A protection device for a photovoltaic system

Abstract

The application discloses a protection device of a photovoltaic system and belongs to the technical field of photovoltaic power generation. The protection device comprises a plurality of voltage sensors, a plurality of current sensors, an electronic switch group, a bypass switch group and a control module. In use, the control module determines a fault position and a fault type based on voltage and current, and then controls the on-off of the bypass switch based on the fault position and the fault type, so that the connection between a photovoltaic panel and the whole photovoltaic system is disconnected when the photovoltaic panel has a hot spot, a short circuit or a poor contact leading to an arc fault, thereby realizing bypass protection. The protection device can accurately position a fault warning of the photovoltaic system and timely perform physical protection.

Description

Technical Field

[0001] This application relates to the field of photovoltaic power generation technology, and in particular to a protection device for a photovoltaic system. Background Technology

[0002] With the development of photovoltaic systems, the issues of fault early warning and location and system protection during power generation and energy storage have attracted widespread attention.

[0003] In related technologies, the protection devices for photovoltaic systems have relatively limited functions and cannot meet the multi-functional protection requirements of physical protection, fault early warning and location, and grounding detection. Furthermore, they suffer from poor fault location accuracy, lack of bypass protection, and poor compatibility. Therefore, there is an urgent need to develop a protection device for photovoltaic systems to solve these problems. Utility Model Content

[0004] In view of this, this application provides a protection device for a photovoltaic system, which can accurately locate and provide timely physical protection for the photovoltaic system in case of faults.

[0005] Specifically, the following technical solutions are included:

[0006] This application provides a protection device for a photovoltaic system. The photovoltaic system includes two photovoltaic panels connected in series. The protection device includes: multiple voltage sensors, multiple current sensors, an electronic switch group, a bypass switch group, and a control module.

[0007] The electronic switch group includes three electronic switches, which are used to continue the main circuit in series when a photovoltaic panel fails. The bypass switch group includes two bypass switches, which are connected in series with the photovoltaic panels at intervals. They are used to receive the on / off signal from the control module to conduct or disconnect when a photovoltaic panel fails, so as to ensure the normal operation of the photovoltaic panel or bypass the photovoltaic panel that caused the failure.

[0008] Voltage sensors are connected in parallel across the two ends of the photovoltaic panel to detect the voltage of the corresponding photovoltaic panel;

[0009] A current sensor is connected in series between the photovoltaic panels to detect the current in the main circuit of the two photovoltaic panels connected in series.

[0010] The control module is connected to the electronic switch group, bypass switch group, voltage sensor and current sensor. It is used to determine the fault location and fault type based on voltage and current, and then control the opening and closing of the bypass switch based on the fault location and fault type. The fault types include hot spots, short circuits and arcing caused by poor contact.

[0011] In some embodiments, the protection device includes a signal coupler connected in series in the main circuit for coupling communication signals to the power supply line.

[0012] In some embodiments, the protection device includes a power line carrier communication module located on one side of the signal coupler, connected to the signal coupler, and signal-connected to the control module for communication transmission of voltage, current, and control signals for switching on and off the bypass switch.

[0013] In some embodiments, the control module is specifically used for:

[0014] If the voltage difference between a certain photovoltaic panel and the voltages of other photovoltaic panels is greater than the voltage difference, the fault type is determined to be a hot spot.

[0015] When the fault type is hot spot, the bypass switch corresponding to the photovoltaic panel is disconnected.

[0016] In some embodiments, the control module is specifically used for:

[0017] In response to a photovoltaic panel's voltage being less than a threshold voltage, the fault type is determined to be a short circuit;

[0018] When the fault type is a short circuit, the bypass switch corresponding to the photovoltaic panel is disconnected.

[0019] In some embodiments, the control module is specifically used for:

[0020] In response to the presence of high-frequency current components in a specific frequency band, the fault type is determined to be arcing caused by poor contact, where the specific frequency band ranges from 10kHz to 100kHz.

[0021] When the fault type is poor contact causing an electric arc, the bypass switch corresponding to the photovoltaic panel is disconnected.

[0022] In some embodiments, the control module is specifically used for:

[0023] Wavelet transform is used to extract the signal abrupt change components of current and voltage. Combined with the spatial correlation of the positions of voltage and current sensors corresponding to voltage and current, preliminary position results are determined. Compensation analysis is performed on the preliminary position results to determine the fault location.

[0024] In some embodiments, the control module is further configured to:

[0025] When a user sends a signal to start the photovoltaic system, the electronic switch and the bypass switch are turned on.

[0026] When a user sends a signal to shut down the photovoltaic system, the electronic switch and the bypass switch are disconnected.

[0027] In some embodiments, the control module is further configured to:

[0028] The photovoltaic system's operating status is sent to the user's central control room via the power line carrier communication module. The operating status includes normal status and abnormal status, and the abnormal status includes the fault type and fault location.

[0029] In some embodiments, the electronic switch is any one of a diode, a transistor, and a field-effect transistor, and the bypass switch is any one of a relay, a contactor, and a field-effect transistor.

[0030] The beneficial effects of the technical solutions provided in this application include at least the following:

[0031] This application provides a protection device for a photovoltaic system. The device includes multiple voltage sensors, multiple current sensors, an electronic switch group, a bypass switch group, and a control module. In use, the control module determines the fault location and type based on voltage and current. Then, based on the fault location and type, it controls the opening and closing of the bypass switch. This disconnects the photovoltaic panel from the entire photovoltaic system when a fault such as a hot spot, short circuit, or arcing due to poor contact occurs on a particular photovoltaic panel, thus achieving bypass protection. This protection device can accurately locate and warn of faults in the photovoltaic system and provide timely physical protection. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This application provides a schematic diagram of the structure of a protection device for a photovoltaic system. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] To make the technical solutions and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0036] This application provides a protection device for a photovoltaic system. The photovoltaic system includes two photovoltaic panels connected in series, such as... Figure 1 As shown, the protection device includes: multiple voltage sensors, multiple current sensors, an electronic switch group, a bypass switch group, and a control module;

[0037] The electronic switch group includes three electronic switches, which are used to continue the main circuit in series when a photovoltaic panel fails. The bypass switch group includes two bypass switches, which are connected in series with the photovoltaic panels at intervals. They are used to receive the on / off signal from the control module to conduct or disconnect when a photovoltaic panel fails, so as to ensure the normal operation of the photovoltaic panel or bypass the photovoltaic panel that caused the failure.

[0038] Voltage sensors are connected in parallel across the two ends of the photovoltaic panel to detect the voltage of the corresponding photovoltaic panel;

[0039] A current sensor is connected in series between the photovoltaic panels to detect the current in the main circuit of the two photovoltaic panels connected in series.

[0040] The control module is connected to the electronic switch group, bypass switch group, voltage sensor and current sensor. It is used to determine the fault location and fault type based on voltage and current, and then control the opening and closing of the bypass switch based on the fault location and fault type. Fault types include hot spots, short circuits and arcing caused by poor contact.

[0041] For example, such as Figure 1 As shown in the figure, S1 and S2 are electronic switches, D1, D2 and D3 are diodes, BT1 and BT2 are photovoltaic solar panel 1 and photovoltaic solar panel 2, IN1+ and IN1- are the positive and negative terminals of photovoltaic solar panel 1, IN2+ and IN2- are the positive and negative terminals of photovoltaic solar panel 2, and OUT+ and OUT- are the positive and negative output terminals of the photovoltaic system. When the photovoltaic system is working normally, the current flows in the following order: OUT-, IN2-, BT2, IN2+, S2, IN1-, BT1, IN1+, S2, OUT+, completing the normal series connection of the two photovoltaic panels. When poor contact of photovoltaic panel BT1 generates an electric arc (spark), causing BT2 to malfunction, the voltage sensor and current sensor will send the detected abnormal voltage and current to the control module. Based on the voltage and current, the control module determines that the fault location is photovoltaic panel BT2 and the fault type is poor contact causing an electric arc. Then, it controls the bypass switch S2 to open, thereby bypassing the damaged photovoltaic panel BT2. After the protection device performs bypass protection, the current direction is OUT-, D1, IN1-, BT1, IN1+, S2, OUT+, thus bypassing the damaged photovoltaic panel BT2, allowing the entire photovoltaic system to continue to work normally without paralyzing the entire photovoltaic system due to the damage to photovoltaic panel BT2.

[0042] In some embodiments, the protection device includes a signal coupler connected in series in the main circuit for coupling communication signals to the power supply line.

[0043] In some embodiments, the protection device includes a power line carrier communication module located on one side of the signal coupler, connected to the signal coupler, and signal-connected to the control module for communication transmission of voltage, current, and on / off signals of the control bypass switch, so as to facilitate subsequent notification to the user for maintenance of the photovoltaic panel.

[0044] In some embodiments, the control module is specifically used for:

[0045] If the voltage difference between a certain photovoltaic panel and the voltages of other photovoltaic panels is greater than the voltage difference, the fault type is determined to be a hot spot.

[0046] When the fault type is hot spot, the bypass switch corresponding to the photovoltaic panel is disconnected.

[0047] In some embodiments, the voltage difference can be 30V, which allows for accurate detection of hot spot faults.

[0048] In some embodiments, the control module is specifically used for:

[0049] If the voltage of a photovoltaic panel is lower than the threshold voltage, the fault type is determined to be a short circuit.

[0050] When the fault type is short circuit, the bypass switch corresponding to the photovoltaic panel is disconnected.

[0051] In some embodiments, the threshold voltage can be a DC voltage of 30V.

[0052] In some embodiments, the control module is specifically used for:

[0053] In response to the presence of high-frequency current components in the current, the fault type is determined to be arcing caused by poor contact, with the specific frequency range being 10kHz to 100kHz.

[0054] When the fault type is poor contact causing an electric arc, the bypass switch corresponding to the photovoltaic panel is disconnected.

[0055] In some embodiments, the control module is specifically used for:

[0056] Wavelet transform is used to extract the signal abrupt change components of current and voltage. Combined with the spatial correlation of the positions of voltage and current sensors corresponding to voltage and current, preliminary position results are determined. Compensation analysis is performed on the preliminary position results to determine the fault location.

[0057] Because the current sensors are connected in series, the DC components of all current sensors are of equal magnitude. In some embodiments, the protection device may also include an inductor, such as... Figure 1 By setting L1 in this way, the high-frequency components of the current in the photovoltaic panel can be different, which can help determine the location of the photovoltaic panel that generates the electric arc.

[0058] In some embodiments, the control module is further configured to:

[0059] When a user sends a signal to start the photovoltaic system, the control electronic switch and bypass switch are turned on;

[0060] When a user sends a signal to shut down the photovoltaic system, the control electronic switch and bypass switch are disconnected.

[0061] In some embodiments, the control module is further configured to:

[0062] The photovoltaic system's operating status is sent to the user's central control room via a power line carrier communication module. The operating status includes normal and abnormal states, and the abnormal state includes the fault type and fault location.

[0063] In some embodiments, the electronic switch is any one of a diode, a transistor, and a field-effect transistor, and the bypass switch is any one of a relay, a contactor, and a field-effect transistor.

[0064] In summary, the embodiments of this application provide a protection device for a photovoltaic system. This device can disconnect the photovoltaic panel from the entire photovoltaic system when a fault occurs in a photovoltaic panel, such as a hot spot, short circuit, or arcing due to poor contact, thereby achieving bypass protection. This protection device can accurately locate and warn of faults in the photovoltaic system and provide timely physical protection.

[0065] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0066] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A protection device for a photovoltaic system, characterized in that, The photovoltaic system includes two photovoltaic panels connected in series. The protection device includes: multiple voltage sensors, multiple current sensors, electronic switch group and bypass switch group and control module. The electronic switch group includes three electronic switches, which are used to continue the main circuit in series when a photovoltaic panel fails. The bypass switch group includes two bypass switches, which are connected in series with the photovoltaic panels at intervals. They are used to receive the on / off signal from the control module to conduct or disconnect when a photovoltaic panel fails, so as to ensure the normal operation of the photovoltaic panel or bypass the photovoltaic panel that caused the failure. Voltage sensors are connected in parallel across the two ends of the photovoltaic panel to detect the voltage of the corresponding photovoltaic panel; A current sensor is connected in series between the photovoltaic panels to detect the current in the main circuit of the two photovoltaic panels connected in series. The control module is connected to the electronic switch group, bypass switch group, voltage sensor and current sensor. It is used to determine the fault location and fault type based on voltage and current, and then control the opening and closing of the bypass switch based on the fault location and fault type. The fault types include hot spots, short circuits and arcing caused by poor contact.

2. The protection device for a photovoltaic system according to claim 1, characterized in that, The protection device includes a signal coupler connected in series in the main circuit to couple communication signals to the power supply line.

3. The protection device for a photovoltaic system according to claim 1, characterized in that, The protection device includes a power line carrier communication module, which is located on one side of the signal coupler, connected to the signal coupler, and signal-connected to the control module for communication transmission of voltage, current, and control signals for switching on and off the bypass switch.

4. The protection device for a photovoltaic system according to claim 1, characterized in that, The control module is specifically used for: If the voltage difference between a certain photovoltaic panel and the voltages of other photovoltaic panels is greater than the voltage difference, the fault type is determined to be a hot spot. When the fault type is hot spot, the bypass switch corresponding to the photovoltaic panel is disconnected.

5. A protection device for a photovoltaic system according to claim 1, characterized in that, The control module is specifically used for: In response to a photovoltaic panel's voltage being less than a threshold voltage, the fault type is determined to be a short circuit; When the fault type is a short circuit, the bypass switch corresponding to the photovoltaic panel is disconnected.

6. A protection device for a photovoltaic system according to claim 1, characterized in that, The control module is specifically used for: In response to the presence of high-frequency current components in a specific frequency band, the fault type is determined to be arcing caused by poor contact, where the specific frequency band ranges from 10kHz to 100kHz. When the fault type is poor contact causing an electric arc, the bypass switch corresponding to the photovoltaic panel is disconnected.

7. A protection device for a photovoltaic system according to claim 1, characterized in that, The control module is specifically used for: Wavelet transform is used to extract the signal abrupt change components of current and voltage. Combined with the spatial correlation of the positions of voltage and current sensors corresponding to voltage and current, preliminary position results are determined. Compensation analysis is performed on the preliminary position results to determine the fault location.

8. A protection device for a photovoltaic system according to claim 1, characterized in that, The control module is also used for: When a user sends a signal to start the photovoltaic system, the electronic switch and the bypass switch are turned on. When a user sends a signal to shut down the photovoltaic system, the electronic switch and the bypass switch are disconnected.

9. A protection device for a photovoltaic system according to claim 1, characterized in that, The control module is also used for: The photovoltaic system's operating status is sent to the user's central control room via the power line carrier communication module. The operating status includes normal status and abnormal status, and the abnormal status includes the fault type and fault location.

10. A protection device for a photovoltaic system according to claim 1, characterized in that, The electronic switch is any one of diodes, transistors, and field-effect transistors, and the bypass switch is any one of relays, contactors, and field-effect transistors.

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