group of switching transistors is the second input terminal of the bidirectional lifting unit, and the other end of the second group of switching transistors is connected to one end of the fourth group of switching transistors and one end of the capacitor C4. The other end of the fourth group of switching transistors is the second output terminal of the bidirectional lifting unit.

[0056] The other end of resistor R1 is connected to the other end of capacitor C4, one end of resistor R2 is connected to the other end of the third group of switching transistors, the other end of resistor R2 is connected to one end of capacitor C5, and the other end of capacitor C5 is connected to the other end of the fourth group of switching transistors.

[0057] The first group of switching transistors, the second group of switching transistors, the third group of switching transistors, and the fourth group of switching transistors may include switching transistors connected in series. For example, any one of the first group of switching transistors, the second group of switching transistors, the third group of switching transistors, and the fourth group of switching transistors may consist of two common-source NMOS transistors connected in series.

[0058] Among them, the aforementioned switching transistors Q5 to Q8 can be any combination of switching devices such as relays, bipolar junction transistors, insulated gate bipolar transistors, and metal-oxide-semiconductor field-effect transistors, and the relays include electromagnetic relays or semiconductor solid-state relays.

[0059] like Figure 4 , Figure 7 As shown, in one example, the voltage regulating unit includes a DC / DC unit, a polarity switching unit, and a unidirectional lifting unit;

[0060] The positive input terminal of the DC / DC unit is the positive input terminal VIN+ of the voltage regulation unit, and the negative input terminal of the DC / DC unit is the negative input terminal VIN- of the voltage regulation unit. The output terminal of the DC / DC unit is connected to the polarity switching unit through the unidirectional lifting unit. The first output terminal of the polarity switching unit is the output terminal VO of the voltage regulation unit, and the second output terminal of the polarity switching unit is the ground terminal of the voltage regulation unit.

[0061] The unidirectional lifting unit includes a first switch (Q5 in the figure), a second switch (Q6 in the figure), a third switch (Q7 in the figure), a fourth switch (Q8 in the figure), a resistor R1, a capacitor C4, a resistor R2, and a capacitor C5.

[0062] One end of the first switch is the first input terminal of the unidirectional lifting unit, and the other end of the first switch is connected to one end of the third switch and one end of the resistor R1. The other end of the third switch is the first output terminal of the unidirectional lifting unit.

[0063] One end of the second switch is the second input terminal of the unidirectional lifting unit, and the other end of the second switch is connected to one end of the fourth switch and one end of the capacitor C4. The other end of the fourth switch is the second output terminal of the unidirectional lifting unit.

[0064] The other end of resistor R1 is connected to the other end of capacitor C4, one end of resistor R2 is connected to the other end of the third switch, the other end of resistor R2 is connected to one end of capacitor C5, and the other end of capacitor C5 is connected to the other end of the fourth switch.

[0065] Among them, the aforementioned switching transistors Q5 to Q8 can be any combination of switching devices such as relays, bipolar junction transistors, insulated gate bipolar transistors, and metal-oxide-semiconductor field-effect transistors, and the relays include electromagnetic relays or semiconductor solid-state relays.

[0066] like Figure 5 As shown, in one example, the polarity switching unit includes a first switching circuit and a second switching circuit connected in parallel;

[0067] The first switching circuit includes a series-connected switching transistor Q1 and a switching transistor Q2, and the connection point between the switching transistors Q1 and Q2 is the first output terminal of the polarity switching unit; the second switching circuit includes a series-connected switching transistor Q3 and a switching transistor Q4, and the connection point between the switching transistors Q3 and Q4 is the second output terminal of the polarity switching unit.

[0068] Among them, the aforementioned switching transistors Q1 to Q4 can be any combination of switching devices such as relays, bipolar junction transistors, insulated gate bipolar transistors, and metal-oxide-semiconductor field-effect transistors, and the relays include electromagnetic relays or semiconductor solid-state relays.

[0069] like Figures 2-4 As shown, in one example, the bus selection unit includes a switch Q9 and a switch Q10. One end of the switch Q9 is the first input terminal of the bus selection unit, and one end of the switch Q10 is the second input terminal of the bus selection unit. The other end of the switch Q9 is connected to the other end of the switch Q10 to form the output terminal of the bus selection unit.

[0070] Among them, the aforementioned switching transistors Q9 to Q10 can be relays, including electromagnetic relays or semiconductor solid-state relays.

[0071] It should be noted that the aforementioned DC / DC unit (i.e., DC-to-DC conversion unit) is the smallest unit necessary for a power converter, including diodes, switches, power inductors, etc. The DC / DC unit is not limited to DC-DC converters or converters in the form of switching power supplies, and the switches are not limited to any combination of switching devices such as bipolar junction transistors, insulated gate bipolar transistors, and metal-oxide-semiconductor field-effect transistors.

[0072] The following is Figure 3 Let's take an example to illustrate:

[0073] When the photovoltaic module is a P-type module, Q1 and Q4 of the polarity switching unit are closed, and Q2 and Q3 are open, changing the input voltage polarity of the bidirectional lift unit to positive. Conversely, when the photovoltaic module is an N-type module, Q1 and Q4 of the polarity switching unit are open, and Q2 and Q3 are closed, changing the input voltage polarity of the bidirectional lift unit to negative. Q5 and Q6 of the bidirectional lift unit are closed, and Q7 and Q8 are open, transferring the energy from the input to the current-limiting resistor R1 to charge capacitor C4. Subsequently, Q5, Q6, Q7, and Q8 are all open. After a certain dead time, Q7 and Q8 close, while Q5 and Q6 remain open, transferring the energy charged in capacitor C4 to the current-limiting resistor R2 at the output end to charge capacitor C5. The output of the bidirectional lifting unit is connected between the bus selection unit and the functional ground FE. The bus selection unit, determined by the control unit, selects to lift either bus BUS+ or BUS-. By injecting positive or negative DC voltage between this bus BUS+ or BUS- and the functional ground FE, the potential between the AC and ground is changed, thereby indirectly lifting the potential of the negative electrode PV- or positive electrode PV+ of the photovoltaic module relative to ground. The output voltage of the bidirectional lifting unit is then controlled by the DC / DC unit, enabling precise adjustment of the potential of the photovoltaic module PV- or PV+ relative to ground above or below zero.

[0074] Figure 4 The working process and Figure 3 similar, Figure 4 Compared to the solution Figure 3 The advantage of this solution is that the input of the unidirectional lift-up unit will no longer be subjected to positive and negative bipolar voltages. This means that when the unidirectional lift-up unit uses semiconductor devices, such as IGBTs or MOS, the reverse conduction effect caused by the body diode does not need to be considered, thus eliminating the need to use twice the number of devices to form a bidirectional switch. Therefore, compared to... Figure 3 The plan, Figure 4 The solution offers greater cost and size advantages, while the power consumption of the unit is halved due to the reduction in the number of switches connected in series by half.

[0075] It should be noted that while preferred embodiments of this application are provided in the specification and accompanying drawings, this application can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this application; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this application. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this application's specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A potential-induced degradation repair device, wherein the device is connected to the AC terminal of an inverter in a photovoltaic power generation system; characterized in that, The device includes a rectifier unit, a positive DC bus, a negative DC bus, a virtual neutral point, a first capacitor, a second capacitor, a third capacitor, a bus selection unit, a voltage regulation unit, and a control unit. The input terminal of the rectifier unit is connected to the AC terminal of the inverter. The positive output terminal of the rectifier unit is connected to the positive input terminal of the voltage regulator unit through the positive DC bus. The negative output terminal of the rectifier unit is connected to the negative input terminal of the voltage regulator unit through the negative DC bus. One end of the first capacitor is connected to the positive DC bus, and the other end of the first capacitor is connected to the virtual neutral point. One end of the second capacitor is connected to the negative DC bus, and the other end of the second capacitor is connected to the virtual neutral point. One end of the third capacitor is connected to the input terminal of the rectifier unit or the AC terminal of the inverter, and the other end of the third capacitor is connected to the virtual neutral point. The first input terminal of the bus selection unit is connected to the positive DC bus, the second input terminal of the bus selection unit is connected to the negative DC bus, the output terminal of the bus selection unit is connected to the output terminal of the voltage regulating unit, and the grounding terminal of the voltage regulating unit is connected to ground. The control unit is connected to the rectifier unit, the bus selection unit, and the voltage regulation unit.

2. The potential-induced decay repair device according to claim 1, characterized in that, The voltage regulation unit includes a first DC / DC unit, a first polarity switching unit, and a bidirectional lifting unit; The positive input terminal of the first DC / DC unit is the positive input terminal of the voltage regulating unit, the negative input terminal of the first DC / DC unit is the negative input terminal of the voltage regulating unit, the output terminal of the first DC / DC unit is connected to the bidirectional lifting unit through the first polarity switching unit, the first output terminal of the bidirectional lifting unit is the output terminal of the voltage regulating unit, and the second output terminal of the bidirectional lifting unit is the ground terminal of the voltage regulating unit.

3. The potential-induced decay repair device according to claim 2, characterized in that, The bidirectional lifting unit includes a first set of switching transistors, a second set of switching transistors, a third set of switching transistors, a fourth set of switching transistors, a first resistor, a third capacitor, a second resistor, and a fourth capacitor; One end of the first set of switching transistors is the first input terminal of the bidirectional lifting unit, the other end of the first set of switching transistors is connected to one end of the third set of switching transistors and one end of the first resistor, and the other end of the third set of switching transistors is the first output terminal of the bidirectional lifting unit. One end of the second set of switching transistors is the second input terminal of the bidirectional lifting unit, and the other end of the second set of switching transistors is connected to one end of the fourth set of switching transistors and one end of the third capacitor. The other end of the fourth set of switching transistors is the second output terminal of the bidirectional lifting unit. The other end of the first resistor is connected to the other end of the third capacitor, one end of the second resistor is connected to the other end of the third group of switching transistors, the other end of the second resistor is connected to one end of the fourth capacitor, and the other end of the fourth capacitor is connected to the other end of the fourth group of switching transistors.

4. The potential-induced decay repair device according to claim 3, characterized in that, Any one of the first group of switching transistors, the second group of switching transistors, the third group of switching transistors, and the fourth group of switching transistors includes switching transistors connected in series.

5. The potential-induced decay repair device according to claim 1, characterized in that, The voltage regulation unit includes a second DC / DC unit, a second polarity switching unit, and a unidirectional lifting unit; The positive input terminal of the second DC / DC unit is the positive input terminal of the voltage regulating unit, the negative input terminal of the second DC / DC unit is the negative input terminal of the voltage regulating unit, the output terminal of the second DC / DC unit is connected to the second polarity switching unit through the unidirectional lifting unit, the first output terminal of the second polarity switching unit is the output terminal of the voltage regulating unit, and the second output terminal of the second polarity switching unit is the ground terminal of the voltage regulating unit.

6. The potential-induced decay repair device according to claim 5, characterized in that, The unidirectional lifting unit includes a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a third resistor, a fifth capacitor, a fourth resistor, and a sixth capacitor. One end of the first switching transistor is the first input terminal of the unidirectional lifting unit, and the other end of the first switching transistor is connected to one end of the third switching transistor and one end of the third resistor. The other end of the third switching transistor is the first output terminal of the unidirectional lifting unit. One end of the second switch is the second input terminal of the unidirectional lifting unit, and the other end of the second switch is connected to one end of the fourth switch and one end of the fifth capacitor. The other end of the fourth switch is the second output terminal of the unidirectional lifting unit. The other end of the third resistor is connected to the other end of the fifth capacitor, one end of the fourth resistor is connected to the other end of the third switch, the other end of the fourth resistor is connected to one end of the sixth capacitor, and the other end of the sixth capacitor is connected to the other end of the fourth switch.

7. The potential-induced decay repair device according to claim 2, characterized in that, The first polarity switching unit includes a first switching circuit and a second switching circuit connected in parallel. The first switching circuit includes a fifth and a sixth switching transistor connected in series, and the connection point between the fifth and the sixth switching transistors is the first output terminal of the polarity switching unit; the second switching circuit includes a seventh and an eighth switching transistor connected in series, and the connection point between the seventh and the eighth switching transistors is the second output terminal of the polarity switching unit.

8. The potential-induced decay repair device according to claim 5, characterized in that, The second polarity switching unit includes a first switching circuit and a second switching circuit connected in parallel; The first switching circuit includes a fifth and a sixth switching transistor connected in series, and the connection point between the fifth and the sixth switching transistors is the first output terminal of the polarity switching unit; the second switching circuit includes a seventh and an eighth switching transistor connected in series, and the connection point between the seventh and the eighth switching transistors is the second output terminal of the polarity switching unit.

9. The potential-induced decay repair device according to claim 1, characterized in that, The bus selection unit includes a ninth switch and a tenth switch. One end of the ninth switch is the first input terminal of the bus selection unit, and one end of the tenth switch is the second input terminal of the bus selection unit. The other end of the ninth switch and the other end of the tenth switch are connected to form the output terminal of the bus selection unit.

10. A photovoltaic power generation system, characterized in that, Includes the potential-induced degradation repair device, photovoltaic module, and inverter as described in any one of claims 1-9; The photovoltaic module is connected to the DC terminal of the inverter, and the AC terminal of the inverter is connected to the power grid or load.

11. The photovoltaic power generation system according to claim 10, characterized in that, The photovoltaic power generation system also includes a grid-connected transformer, and the AC terminal of the inverter is connected to the power grid or load through the grid-connected transformer.

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