Photovoltaic system
By using a combination of access control circuits and diodes in the photovoltaic system, the problem of excessive switching current and voltage load when the polarity of the photovoltaic group is incorrect is solved, reducing costs and improving system stability.
Patent Information
- Application Number
- CN202420662461.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-02
- Publication Date
- 2025-01-14
- Estimated Expiration
- 2034-04-02
AI Technical Summary
When the polarity of existing photovoltaic groups is incorrect in series, the disconnect switches bear high voltage and current, resulting in increased performance parameters and increased costs.
A photovoltaic system is designed, through the combination of the first access control circuit and the second access control circuit and the diode, to ensure that when the polarity of the photovoltaic group is incorrect in series, the current and voltage flowing through the control circuit are not greater than the access. Double the polarity when the correct one is used to break the current and voltage by combining switches and diodes.
It effectively reduces the current and voltage load of the switch in the case of polarity errors, avoids cost increases, and ensures the stability and safety of the system.
Smart Images
Figure CN222356326U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of photovoltaic power generation, in particular to a photovoltaic system. Background Art
[0002] Photovoltaic cell modules are an important component of solar grid-connected power generation. Their function is to convert solar energy into direct current. Their output is usually connected to a photovoltaic inverter, and then converted into alternating current of a specific amplitude and phase and fed into the grid. In the common access form of photovoltaic cell modules, in order to improve the utilization rate of the power conversion unit, multiple groups of two-in-one photovoltaic strings can be connected in parallel through a disconnect switch to the same confluence device, and the number of connections can be changed to adapt to photovoltaic strings of different power or current levels. However, a problem with this access method is that once a photovoltaic string is connected to the wrong polarity and needs to be disconnected, the disconnect switch will be subjected to higher voltage and current, and as the number of branches of the photovoltaic string connected to a single confluence device increases, the short-circuit fault current will also increase exponentially. This undoubtedly places high demands on the performance parameters of the disconnect switch, and the cost will also increase significantly. Utility Model Content
[0003] In view of this, it is necessary to provide a photovoltaic system to solve the problem in the prior art that when the photovoltaic string access circuit is connected with the wrong polarity, the disconnect switch needs to have higher performance parameters, resulting in increased costs.
[0004] In a first aspect, a photovoltaic system is provided in this embodiment, the photovoltaic system comprising a plurality of photovoltaic strings, a busbar device, and an access circuit for connecting the photovoltaic strings and the busbar device, the plurality of photovoltaic strings comprising a first photovoltaic string, a second photovoltaic string, and a third photovoltaic string, the access circuit comprising a first access control circuit, a second access control circuit, and a diode;
[0005] One end of the first access control circuit is connected to the output ends of the first photovoltaic string and the second photovoltaic string, and the other end of the first access control circuit is connected to the input end of the converging device;
[0006] One end of the second access control circuit is connected to one end of the diode, and the other end of the second access control circuit is connected to the input end of the converging device; the other end of the diode is connected to the output end of the third photovoltaic string.
[0007] In a further embodiment, the first access control circuit and the second access control circuit are connected to the positive output terminals of the corresponding photovoltaic strings, and the positive electrode of the diode is connected to the positive output terminal of the third photovoltaic string; or
[0008] The first access control circuit and the second access control circuit are connected to the negative output end of the corresponding photovoltaic string, and the cathode of the diode is connected to the negative output end of the third photovoltaic string.
[0009] In a further embodiment, the first access control circuit includes a first switch, and the first switch disconnects the first photovoltaic string, the second photovoltaic string, and the busbar device based on a received first disconnection control signal.
[0010] In a further embodiment, the second access control circuit includes a second switch, and the second switch disconnects the third photovoltaic string from the busbar device based on a received second disconnection control signal.
[0011] In a further embodiment, the access circuit also includes a controller connected to the first access control circuit and the second access control circuit, and the controller performs abnormality determination on the input voltage or input current of the first access control circuit and the second access control circuit, and sends a disconnection control signal to the corresponding access control circuit when the determination result is abnormal.
[0012] In a further embodiment, the access circuit also includes a sampling circuit, which is connected to the first access control circuit, the second access control circuit and the controller, and is used to sample the input voltage or input current of the first access control circuit and the second access control circuit and send it to the controller.
[0013] In a further embodiment, the first photovoltaic string, the second photovoltaic string and the third photovoltaic string are all single photovoltaic components.
[0014] In a further embodiment, the first photovoltaic string, the second photovoltaic string and the third photovoltaic string are composed of the same number of multiple photovoltaic modules connected in series.
[0015] In a further embodiment, the first switch includes any one or more devices selected from the group consisting of MOSFET, IGBT, triode, relay, and circuit breaker.
[0016] In a further embodiment, the current converging device comprises a DC / DC converter or a DC / AC converter.
[0017] The photovoltaic system of the utility model connects the first photovoltaic string and the second photovoltaic string to the convergence device accordingly through the first access control circuit, and connects the third photovoltaic string to the convergence device accordingly through the second access control circuit and the diode. Based on the above connection, when any photovoltaic string among the first photovoltaic string, the second photovoltaic string and the third photovoltaic string is connected with wrong polarity, the current and voltage flowing through the first access control circuit and the second access control circuit are not more than twice the current and voltage when the access polarity is correct, which solves the problem in the prior art that when the photovoltaic string is connected with wrong polarity, the disconnecting switch needs to have higher performance parameters, resulting in increased costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 is a schematic diagram of the structure of a photovoltaic system in some embodiments of the present application;
[0019] Figure 2 is a circuit connection topology diagram of a photovoltaic system according to some embodiments of the present application;
[0020] Figure 3 is a circuit diagram of a first photovoltaic string connected to an incorrect polarity in some embodiments of the present application;
[0021] Figure 4 is a circuit diagram of a third photovoltaic string connected to an incorrect polarity in some embodiments of the present application;
[0022] Figure 5 is a circuit connection topology diagram of a photovoltaic system in some other embodiments of the present application;
[0023] Figure 6 is a schematic diagram of the structure of a photovoltaic system in some other embodiments of the present application;
[0024] Figure 7 Schematic diagram of the structure of photovoltaic systems according to some other embodiments of the present application. DETAILED DESCRIPTION
[0025] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0026] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a component centered at the same time. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a component centered at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only. "First" and "second" are only for the distinction of component names and do not indicate order.
[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0028] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. Among them, the utility model embodiment is described in detail in conjunction with the schematic diagram, and the schematic diagram is only an example, which should not limit the scope of protection of the utility model.
[0029] The photovoltaic system provided by the embodiment of the utility model is further described in detail below in conjunction with the accompanying drawings.
[0030] See also Figure 1 , which is a schematic diagram of the structure of a photovoltaic system in some embodiments of the present application. The photovoltaic system includes a plurality of photovoltaic strings 11, 12, 13 and a confluence device 30, and an access circuit 20 for connecting the photovoltaic strings 11, 12, 13 and the confluence device 30. The plurality of photovoltaic strings include a first photovoltaic string 11, a second photovoltaic string 12, and a third photovoltaic string 13, and the access circuit 20 includes a first access control circuit 21, a second access control circuit 22, and a diode 23.
[0031] One end of the first access control circuit 21 is connected to the output ends of the first photovoltaic string 11 and the second photovoltaic string 12, and the other end of the first access control circuit 21 is connected to the input end of the convergence device 30; one end of the second access control circuit 22 is connected to one end of the diode 23, and the other end of the second access control circuit 22 is connected to the input end of the convergence device 30; the other end of the diode 23 is connected to the output end of the third photovoltaic string 13.
[0032] In some embodiments, the first photovoltaic string 11 , the second photovoltaic string 12 , and the third photovoltaic string 13 are all single photovoltaic modules.
[0033] In some other embodiments, the first photovoltaic string 11, the second photovoltaic string 12, and the third photovoltaic string 13 are composed of the same number of multiple photovoltaic modules connected in series.
[0034] In some embodiments, the current converging device 30 includes a DC / DC converter or a DC / AC converter.
[0035] The first access control circuit 21 can control the connection between the first photovoltaic string 11, the second photovoltaic string 12 and the convergence device 30 to be turned on or off; the second access control circuit 22 can control the connection between the third photovoltaic string 13 and the convergence device 30 to be turned on or off.
[0036] During the operation of the photovoltaic system, the output voltage or current of the photovoltaic string may be abnormal due to its own fault or external factors. When the abnormal voltage or abnormal current is sent to the convergence device 30 through the access circuit 20, it may cause the convergence device to work abnormally or even damage the device, and may also affect the working state of other photovoltaic strings. Therefore, it is necessary to detect each voltage or current signal connected, and cut off the connection between the photovoltaic string and the convergence device 30 in time when the voltage or current is abnormal, so as to avoid affecting the working state of the convergence device or even damaging the device.
[0037] In a specific embodiment, the first photovoltaic string 11, the second photovoltaic string 12 and the converging device 30 are connected by default. The first access control circuit 21 includes a first switch K1, and the first switch K1 disconnects the first photovoltaic string 11, the second photovoltaic string 12 and the converging device 30 based on the received first disconnection control signal.
[0038] In a specific embodiment, the third photovoltaic string 13 is connected to the converging device 30 by default. The second access control circuit 22 includes a second switch K2, which disconnects the third photovoltaic string 13 from the converging device 30 based on the received second disconnection control signal.
[0039] The first switch K1 may be any one or more devices selected from the group consisting of MOSFET, IGBT, triode, relay, and circuit breaker.
[0040] The second switch K2 may be any one or more devices selected from the group consisting of MOSFET, IGBT, triode, relay, and circuit breaker.
[0041] Figure 2is a circuit connection topology diagram of a photovoltaic system in some embodiments of the present application, such as Figure 2 As shown, the first access control circuit 21 and the second access control circuit 22 are connected to the positive output ends of the corresponding photovoltaic strings 11 and 12 , and the positive electrode of the diode 23 is connected to the positive output end of the third photovoltaic string 13 .
[0042] The first access control circuit 21 and the second access control circuit 22 are connected to the positive input terminal of the converging device. The negative output terminals of the first photovoltaic string 11, the second photovoltaic string 12, and the third photovoltaic string 13 are connected to the negative input terminal of the converging device. The first access control circuit 21 includes a first switch K1, and the second access control circuit 22 includes a second switch K2.
[0043] When the first photovoltaic string 11, the second photovoltaic string 12, and the third photovoltaic string 13 are connected with correct polarity, assuming that the voltage between the positive output terminal and the negative output terminal of each photovoltaic string is U, and the output current of each photovoltaic string is I, the current passing through the first switch K1 is 2I, and the voltage borne by the first switch K1 is U; the current passing through the second switch K2 is I, and the voltage borne by the second switch K2 is U.
[0044] Figure 3 is a circuit diagram of a first photovoltaic string connected to an incorrect polarity in some embodiments of the present application, such as Figure 3 As shown, in the case where the first photovoltaic string 11 is connected with the wrong polarity, the first photovoltaic string 11 and the second photovoltaic string 12 are connected in series and form a closed loop, which can be regarded as a wire; the third photovoltaic string 13 normally outputs current I, and the current I enters the wire through the second switch K2 and the first switch K1 in sequence, so the current passing through the first switch K1 is I, and the current passing through the second switch K2 is I. The positive output terminal voltage of the third photovoltaic string 13 is U, and the wire voltage formed by the first photovoltaic string 11 and the second photovoltaic string 12 is 0, so the voltages borne by the first switch K1 and the second switch K2 are both U. It can be seen that in the case where the first photovoltaic string 11 is connected with the wrong polarity, the voltage and current borne by the first switch K1 and the second switch K2 do not exceed the voltage and current borne under normal circumstances.
[0045] The situation in which the second photovoltaic string 12 is connected with the wrong polarity is the same as that of the first photovoltaic string 11 , and will not be described again.
[0046] Figure 4 is a circuit diagram of a third photovoltaic string connected to an incorrect polarity in some embodiments of the present application, such as Figure 4As shown, when the third photovoltaic string 13 is connected with the wrong polarity, since the positive electrode of the diode 23 is connected to the positive output terminal of the third photovoltaic string 13, the negative electrode of the diode 23 is connected to the second switch K2, and the voltage of the negative electrode of the diode 23 is higher than the positive electrode, the diode 23 is not turned on, and the current through the second switch K2 is 0. The currents of the first photovoltaic string 11 and the second photovoltaic string 12 are output normally, so the current through the first switch K1 is 2I. Since the output voltage of the positive output terminal of the first photovoltaic string 11 and the second photovoltaic string 12 is U, and the voltage of the negative output terminal of the third photovoltaic string 13 connected with the wrong polarity is -U, the voltages borne by the first switch K1 and the second switch K2 are both 2U. It can be seen that when the third photovoltaic string 13 is connected with the wrong polarity, the current borne by the first switch K1 and the second switch K2 does not exceed the current borne under normal circumstances, and the voltage borne by the first switch K1 and the second switch K2 does not exceed twice the voltage borne under normal circumstances, which solves the problem in the prior art that when the photovoltaic string is connected with the wrong polarity, the disconnecting switch needs to have higher performance parameters, resulting in increased costs.
[0047] Figure 5 is a circuit connection topology diagram of a photovoltaic system in some other embodiments of the present application, such as Figure 5 As shown, the first access control circuit 21 and the second access control circuit 22 are connected to the negative output end of the corresponding photovoltaic string, and the cathode of the diode 23 is connected to the negative output end of the third photovoltaic string 13 .
[0048] The first access control circuit 21 and the second access control circuit 22 are connected to the negative input terminal of the converging device. The positive output terminals of the first photovoltaic string 11, the second photovoltaic string 12, and the third photovoltaic string 13 are connected to the positive input terminal of the converging device. The first access control circuit 21 includes a first switch K1, and the second access control circuit 22 includes a second switch K2.
[0049] When the first photovoltaic string 11, the second photovoltaic string 12, and the third photovoltaic string 13 are connected with correct polarity, assuming that the voltage between the positive output terminal and the negative output terminal of each photovoltaic string is U, and the output current of each photovoltaic string is I, the current passing through the first switch K1 is 2I, and the voltage borne by the first switch K1 is U; the current passing through the second switch K2 is I, and the voltage borne by the second switch K2 is U.
[0050] Similar to the above embodiment, when the first photovoltaic string 11 is connected with the wrong polarity, the first photovoltaic string 11 and the second photovoltaic string 12 are connected in series and form a closed loop, which can be regarded as a wire; the third photovoltaic string 13 normally outputs current I, and the current I enters the wire through the second switch K2 and the first switch K1 in sequence, so the current passing through the first switch K1 is I, and the current passing through the second switch K2 is I. The negative output terminal voltage of the third photovoltaic string 13 is -U, and the voltage of the wire formed by the first photovoltaic string 11 and the second photovoltaic string 12 is 0, so the voltages borne by the first switch K1 and the second switch K2 are both U. It can be seen that when the first photovoltaic string 11 is connected with the wrong polarity, the voltage and current borne by the first switch K1 and the second switch K2 do not exceed the voltage and current borne under normal circumstances.
[0051] The situation in which the second photovoltaic string 12 is connected with the wrong polarity is the same as that of the first photovoltaic string 11 , and will not be described again.
[0052] Similar to the above embodiment, when the third photovoltaic string 13 is connected with the wrong polarity, since the cathode of the diode 23 is connected to the negative output terminal of the third photovoltaic string 13 and the anode of the diode 23 is connected to the second switch K2, the voltage of the cathode of the diode 23 is higher than that of the anode, the diode 23 is not conducting, the current passing through the second switch K2 is 0, and the current of the first photovoltaic string 11 and the second photovoltaic string 12 is output normally, so the current passing through the first switch K1 is 2I. Since the output voltage of the positive output terminal of the first photovoltaic string 11 and the second photovoltaic string 12 is U and the voltage of the negative output terminal is 0, and the voltage of the negative output terminal of the third photovoltaic string 13 is U and the voltage of the positive output terminal is 2U due to the wrong polarity connection, the voltage of the negative output terminal is U and the voltage of the positive output terminal is 2U, so the voltages borne by the first switch K1 and the second switch K2 are both 2U. It can be seen that when the third photovoltaic string 13 is connected with the wrong polarity, the current borne by the first switch K1 and the second switch K2 does not exceed the current borne under normal circumstances, and the voltage borne by the first switch K1 and the second switch K2 does not exceed twice the voltage borne under normal circumstances, which solves the problem in the prior art that when the photovoltaic string is connected with the wrong polarity, the disconnecting switch needs to have higher performance parameters, resulting in increased costs.
[0053] In some embodiments, Figure 6 is a schematic diagram of the structure of a photovoltaic system in some other embodiments of the present application, such as Figure 6 As shown, the access circuit 20 also includes a controller 24 connected to the first access control circuit 21 and the second access control circuit 22. The controller 24 performs abnormality determination on the input voltage or input current of the first access control circuit 21 and the second access control circuit 22, and sends a disconnection control signal to the corresponding access control circuit when the determination result is abnormal.
[0054] In this embodiment, the controller 24 may be a device with signal processing, data storage, and signal sending and receiving functions, including but not limited to a single chip microcomputer, an MCU, a CPU, etc. The controller 24 may receive a digital signal corresponding to the input voltage or input current of the first access control circuit 21 and the second access control circuit 22, and perform an abnormality determination based on a pre-stored voltage threshold or current threshold. When an abnormal condition is met, a disconnection control signal is sent to the corresponding access control circuit, and the corresponding control circuit controls the first switch K1 or the second switch K2 to disconnect according to the disconnection control signal, that is, disconnects the connection between the corresponding photovoltaic string and the converging device 30.
[0055] In a further embodiment, Figure 7 is a schematic diagram of the structure of a photovoltaic system in some other embodiments of the present application, such as Figure 7 As shown, the access circuit 20 also includes a sampling circuit 25, which is connected to the first access control circuit 21, the second access control circuit 22 and the controller 24, and is used to sample the input voltage or input current of the first access control circuit 21 and the second access control circuit 22 and send it to the controller 24.
[0056] The sampling circuit 25 is used to sample the input voltage or input current of the first access control circuit 21 and the second access control circuit 22, and convert the sampled analog signal into a digital signal and send it to the controller 24. The sampling circuit 25 may include but is not limited to an amplifier circuit and an analog-to-digital conversion circuit.
[0057] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0058] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.
Claims
1. A photovoltaic system, comprising a plurality of photovoltaic strings, a busbar device, and an access circuit for connecting the photovoltaic strings and the busbar device, wherein the plurality of photovoltaic strings comprises a first photovoltaic string, a second photovoltaic string, and a third photovoltaic string, wherein: The access circuit includes a first access control circuit, a second access control circuit and a diode; One end of the first access control circuit is connected to the output ends of the first photovoltaic string and the second photovoltaic string, and the other end of the first access control circuit is connected to the input end of the converging device; One end of the second access control circuit is connected to one end of the diode, and the other end of the second access control circuit is connected to the input end of the converging device; the other end of the diode is connected to the output end of the third photovoltaic string.
2. The photovoltaic system according to claim 1, characterized in that: The first access control circuit and the second access control circuit are connected to the positive output terminals of the corresponding photovoltaic strings, and the positive electrode of the diode is connected to the positive output terminal of the third photovoltaic string; or The first access control circuit and the second access control circuit are connected to the negative output end of the corresponding photovoltaic string, and the cathode of the diode is connected to the negative output end of the third photovoltaic string.
3. The photovoltaic system according to claim 1, characterized in that: The first access control circuit includes a first switch, and the first switch disconnects the first photovoltaic string, the second photovoltaic string, and the busbar device based on a received first disconnection control signal.
4. The photovoltaic system according to claim 1, characterized in that: The second access control circuit includes a second switch, and the second switch disconnects the third photovoltaic string from the busbar device based on a received second disconnection control signal.
5. The photovoltaic system according to claim 1, characterized in that: The access circuit also includes a controller connected to the first access control circuit and the second access control circuit. The controller performs abnormality determination on the input voltage or input current of the first access control circuit and the second access control circuit, and sends a disconnection control signal to the corresponding access control circuit when the determination result is abnormal.
6. The photovoltaic system according to claim 5, characterized in that: The access circuit also includes a sampling circuit, which is connected to the first access control circuit, the second access control circuit and the controller, and is used to sample the input voltage or input current of the first access control circuit and the second access control circuit and send it to the controller.
7. The photovoltaic system according to claim 1, characterized in that: The first photovoltaic string, the second photovoltaic string and the third photovoltaic string are all single photovoltaic components.
8. The photovoltaic system according to claim 1, characterized in that: The first photovoltaic string, the second photovoltaic string and the third photovoltaic string are composed of a same number of multiple photovoltaic modules connected in series.
9. The photovoltaic system according to claim 3, characterized in that: The first switch includes any one or more devices selected from the group consisting of MOSFET, IGBT, triode, relay, and circuit breaker.
10. The photovoltaic system according to claim 1, characterized in that: The current converging device includes a DC / DC converter or a DC / AC converter.