CN113014198A

CN113014198A - Photovoltaic system

Info

Publication number: CN113014198A
Application number: CN202110354582.3A
Authority: CN
Inventors: 陈爱棠; 李琳; 郭海滨; 林建飞
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2021-06-22
Anticipated expiration: 2041-03-31
Also published as: WO2022206576A1; CN113014198B

Abstract

The application provides a photovoltaic system, wherein a controller obtains a first working parameter of a first DC/DC converter and a second working parameter of a first inverter, wherein the first working parameter is a relevant parameter which can be used for representing the power-on state of the first DC/DC converter, and the second working parameter is a relevant parameter which can be used for representing the power-on state of the first inverter; then, when the controller determines that at least one first working parameter is a first preset parameter and at least one second working parameter is a second preset parameter in the photovoltaic system, it may be determined that a wrong wiring condition exists between a first DC/DC converter and a first inverter in the photovoltaic system at the time. The controller can realize wiring error detection by utilizing the first working parameter and the second working parameter, has high detection accuracy, is simple to realize and does not need to increase an additional hardware circuit.

Description

Photovoltaic system

Technical Field

The embodiment of the invention relates to the field of photovoltaics, in particular to a photovoltaic system.

Background

The photovoltaic system includes a dc unit outputting dc power and an inverter for converting ac power and dc power, and it is important to ensure accurate connection between the dc unit and the inverter.

Disclosure of Invention

The application provides a photovoltaic system, which can quickly and accurately identify wiring errors between a DC/DC converter and an inverter of the photovoltaic system.

In a first aspect, the embodiment of the present invention provides a photovoltaic system, where the photovoltaic system includes a controller, at least one first DC/DC converter, at least one first inverter, and at least one first DC/DC converter, where a bus voltage of the at least one first DC/DC converter is input to the at least one first inverter, where the controller is configured to obtain a first operating parameter of the at least one first DC/DC converter and a second operating parameter of the at least one first inverter in the photovoltaic system; and when the at least one first working parameter is a first preset parameter and the at least one second working parameter is a second preset parameter, determining that the connection fault condition exists between the first DC/DC converter and the first inverter. The first DC/DC converter may be a DC/DC converter that outputs a positive bus voltage or a DC/DC converter that outputs a negative bus voltage.

In the photovoltaic system in the embodiment of the invention, the controller acquires a first working parameter of the first DC/DC converter and a second working parameter of the first inverter, wherein the first working parameter is a relevant parameter which can be used for representing a power-on state of the first DC/DC converter, and the second working parameter is a relevant parameter which can be used for representing a power-on state of the first inverter; then, when the controller determines that at least one first working parameter is a first preset parameter and at least one second working parameter is a second preset parameter in the photovoltaic system, it may be determined that a wrong wiring condition exists between a first DC/DC converter and a first inverter in the photovoltaic system at the time. Therefore, the controller can realize the wiring error detection by utilizing the first working parameter and the second working parameter, the detection accuracy is high, the realization is simple, and no additional hardware circuit is required to be added.

In one possible embodiment, the photovoltaic system further comprises at least one second DC/DC converter and at least one second inverter, the bus voltage of the at least one second DC/DC converter is input to the at least one second inverter, the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and the first DC/DC converter and the second DC/DC converter share a neutral line.

In an embodiment of the present invention, the photovoltaic system may further include a second DC/DC converter and a second inverter, wherein the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and the first DC/DC converter and the second DC/DC converter share a zero line. Specifically, when the bus voltage output by the first DC/DC converter is a positive voltage, the bus voltage of the second DC/DC converter is a negative voltage; when the bus voltage output by the first DC/DC converter is negative voltage, the bus voltage of the second DC/DC converter is positive voltage. In this embodiment, in the photovoltaic system, the first DC/DC converter and the second DC/DC converter share the zero line, so long as it is ensured that the input powers of the two are substantially the same, when power is transmitted, the current does not substantially flow through the zero line, and the bus voltage difference between the two is twice the original DC bus voltage, so that the transmission current is substantially halved.

In a possible embodiment, the controller is further configured to obtain a third operating parameter of the at least one second DC/DC converter and a fourth operating parameter of the at least one second inverter in the photovoltaic system; and when the at least one third working parameter is a first preset parameter and the at least one fourth working parameter is a second preset parameter, determining that the wiring between the second DC/DC converter and the second inverter has a wrong wiring condition.

In the embodiment of the present invention, when detecting whether a wiring error exists in the photovoltaic system, the controller may further obtain a third operating parameter of the second DC/DC converter and a fourth operating parameter of the second inverter, where the third operating parameter is a relevant parameter that may be used to characterize a power-on state of the second DC/DC converter, and the fourth operating parameter is a relevant parameter that may be used to characterize a power-on state of the second inverter; when the controller determines that the at least one third operating parameter is the first preset parameter and the at least one fourth operating parameter is the second preset parameter, it may be determined that a wrong wiring condition exists in a wiring between a first DC/DC converter and a first inverter in the photovoltaic system at the time.

In one possible embodiment, the first operating parameter and/or the third operating parameter includes an output voltage of the DC/DC converter and/or first heartbeat packet status information, and the first heartbeat packet status information is used to characterize whether the controller receives a heartbeat packet sent by the DC/DC converter. Specifically, the first operating parameter may be an output voltage of the first DC/DC converter and/or first heartbeat packet status information of the first DC/DC converter, where the first heartbeat packet status information of the first DC/DC converter represents whether the controller receives a heartbeat packet sent by the first DC/DC converter. And the third operating parameter may be the output voltage of the second DC/DC converter and/or the first heartbeat packet status information of the second DC/DC converter, where the first heartbeat packet status information of the second DC/DC converter indicates whether the controller receives the heartbeat packet sent by the second DC/DC converter.

The second working parameter and/or the fourth working parameter comprise input voltage of the inverter and/or second heartbeat packet state information, and the second heartbeat packet state parameter is used for representing whether the controller receives heartbeat packets sent by the inverter or not. Specifically, the second operating parameter may be an input voltage of the first inverter and/or second heartbeat packet state information of the first inverter, where the second heartbeat packet state information of the first inverter represents whether the controller receives a heartbeat packet sent by the first inverter. And the fourth operating parameter may be an input voltage of the second inverter and/or second heartbeat packet state information of the second inverter, and at this time, the second heartbeat packet state information of the second inverter represents whether the controller receives a heartbeat packet sent by the second inverter.

In one possible embodiment, the photovoltaic system further includes an inverter monitor connected to the first inverter and/or the second inverter to receive the heartbeat packet sent by the first inverter and/or the second inverter, wherein the inverter monitor is configured to obtain second heartbeat packet status information of the first inverter and/or the second inverter and send the second heartbeat packet status information to the controller.

In an embodiment of the present invention, the second heartbeat packet status information of the first inverter and/or the second inverter may be obtained by the inverter monitor. The inverter monitor can be communicated with the first inverter and/or the second inverter, and the inverter monitor determines second heartbeat packet state information corresponding to the first inverter and/or the second inverter respectively according to whether heartbeat packets of the first inverter and/or the second inverter are received.

In one possible embodiment, when the at least one first DC/DC converter is at least two first DC/DC converters, the first DC/DC converters are connected to the photovoltaic system in the front, and the second DC/DC converters are connected after the first DC/DC converters are connected to generate the bus voltage, wherein the controller is further configured to obtain voltage information of the at least one first DC/DC converter, wherein the voltage information is obtained after the second DC/DC converters are connected to the photovoltaic system; and determining whether a wrong connection condition exists in the connection between the at least two first DC/DC converters and the at least one first inverter according to the voltage information.

In the embodiment of the invention, when the first-class DC/DC converter and the second-class DC/DC converter which are connected in sequence exist, after the second-class DC/DC converter is connected in, the controller acquires the voltage information of at least one first DC/DC converter, and according to the at least one voltage information, whether the wiring between at least two first DC/DC converters and at least one first inverter has the wiring fault condition can be determined.

In a possible embodiment, the controller is further configured to obtain a first input voltage of the at least one first inverter when the first DC/DC converter is connected to the photovoltaic system; and when the voltage type of the at least one first input voltage is a preset voltage type, determining that the connection between the first DC/DC converter and the first inverter has a wrong connection condition.

In the embodiment of the invention, when the first DC/DC converter is connected to the photovoltaic system, the controller may determine that a wrong connection condition exists in a connection between the first DC/DC converter and the first inverter when determining that the voltage type of the at least one first input voltage is the preset voltage type by acquiring the first input voltage of the at least one first inverter.

In one possible embodiment, the controller is further configured to output a wiring error warning message when it is determined that a wiring error condition exists.

In the embodiment of the invention, when the controller determines that the condition of wrong wiring exists in the photovoltaic system, the controller outputs the wiring error warning information to remind workers of paying attention to the abnormal wiring condition and timely process the wiring error condition, so that the photovoltaic system is prevented from being further damaged due to the wiring error.

In a second aspect, the embodiment of the present invention further provides a photovoltaic system, which includes a controller, at least two first DC/DC converters, at least one first inverter, wherein bus voltages of the at least two first inverters are input to the at least one first inverter; the at least two first DC/DC converters are divided into a first type DC/DC converter which is connected into the photovoltaic system in front and a second type DC/DC converter which is connected after the first type DC/DC converter is connected and generates bus voltage; the controller is used for acquiring voltage information of at least one first DC/DC converter, wherein the voltage information is acquired after the second type of DC/DC converter is connected to the photovoltaic system; and determining whether a wrong connection condition exists in the connection between the at least two first DC/DC converters and the at least one first inverter according to the voltage information.

In the embodiment of the invention, when the first type DC/DC converter and the second type DC/DC converter which are connected in sequence exist, after the second type DC/DC converter is connected in, the controller acquires the voltage information of at least one first DC/DC converter, and can determine whether the wiring between at least two first DC/DC converters and at least one first inverter has the wiring error condition or not according to at least one voltage information, so that the wiring error detection can be realized by using the voltage information of the first DC/DC converter, the detection is accurate and simple to realize, and no additional hardware circuit is required to be added.

In one possible embodiment, the controller is specifically configured to: when the first DC/DC converter is a DC/DC converter outputting a positive bus voltage, acquiring a first voltage state parameter and a first working current of the first DC/DC converter as voltage information, wherein the first voltage state parameter is used for representing the bus voltage change condition of the first DC/DC converter; at the at least one first DC/DC converter: and when the first working current is not equal to zero and the first voltage state parameter meets a first preset voltage state condition, determining that the condition of wrong line connection exists.

In an embodiment of the present invention, when the first DC/DC converter is a DC/DC converter outputting a positive bus voltage, the first voltage state parameter and the first operating current of the first DC/DC converter may be used as the voltage information. The first working current is an input current or an output current of the first DC/DC converter. The first voltage status parameter may include a bus voltage of the first DC/DC converter and/or a bus voltage droop rate of the first DC/DC converter; in another possible case, the first voltage status parameter may comprise a bus voltage of the at least two first DC/DC converters and/or a bus voltage drop rate of the at least two first DC/DC converters. The controller, upon determining that the at least one first DC/DC converter satisfies: when the first working current is not equal to zero and the first voltage state parameter meets the first preset voltage state condition, it can be determined that a wrong connection condition exists between the at least two first DC/DC converters and the at least one first inverter in the photovoltaic system.

In one possible embodiment, the controller is specifically configured to: when the first DC/DC converter is a DC/DC converter with a level inversion function to output negative bus voltage, acquiring a level inversion state parameter of the first DC/DC converter as voltage information, wherein the level inversion state parameter is used for representing a level inversion working state of the first DC/DC converter; and when at least one level turnover state parameter meets the preset level turnover state parameter condition, determining that the condition of wrong line connection exists.

In the embodiment of the present invention, when the first DC/DC converter is a DC/DC converter having a level flipping function to output a negative bus voltage, a level flipping state parameter of the first DC/DC converter may be used as voltage information, where the level flipping state parameter is used to represent a level flipping operating state of the first DC/DC converter, the level flipping operating state includes a flipping success and a flipping failure, and when the level flipping state parameter satisfies a preset level flipping state parameter condition, it indicates that the level flipping of the first DC/DC converter fails, and otherwise, when the level flipping state parameter does not satisfy the preset level flipping state parameter condition, it indicates that the first DC/DC converter successfully flips the level. The level inversion state parameters comprise level inversion time and/or inversion voltage of the first DC/DC converter, and the inversion voltage is bus voltage output by the first DC/DC converter after level inversion. And when the controller determines that the at least one level upset state parameter meets the preset level upset state parameter condition, the controller can determine that the wiring between the at least two first DC/DC converters and the at least one first inverter in the photovoltaic system has a wrong wiring condition.

In one possible embodiment, the photovoltaic system further comprises at least two second DC/DC converters and at least one second inverter, the bus voltage of the at least one second DC/DC converter is input to the at least one second inverter, the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and the first DC/DC converter and the second DC/DC converter share a zero line; the controller is further used for determining whether the connection between the first DC/DC converter and the second DC/DC converter and the connection between the first inverter and the second inverter have a wrong connection condition or not according to the voltage information.

In the embodiment of the invention, the photovoltaic system can further comprise a second DC/DC converter and a second inverter, and similarly, whether a wrong wiring condition exists in the wiring between the first DC/DC converter and the second DC/DC converter and between the first inverter and the second inverter can be determined according to the acquired at least one piece of voltage information, so that the wrong wiring detection is accurate and is simple to implement.

In a third aspect, embodiments of the present invention further provide a photovoltaic system, where the photovoltaic system includes a controller, at least one first DC/DC converter, at least one first inverter, and a bus voltage of the at least one first DC/DC converter is input to the at least one first inverter, where the controller is configured to obtain a first input voltage of the at least one first inverter when the first DC/DC converter is connected to the photovoltaic system; and when the voltage type of the at least one first input voltage is a preset voltage type, determining that the connection between the first DC/DC converter and the first inverter has a wrong connection condition. In addition, the first DC/DC converter may be a DC/DC converter that outputs a positive bus voltage or a DC/DC converter having a level inversion function to output a negative bus voltage.

In the embodiment of the invention, when the photovoltaic system is connected to the first DC/DC converter, the controller may determine that the wiring between the first DC/DC converter and the first inverter has the wiring error condition by acquiring the first input voltage of the at least one first inverter when determining that the voltage type of the at least one first input voltage is the preset voltage type, and the wiring error detection accuracy is high and the implementation is simple.

In the embodiment of the invention, the photovoltaic system may further include a second DC/DC converter and a second inverter, and likewise, when the photovoltaic system is connected to the first DC/DC converter and the first second DC/DC converter, by acquiring the first input voltage of the at least one first inverter, when the voltage type of the at least one first input voltage is determined to be the preset voltage type, it may be determined that a wiring fault condition exists in the wiring between the first DC/DC converter and the first inverter, and the wiring fault detection is accurate and is simple to implement.

In one possible embodiment, the second DC/DC converter may be a DC/DC converter that outputs a positive bus voltage or a DC/DC converter having a level inversion function to output a negative bus voltage; the controller is further configured to, when the photovoltaic system is connected to the first DC/DC converter and the first second DC/DC converter, obtain at least one of the following voltage data: a second input voltage that is an input voltage of at least one inverter to which a DC/DC converter having a level-reversal function is connected before turning on level reversal; a third input voltage which is an input voltage of at least one inverter to which the DC/DC converter having the level-reversal function is connected after the level reversal is turned on; a fourth input voltage that is an input voltage of at least one inverter to which the DC/DC converter having no level flip function is connected after turning on the level flip; and when at least one item of voltage data meets a preset voltage condition, determining whether the connection between the first DC/DC converter and the second DC/DC converter and the connection between the first inverter and the second inverter have a wrong connection condition.

In the embodiment of the invention, when the photovoltaic system is connected to the first DC/DC converter and the first second DC/DC converter, at least one item of voltage data of the second input voltage, the third input voltage and the fourth input voltage may be obtained, and according to whether the at least one item of voltage data meets a preset voltage condition, whether a wiring fault condition exists among the first DC/DC converter, the second DC/DC converter, the first inverter and the second inverter is determined, so that the wiring fault detection of the photovoltaic system is realized.

Drawings

The drawings used in the embodiments of the present application are described below.

Fig. 1 is a schematic structural diagram of a photovoltaic system according to an embodiment of the present invention;

FIG. 2 is a flow chart of a detection method according to an embodiment of the present invention;

FIG. 3a is a schematic structural diagram of another photovoltaic system provided by an embodiment of the present invention;

fig. 3b is a schematic structural diagram of another photovoltaic system provided by the embodiment of the invention;

FIG. 3c is a simplified equivalent schematic of a portion of FIG. 3 b;

FIG. 3d is a schematic illustration of a miswiring of a photovoltaic system according to an embodiment of the present invention;

FIG. 4 is a flow chart of another detection method provided by embodiments of the present invention;

fig. 5a, 5b and 5c are schematic diagrams of a wrong wiring of another photovoltaic system provided by the embodiment of the invention;

FIG. 6 is a flow chart of another detection method provided by the embodiment of the invention;

fig. 7a, 7b, 7c, 7d, 7e and 7f are schematic diagrams of wrong wiring of another photovoltaic system according to an embodiment of the present invention.

Detailed Description

The technical solution in the present application will be described below with reference to the accompanying drawings.

In the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple. In addition, the embodiments of the present application use the words "first", "second", etc. to distinguish between similar items or items having substantially the same function or effect. For example, the first inverter and the second inverter are only for distinguishing different inverters, and the sequence order thereof is not limited. Those skilled in the art will appreciate that the words "first," "second," and the like do not limit the number or order of execution.

It is noted that the words "exemplary," "for example," and "such as" are used herein to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "e.g.," is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.

In the prior art, the photovoltaic system comprises a direct current unit for outputting direct current and an inverter for realizing alternating current-direct current conversion, and it is crucial to ensure that the wiring between the direct current unit and the inverter is accurate, however, the wiring error between the direct current unit and the inverter cannot be detected in the prior art, so that the application provides a new photovoltaic system which can effectively detect and judge the wiring condition between the direct current unit and the inverter, the detection accuracy is high, the detection is simple, and no additional hardware circuit is required to be added.

It is noted that, in the embodiment of the present invention, three types of photovoltaic systems are provided, which correspond to the following first embodiment, second embodiment and third embodiment, respectively; the three embodiments are not independent, but can be combined with each other. In addition, the first embodiment, the second embodiment and the third embodiment may correspond to the same photovoltaic system, except that the application scenarios of the three embodiments are different, specifically, the detection method of the first embodiment does not need to pay attention to the access sequence and the access number of the DC/DC converter (the DC/DC converter outputting the positive bus voltage and/or the negative bus voltage), and after the DC/DC converter is accessed to the inverter, the detection method of the first embodiment may be used for detection. The detection method of the second embodiment is applied to a scenario that the photovoltaic system is connected to a first DC/DC converter (a DC/DC converter that outputs a positive bus voltage and/or outputs a negative bus voltage). The detection method of the third embodiment is applied to a scenario where two types of DC/DC converters (DC/DC converters outputting positive bus voltage and/or outputting negative bus voltage) are connected in series. In other words, in the process of building the photovoltaic system, when the first DC/DC converter is connected to the system, the method of the second embodiment may be used to detect whether the system has a wrong connection; if the first DC/DC converter is correctly wired, then, for example, a second DC/DC converter is connected, at this time, the method of the third embodiment may be used to detect whether the system has a wrong connection condition; after the first DC/DC converter and the second DC/DC converter are correctly connected, the DC/DC converters can be continuously connected, and for the subsequently connected DC/DC converters, the method of the second embodiment can be adopted to detect whether the system has a connection error. Finally, when it is not possible to determine whether there is a miswire connection condition by using either the method of the second embodiment or the method of the third embodiment, the method of the first embodiment may be used to perform the detection. Of course, the method of the first embodiment may be used in any scenario (only the DC/DC converter needs to be connected to the photovoltaic system) during the building process of the photovoltaic system.

The following description specifically explains the first embodiment, the second embodiment, and the third embodiment, respectively:

example one

Referring to fig. 1, fig. 1 is a schematic structural diagram of a photovoltaic system according to an embodiment of the present invention, and the photovoltaic system 100 includes a controller (not shown), at least one first DC/DC converter (e.g., the first DC/DC converter 1, … …, the first DC/DC converter n, n ≧ 1), at least one first inverter (fig. 1 illustrates one first inverter 104 as an example), and at least one first inverter to which a bus voltage of the at least one first DC/DC converter is input. For example, the at least one first inverter may further be connected to at least one transformer, and the way in which the at least one first inverter is connected to the at least one transformer is not particularly limited. Taking the first inverter 104 as an example, the first inverter 104 may be connected to a transformer 105 for further voltage conversion, so as to input the voltage after voltage conversion into the power grid 106, thereby implementing grid connection.

Referring to fig. 2, fig. 2 is a flowchart of a detection method according to an embodiment of the present invention; wherein:

a controller for performing the detection method 200, the detection method 200 comprising:

201: a first operating parameter of at least one first DC/DC converter and a second operating parameter of at least one first inverter in a photovoltaic system are obtained.

Specifically, the first operating parameter is a relevant parameter that can be used to characterize a power-on state of the first DC/DC converter, and the second operating parameter is a relevant parameter that can be used to characterize a power-on state of the first inverter, further, the power-on state includes a power-on state and a power-off state.

202: and when the at least one first working parameter is a first preset parameter and the at least one second working parameter is a second preset parameter, determining that the connection fault condition exists between the first DC/DC converter and the first inverter.

Specifically, the first preset parameter is used for representing that the first DC/DC converter is in a power-on state, and the second preset parameter is used for representing that the first inverter is in a power-off state. When the controller determines that at least one first working parameter is a first preset parameter and at least one second working parameter is a second preset parameter in the photovoltaic system, it can be determined that a wrong wiring condition exists between a first DC/DC converter and a first inverter in the photovoltaic system at the moment. In the photovoltaic system provided by the embodiment of the invention, the controller can realize wiring error detection by utilizing the first working parameter and the second working parameter, the detection accuracy is high, the realization is simple, and no additional hardware circuit is required to be added.

Further, the first DC/DC converter may be a DC/DC converter that outputs a positive bus voltage or a DC/DC converter that outputs a negative bus voltage.

Further, referring to fig. 1, for convenience of wiring, the photovoltaic system 100 may further include a wiring cabinet 103, and the first DC/DC converter and the first inverter in the photovoltaic system 100 may be connected through the wiring cabinet 103, for example, the bus bar and the neutral line (i.e., N line) of the first DC/DC converter 1, the bus bar and the neutral line of the first DC/DC converter N may be connected into the first inverter 104 through the wiring cabinet 103. In addition, the photovoltaic system 100 further comprises a direct current power source connected to the input of the first DC/DC converter, for example, a direct current power source 101 connected to the input of the first DC/DC converter 1, and a direct current power source 102 connected to the input of the first DC/DC converter n. The dc power source may be composed of n photovoltaic strings, where each photovoltaic string may include a plurality of photovoltaic modules connected in series and/or in parallel, and the photovoltaic modules may be solar cell modules (also referred to as PV modules). The single solar cell is the minimum unit for converting light energy into electric energy, and the solar cell module is formed by connecting a plurality of single solar cells in series and parallel according to electric property classification and packaging the single solar cells to form the minimum unit used as a cell. The solar cell modules can form a string in a serial and/or parallel mode, the output voltage can be increased in proportion in the serial mode under the condition that the output current is not changed, the output current can be increased in proportion in the parallel mode under the condition that the output voltage is not changed, and the output voltage and the output current can be increased in the serial and parallel mixed mode. The number of the photovoltaic strings of the direct current power supplies connected with different first DC/DC converters can be the same or different.

For each of the photovoltaic strings, under a certain illumination intensity and an ambient temperature, the string may operate at different output voltages, that is, the output power of the string may vary with the illumination intensity, the ambient temperature, and the output voltage, but at a certain illumination intensity and an ambient temperature, there is only one Maximum Power Point (MPP). Maximum Power Point Tracking (MPPT) is to constantly adjust the operating point of the string set according to different external characteristics such as illumination intensity and ambient temperature, so that the string set always operates at the maximum power point, even if the string set always outputs the maximum power. The maximum power point voltage may refer to the output voltage of the set of strings at which the maximum power point corresponds.

Accordingly, when the direct current power supply is implemented using the solar cell module, the first DC/DC converter may be implemented using an MPPT module, and when the first DC/DC converter is a DC/DC converter outputting a positive bus voltage, the first DC/DC converter is an MPPT module implementing a maximum power point voltage output, and when the first DC/DC converter is a DC/DC converter outputting a negative bus voltage, the first DC/DC converter is an MPPT module implementing a maximum power point voltage output and having a level inversion function, in other words, the first DC/DC converter at this time may be understood to be composed of an MPPT module implementing a maximum power point voltage output and a level inversion module.

In some possible embodiments, for the photovoltaic system 100 shown in fig. 1, when the photovoltaic system is connected to the first DC/DC converter, the controller may use another detection method to detect the wiring condition, for details, refer to embodiment two, and are not described herein.

In some possible embodiments, for the photovoltaic system 100 shown in fig. 1, when at least one first DC/DC converter is at least two first DC/DC converters, the controller may use another detection method to detect the wiring condition, please refer to embodiment three for details, which is not described herein in detail.

In some possible embodiments, the photovoltaic system further comprises at least one second DC/DC converter and at least one second inverter, the bus voltage of the at least one second DC/DC converter is input to the at least one second inverter, the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and the first DC/DC converter and the second DC/DC converter share a neutral line.

Specifically, when the bus voltage output by the first DC/DC converter is a positive voltage, the bus voltage of the second DC/DC converter is a negative voltage; when the bus voltage output by the first DC/DC converter is negative voltage, the bus voltage of the second DC/DC converter is positive voltage. In this embodiment, in the photovoltaic system, the first DC/DC converter and the second DC/DC converter share the zero line, so long as it is ensured that the input powers of the two are substantially the same, when power is transmitted, the current does not substantially flow through the zero line, and the bus voltage difference between the two is twice the original DC bus voltage, so that the transmission current is substantially halved.

Wherein the second DC/DC converter is a DC/DC converter outputting a positive bus voltage or a DC/DC converter having a level inversion function to output a negative bus voltage. Referring to fig. 3a, fig. 3a is a schematic structural diagram of another photovoltaic system provided by an embodiment of the present invention; in fig. 3a, the photovoltaic system 100 includes a first DC/DC converter 301 and a second DC/DC converter 306, wherein the first DC/DC converter 301 is a DC/DC converter outputting a positive bus voltage, and the first DC/DC converter 301 is connected to a DC power supply 304. And the second DC/DC converter 306 is a DC/DC converter that outputs a negative bus voltage, and the second DC/DC converter 306 is connected to a direct-current power supply 309. The N-lines of the first DC/DC converter 301 and the N-lines of the second DC/DC converter 306 are connected and connected to the bus N-lines of the junction box 303, while the positive bus of the first DC/DC converter 301 is connected to the bus positive bus of the junction box 303 and the negative bus of the second DC/DC converter 306 is connected to the bus negative bus of the junction box 303. In addition, a bus positive bus, a bus N line, and a bus negative bus are connected to the input of the first inverter 305, and a bus N line are connected to the input of the second inverter 310. The first inverter 305 and the second inverter 310 are then transformer connected for incorporation into the grid 308, for example, the first inverter 305 and the second inverter 310 may be connected to different windings of a double split transformer 307 for isolation. In practice, a first DC/DC converter 301 and a second DC/DC converter 306 may form a photovoltaic unit 302, the photovoltaic system 100 may include more than one photovoltaic unit, and the connection manner of the more than one photovoltaic unit with the first inverter 305 and the second inverter 310 may refer to the photovoltaic unit 302.

Further, referring to fig. 3b, fig. 3b is a schematic structural diagram of another photovoltaic system provided in the embodiment of the present invention; in fig. 3b, the photovoltaic system 100 is exemplified to have a first photovoltaic unit 311 and a second photovoltaic unit 320, wherein the first photovoltaic unit 311 and the second photovoltaic unit 320 have the same structure and wiring. Taking the first photovoltaic unit 311 as an example, the first photovoltaic unit 311 includes a first DC/DC converter 312, in this embodiment, the first DC/DC converter 312 is an MPPT module, and fig. 3b illustrates a basic composition of the MPPT module. And the second DC/DC converter includes a level flipping module 315 connected to the MPPT module for implementing a level flipping function, in addition to the MPPT module as the first DC/DC converter 312, wherein the diode 319 is a diode used by the level flipping module 315 for implementing a level flipping. The first DC/DC converter 312 and the second DC/DC converter of the first photovoltaic unit 311 are connected to the input terminal of the first inverter 313 and the input terminal of the second inverter 318 through the wiring cabinet 321, respectively. Wherein, optionally, the first inverter 313 comprises a diode 314 with prevention of reverse connection; likewise, an anti-reverse diode may also be provided in the second inverter 318. The first inverter 313 and the second inverter 318 are respectively connected to different direct current side windings of the transformer 316 so as to be connected to the power grid 317 through the transformer 316. With further reference to FIG. 3c, FIG. 3c is a partially simplified equivalent schematic diagram of FIG. 3 b; fig. 3c is a schematic diagram of equivalent wiring of the first photovoltaic unit 311, the second photovoltaic unit 320, and the wiring cabinet 321, where fig. 3c illustrates a simplified structure of the photovoltaic unit, where the diode 322 is a diode that realizes a level flipping function in the photovoltaic unit 311, the wiring cabinet 321 corresponds to a converging positive bus a, a converging zero line b, and a converging negative bus c, the positive bus of the first photovoltaic unit 311 and the positive bus of the second photovoltaic unit 320 are connected to the converging positive bus a, the zero line of the first photovoltaic unit 311 and the zero line of the second photovoltaic unit 320 are connected to the converging zero line b, and the negative bus of the first photovoltaic unit 311 and the negative bus of the second photovoltaic unit 320 are connected to the converging negative bus c.

In particular, the MPPT module may be a two-level topology, a three-level topology, or another topology, and the first DC/DC converter and the second DC/DC converter may be implemented by using other topologies that can implement voltage conversion, besides the MPPT module to implement voltage conversion. The level flipping module may be any other topology that can implement level flipping, and the first inverter and/or the second inverter may be a two-level, multi-level, or other single-phase or multi-phase topology.

In some possible embodiments, in the photovoltaic system, the detection method 200 further includes:

acquiring a third working parameter of at least one second DC/DC converter and a fourth working parameter of at least one second inverter in the photovoltaic system; and when the at least one third working parameter is a first preset parameter and the at least one fourth working parameter is a second preset parameter, determining that the wiring between the second DC/DC converter and the second inverter has a wrong wiring condition.

Specifically, in the photovoltaic system, in addition to the connection condition between the first DC/DC converter and the first inverter may be determined through a first operating parameter of the first DC/DC converter and a second operating parameter of the first inverter, a third operating parameter of the second DC/DC converter and a fourth operating parameter of the second inverter may be obtained, where the third operating parameter is a relevant parameter that may be used to characterize a power-on state of the second DC/DC converter, and the fourth operating parameter is a relevant parameter that may be used to characterize a power-on state of the second inverter, and further, similarly, the power-on state includes a power-on state and a power-off state. The first preset parameter is used for representing that the first DC/DC converter is in a power-on state, and the second preset parameter is used for representing that the first inverter is in a power-off state. In this way, when the controller determines that the at least one third operating parameter is the first preset parameter and the at least one fourth operating parameter is the second preset parameter, it may determine that a wrong connection condition exists between the second DC/DC converter and the second inverter.

Therefore, in the embodiment of the invention, the controller can detect whether a wrong connection line condition exists between the first DC/DC converter and the first inverter according to the first operating parameter and the second operating parameter, and/or detect whether a wrong connection line condition exists between the second DC/DC converter and the second inverter according to the third operating parameter and the fourth operating parameter, so as to comprehensively detect the wiring condition of the photovoltaic system, and thus, the construction efficiency of the photovoltaic system is improved.

In some possible embodiments, for the photovoltaic system 100 shown in fig. 3a, when the photovoltaic system is connected to the first DC/DC converter and the first second DC/DC converter, the controller may use another detection method to implement the wiring condition detection, please refer to embodiment two for details, which is not described herein again.

In some possible embodiments, for the photovoltaic system 100 shown in fig. 3a, when the at least one first DC/DC converter is at least two first DC/DC converters and the at least one second DC/DC converter is at least two second DC/DC converters, the controller may use another detection method to detect the wiring condition, which is described in detail in embodiment three and not described in detail herein.

In some possible embodiments, the first operating parameter and/or the third operating parameter includes an output voltage of the DC/DC converter and/or first heartbeat packet status information, the first heartbeat packet status information characterizing whether the controller receives a heartbeat packet sent by the DC/DC converter.

Specifically, the first operating parameter may be an output voltage of the first DC/DC converter and/or first heartbeat packet status information of the first DC/DC converter, where the first heartbeat packet status information of the first DC/DC converter represents whether the controller receives a heartbeat packet sent by the first DC/DC converter. Wherein it may be determined that the first DC/DC converter is in a powered state when the first DC/DC converter has an output voltage (i.e. the output voltage is not zero) or a heartbeat packet is sent to the controller; conversely, when the first DC/DC converter does not have an output voltage or the controller does not receive a heartbeat packet it sends, it may be determined that the first DC/DC converter is in an unpowered state. And the third operating parameter may be the output voltage of the second DC/DC converter and/or the first heartbeat packet status information of the second DC/DC converter, where the first heartbeat packet status information of the second DC/DC converter indicates whether the controller receives the heartbeat packet sent by the second DC/DC converter. Similarly, when the second DC/DC converter has an output voltage (i.e., the output voltage is not zero) or a heartbeat packet is sent to the controller, it may be determined that the second DC/DC converter is in a powered state; conversely, when the second DC/DC converter does not have an output voltage or the controller does not receive a heartbeat packet it sends, it may be determined that the second DC/DC converter is in an unpowered state.

In some possible embodiments, the second operating parameter and/or the fourth operating parameter includes an input voltage of the inverter and/or second heartbeat packet status information, and the second heartbeat packet status parameter characterizes whether the controller receives a heartbeat packet sent by the inverter.

Specifically, the second operating parameter may be an input voltage of the first inverter and/or second heartbeat packet state information of the first inverter, where the second heartbeat packet state information of the first inverter represents whether the controller receives a heartbeat packet sent by the first inverter. Wherein when the first inverter has an input voltage (i.e., the input voltage is not zero) or a heartbeat packet is sent to the controller, it may be determined that the first inverter is in a powered state; conversely, when the first inverter does not have an output voltage or the controller does not receive a heartbeat packet it sends, it may be determined that the first inverter is in an unpowered state. And the fourth operating parameter may be an input voltage of the second inverter and/or second heartbeat packet state information of the second inverter, and at this time, the second heartbeat packet state information of the second inverter represents whether the controller receives a heartbeat packet sent by the second inverter. When the second inverter has an input voltage (i.e., the input voltage is not zero) or a heartbeat packet is sent to the controller, it may be determined that the second inverter is in a powered state; conversely, when the second inverter does not have an output voltage or the controller does not receive a heartbeat packet it sends, it may be determined that the second inverter is in an unpowered state.

In some possible embodiments, in obtaining the second heartbeat packet state of the first inverter and/or the second inverter, an embodiment of the invention provides a method of obtaining:

the photovoltaic system further comprises an inverter monitor, the inverter monitor is connected with the first inverter and/or the second inverter to receive the heartbeat packet sent by the first inverter and/or the second inverter, and the inverter monitor is used for obtaining second heartbeat packet state information of the first inverter and/or the second inverter and sending the second heartbeat packet state information to the controller.

Specifically, the inverter monitor is powered by other power supply sources to be always in an operating state, the inverter monitor can communicate with the first inverter and/or the second inverter, and the inverter monitor determines second heartbeat packet state information corresponding to the first inverter and/or the second inverter respectively according to whether heartbeat packets of the first inverter and/or the second inverter are received or not. More specifically, the first inverter and the second inverter respectively comprise an inversion main controller for controlling an inversion process, the inversion main controller is a first inversion main controller and a second inversion main controller, the first inversion main controller and the second inversion main controller respectively take electricity on a direct current bus, and the first inverter and the second inverter can only work after the bus voltage is stably established. The first inversion main controller and the second inversion main controller are respectively communicated with the inverter monitor, and the first inversion main controller and the second inversion main controller can be in a wired or wireless communication mode, such as Power Line Communication (PLC) protocol communication and the like. In fact, taking the first inversion master as an example, the first inversion master sends a heartbeat packet to the inverter monitor according to a certain period, and the inverter monitor feeds back a response message after receiving the heartbeat packet, where the second heartbeat packet state information of the first inverter is characterized as a received heartbeat packet state, and may be represented by "1" or "true". And when the inverter monitor cannot receive the heartbeat packet of the first inverter master controller in the receiving period, the second heartbeat packet state information of the first inverter represents that the heartbeat packet state is not received, and can be represented by "0" or "false". The inverter monitor can determine the second heartbeat packet state information corresponding to the first inverter through heartbeat monitoring. The heartbeat packet communication between the second inversion main controller and the inverter monitor is the same as that of the first inversion main controller, and is not described in detail.

Further, similar to the inverter, the first DC/DC converter and/or the second DC/DC converter has a DC/DC conversion master controller, which is the first DC/DC conversion master controller and the second DC/DC conversion master controller, respectively, and both the first DC/DC conversion master controller and the second DC/DC conversion master controller take electricity on the DC bus, and the two can only operate after the bus voltage is stably established. The first DC/DC conversion master and/or the second DC/DC conversion master may send a heartbeat packet to the controller, and the controller determines the first heartbeat packet status information of the first DC/DC converter and/or the second DC/DC converter according to whether the heartbeat packet sent by the first DC/DC conversion master and/or the second DC/DC conversion master is received.

In addition, the first DC/DC conversion master and/or the second DC/DC conversion master may also send a heartbeat packet to the DC/DC conversion monitor (taking power from the DC bus), and the DC/DC conversion monitor determines the first heartbeat packet status information of the first DC/DC converter and/or the second DC/DC converter according to whether the heartbeat packet sent by the first DC/DC conversion master and/or the second DC/DC conversion master is received, and sends the first heartbeat packet status information to the controller.

Still alternatively, the first DC/DC conversion master and/or the second DC/DC conversion master may send a heartbeat packet to the inverter monitor, and the inverter monitor determines the first heartbeat packet status information of the first DC/DC converter and/or the second DC/DC converter according to whether the heartbeat packet sent by the first DC/DC conversion master and/or the second DC/DC conversion master is received, and sends the first heartbeat packet status information to the controller.

In another possible case, the controller may also monitor the heartbeat of the DC/DC conversion monitor to determine whether the photovoltaic unit outputs the voltage, for example, the controller monitors the heartbeat of the DC/DC conversion monitor (indicating that the output voltage of the photovoltaic unit is established) but does not monitor the heartbeat of the first inverter or the second inverter by monitoring the heartbeat, and then may determine that the wiring error exists in the photovoltaic system at this time.

Further, the controller and at least one of the DC/DC conversion monitor and the inverter monitor may be the same controller, i.e. the controller has the functionality of both the inverter monitor and/or the DC/DC conversion monitor.

In some possible embodiments, the controller is further configured to output a wiring error warning message when it is determined that a wiring error condition exists.

In the embodiment of the invention, when the controller determines that the condition of wrong wiring exists in the photovoltaic system, the controller outputs the wiring error warning information to remind workers of paying attention to the abnormal wiring condition and timely process the wiring error condition, so that the photovoltaic system is prevented from being further damaged due to the wiring error. Specifically, the manner of outputting the wiring error warning information may be at least one of an acoustic warning, an optical warning, an audible and visual warning, a short message notification, a mail notification, and the like.

In addition, when the photovoltaic system is detected to have wiring errors, the controller can control the photovoltaic system to stop and inform other devices in the system to stop, for example, inform the first DC/DC conversion main controller, the second DC/DC conversion main controller, the first inversion main controller, the second inversion main controller and the like, so as to protect the devices in the photovoltaic system.

It is specifically noted that in some possible embodiments, the controller may be implemented with any one of at least one first DC/DC conversion master, at least one second DC/DC conversion master, at least one first inversion master, at least one second inversion master in the photovoltaic system.

Referring to fig. 3d, fig. 3d is a schematic diagram of a photovoltaic system according to an embodiment of the present invention; fig. 3d illustrates one possible wiring error scenario for a photovoltaic system. In fig. 3d, a photovoltaic unit 323 is taken as an example. In the wrong wiring scenario illustrated in fig. 3d, both the positive and negative inputs of the first inverter 324 are connected to the positive bus of the photovoltaic unit 323, resulting in the first inverter 324 being inoperable. Another possible wiring error scenario is: the positive and negative input terminals of the second inverter of the photovoltaic system are both connected to the negative bus of the photovoltaic unit 323. The remaining possible wiring error scenarios are not particularly limited.

In summary, with the detection method 200 provided in the embodiment of the present invention, the controller can determine whether the photovoltaic system has a wiring error by using at least one set of data (the first working parameter and the second working parameter), (the third working parameter and the fourth working parameter), and the detection is accurate and is convenient to implement.

Example two

Referring to fig. 1, the photovoltaic system includes a controller, at least one first DC/DC converter, at least one first inverter, and a bus voltage of the at least one first DC/DC converter is input to the at least one first inverter, wherein, referring to fig. 4, fig. 4 is a flowchart of another detection method provided by the embodiment of the invention; the controller is configured to perform the detection method 400, the detection method 400 including:

401: when the first DC/DC converter is connected to the photovoltaic system, a first input voltage of the at least one first inverter is obtained.

Specifically, when the photovoltaic system 100 is connected to the first DC/DC converter, the controller may detect whether there is a miswire connection condition in the current photovoltaic system 100 by obtaining the first input voltage of the at least one first inverter.

402: and when the voltage type of the at least one first input voltage is a preset voltage type, determining that the connection between the first DC/DC converter and the first inverter has a wrong connection condition.

Specifically, the preset voltage type is a negative voltage, when the controller determines that the voltage type of the at least one first input voltage is the preset voltage type, it can be determined that a wiring error condition exists in a wiring between the first DC/DC converter and the first inverter, and the wiring error detection accuracy is high and the implementation is simple.

In some possible embodiments, the first DC/DC converter is a DC/DC converter outputting a positive bus voltage or a DC/DC converter having a level flipping function to output a negative bus voltage, and the detailed description of the first DC/DC converter may refer to the description of the first embodiment, which is not repeated herein.

In some possible embodiments, the photovoltaic system further comprises at least one second DC/DC converter and at least one second inverter, the bus voltage of the at least one second DC/DC converter is input to the at least one second inverter, the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and the first DC/DC converter and the second DC/DC converter share a neutral line. Wherein the second DC/DC converter may be a DC/DC converter outputting a positive bus voltage or a DC/DC converter having a level inversion function to output a negative bus voltage; similarly, for specific descriptions of the second DC/DC converter and the second inverter, reference may be made to the description of the first embodiment, and details are not repeated here.

Specifically, when the photovoltaic system comprises at least one second DC/DC converter and at least one second inverter, it is still possible to determine whether a wrong wiring condition exists between the first DC/DC converter and the second DC/DC converter and between the first inverter and the second inverter by obtaining at least one first input voltage according to whether the first input voltage is a preset voltage type.

In some possible embodiments, the detection method 400 further includes: when the photovoltaic system is connected into the first DC/DC converter and the first second DC/DC converter, at least one of the following voltage data is obtained: a second input voltage that is an input voltage of at least one inverter to which a DC/DC converter having a level-reversal function is connected before turning on level reversal; a third input voltage which is an input voltage of at least one inverter to which the DC/DC converter having the level-reversal function is connected after the level reversal is turned on; a fourth input voltage that is an input voltage of at least one inverter to which the DC/DC converter having no level flip function is connected after turning on the level flip; and when at least one item of voltage data meets a preset voltage condition, determining whether the connection between the first DC/DC converter and the second DC/DC converter and the connection between the first inverter and the second inverter have a wrong connection condition.

Specifically, when the photovoltaic system is connected to the first DC/DC converter and the first second DC/DC converter, the controller may further obtain the at least one item of voltage data, and determine whether a wrong connection condition exists between the first DC/DC converter and the wiring between the second DC/DC converter and the first inverter or between the first DC/DC converter and the wiring between the second inverter according to the at least one item of voltage data and a preset voltage condition.

Optionally, the preset voltage condition corresponding to the second input voltage is that the voltage type of the second input voltage is a negative voltage. The preset voltage condition corresponding to the third input voltage is that the voltage type of the third input voltage is a negative voltage, or the third input voltage exceeds the rated working voltage range of the corresponding inverter, that is, the third input voltage is less than the minimum working voltage of the inverter or the third input voltage is greater than the maximum working voltage of the inverter. For example, assuming that the third input voltage of the inverter to which a certain DC/DC converter with a level flipping function is connected is a, and the rated operating voltage range of the inverter is [ a, b ], when a is greater than b, or a is less than a, it can be determined whether there is a miswiring situation in the wiring between the first DC/DC converter and the second DC/DC converter and the first inverter and the second inverter in the photovoltaic system at that time. The preset voltage condition corresponding to the fourth input voltage is that the fourth input voltage exceeds the rated working voltage range of the corresponding inverter, namely the fourth input voltage is less than the minimum working voltage of the inverter or the fourth input voltage is greater than the maximum working voltage of the inverter.

In some possible embodiments, the detection method 400 further includes: and outputting the wiring error alarm information when the condition of wiring error is determined. The manner of outputting the wiring error warning information may refer to the description related to the first embodiment, and is not described again.

Referring to fig. 5a, 5b, and 5c, fig. 5a, 5b, and 5c are schematic diagrams of a wrong wiring of another photovoltaic system according to an embodiment of the present invention; in fig. 5a and 5b, the photovoltaic system includes one photovoltaic unit 501 as an example. In fig. 5a, the positive bus and N line of the photovoltaic unit 501 are connected in reverse to the positive and negative inputs of the first inverter 502. In fig. 5b, the positive and negative busbars of the photovoltaic unit 501 are connected in series. In fig. 5c, the positive bus and the N line of the photovoltaic unit 501 are connected to the second inverter 503, and the N line and the negative bus of the photovoltaic unit 501 are connected to the first inverter 502. In addition, the embodiment of the present application is not particularly limited to the remaining possible wiring error scenarios.

In summary, with the detection method 400 provided in the embodiment of the present invention, the controller can determine whether there is a line fault in the photovoltaic system by using at least one of the first input voltage, the second input voltage, the third input voltage, and the fourth input voltage, so that the detection is accurate and is convenient to implement.

EXAMPLE III

Referring to fig. 1, a photovoltaic system includes a controller, at least two first DC/DC converters, at least one first inverter, wherein bus voltages of the at least two first inverters are input to the at least one first inverter; the at least two first DC/DC converters are divided into a first type DC/DC converter which is connected into the photovoltaic system in front and a second type DC/DC converter which is connected after the first type DC/DC converter is connected and generates bus voltage; the first type DC/DC converter may be one or more first DC/DC converters, and similarly, the second type DC/DC converter may be one or more first DC/DC converters. Referring to fig. 6, fig. 6 is a flowchart of another detection method provided by the embodiment of the invention; the controller is configured to perform the detection method 600, the detection method 600 comprising:

601: acquiring voltage information of at least one first DC/DC converter, wherein the voltage information is acquired after a second type of DC/DC converter is connected to a photovoltaic system;

specifically, the voltage information of the first DC/DC converter is a parameter related to the voltage of the first DC/DC converter, and the voltage information is acquired after the second type of DC/DC converter is connected to the photovoltaic system.

602: and determining whether a wrong connection condition exists in the connection between the at least two first DC/DC converters and the at least one first inverter according to the voltage information.

Specifically, according to the obtained at least one piece of voltage information, whether a wrong wiring condition exists in the wiring between the at least two first DC/DC converters and the at least one first inverter can be determined, and the wiring error detection accuracy is high and the realization is simple.

In some possible embodiments, step 601 specifically includes:

a1: when the first DC/DC converter is a DC/DC converter outputting a positive bus voltage, a first voltage state parameter and a first working current of the first DC/DC converter are obtained as voltage information, and the first voltage state parameter is used for representing the bus voltage change condition of the first DC/DC converter.

Specifically, the first operating current may be an input current or an output current of a first DC/DC converter, and referring to fig. 7a, fig. 7b, fig. 7c, fig. 7d, fig. 7e, and fig. 7f, the schematic diagram of a wrong wiring of another photovoltaic system according to an embodiment of the present invention is shown, where the first DC/DC converter in the photovoltaic unit 701 is an MPPT module as an example, and the input current of the first DC/DC converter is Imppt in fig. 7 a. And the first voltage status parameter may include a bus voltage of the first DC/DC converter and/or a bus voltage drop rate of the first DC/DC converter, when the bus voltage of the first DC/DC converter is a positive bus voltage of the first DC/DC converter, the bus voltage drop rate of the first DC/DC converter is a positive bus voltage drop rate of the first DC/DC converter. Still alternatively, the first voltage status parameter may comprise a bus voltage of the at least two first DC/DC converters and/or a bus voltage drop rate of the at least two first DC/DC converters, in which case the bus voltage of the at least two first DC/DC converters is a bus positive bus voltage of the at least two first DC/DC converters and the bus voltage drop rate of the at least two first DC/DC converters is a bus positive bus voltage drop rate of the at least two first DC/DC converters. It should be understood that the "at least two first DC/DC converters" shall at least comprise the first DC/DC converter obtaining the first operating current.

A2: at the at least one first DC/DC converter: and when the first working current is not equal to zero and the first voltage state parameter meets a first preset voltage state condition, determining that the condition of wrong line connection exists.

Specifically, when the first voltage state parameter is the bus voltage of the first DC/DC converter and/or the bus voltage reduction rate of the first DC/DC converter, the first preset voltage state condition is: the bus voltage of the first DC/DC converter is zero and/or the bus voltage drop rate of the first DC/DC converter is greater than or equal to a first preset drop rate. When the first voltage state parameter is the bus bar voltage of the at least two first DC/DC converters and/or the bus bar voltage drop rate of the at least two first DC/DC converters, the first preset voltage state condition is: the bus voltage is zero and/or the bus voltage drop rate is greater than or equal to a second preset drop rate. The specific values of the first preset falling rate and the second preset falling rate may be set according to actual circuit characteristics, and are not particularly limited herein.

The controller, upon determining that the at least one first DC/DC converter satisfies: when the first operating current is not equal to zero and the first voltage state parameter meets the first preset voltage state condition, it may be determined whether a miswire connection condition exists in the connection between the at least two first DC/DC converters and the at least one first inverter.

In some possible embodiments, step 601 specifically includes:

b1: when the first DC/DC converter is a DC/DC converter with a level inversion function to output a negative bus voltage, a level inversion state parameter of the first DC/DC converter is acquired as voltage information, and the level inversion state parameter is used for representing a level inversion working state of the first DC/DC converter.

Specifically, the level flipping operating state includes a flipping completed state and a flipping failed state, wherein the level flipping operating state of the first DC/DC converter is determined according to whether the level flipping state parameter satisfies a preset level flipping state parameter condition. When the level turnover state parameter meets the preset level turnover state parameter condition, the first DC/DC converter is in a turnover failure state, otherwise, when the level turnover state parameter does not meet the preset level turnover state parameter condition, the first DC/DC converter is in a turnover completed state.

Further, optionally, the level-reversal state parameter includes a level-reversal time and/or a reversal voltage of the first DC/DC converter, the level-reversal time is a sum of time elapsed from the start of level reversal to the completion of level reversal of the first DC/DC converter, and the reversal voltage is a bus voltage size output by the first DC/DC converter after the level reversal. Correspondingly, when the level turnover state parameter is the level turnover time threshold, the preset level turnover state parameter condition is the level turnover time threshold, and when the level turnover time threshold of a certain first DC/DC converter is less than or equal to the level turnover time threshold, the level turnover working state of the first DC/DC converter is the turnover completed state, otherwise, the level turnover working state of the first DC/DC converter is the turnover failed state. When the level turnover state parameter is a turnover voltage, the preset level turnover state parameter condition is a turnover voltage threshold, when the turnover voltage threshold of a certain first DC/DC converter is greater than or equal to the turnover voltage threshold, the level turnover working state of the first DC/DC converter is a turnover completed state, otherwise, the level turnover working state of the first DC/DC converter is a turnover failed state. Further, specific values of the level-inversion time threshold and the inversion voltage threshold may be set according to actual situations, and are not particularly limited.

B2: and when at least one level turnover state parameter meets the preset level turnover state parameter condition, determining that the condition of wrong line connection exists.

Specifically, when the controller determines that the at least one level upset state parameter satisfies the preset level upset state parameter condition, it may determine whether a miswiring condition exists in the wiring between the at least two first DC/DC converters and the at least one first inverter.

Specifically, when the photovoltaic system comprises at least one second DC/DC converter and at least one second inverter, the controller may still determine whether a wrong wiring condition exists in the wiring between the first DC/DC converter and the second DC/DC converter and between the first inverter and the second inverter by acquiring at least one voltage information according to the voltage information.

In some possible embodiments, the detection method 600 further includes: and outputting the wiring error alarm information when the condition of wiring error is determined. The manner of outputting the wiring error warning information may refer to the description related to the first embodiment, and is not described again.

Referring to fig. 7a, 7b, 7c, 7d, 7e, and 7f, possible wiring error scenarios of the photovoltaic system are illustrated, wherein the first type of DC/DC converter is a first DC/DC converter 701, and the second type of DC/DC converter is a first DC/DC converter 702. In addition, the embodiment of the present application is not particularly limited to the remaining possible wiring error scenarios.

In summary, with the detection method 600 provided in the embodiment of the present invention, the controller can determine whether there is a line fault in the photovoltaic system by using at least one of the (first operating current, first voltage state parameter), and the (level flip state parameter), so that the detection is accurate and is convenient to implement.

In the several embodiments provided in the present application, it should be understood that the disclosed system may be implemented in other ways. For example, the system embodiments described above are merely illustrative, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (ssd)), among others.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A photovoltaic system comprising a controller, at least one first DC/DC converter, at least one first inverter to which a bus voltage of the at least one first DC/DC converter is input, wherein,

the controller is configured to obtain a first operating parameter of at least one first DC/DC converter and a second operating parameter of at least one first inverter in the photovoltaic system;

and when at least one first working parameter is a first preset parameter and at least one second working parameter is a second preset parameter, determining that the wiring between the first DC/DC converter and the first inverter has a wiring fault condition.

2. The photovoltaic system of claim 1, wherein the first DC/DC converter is a DC/DC converter that outputs a positive bus voltage or a DC/DC converter that outputs a negative bus voltage.

3. The photovoltaic system according to claim 1 or 2, further comprising at least one second DC/DC converter and at least one second inverter, wherein a bus voltage of the at least one second DC/DC converter is input to the at least one second inverter, wherein the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and wherein the first DC/DC converter and the second DC/DC converter share a zero line.

4. The photovoltaic system of claim 3,

the controller is further configured to obtain a third operating parameter of at least one second DC/DC converter and a fourth operating parameter of at least one second inverter in the photovoltaic system;

and when at least one third working parameter is the first preset parameter and at least one fourth working parameter is the second preset parameter, determining that the wiring between the second DC/DC converter and the second inverter has a wrong wiring condition.

5. The photovoltaic system of claim 3, wherein the first and/or third operating parameters comprise an output voltage of a DC/DC converter and/or first heartbeat packet status information characterizing whether a heartbeat packet sent by a DC/DC converter is received by the controller;

and/or the presence of a gas in the gas,

the second working parameter and/or the fourth working parameter include input voltage of the inverter and/or second heartbeat packet state information, and the second heartbeat packet state parameter represents whether the controller receives a heartbeat packet sent by the inverter.

6. The photovoltaic system of claim 5, further comprising an inverter monitor coupled to the first inverter and/or the second inverter to receive heartbeat packets sent by the first inverter and/or the second inverter, wherein,

the inverter monitor is configured to obtain the second heartbeat packet state information of the first inverter and/or the second inverter, and send the second heartbeat packet state information to the controller.

7. The photovoltaic system according to any of claims 1 to 6, wherein the at least one first DC/DC converter is divided into a first type of DC/DC converter connected to the photovoltaic system before and a second type of DC/DC converter connected after the first type of DC/DC converter is connected to generate the bus voltage, when the at least one first DC/DC converter is at least two first DC/DC converters, wherein,

the controller is further configured to obtain voltage information of at least one first DC/DC converter, where the voltage information is obtained after the second type of DC/DC converter is connected to the photovoltaic system;

and determining whether a wrong wiring condition exists in the wiring between the at least two first DC/DC converters and the at least one first inverter according to the voltage information.

8. The photovoltaic system of any one of claims 1 to 7, wherein,

the controller is further configured to obtain a first input voltage of at least one first inverter when the first DC/DC converter is connected to the photovoltaic system;

and when the voltage type of at least one first input voltage is a preset voltage type, determining that the connection between the first DC/DC converter and the first inverter has a wrong connection condition.

9. The photovoltaic system of any of claims 1 to 8, wherein the controller is further configured to output a miswire alarm message upon determining that a miswire condition exists.

10. A photovoltaic system, characterized in that the photovoltaic system comprises a controller, at least two first DC/DC converters, at least one first inverter, wherein the bus voltage of the at least two first inverters is input into the at least one first inverter; the at least two first DC/DC converters are divided into a first type of DC/DC converter which is connected to the photovoltaic system in the front and a second type of DC/DC converter which is connected after the first type of DC/DC converter is connected and generates bus voltage;

the controller is configured to acquire voltage information of at least one first DC/DC converter, where the voltage information is acquired after the second type of DC/DC converter is connected to the photovoltaic system;

11. The photovoltaic system of claim 10, wherein the controller is specifically configured to:

when the first DC/DC converter is a DC/DC converter outputting a positive bus voltage, acquiring a first voltage state parameter and a first working current of the first DC/DC converter as the voltage information, wherein the first voltage state parameter is used for representing the bus voltage change condition of the first DC/DC converter;

at least one of the first DC/DC converters satisfies: and when the first working current is not equal to zero and the first voltage state parameter meets a first preset voltage state condition, determining that the condition of wire connection fault exists.

12. The photovoltaic system of claim 11, wherein the first operating current is an input current or an output current of the first DC/DC converter;

and/or the presence of a gas in the gas,

the first voltage state parameter comprises a bus voltage of the first DC/DC converter and/or a bus voltage droop rate of the first DC/DC converter;

and/or the presence of a gas in the gas,

the first voltage status parameter comprises a bus voltage of the at least two first DC/DC converters and/or a bus voltage drop rate of the at least two first DC/DC converters.

13. The photovoltaic system of claim 10, wherein the controller is specifically configured to:

when the first DC/DC converter is a DC/DC converter with a level inversion function to output a negative bus voltage, acquiring a level inversion state parameter of the first DC/DC converter as the voltage information, wherein the level inversion state parameter is used for representing a level inversion working state of the first DC/DC converter;

and when at least one level turnover state parameter meets the preset level turnover state parameter condition, determining that the condition of wrong line connection exists.

14. The photovoltaic system according to claim 13, wherein the level-reversal state parameter includes a level-reversal time and/or a reversal voltage of the first DC/DC converter, and the reversal voltage is a bus voltage output by the first DC/DC converter after level reversal.

15. The photovoltaic system according to any one of claims 10 to 14, further comprising at least two second DC/DC converters and at least one second inverter, wherein the bus voltage of the at least one second DC/DC converter is input to the at least one second inverter, the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and the first DC/DC converter and the second DC/DC converter share a zero line; wherein,

the controller is further used for determining whether the connection between the first DC/DC converter and the second DC/DC converter and the connection between the first inverter and the second inverter have a wrong connection condition or not according to the voltage information.

16. The photovoltaic system of any of claims 10 to 15,

the controller is also used for outputting the wiring error warning information when the wiring error condition is determined.

17. A photovoltaic system comprising a controller, at least one first DC/DC converter, at least one first inverter to which a bus voltage of the at least one first DC/DC converter is input, wherein,

the controller is used for acquiring a first input voltage of at least one first inverter when the photovoltaic system is connected to a first DC/DC converter;

18. The photovoltaic system of claim 17, wherein the first DC/DC converter is a DC/DC converter that outputs a positive bus voltage or a DC/DC converter having a level flipping function to output a negative bus voltage.

19. The pv system according to claim 17 or 18, further comprising at least one second DC/DC converter and at least one second inverter, wherein the bus voltage of the at least one second DC/DC converter is input to the at least one second inverter, wherein the bus voltages of the first DC/DC converter and the second DC/DC converter are of opposite voltage types, and wherein the first DC/DC converter and the second DC/DC converter share a neutral line.

20. The photovoltaic system according to claim 19, wherein the second DC/DC converter is a DC/DC converter that outputs a positive bus voltage or a DC/DC converter having a level-reversing function to output a negative bus voltage; wherein,

the controller is further configured to, when the first DC/DC converter and the first second DC/DC converter are connected to the photovoltaic system, obtain at least one of the following voltage data: a second input voltage that is an input voltage of at least one inverter to which a DC/DC converter having a level-reversal function is connected before turning on level reversal; a third input voltage that is an input voltage of at least one inverter to which a DC/DC converter having a level-flip function is connected after turning on level-flip; a fourth input voltage that is an input voltage of at least one inverter to which the DC/DC converter having no level flip function is connected after turning on the level flip;

and when at least one item of voltage data meets a preset voltage condition, determining whether the connection between the first DC/DC converter and the second DC/DC converter and the connection between the first inverter and the second inverter have a wrong connection condition.

21. The photovoltaic system of any of claims 17 to 20,