CN113241734B - Photovoltaic panel negative electrode grounding detection and protection device - Google Patents
Photovoltaic panel negative electrode grounding detection and protection device Download PDFInfo
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- CN113241734B CN113241734B CN202110480730.6A CN202110480730A CN113241734B CN 113241734 B CN113241734 B CN 113241734B CN 202110480730 A CN202110480730 A CN 202110480730A CN 113241734 B CN113241734 B CN 113241734B
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- 238000001514 detection method Methods 0.000 title claims abstract description 37
- 238000005070 sampling Methods 0.000 claims abstract description 17
- 238000004891 communication Methods 0.000 claims abstract description 5
- 238000010248 power generation Methods 0.000 abstract description 12
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/122—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. DC/AC converters
- H02H7/1225—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for inverters, i.e. DC/AC converters responsive to internal faults, e.g. shoot-through
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
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Abstract
The invention relates to a photovoltaic panel cathode grounding detection and protection device, which comprises: the fuses are connected in series with the photovoltaic panel group strings in a one-to-one corresponding mode; the voltage and current sampling and signal isolating units are arranged in one-to-one correspondence with the photovoltaic panel group strings and are used for detecting and isolating voltage and short-circuit current at two ends of a corresponding fuse and outputting corresponding detection signals; and the controller is respectively in communication connection with each voltage and current sampling and signal isolating unit and the control unit of the photovoltaic inverter and is used for judging the photovoltaic panel group string with the grounded negative electrode according to the detection signal output by the voltage and current sampling and signal isolating unit and sending out a corresponding control signal, and the control unit of the photovoltaic inverter closes the MPPT control unit corresponding to the photovoltaic panel group string with the grounded negative electrode based on the control signal. The invention can detect the grounding of the negative electrode of the photovoltaic panel in time and disconnect the corresponding loop, protect the inverter and reduce the power generation loss caused by the shutdown of the whole machine.
Description
Technical Field
The invention relates to the technical field of power electronics and electrical equipment, in particular to a photovoltaic panel cathode grounding detection and protection device in the solar photovoltaic power generation system industry.
Background
Photovoltaic power generation technology is being developed vigorously all over the world as a renewable energy power generation technology. In the initial installation and construction process of the photovoltaic power station, the negative wire cable of the photovoltaic panel is likely to be grounded through skin breaking, or the negative wire cable of the photovoltaic panel is poor in aging insulation property and grounded after the photovoltaic power station operates for a long time. When such a grounding condition occurs, a current loop exists between the photovoltaic panel, the inverter and the transformer, which causes a large ratio of current flowing through the inverter to damage the inverter. The insulating monitoring circuit and the leakage current detection circuit that rely on present photovoltaic inverter internal integration can't cut off the return circuit between dc-to-ac converter and the transformer fast now and lead to the dc-to-ac converter to damage, can't play the function of protection inverter, the concrete expression is in: (1) In the prior art, a photovoltaic inverter controller is required to sample a ground fault signal firstly, extract the fault signal and send a relay for disconnecting the output side of the photovoltaic inverter, the whole action time is long, and the inverter cannot be protected; (2) The prior art cannot judge which specific string of negative cables of the photovoltaic panel connected into the inverter is grounded; (3) For the inverter with multi-path MPPT input, after a negative cable of a string of photovoltaic panels is grounded, the whole inverter stops grid-connected power generation, and more power generation loss is brought to a power station owner.
Disclosure of Invention
The invention aims to provide a photovoltaic panel cathode grounding detection and protection device which can detect grounding in time and process the grounding in time so as to avoid damage of an inverter.
In order to achieve the purpose, the invention adopts the technical scheme that:
the utility model provides a photovoltaic panel negative pole ground connection detects and protection device, sets up in the photovoltaic inverter who is connected with photovoltaic panel group cluster, photovoltaic panel negative pole ground connection detects and protection device includes:
the fuses are connected in series with the photovoltaic panel group strings in a one-to-one correspondence mode;
the voltage and current sampling and signal isolating units are arranged in one-to-one correspondence with the photovoltaic panel group strings and are used for detecting voltages and short-circuit currents at two ends of the corresponding fuses, isolating the voltages and the short-circuit currents and outputting corresponding detection signals;
the controller is in communication connection with the voltage and current sampling and signal isolating units and the control unit of the photovoltaic inverter respectively and used for judging the photovoltaic panel group string with the grounded negative electrode and sending a corresponding control signal according to the detection signal output by the voltage and current sampling and signal isolating units, and the control unit of the photovoltaic inverter closes the MPPT control unit corresponding to the photovoltaic panel group string with the grounded negative electrode based on the control signal.
The voltage and current sampling and signal isolating unit comprises a current detection module which is connected in series with the corresponding photovoltaic panel group and used for detecting the short-circuit current, and a voltage detection module which is connected with the corresponding fuse and used for detecting the voltage at two ends of the fuse.
The current detection module comprises a current transformer.
The voltage detection module comprises a first resistor, a second resistor and an amplifier, wherein two ends of the first resistor are respectively connected with one end of the fuse and one input end of the amplifier, two ends of the second resistor are respectively connected with the other end of the fuse and the other input end of the amplifier, and the output end of the amplifier is connected with the controller.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the invention can detect the grounding of the negative electrode of the photovoltaic panel in time and disconnect the corresponding loop in time, thereby protecting the inverter and reducing the power generation loss caused by the shutdown of the whole machine.
Drawings
Fig. 1 is a schematic diagram of a photovoltaic power generation system to which the negative electrode grounding detection and protection device of a photovoltaic panel of the present invention is applied.
Fig. 2 is a circuit diagram of a single-phase photovoltaic power generation system to which the negative electrode grounding detection and protection device of a photovoltaic panel is applied.
Fig. 3 is a circuit diagram of a three-phase photovoltaic power generation system using the photovoltaic panel cathode grounding detection and protection device of the present invention.
Fig. 4 is a control flow chart of the photovoltaic panel cathode grounding detection and protection device of the present invention.
Detailed Description
The invention will be further described with reference to examples of embodiments shown in the drawings to which the invention is attached.
The first embodiment is as follows: as shown in fig. 1, the photovoltaic power generation system includes n photovoltaic panel string (solar panel string), a photovoltaic inverter (grid-connected inverter) connected to each photovoltaic panel string, and a grid-connected transformer connected to the photovoltaic inverter. The photovoltaic inverter comprises a DC/DC conversion circuit and a DC/AC conversion circuit which are connected, wherein the DC/DC conversion circuit comprises MPPT control units which are arranged in one-to-one correspondence with the photovoltaic panel groups. The photovoltaic panel cathode grounding detection and protection device is arranged in a DC/DC conversion circuit of a photovoltaic inverter and is connected with each photovoltaic panel group string and each MPPT control unit.
As shown in fig. 2 and fig. 3, the photovoltaic panel negative electrode grounding detection and protection device comprises a fuse, a voltage and current sampling and signal isolating unit and a controller. Fuses (fuses) are correspondingly connected in series with the photovoltaic panel group strings in a one-to-one mode and are connected with the MPPT control units in the corresponding DC/DC conversion circuits. Each fuse in the embodiment is F1-Fn. The voltage and current sampling and signal isolating units are arranged in one-to-one correspondence with the photovoltaic panel group strings, detect voltages and short-circuit currents at two ends of corresponding fuses, and output corresponding detection signals after isolation. Specifically, each voltage and current sampling and signal isolating unit comprises a current detection module and a voltage detection module, the current detection module is connected with the corresponding photovoltaic panel group in series and used for detecting short-circuit current, and the voltage detection module is connected with the corresponding fuse and used for detecting voltages at two ends of the fuse. The current detection module comprises current transformers, and each current transformer in the embodiment is CT 1-CTn. The voltage detection module comprises a first resistor, a second resistor and an amplifier, wherein two ends of the first resistor are respectively connected with one end of the fuse and one input end of the amplifier, two ends of the second resistor are respectively connected with the other end of the fuse and the other input end of the amplifier, and an output end of the amplifier is connected with the controller. In this embodiment, the first resistors are R11 to Rn1, the second resistors are R12 to Rn2, and the amplifiers are OP1 to OPn.
The controller is respectively in communication connection with each voltage and current sampling and signal isolating unit and the control unit of the photovoltaic inverter and is used for judging the photovoltaic panel group string with the grounded negative electrode according to the detection signal output by the voltage and current sampling and signal isolating unit and sending out a corresponding control signal, and then the control unit of the photovoltaic inverter closes the MPPT control unit corresponding to the photovoltaic panel group string with the grounded negative electrode based on the control signal.
The specific principle of the invention is as follows: when the negative electrode of the photovoltaic panel group string is grounded, a short-circuit current loop between the negative electrode of the photovoltaic panel and the ground is formed among the photovoltaic panel group string, the photovoltaic inverter and the grid-connected transformer, namely, the grounding current of the negative electrode of the photovoltaic panel flows through the fuse F1 or Fn which is correspondingly connected in series, flows through the inverter tubes (Q2 and Q4 in the figure 2, Q4, Q8 and Q12 in the figure 3), flows through the L1/L2/L3, flows into the central point of the transformer through the output live wire, and finally flows to the ground of the negative electrode of the photovoltaic panel. Since the impedance in the loop is relatively low and the voltage of the negative electrode to the ground is relatively high, the current at the moment of short circuit is relatively large. When the short-circuit current passes through the fuse, the fuse is blown, and the voltage at two ends of the fuse is not zero any more at the moment. The sampling voltage signal is conducted to the controller after physical isolation, the controller can judge which photovoltaic panel group string is grounded at the moment according to the signal, a corresponding control signal is sent to the control unit of the photovoltaic inverter, the control unit of the photovoltaic inverter controls to close the MPPT control unit corresponding to the photovoltaic panel group string with the grounded cathode, and the controller transmits grounding error information to a human-computer interaction interface of a power station maintainer through communication. The inverter is still operating normally. The specific logic flow of the detection and protection device is shown in fig. 4.
The beneficial effect of above-mentioned scheme lies in: (1) After the negative pole grounding condition of the photovoltaic panel occurs, the grounding detection protection device can disconnect the whole loop within us-level time and protect a power tube inside the inverter, so that other key components of the inverter cannot be damaged. (2) The grounding detection protection device can judge which string of photovoltaic panels generates the condition of grounding of the negative electrode, so that power station maintenance personnel can quickly troubleshoot problems. (3) For the inverter with multi-path MPPT input, after a negative electrode cable of a string of photovoltaic panels is grounded, the inverter stops the MPPT of the inverter, but other MPPT of the inverter are still in normal grid-connected power generation, and the generated energy loss caused by the shutdown of the whole inverter is reduced under the condition.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (4)
1. The utility model provides a photovoltaic panel negative pole ground connection detects and protection device, sets up in the photovoltaic inverter who is connected with photovoltaic panel group cluster, its characterized in that: photovoltaic panel negative pole ground connection detects and protection device includes:
the fuses are connected in series with the photovoltaic panel group strings in a one-to-one correspondence mode;
the voltage and current sampling and signal isolating units are arranged in one-to-one correspondence with the photovoltaic panel group strings and are used for detecting voltages and short-circuit currents at two ends of the corresponding fuses, isolating the voltages and the short-circuit currents and outputting corresponding detection signals;
the controller is in communication connection with the voltage and current sampling and signal isolating units and the control unit of the photovoltaic inverter respectively and used for judging the photovoltaic panel group string with the grounded negative electrode and sending a corresponding control signal according to the detection signal output by the voltage and current sampling and signal isolating units, and the control unit of the photovoltaic inverter closes the MPPT control unit corresponding to the photovoltaic panel group string with the grounded negative electrode based on the control signal.
2. The device of claim 1, wherein the device for detecting and protecting the negative electrode of the photovoltaic panel comprises: the voltage and current sampling and signal isolating unit comprises a current detection module which is connected in series with the corresponding photovoltaic panel group and used for detecting the short-circuit current, and a voltage detection module which is connected with the corresponding fuse and used for detecting the voltage at two ends of the fuse.
3. The device of claim 2, wherein the device for detecting and protecting the negative electrode of the photovoltaic panel comprises: the current detection module comprises a current transformer.
4. The device according to claim 2, wherein the device for detecting and protecting the grounding of the negative electrode of the photovoltaic panel comprises: the voltage detection module comprises a first resistor, a second resistor and an amplifier, wherein two ends of the first resistor are respectively connected with one end of the fuse and one input end of the amplifier, two ends of the second resistor are respectively connected with the other end of the fuse and the other input end of the amplifier, and the output end of the amplifier is connected with the controller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110480730.6A CN113241734B (en) | 2021-04-30 | 2021-04-30 | Photovoltaic panel negative electrode grounding detection and protection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110480730.6A CN113241734B (en) | 2021-04-30 | 2021-04-30 | Photovoltaic panel negative electrode grounding detection and protection device |
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| Publication Number | Publication Date |
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| CN113241734A CN113241734A (en) | 2021-08-10 |
| CN113241734B true CN113241734B (en) | 2023-03-31 |
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| CN202110480730.6A Active CN113241734B (en) | 2021-04-30 | 2021-04-30 | Photovoltaic panel negative electrode grounding detection and protection device |
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Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2997240B1 (en) * | 2012-10-18 | 2016-02-05 | Schneider Electric Ind Sas | SYSTEM FOR PROTECTING A PLURALITY OF CONTINUOUS VOLTAGE SOURCES, ALTERNATIVE VOLTAGE GENERATION PLANT WITH A PLURALITY OF CONTINUOUS VOLTAGE SOURCES, A VOLTAGE INVERTER AND SUCH A PROTECTIVE SYSTEM, AND ASSOCIATED PROTECTION METHOD |
| CN205404714U (en) * | 2016-03-18 | 2016-07-27 | 厦门科华恒盛股份有限公司 | Fuse failure detector circuit |
| CN106788220B (en) * | 2017-03-31 | 2020-03-24 | 阳光电源股份有限公司 | Photovoltaic group string wiring terminal |
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Address after: 215000 No. 90, Zijin Road, high tech Zone, Suzhou, Jiangsu Applicant after: Goodway Technology Co.,Ltd. Address before: No. 90, Zijin Road, high tech Zone, Suzhou City, Jiangsu Province, 215011 Applicant before: JIANGSU GOODWE POWER SUPPLY TECHNOLOGY Co.,Ltd. |
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