Photovoltaic power generation system

Abstract

The utility model provides a photovoltaic power generation system, which relates to the technical field of photovoltaic power generation and comprises at least two photovoltaic units, a bridging photovoltaic group string, at least two switch units and a power converter. Each photovoltaic unit comprises at most two photovoltaic group strings, the two photovoltaic group strings are connected in parallel, and the photovoltaic units are in one-to-one correspondence with the switch units. The positive electrode of the photovoltaic unit is connected with the corresponding first pin of the switch unit, the second pin of the switch unit, the positive electrode of the input end of the power converter, the negative electrode of the input end of the power converter, the third pin of the switch unit, the fourth pin of the switch unit and the negative electrode of the corresponding photovoltaic unit are connected in sequence, and a bridging photovoltaic group string is arranged in at least one photovoltaic unit group. And each photovoltaic unit group comprises two photovoltaic units. A large amount of heat is not generated at the switch unit, the condition of three-parallel connection of the photovoltaic group strings is avoided, other photovoltaic group strings are not damaged, the safety of the photovoltaic power generation system is ensured, and the number of the connected photovoltaic group strings is increased at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of photovoltaic power generation, and in particular to a photovoltaic power generation system. Background Art

[0002] Photovoltaic power generation systems use photovoltaic array components made based on the principle of photoelectric effect to directly convert solar energy into electrical energy. Photovoltaic power generation systems are mainly composed of photovoltaic components, controllers, inverters, batteries and other accessories. At present, in order to improve the photovoltaic power generation rate, several photovoltaic components are connected in series to form photovoltaic strings, and then the photovoltaic strings are connected in parallel to the inverter for grid-connected power generation.

[0003] Generally, after PV strings are connected in parallel, they are connected to the inverter through switches to facilitate the on and off control of the PV strings. However, when more than three PV strings are connected in parallel, the current is too large and the heat generated by the switch increases, which is prone to safety accidents. Moreover, when the positive and negative poles of a PV string are connected in reverse, even if the switch is disconnected, a large reverse current will be generated between the other parallel PV strings and the reversely connected PV string, which is unsafe to use and prone to safety problems. Utility Model Content

[0004] The problem to be solved by the utility model is that safety problems are easily generated when multiple photovoltaic groups are used in series and parallel.

[0005] To solve the above problems, on the one hand, the utility model provides a photovoltaic power generation system, including at least two photovoltaic units, a cross-connected photovoltaic string, at least two switch units and a power converter;

[0006] The photovoltaic unit includes at most two photovoltaic strings, the positive poles of the two photovoltaic strings are connected to form the positive pole of the photovoltaic unit, the negative poles of the two photovoltaic strings are connected to form the negative pole of the photovoltaic unit, the photovoltaic unit corresponds to the switch unit one by one, the positive pole of the photovoltaic unit is connected to the first pin of the corresponding switch unit, the second pin of the switch unit is connected to the positive pole of the corresponding input end of the power converter, the negative pole of the input end of the power converter is connected to the third pin of the switch unit, and the fourth pin of the switch unit is connected to the negative pole of the corresponding photovoltaic unit. The jumper photovoltaic string is provided in at least one photovoltaic unit group, and each photovoltaic unit group includes two photovoltaic units, the positive pole of the jumper photovoltaic string is connected to the positive pole of one photovoltaic unit, and the negative pole of the jumper photovoltaic string is connected to the negative pole of another photovoltaic unit.

[0007] Optionally, the switch unit includes a first switch and a second switch, one end of the first switch is connected to the first pin, the other end of the first switch is connected to the second pin, one end of the second switch is connected to the third pin, and the other end of the second switch is connected to the fourth pin.

[0008] Optionally, every two adjacent photovoltaic units form a photovoltaic unit group.

[0009] Optionally, the two photovoltaic units in each photovoltaic unit group are connected via one cross-connected photovoltaic string.

[0010] Optionally, the number of the jumper photovoltaic strings set in at least one of the photovoltaic unit groups is two, wherein the positive pole of one of the jumper photovoltaic strings is connected to the positive pole of one of the photovoltaic units in the corresponding photovoltaic unit group, the positive pole of another of the jumper photovoltaic strings is connected to the positive pole of another of the photovoltaic units in the corresponding photovoltaic unit group, the negative pole of one of the jumper photovoltaic strings is connected to the negative pole of another of the photovoltaic units in the corresponding photovoltaic unit group, and the negative pole of another of the jumper photovoltaic strings is connected to the negative pole of one of the photovoltaic units in the corresponding photovoltaic unit group.

[0011] Optionally, both the first switch and the second switch are manual switches.

[0012] Optionally, both the first switch and the second switch are controllable switches.

[0013] Optionally, the first switch and the second switch are respectively any one of a relay, a transistor or a field effect transistor.

[0014] Optionally, a controller is further included, wherein the controller is electrically connected to the first switch and the second switch respectively, and is used to control the on and off of the first switch and the second switch.

[0015] Optionally, the controller is electrically connected to the power converter for controlling the power converter.

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] The utility model provides a photovoltaic power generation system, in which photovoltaic units correspond to switch units one by one, the positive pole of the photovoltaic unit is connected to the first pin of the corresponding switch unit, the second pin of the switch unit is connected to the positive pole of the input end of the power converter, the negative pole of the input end of the power converter is connected to the third pin of the switch unit, and the fourth pin of the switch unit is connected to the negative pole of the corresponding photovoltaic unit. The switch unit is controlled to be closed and connected, so that current flows out from the positive pole of the photovoltaic unit, passes through the switch unit and the power converter in sequence, and flows back to the negative pole of the photovoltaic unit to form a loop. The photovoltaic unit includes at most two photovoltaic strings, and the two photovoltaic strings are connected in parallel. The current output by the photovoltaic unit is small, and a large amount of heat will not be generated at the switch unit, thereby improving the safety of the photovoltaic system. In addition, at least one photovoltaic unit group is provided with a cross-connected photovoltaic string, and each photovoltaic unit group includes two photovoltaic units, that is, a cross-connected photovoltaic string is provided between two photovoltaic units in at least one photovoltaic unit group, and the positive pole of the cross-connected photovoltaic string is connected to the positive pole of one photovoltaic unit, and the negative pole of the cross-connected photovoltaic string is connected to the negative pole of another photovoltaic unit, so as to avoid the occurrence of three parallel photovoltaic strings. When the positive and negative poles of a photovoltaic string in the photovoltaic unit are reversed, the magnitude of the backflow current generated is similar to the normal operating current of the photovoltaic string, and will not cause damage to the reverse-connected photovoltaic string or other photovoltaic strings; when the cross-connected photovoltaic string is reversely connected, no backflow current will be generated, and no damage will be caused to the photovoltaic string, which can further improve the safety of the use of the photovoltaic system. On the basis of improving the safety of the photovoltaic power generation system, due to the addition of the cross-connected photovoltaic string, the number of photovoltaic strings connected to the photovoltaic power generation system is increased, and the output power of the photovoltaic power generation system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of a photovoltaic power generation system in an embodiment of the utility model;

[0019] Figure 2 This is a schematic diagram of the structure of another photovoltaic power generation system in an embodiment of the utility model;

[0020] Figure 3 for Figure 1 A simplified schematic diagram of a photovoltaic power generation system;

[0021] Figure 4 for Figure 2 A simplified schematic diagram of a photovoltaic power generation system;

[0022] Figure 5 for Figure 3 A simplified structural diagram of a photovoltaic power generation system when the positive and negative poles of PV1 are connected in reverse;

[0023] Figure 6 for Figure 3 A simplified structural diagram of the photovoltaic power generation system when the positive and negative poles of PV3 are connected in reverse;

[0024] Figure 7 It is a schematic diagram of the structure of a photovoltaic power generation system containing 6 PVs in an embodiment of the utility model;

[0025] Figure 8 for Figure 7 A simplified schematic diagram of the photovoltaic power generation system.

[0026] Description of reference numerals:

[0027] 1. Protection switch assembly; 2. Power converter. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the utility model described here can be implemented in an order other than those illustrated or described here.

[0030] In the description of this specification, the description with reference to the terms "embodiment", "one embodiment" and "one implementation" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or implementation are included in at least one embodiment or implementation of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or implementation. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or implementations in a suitable manner.

[0031] In an optional embodiment of the present utility model, as Figure 1 As shown, a photovoltaic power generation system includes at least two photovoltaic units, a cross-connected photovoltaic string, at least two switch units and a power converter 2;

[0032] The photovoltaic unit includes at most two photovoltaic strings, the positive poles of the two photovoltaic strings are connected to form the positive pole of the photovoltaic unit, the negative poles of the two photovoltaic strings are connected to form the negative pole of the photovoltaic unit, the photovoltaic unit corresponds to the switch unit one by one, the positive pole of the photovoltaic unit is connected to the first pin of the corresponding switch unit, the second pin of the switch unit is connected to the positive pole of the input end of the power converter 2, the negative pole of the input end of the power converter 2 is connected to the third pin of the switch unit, and the fourth pin of the switch unit is connected to the negative pole of the corresponding photovoltaic unit. The jumper photovoltaic string is provided in at least one photovoltaic unit group, and each photovoltaic unit group includes two photovoltaic units, that is, the jumper photovoltaic string is provided between two photovoltaic units in at least one photovoltaic unit group, the positive pole of the jumper photovoltaic string is connected to the positive pole of one photovoltaic unit, and the negative pole of the jumper photovoltaic string is connected to the negative pole of another photovoltaic unit.

[0033] Specifically, Figure 1 , two photovoltaic units are set, and the photovoltaic units can include PV1 and PV2, or include PV4 and PV5, or only include one photovoltaic string; two switch units are set in the protection switch component 1, and the switch units correspond to the photovoltaic units one by one. If there are too many photovoltaic strings connected in parallel in a photovoltaic unit, the current generated will be too large, which will generate more heat in the protection switch component 1. If the heating current increases, higher requirements will be placed on the switch unit, or the service life of the switch unit will be reduced, or safety problems will easily occur during the use of the switch unit. Therefore, the number of photovoltaic strings in the photovoltaic unit is limited to no more than two to improve the safety of the photovoltaic system. For example Figure 1 As shown, when the photovoltaic unit includes two photovoltaic strings, the two photovoltaic strings are connected in parallel, photovoltaic string PV1 and photovoltaic string PV2 are connected in parallel, and photovoltaic string PV4 and photovoltaic string PV5 are connected in parallel. The positive pole of the photovoltaic unit is connected to the first pin of the switch unit, the second pin of the switch unit is connected to the positive pole of the input end of the power converter 2, the negative pole of the input end of the power converter 2 is connected to the third pin of the switch unit, and the fourth pin of the switch unit is connected to the negative pole of the corresponding photovoltaic unit, and the switch unit is controlled to be closed, so that the positive and negative poles of the photovoltaic unit are connected to form a current.

[0034] In addition, a jumper photovoltaic string PV3 is also provided, such as Figure 1 As shown, the positive pole of the jumper photovoltaic string PV3 is connected to the positive pole of the photovoltaic unit composed of PV4 and PV5, and the negative pole of the jumper photovoltaic string PV3 is connected to the negative pole of the photovoltaic unit composed of PV1 and PV2; or as Figure 2As shown, the positive pole of the jumper photovoltaic string PV3 can also be connected to the positive pole of the photovoltaic unit composed of PV1 and PV2, and the negative pole of the jumper photovoltaic string PV3 can be connected to the negative pole of the photovoltaic unit composed of PV4 and PV5. Figure 1 The connection relationship of the photovoltaic strings in the photovoltaic system is simplified as follows Figure 3 The structural diagram shown in Figure 2 The connection relationship of the photovoltaic strings in the photovoltaic system is simplified as follows Figure 4 The structural diagram shown is composed of Figure 3 or Figure 4 It can be seen that the jumper photovoltaic string PV3 is not connected in parallel with the photovoltaic unit composed of PV1 and PV2, nor is it connected in parallel with the photovoltaic unit composed of PV4 and PV5. An additional jumper photovoltaic string can be connected between the two photovoltaic units to avoid the occurrence of three parallel photovoltaic strings. When one photovoltaic string in the photovoltaic unit is connected incorrectly, the positive and negative poles are reversed, and the control switch units are all disconnected. If the photovoltaic unit includes two photovoltaic strings, although current will be generated between the two photovoltaic strings, the reverse current will not exceed the safe operating current of the photovoltaic string. When the positive and negative poles of PV1 are reversed and the switch units are all disconnected, the following occurs. Figure 5 In the state shown, current is generated between PV1 and PV2, and current backflow occurs. However, when only two PV strings are connected in parallel, that is, Figure 5 As shown, PV1 and PV2 are connected in series, and the reverse-connected PV1 is only impacted by the current and voltage of PV2. At this time, the current and voltage are not large, which is equivalent to the current of normal operation of PV1, and will not cause damage to the reverse-connected PV1. Similarly, when the positive and negative poles of PV2 are reversed, a similar situation will occur. The reverse-connected PV2 is only impacted by the current and voltage of PV1, and will not cause damage to the reverse-connected PV2. However, when there are many photovoltaic strings connected in parallel in the photovoltaic unit, the reverse-connected PV1 will be impacted by the current and voltage of multiple photovoltaic strings. At this time, the current and voltage generated by multiple photovoltaic strings will be superimposed on each other, which is equivalent to several times the normal operating current of PV1. The impact on the reverse-connected PV1 is large and easy to damage. When the positive and negative poles of the jumper photovoltaic string PV3 are reversed and the protection switch components 1 are all disconnected, the following occurs. Figure 6 In the state shown, no reverse current will be generated, and no PV string short circuit will occur, and no damage will be caused to the PV strings. This not only increases the number of PV strings connected to the PV system, but also further improves the safety of the use of the PV system.

[0035] It should be noted that if a photovoltaic power generation system includes multiple photovoltaic units, any two photovoltaic units among the multiple photovoltaic units constitute a photovoltaic unit group, as long as a jumper photovoltaic string is connected between two photovoltaic units in a photovoltaic unit group, the photovoltaic power generation system can increase the number of connected photovoltaic strings under the premise of safe operation. If the photovoltaic power generation system wants to connect the most photovoltaic strings, a jumper photovoltaic string can be connected between each photovoltaic unit group. Only one jumper photovoltaic string can be connected between two photovoltaic units in each photovoltaic unit group, or two jumper photovoltaic strings can be cross-connected.

[0036] In this embodiment, the photovoltaic unit corresponds to the switch unit one by one, the positive pole of the photovoltaic unit is connected to the first pin of the corresponding switch unit, the second pin of the switch unit is connected to the positive pole of the input end of the power converter 2, the negative pole of the input end of the power converter 2 is connected to the third pin of the switch unit, and the fourth pin of the switch unit is connected to the negative pole of the corresponding photovoltaic unit. The switch unit is controlled to be closed and connected, so that the current flows out from the positive pole of the photovoltaic unit, passes through the switch unit and the power converter 2 in turn, and flows back to the negative pole of the photovoltaic unit to form a loop. The photovoltaic unit includes at most two photovoltaic strings, and the two photovoltaic strings are connected in parallel. The current output by the photovoltaic unit is small, and a large amount of heat will not be generated at the switch unit, thereby improving the safety of the photovoltaic system. In addition, at least one photovoltaic unit group is provided with a cross-connected photovoltaic string, and each photovoltaic unit group includes two photovoltaic units, that is, a cross-connected photovoltaic string is provided between two photovoltaic units in at least one photovoltaic unit group, and the positive pole of the cross-connected photovoltaic string is connected to the positive pole of one photovoltaic unit, and the negative pole of the cross-connected photovoltaic string is connected to the negative pole of another photovoltaic unit, so as to avoid the situation where three photovoltaic strings are connected in parallel. When the positive and negative poles of a photovoltaic string in the photovoltaic unit are reversed, the magnitude of the backflow current generated is similar to the normal operating current of the photovoltaic string, and will not cause damage to the reverse-connected photovoltaic string or other photovoltaic strings; when the cross-connected photovoltaic string is reversely connected, no backflow current will be generated, and no damage will be caused to the photovoltaic string, which can further improve the safety of the use of the photovoltaic system. On the basis of improving the safety of the photovoltaic power generation system, due to the addition of the cross-connected photovoltaic string, the number of photovoltaic strings connected to the photovoltaic power generation system is increased, and the output power of the photovoltaic power generation system is improved.

[0037] In an optional embodiment of the present utility model, the switch unit includes a first switch and a second switch, one end of the first switch is connected to the first pin, the other end of the first switch is connected to the second pin, one end of the second switch is connected to the third pin, and the other end of the second switch is connected to the fourth pin.

[0038] Specifically, Figure 1As shown, the switch unit corresponding to the photovoltaic unit composed of PV1 and PV2 includes a first switch K11 and a second switch K13, and the switch unit corresponding to the photovoltaic unit composed of PV4 and PV5 includes a first switch K12 and a second switch K14. Figure 2 As shown, the switch unit corresponding to the photovoltaic unit composed of PV1 and PV2 includes a first switch K21 and a second switch K23, and the switch unit corresponding to the photovoltaic unit composed of PV4 and PV5 includes a first switch K22 and a second switch K24. Figure 1 As shown, the first switch K11 is connected to the second switch K13 through the power converter 2, so one end of the first switch K11 (i.e., the first pin of the switch unit) is connected to the positive pole of the photovoltaic unit composed of PV1 and PV2, the other end of the first switch K11 (i.e., the second pin of the switch unit) is connected to the positive pole of the input end of the power converter 2, one end of the second switch K13 (i.e., the third pin of the switch unit) is connected to the negative pole of the input end of the power converter 2, and the other end of the second switch K13 (i.e., the fourth pin of the switch unit) is connected to the negative pole of the photovoltaic unit composed of PV1 and PV2; similarly, the first switch K12 is connected to the second switch K14 through the power converter 2, so ... One end of the switch K12 (i.e., the first pin of the switch unit) is connected to the positive pole of the photovoltaic unit composed of PV4 and PV5, the other end of the first switch K12 (i.e., the second pin of the switch unit) is connected to the positive pole of the input end of the power converter 2, one end of the second switch K14 (i.e., the third pin of the switch unit) is connected to the negative pole of the input end of the power converter 2, and the other end of the second switch K14 (i.e., the fourth pin of the switch unit) is connected to the negative pole of the photovoltaic unit composed of PV4 and PV5; the positive pole of the jumper photovoltaic string PV3 is connected to the positive pole of the photovoltaic unit composed of PV4 and PV5, and the negative pole of the jumper photovoltaic string PV3 is connected to the negative pole of the photovoltaic unit composed of PV1 and PV2. Similarly, if Figure 2As shown, the first switch K21 is connected to the second switch K23 through the power converter 2, so one end of the first switch K21 is connected to the positive electrode of the photovoltaic unit composed of PV1 and PV2, and the other end of the first switch K21 is connected to the positive electrode of the input end of the power converter 2, one end of the second switch K23 is connected to the negative electrode of the input end of the power converter 2, and the other end of the second switch K23 is connected to the negative electrode of the photovoltaic unit composed of PV1 and PV2; similarly, the first switch K22 is connected to the second switch K24 through the power converter 2, so the first One end of the switch K22 is connected to the positive pole of the photovoltaic unit composed of PV4 and PV5, the other end of the first switch K22 is connected to the positive pole of the input end of the power converter 2, one end of the second switch K24 is connected to the negative pole of the input end of the power converter 2, and the other end of the second switch K24 is connected to the negative pole of the photovoltaic unit composed of PV4 and PV5; the positive pole of the jumper photovoltaic string PV3 is connected to the positive pole of the photovoltaic unit composed of PV1 and PV2, and the negative pole of the jumper photovoltaic string PV3 is connected to the negative pole of the photovoltaic unit composed of PV4 and PV5.

[0039] In this embodiment, while ensuring that the photovoltaic strings are not connected in parallel with three, the total number of poles of the protection switch remains unchanged, but a jumper photovoltaic string can be added, and the heating current is agreed to be minimized; or the total number of poles of the protection switch can be minimized while the heating current is agreed to remain unchanged.

[0040] In an optional embodiment of the present utility model, the first switch and the second switch are both controllable switches or manual switches.

[0041] Specifically, a controllable switch is a switch whose switch state can be controlled by an external signal or a controller. It can be a common electronic switch, a relay, a transistor, a field effect tube and other different types of switches. Therefore, the photovoltaic power generation system can also include a controller, which is electrically connected to the first switch and the second switch respectively, and is used to control the on and off of the first switch and the second switch. The controller can also be electrically connected to the power converter 2 to control the power converter 2, thereby realizing automatic on and off of the photovoltaic system, and can be remotely controlled to improve the safety of system operation.

[0042] In an optional embodiment of the present invention, every two adjacent photovoltaic units form a photovoltaic unit group, and the two photovoltaic units in at least one photovoltaic unit group can be connected through a jumper photovoltaic string, or the two photovoltaic units in each photovoltaic unit group can be connected through a jumper photovoltaic string, that is, every two adjacent photovoltaic units are connected through a jumper photovoltaic string. Figure 1As shown, if the photovoltaic unit composed of PV1 and PV2 is called the first photovoltaic unit, and the photovoltaic unit composed of PV4 and PV5 is called the second photovoltaic unit, a jumper photovoltaic string PV3 is connected between two adjacent photovoltaic units. When the number of photovoltaic units increases, for example, a third photovoltaic unit and a fourth photovoltaic unit are added, a jumper photovoltaic string can also be set between the second photovoltaic unit and the third photovoltaic unit, and between the third photovoltaic unit and the fourth photovoltaic unit. In this way, as the number of photovoltaic units increases, the number of switches increases accordingly, and there are no extra redundant switches, which ensures that the heat generated by the switch unit is not large. More jumper photovoltaic strings can also be added to improve the output efficiency of the photovoltaic power generation system.

[0043] In an optional embodiment of the utility model, the number of the jumper photovoltaic strings set in at least one of the photovoltaic unit groups is two, wherein the positive pole of one of the jumper photovoltaic strings is connected to the positive pole of one of the photovoltaic units in the corresponding photovoltaic unit group, the positive pole of another of the jumper photovoltaic strings is connected to the positive pole of another of the photovoltaic units in the corresponding photovoltaic unit group, the negative pole of one of the jumper photovoltaic strings is connected to the negative pole of another of the photovoltaic units in the corresponding photovoltaic unit group, and the negative pole of another of the jumper photovoltaic strings is connected to the negative pole of one of the photovoltaic units in the corresponding photovoltaic unit group, that is, two jumper photovoltaic strings are cross-connected between two photovoltaic units.

[0044] Specifically, Figure 7As shown, the first switch K31 is connected to the second switch K33 through the power converter 2, so one end of the first switch K31 is connected to the positive electrode of the photovoltaic unit composed of PV1 and PV2, and one end of the second switch K33 is connected to the negative electrode of the photovoltaic unit composed of PV1 and PV2; the first switch K32 is connected to the second switch K34 through the power converter 2, so one end of the first switch K32 is connected to the positive electrode of the photovoltaic unit composed of PV4 and PV5, and one end of the second switch K34 is connected to the negative electrode of the photovoltaic unit composed of PV4 and PV5; the positive electrode of the jumper photovoltaic string PV3 is connected to the positive electrode of the photovoltaic unit composed of PV1 and PV2, and the negative electrode of the jumper photovoltaic string PV3 is connected to the negative electrode of the photovoltaic unit composed of PV4 and PV5; the positive electrode of the jumper photovoltaic string PV6 is connected to the positive electrode of the photovoltaic unit composed of PV4 and PV5, and the negative electrode of the jumper photovoltaic string PV6 is connected to the negative electrode of the photovoltaic unit composed of PV1 and PV2. Therefore, two cross-connected photovoltaic strings can be added between two photovoltaic units. When the number of protective switches in the photovoltaic system remains unchanged, the number of connected photovoltaic strings can be increased while ensuring that the backflow current will not cause damage to the photovoltaic strings, thereby ensuring the safe operation of the photovoltaic system. In addition, when the number of photovoltaic units in the photovoltaic system increases, cross-connected photovoltaic strings can be cross-connected between different photovoltaic units, or two adjacent photovoltaic units can be connected through two cross-connected photovoltaic strings, for example, two cross-connected photovoltaic strings can be cross-connected between the second photovoltaic unit and the third photovoltaic unit, and between the third photovoltaic unit and the fourth photovoltaic unit, thereby further increasing the number of photovoltaic strings.

[0045] It should be noted that when a photovoltaic string is connected with the positive and negative poles reversed, the control protection switch assembly 1 is completely disconnected. For example, when the protection switch assembly 1 is completely disconnected and the positive and negative poles of PV1 are reversed, refer to Figure 8 In the simplified structural diagram of the photovoltaic power generation system shown in the figure, current is generated between PV1 and PV2, and current backflow occurs. The reverse-connected PV1 is only impacted by the current and voltage of PV2. At this time, the current and voltage are not large, and will not cause damage to the reverse-connected PV1. Similarly, when the positive and negative poles of PV2 are reversed, a similar situation will occur. The reverse-connected PV2 is only impacted by the current and voltage of PV1, and will not cause damage to the reverse-connected PV2. However, when there are many photovoltaic strings connected in parallel in the photovoltaic unit, the reverse-connected PV will be impacted by the current and voltage of multiple photovoltaic strings. At this time, the current and voltage generated by multiple photovoltaic strings will be superimposed on each other, which will have a greater impact on the reverse-connected PV and is easy to be damaged. When the positive and negative poles of the cross-connected photovoltaic string PV3 are reversed, and the protection switch component 1 is completely disconnected, such as Figure 8 As shown, no reverse current will be generated, and there will be no short circuit of the photovoltaic strings, and no damage will be caused to the photovoltaic strings, thereby further improving the safety of the use of the photovoltaic system.

[0046] Although the utility model is disclosed as above, the utility model is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the utility model. Therefore, the protection scope of the utility model shall be subject to the scope defined by the claims.

Claims

1. A photovoltaic power generation system, characterized in that: The device comprises at least two photovoltaic units, a cross-connected photovoltaic string, at least two switch units and a power converter; The photovoltaic unit includes at most two photovoltaic strings, the positive poles of the two photovoltaic strings are connected to form the positive pole of the photovoltaic unit, the negative poles of the two photovoltaic strings are connected to form the negative pole of the photovoltaic unit, the photovoltaic unit corresponds to the switch unit one by one, the positive pole of the photovoltaic unit is connected to the first pin of the corresponding switch unit, the second pin of the switch unit is connected to the positive pole of the corresponding input end of the power converter, the negative pole of the input end of the power converter is connected to the third pin of the switch unit, and the fourth pin of the switch unit is connected to the negative pole of the corresponding photovoltaic unit. The jumper photovoltaic string is provided in at least one photovoltaic unit group, and each photovoltaic unit group includes two photovoltaic units, the positive pole of the jumper photovoltaic string is connected to the positive pole of one photovoltaic unit, and the negative pole of the jumper photovoltaic string is connected to the negative pole of another photovoltaic unit.

2. The photovoltaic power generation system according to claim 1, characterized in that: The switch unit includes a first switch and a second switch, one end of the first switch is connected to the first pin, the other end of the first switch is connected to the second pin, one end of the second switch is connected to the third pin, and the other end of the second switch is connected to the fourth pin.

3. The photovoltaic power generation system according to claim 1, characterized in that: Every two adjacent photovoltaic units form a photovoltaic unit group.

4. The photovoltaic power generation system according to claim 3, characterized in that: The two photovoltaic units in each photovoltaic unit group are connected via a cross-connected photovoltaic string.

5. The photovoltaic power generation system according to claim 1, characterized in that: The number of the jumper photovoltaic strings set in at least one of the photovoltaic unit groups is two, wherein the positive pole of one of the jumper photovoltaic strings is connected to the positive pole of one of the photovoltaic units in the corresponding photovoltaic unit group, the positive pole of another of the jumper photovoltaic strings is connected to the positive pole of another of the photovoltaic units in the corresponding photovoltaic unit group, the negative pole of one of the jumper photovoltaic strings is connected to the negative pole of another of the photovoltaic units in the corresponding photovoltaic unit group, and the negative pole of another of the jumper photovoltaic strings is connected to the negative pole of one of the photovoltaic units in the corresponding photovoltaic unit group.

6. The photovoltaic power generation system according to claim 2, characterized in that: The first switch and the second switch are both manual switches.

7. The photovoltaic power generation system according to claim 2, characterized in that: The first switch and the second switch are both controllable switches.

8. The photovoltaic power generation system according to claim 2, characterized in that: The first switch and the second switch are respectively any one of a relay, a transistor or a field effect transistor.

9. The photovoltaic power generation system according to claim 7, characterized in that: A controller is also included. The controller is electrically connected to the first switch and the second switch, respectively, and is used to control the on and off of the first switch and the second switch.

10. The photovoltaic power generation system according to claim 9, characterized in that: The controller is electrically connected to the power converter and is used to control the power converter.

Images