CN117424465A - Photovoltaic inverter assembly with open-circuit voltage protection function and photovoltaic inverter - Google Patents
Photovoltaic inverter assembly with open-circuit voltage protection function and photovoltaic inverter Download PDFInfo
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- CN117424465A CN117424465A CN202311737929.8A CN202311737929A CN117424465A CN 117424465 A CN117424465 A CN 117424465A CN 202311737929 A CN202311737929 A CN 202311737929A CN 117424465 A CN117424465 A CN 117424465A
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- 230000001681 protective effect Effects 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims description 4
- 230000007423 decrease Effects 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 abstract description 2
- 244000261422 Lysimachia clethroides Species 0.000 description 7
- 238000010586 diagram Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 3
- 238000009434 installation Methods 0.000 description 2
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- 229910052782 aluminium Inorganic materials 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/003—Constructional details, e.g. physical layout, assembly, wiring or busbar connections
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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
- H02H7/1222—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 abnormalities in the input circuit, e.g. transients in the DC input
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/041—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using a short-circuiting device
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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
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a photovoltaic inverter component with an open-circuit voltage protection function and a photovoltaic inverter, and belongs to the field of AC-DC conversion equipment; wherein, photovoltaic inverter assembly with open circuit voltage protect function includes: the direct current overload protection circuit is arranged on the input circuit of the photovoltaic inverter, and the protection module is arranged on the photovoltaic inverter; the protection module includes: the device comprises a direct-current bus overvoltage protection circuit, an alternating-current overvoltage and undervoltage protection circuit and an anti-islanding effect module. According to the invention, the direct-current bus overvoltage protection circuit and the alternating-current overvoltage and undervoltage protection circuit both adopt the zener voltage stabilizing circuit, and the reverse characteristic of the volt-ampere characteristic curve of the zener voltage stabilizing circuit is that when the reverse voltage is lower than the reverse breakdown voltage, the reverse resistance is very large, and the reverse leakage current is very small, so that the voltage stabilizing function is realized.
Description
Technical Field
The invention belongs to the field of AC-DC conversion equipment, and particularly relates to a photovoltaic inverter assembly with an open-circuit voltage protection function; meanwhile, the invention also relates to a photovoltaic inverter comprising the photovoltaic inverter assembly with an open-circuit voltage protection function.
Background
As a core device for converting direct current provided by a solar module into alternating current for civil use or industrial use, the position of a photovoltaic inverter in a new energy field is increasingly important, the output voltage of the photovoltaic module is usually at the maximum power point tracked by the photovoltaic module, however, when the rated voltage of an electrolytic capacitor is selected according to the voltage Vmpp of the maximum power point, the open-circuit voltage of the photovoltaic module is deviated, particularly when the open-circuit voltage VOC of the photovoltaic module is usually 1.2 times of the voltage Vmpp of the maximum power point, the electrolytic capacitor according to the voltage Vmpp is over-voltage, but if the rated voltage is selected according to the VOC, the problem that the over-voltage possibly occurs is solved, but the problem that the electrolytic capacitor at the input side is over-high due to the selection of the rated voltage, and the cost and the volume are increased is solved.
Disclosure of Invention
The invention aims to solve the defects in the prior art, and provides a photovoltaic inverter component with an open-circuit voltage protection function and a photovoltaic inverter.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the photovoltaic inverter assembly with the open-circuit voltage protection function comprises a protective shell and a direct current overload protection circuit integrated inside the protective shell, wherein the direct current overload protection circuit is arranged on a photovoltaic inverter input circuit;
further comprises:
a protection module disposed on the photovoltaic inverter;
the protection module includes: the device comprises a direct-current bus overvoltage protection circuit, an alternating-current overvoltage and undervoltage protection circuit and an anti-islanding effect module;
the direct current overload protection circuit continuously detects direct current side input power, and when the direct current input power is detected to be larger than the limit, the inverter automatically limits maximum output alternating current power to be within a controllable range.
Preferably, a wire connecting block for connecting wires of the photovoltaic inverter is arranged on the protective shell, a detachable extension mechanism capable of being bent at will is connected to the wire connecting block, and a connecting piece with the same structure as the wire connecting block is arranged at one end, opposite to the wire connecting block, of the extension mechanism.
Preferably, the electronic circuit breaker, the current transformer and the controller are arranged on the current overload protection circuit, when the current overload protection circuit detects that the current of the current transformer exceeds a preset value, a relevant signal is sent to the controller, the controller gives a driving signal to the electronic circuit breaker, and the brake-separating electromagnet drives the spring operating mechanism to act, so that the brake separation of the electronic circuit breaker is controlled.
Preferably, the dc bus overvoltage protection circuit and the ac overvoltage/undervoltage protection circuit both adopt a zener voltage stabilizing circuit, the zener voltage stabilizing circuit regulates the input voltage by providing a stabilized voltage and protects the circuit from overvoltage, but when the voltage exceeds a safety limit, the output part is not disconnected, and the output voltage which is smaller than or equal to the rated value of the zener diode is always received.
Preferably, the preset voltage value of the zener voltage stabilizing circuit is a critical value that the power supply is disconnected or any voltage higher than the value is not allowed; the preset voltage value is the rated value of the zener diode;
when the output voltage increases, the base-emitter voltage decreases, and the output voltage is reduced due to fewer transistors being turned on, so that the output voltage is kept constant;
the output voltage is defined as:
V O =V Z -V BE wherein V is O Is the output voltage, V Z Is the zener breakdown voltage, V BE Is the base-emitter voltage.
Preferably, the anti-islanding module specifically comprises the following working procedures:
and (3) performing normal grid-connected voltage outer loop and current inner loop control, performing active disturbance, and then performing the following detection:
detecting whether the voltage value of the power grid is 80% -115%, if yes, returning to the control of the outer ring and the inner ring of the original normal grid-connected voltage, if not, performing under-voltage protection for less than or equal to 2s, detecting whether the voltage value of the power grid is recovered to 80% -115% of the normal value, and after recovering the normal value, maintaining for 5min, and then returning to the control of the outer ring and the inner ring of the normal grid-connected voltage;
and detecting whether the voltage unbalance of the power grid is lower than 4%, if so, returning to the control of the outer ring and the inner ring of the original normal grid-connected voltage, if not, performing protection for less than or equal to 2 seconds, detecting whether the voltage unbalance of the power grid is restored to a normal value lower than 4%, and after the normal value is restored, maintaining for 5 minutes, and then returning to the control of the outer ring and the inner ring of the normal grid-connected voltage.
Preferably, the detecting further includes:
detecting whether the power grid frequency value is between 47.5 and 51.5Hz, if not, carrying out over-frequency protection for less than or equal to 0.2s, detecting whether the power grid frequency is recovered to a normal value, returning to control of a normal grid-connected voltage outer ring and a current inner ring after recovering the normal value, if so, detecting whether the power grid voltage phase is mutually different by 20 degrees and the error is within 10 degrees, and determining whether to control the power grid voltage outer ring and the current inner ring or carrying out protection for less than or equal to 0.2s according to the result, and detecting whether the power grid phase difference is recovered to the normal value;
detecting whether the phase deviation between the phase voltage and the phase current of the power grid is within 25 degrees, if yes, returning to the control of the outer ring and the inner ring of the normal grid-connected voltage, if not, carrying out protection for less than or equal to 0.2s, and restarting after 5 min.
A photovoltaic inverter comprising:
the photovoltaic inverter assembly with the open-circuit voltage protection function comprises an input circuit, a main inverter circuit, an output circuit, a control circuit and an auxiliary circuit.
Preferably, the input circuit is used for providing a direct current working voltage for the main inverter circuit, and the direct current working voltage can ensure the normal operation of the main inverter circuit; the main inverter circuit is a core of the photovoltaic inverter and is used for completing the inversion function through the on and off of the power electronic switch; the output circuit corrects, compensates and conditions the amplitude and the phase of the alternating current waveform, the frequency, the voltage and the current output by the main inverter circuit; the control circuit provides control pulses for the main inverter circuit to control the on and off of the inverter switching device, and the control circuit is matched with the main inverter circuit to complete the inversion function; the auxiliary circuit converts the input voltage into a direct voltage suitable for the operation of the control circuit.
Preferably, the main inverter circuit is provided with four groups of triodes VT1-VT4, and when the main inverter circuit works, control pulse signals are provided for bases of the triodes VT1-VT 4;
when the base pulse signals of VT1 and VT4 are high level and the base pulse signals of VT2 and VT3 are low level, VT1 and VT4 are conducted, VT2 and VT3 are turned off, and current flows through load RL via VT1 and VT4, the current path is that the voltage polarity at two ends of power supply E positive electrode-VT 1-RL-VT 4-power supply E negative electrode is left positive and right negative;
when the base pulse signals of VT2 and VT3 are high level and the base pulse signals of VT1 and VT4 are low level, VT2 and VT3 are on, VT1 and VT4 are off, and current flows through load RL via VT2 and VT3, the current path is that the polarity of the voltages at two ends of power supply E positive electrode-VT 3-RL-VT 2-power supply E negative electrode is left negative and right positive.
The invention has the technical effects and advantages that: compared with the prior art, the photovoltaic inverter component with the open-circuit voltage protection function and the photovoltaic inverter have the advantages that the direct-current bus overvoltage protection circuit and the alternating-current overvoltage and undervoltage protection circuit are both zener voltage stabilizing circuits, the reverse characteristic of the volt-ampere characteristic curve of the zener voltage stabilizing circuits is that when the reverse voltage is lower than the reverse breakdown voltage, the reverse resistance is large, the reverse leakage current is extremely small, and the voltage of the zener voltage stabilizing circuits is basically stabilized near the breakdown voltage, so that the voltage stabilizing function is realized;
secondly, the anti-islanding module aims at a protection device developed by an islanding phenomenon caused by voltage or frequency and other anomalies in a photovoltaic power station, when any one side of the anti-islanding device on the side of the light Fu Ben loses electricity, a tripping signal can be rapidly sent to a grid-connected breaker to enable the breaker to be disconnected, the life safety of maintenance personnel on two sides of the photovoltaic is protected, and meanwhile, the anti-islanding protection device also has the functions of overcurrent protection, low-current protection, PT disconnection protection and reverse power protection.
Drawings
FIG. 1 is a schematic diagram of a Zener voltage regulator circuit according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a photovoltaic inverter according to an embodiment of the present invention;
FIG. 3 is a circuit diagram of an electronic circuit breaker in accordance with one embodiment of the present invention;
FIG. 4 is a schematic diagram of a main inverter circuit according to an embodiment of the present invention;
FIG. 5 is a diagram of an overvoltage protection circuit constructed by a zener diode and PNP transistor in accordance with an embodiment of the present invention;
FIG. 6 is a schematic view of a photovoltaic inverter assembly protecting shell and an extension mechanism connection structure according to an embodiment of the present invention;
FIG. 7 is a schematic illustration of a non-metallic gooseneck of an extension mechanism coupled to a hollow connection in accordance with an embodiment of the present invention.
In the figure: 1. a protective shell; 2. a wire connecting block; 3. an extension mechanism; 4. a connecting piece; 5. a screw; 6. a connecting block; 7. a conductive portion; 8. a hollow connection portion; 9. a nonmetallic gooseneck; 10. a fixing plate; 11. and (5) a heat-shrinkable sleeve.
Detailed Description
The present invention will be described in further detail with reference to specific embodiments in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a photovoltaic inverter assembly with an open circuit voltage protection function, which comprises:
the photovoltaic inverter assembly comprises a protective shell and a direct current overload protection circuit integrated in the protective shell, and the direct current overload protection circuit is arranged on the photovoltaic inverter input circuit;
as shown in fig. 6-7, the protecting shell 1 is provided with a plurality of groups of wire connecting blocks 2 for connecting wires of the photovoltaic inverter and connecting direct current input lines, an extension mechanism 3 which can be bent at will is detachably connected on the wire connecting blocks 2, and one end of the extension mechanism 3 opposite to the wire connecting blocks 3 is provided with a connecting piece 4 with the same structure as the wire connecting blocks;
furthermore, the wire connecting block 2 is a hollow tubular connecting block, and the bottom end and the side wall of the inside of the wire connecting block are provided with metal conducting strips which are connected in series with the direct current overload protection circuit in the protecting shell 1, and the metal conducting strips are made of copper, aluminum and silver materials; the upper end of the wire connecting block 2 is provided with a threaded hole, the interior of the threaded hole is in threaded connection with a screw 5, one end of the screw 5 penetrates through the side wall of the wire connecting block 2 and is positioned in the wire connecting block, and the wire connecting block is used for limiting and fixing a wire or an extension mechanism 3 arranged in the wire connecting block;
as a further explanation of the above embodiment, the extension mechanism 3 capable of arbitrary bending includes:
the connecting block 6, the connecting block 6 comprises a conductive part 7 and a hollow connecting part 8, the conductive part 7 is used for contacting with the conductive sheet on the bottom end and the side wall of the inside of the wire connecting block 2 to form conductive connection, and the hollow connecting part 8 is internally provided with a connecting wire with the end part fixed on the conductive part 7;
a nonmetallic gooseneck 9, one end of the nonmetallic gooseneck 9 is communicated with the hollow connecting part 8, and the end is fixed by two groups of fixing plates 10 arranged at one end outside the hollow connecting part 8, wherein one end of a connecting wire passes through the nonmetallic gooseneck 9 and is connected with the connecting piece 4; wherein, the connecting part of the nonmetallic gooseneck 9 and the connecting block 6 is fixed in an auxiliary way by adopting a heat-shrinkable sleeve 11;
the connecting piece 4 and the wire connecting block 2 are arranged in the same structure, and the length of the connecting piece is one half of that of the wire connecting block 2, so that the connecting piece has the function of connecting wires or connecting the connecting block 6;
the design can be aimed at different installation environments, the direct current overload protection circuit and the photovoltaic inverter input circuit are ensured to be connected, meanwhile, the lead can be bent in any shape according to the actual installation environments while the lead is protected through the use of the nonmetal gooseneck 9, and the direct current overload protection circuit and the photovoltaic inverter input circuit are further convenient to connect.
Further comprises:
a protection module disposed on the photovoltaic inverter;
it should be noted that, as shown in fig. 1, the dc bus overvoltage protection circuit and the ac overvoltage/undervoltage protection circuit both use zener voltage stabilizing circuits, where the zener voltage stabilizing circuits regulate the input voltage by providing a stabilized voltage and protect the circuit from overvoltage, but when the voltage exceeds a safety limit, it will not disconnect the output portion, and will always receive an output voltage less than or equal to the rated value of the zener diode, where the preset voltage value of the zener voltage stabilizing circuit is a critical value for power supply disconnection or not allowing any voltage higher than the value; the preset voltage value is the rated value of the zener diode;
when the output voltage increases, the base-emitter voltage decreases, and the output voltage is reduced due to less conduction of the transistor Q1, so that the output voltage is kept constant;
the output voltage is defined as:
V O =V Z -V BE wherein V is O Is the output voltage, V Z Is the zener breakdown voltage, V BE Is the base-emitter voltage.
In this embodiment, an overvoltage protection circuit constructed by a zener diode and a PNP transistor may be used instead of the zener voltage regulator circuit, which turns off the output when the voltage exceeds a preset level, which is the rated value of the zener diode connected to the circuit.
Further, as shown in fig. 5, when the voltage is lower than the preset level, the base of Q2 is high, and is turned off; and when Q2 is in the off state, the base terminal of Q1 will be low, allowing current to flow.
When the voltage exceeds a preset value, the zener diode starts to conduct, the base electrode of the Q2 is grounded, and the Q2 is opened; when Q2 turns on, the base terminal of Q1 goes high and Q1 turns on, Q1 acting as an open switch; thus, Q1 does not allow current to flow through it and protects the load from excess voltage.
As shown in fig. 3, the electronic circuit breaker, the current transformer and the controller are mounted on the current overload protection circuit, when the current overload protection circuit detects that the current of the current transformer exceeds a preset value, a relevant signal is sent to the controller, the controller gives a driving signal to the electronic circuit breaker, and the opening electromagnet drives the spring operating mechanism to act, so that the opening of the electronic circuit breaker is controlled.
As the comparative example of the electronic circuit breaker, the overload protection circuit can also adopt a thermomagnetic circuit breaker to replace the electronic circuit breaker, the thermomagnetic circuit breaker adopts a spiral tube type design, when short-circuit current flows, the changed current generates a magnetic field to drive the movable iron core to move, the brake separating mechanism is triggered, and the brake separating of the circuit breaker is completed;
specifically, the comparison of the thermo-magnetic circuit breaker and the electronic circuit breaker is shown in the following table:
from the table, it can be seen intuitively that the electronic circuit breaker has the characteristics of high detection reliability and low temperature sensitivity compared with the thermo-magnetic circuit breaker.
The protection module includes: the device comprises a direct-current bus overvoltage protection circuit, an alternating-current overvoltage and undervoltage protection circuit and an anti-islanding effect module;
the direct current overload protection circuit continuously detects the direct current side input power, and when the direct current input power is detected to be larger than the limit, the inverter automatically limits the maximum output alternating current power to be within a controllable range.
Specifically, the anti-islanding module specifically works as follows:
and (3) performing normal grid-connected voltage outer loop and current inner loop control, performing active disturbance, and then performing the following detection:
detecting whether the voltage value of the power grid is 80% -115%, if yes, returning to the control of the outer ring and the inner ring of the original normal grid-connected voltage, if not, performing under-voltage protection for less than or equal to 2s, detecting whether the voltage value of the power grid is recovered to 80% -115% of the normal value, and after recovering the normal value, maintaining for 5min, and then returning to the control of the outer ring and the inner ring of the normal grid-connected voltage;
and detecting whether the voltage unbalance of the power grid is lower than 4%, if so, returning to the control of the outer ring and the inner ring of the original normal grid-connected voltage, if not, performing protection for less than or equal to 2 seconds, detecting whether the voltage unbalance of the power grid is restored to a normal value lower than 4%, and after the normal value is restored, maintaining for 5 minutes, and then returning to the control of the outer ring and the inner ring of the normal grid-connected voltage.
Illustratively, the method further comprises:
detecting whether the power grid frequency value is between 47.5 and 51.5Hz, if not, carrying out over-frequency protection for less than or equal to 0.2s, detecting whether the power grid frequency is recovered to a normal value, returning to control of a normal grid-connected voltage outer ring and a current inner ring after recovering the normal value, if so, detecting whether the power grid voltage phase is mutually different by 20 degrees and the error is within 10 degrees, and determining whether to control the power grid voltage outer ring and the current inner ring or carrying out protection for less than or equal to 0.2s according to the result, and detecting whether the power grid phase difference is recovered to the normal value;
detecting whether the phase deviation between the phase voltage and the phase current of the power grid is within 25 degrees, if yes, returning to the control of the outer ring and the inner ring of the normal grid-connected voltage, if not, carrying out protection for less than or equal to 0.2s, and restarting after 5 min.
The embodiment also provides a photovoltaic inverter, as shown in fig. 2, which includes the photovoltaic inverter assembly with the open-circuit voltage protection function, an input circuit, a main inverter circuit, an output circuit, a control circuit and an auxiliary circuit;
the input circuit is used for providing direct current working voltage for the main inverter circuit, and the normal operation of the main inverter circuit can be ensured;
as shown in fig. 4, the main inverter circuit is a core of the photovoltaic inverter, and is used for completing the inversion function through the on and off of the power electronic switch; the main inverter circuit is provided with four groups of triodes VT1-VT4, and when the main inverter circuit works, control pulse signals are provided for bases of the triodes VT1-VT 4;
when the base pulse signals of VT1 and VT4 are high level and the base pulse signals of VT2 and VT3 are low level, VT1 and VT4 are conducted, VT2 and VT3 are turned off, and current flows through load RL via VT1 and VT4, the current path is that the voltage polarity at two ends of power supply E positive electrode-VT 1-RL-VT 4-power supply E negative electrode is left positive and right negative;
when the base pulse signals of VT2 and VT3 are high level and the base pulse signals of VT1 and VT4 are low level, VT2 and VT3 are on, VT1 and VT4 are off, and current flows through load RL via VT2 and VT3, the current path is that the polarity of the voltages at two ends of power supply E positive electrode-VT 3-RL-VT 2-power supply E negative electrode is left negative and right positive.
The output circuit corrects, compensates and conditions the amplitude and phase of the alternating current waveform, frequency, voltage and current output by the main inverter circuit; the control circuit provides control pulses for the main inverter circuit to control the on and off of the inverter switching device, and the main inverter circuit is matched to complete the inversion function;
the auxiliary circuit converts the input voltage into a direct voltage suitable for the operation of the control circuit.
Finally, it should be noted that: the foregoing description of the preferred embodiments of the present invention is not intended to be limiting, but rather, it will be apparent to those skilled in the art that the foregoing description of the preferred embodiments of the present invention can be modified or equivalents can be substituted for some of the features thereof, and any modification, equivalent substitution, improvement or the like that is within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (10)
1. The photovoltaic inverter assembly with the open-circuit voltage protection function is characterized by comprising a protective shell and a direct current overload protection circuit integrated in the protective shell, wherein the direct current overload protection circuit is arranged on a photovoltaic inverter input circuit;
further comprises:
a protection module disposed on the photovoltaic inverter;
the protection module includes: the device comprises a direct-current bus overvoltage protection circuit, an alternating-current overvoltage and undervoltage protection circuit and an anti-islanding effect module;
the direct current overload protection circuit continuously detects direct current side input power, and when the direct current input power is detected to be larger than the limit, the inverter automatically limits maximum output alternating current power to be within a controllable range.
2. The photovoltaic inverter assembly with open circuit voltage protection function of claim 1, wherein: be provided with the wire connecting block that is used for photovoltaic inverter wire to connect on the protecting crust, detachable connection can crooked extending mechanism wantonly on the wire connecting block, extending mechanism with the opposite one end of wire connecting block is provided with the connecting piece with the same structure of wire connecting block.
3. The photovoltaic inverter assembly with open circuit voltage protection function of claim 1, wherein: the electronic circuit breaker, the current transformer and the controller are arranged on the current overload protection circuit, when the current overload protection circuit detects that the current of the current transformer exceeds a preset value, a relevant signal is sent to the controller, the controller drives the electronic circuit breaker to signal, and the brake separating electromagnet drives the spring operating mechanism to act, so that the brake separating of the electronic circuit breaker is controlled.
4. The photovoltaic inverter assembly with open circuit voltage protection function of claim 1, wherein: the direct current bus overvoltage protection circuit and the alternating current overvoltage and undervoltage protection circuit both adopt a zener voltage stabilizing circuit, the zener voltage stabilizing circuit regulates the input voltage by providing a stabilized voltage and protects the circuit from overvoltage, but when the voltage exceeds a safety limit, the output part is not disconnected, and the output voltage which is smaller than or equal to the rated value of a zener diode is always received.
5. The photovoltaic inverter assembly with open circuit voltage protection of claim 4, wherein: the preset voltage value of the zener voltage stabilizing circuit is a critical value of power off or voltage which is not allowed to be higher than the value; the preset voltage value is the rated value of the zener diode;
when the output voltage increases, the base-emitter voltage decreases, and the output voltage is reduced due to fewer transistors being turned on, so that the output voltage is kept constant;
the output voltage is defined as:
V O =V Z -V BE wherein V is O Is the output voltage, V Z Is the zener breakdown voltage, V BE Is the base-emitter voltage.
6. The photovoltaic inverter assembly with open circuit voltage protection function of claim 1, wherein: the anti-islanding module specifically comprises the following working procedures:
and (3) performing normal grid-connected voltage outer loop and current inner loop control, performing active disturbance, and then performing the following detection:
detecting whether the voltage value of the power grid is 80% -115%, if yes, returning to the control of the outer ring and the inner ring of the original normal grid-connected voltage, if not, performing under-voltage protection for less than or equal to 2s, detecting whether the voltage value of the power grid is recovered to 80% -115% of the normal value, and after recovering the normal value, maintaining for 5min, and then returning to the control of the outer ring and the inner ring of the normal grid-connected voltage;
and detecting whether the voltage unbalance of the power grid is lower than 4%, if so, returning to the control of the outer ring and the inner ring of the original normal grid-connected voltage, if not, performing protection for less than or equal to 2 seconds, detecting whether the voltage unbalance of the power grid is restored to a normal value lower than 4%, and after the normal value is restored, maintaining for 5 minutes, and then returning to the control of the outer ring and the inner ring of the normal grid-connected voltage.
7. The photovoltaic inverter assembly with open circuit voltage protection of claim 6, wherein: the detecting further comprises:
detecting whether the power grid frequency value is between 47.5 and 51.5Hz, if not, carrying out over-frequency protection for less than or equal to 0.2s, detecting whether the power grid frequency is recovered to a normal value, returning to control of a normal grid-connected voltage outer ring and a current inner ring after recovering the normal value, if so, detecting whether the power grid voltage phase is mutually different by 20 degrees and the error is within 10 degrees, and determining whether to control the power grid voltage outer ring and the current inner ring or carrying out protection for less than or equal to 0.2s according to the result, and detecting whether the power grid phase difference is recovered to the normal value;
detecting whether the phase deviation between the phase voltage and the phase current of the power grid is within 25 degrees, if yes, returning to the control of the outer ring and the inner ring of the normal grid-connected voltage, if not, carrying out protection for less than or equal to 0.2s, and restarting after 5 min.
8. A photovoltaic inverter, comprising:
the photovoltaic inverter assembly with open circuit voltage protection function of any of claims 1-7, and input, main inverter, output, control and auxiliary circuits.
9. The photovoltaic inverter of claim 8, wherein: the input circuit is used for providing a direct current working voltage for the main inverter circuit, and the normal working of the main inverter circuit can be ensured; the main inverter circuit is a core of the photovoltaic inverter and is used for completing the inversion function through the on and off of the power electronic switch; the output circuit corrects, compensates and conditions the amplitude and the phase of the alternating current waveform, the frequency, the voltage and the current output by the main inverter circuit; the control circuit provides control pulses for the main inverter circuit to control the on and off of the inverter switching device, and the control circuit is matched with the main inverter circuit to complete the inversion function; the auxiliary circuit converts the input voltage into a direct voltage suitable for the operation of the control circuit.
10. A photovoltaic inverter according to claim 9, characterized in that: the main inverter circuit is provided with four groups of triodes VT1-VT4, and when the main inverter circuit works, control pulse signals are provided for bases of the triodes VT1-VT 4;
when the base pulse signals of VT1 and VT4 are high level and the base pulse signals of VT2 and VT3 are low level, VT1 and VT4 are conducted, VT2 and VT3 are turned off, and current flows through load RL via VT1 and VT4, the current path is that the voltage polarity at two ends of power supply E positive electrode-VT 1-RL-VT 4-power supply E negative electrode is left positive and right negative;
when the base pulse signals of VT2 and VT3 are high level and the base pulse signals of VT1 and VT4 are low level, VT2 and VT3 are on, VT1 and VT4 are off, and current flows through load RL via VT2 and VT3, the current path is that the polarity of the voltages at two ends of power supply E positive electrode-VT 3-RL-VT 2-power supply E negative electrode is left negative and right positive.
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| CN202633963U (en) * | 2012-02-20 | 2012-12-26 | 东莞市盛扬实业有限公司 | Circuit of photovoltaic grid-connected inverter |
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| US20180164367A1 (en) * | 2015-05-14 | 2018-06-14 | China Electric Power Research Institute | Method for detecting anti-island protection performance of inverter |
| CN114865618A (en) * | 2022-04-13 | 2022-08-05 | 国网浙江义乌市供电有限公司 | Reactive power optimization and safety lifting device for photovoltaic inverter |
| CN115313470A (en) * | 2022-04-22 | 2022-11-08 | 国网上海市电力公司 | Photovoltaic grid-connected access system |
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| US20130221755A1 (en) * | 2010-11-09 | 2013-08-29 | Sma Solar Technology Ag | Circuit Arrangement for Setting a Potential of a Photovoltaic Generator |
| CN202633963U (en) * | 2012-02-20 | 2012-12-26 | 东莞市盛扬实业有限公司 | Circuit of photovoltaic grid-connected inverter |
| CN203026919U (en) * | 2012-11-29 | 2013-06-26 | 无锡市金赛德电子有限公司 | Input under-voltage protection circuit of photovoltaic inverter power supply |
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