CN203734325U - Photovoltaic grid-connected power generation system - Google Patents
Photovoltaic grid-connected power generation system Download PDFInfo
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- CN203734325U CN203734325U CN201420093730.6U CN201420093730U CN203734325U CN 203734325 U CN203734325 U CN 203734325U CN 201420093730 U CN201420093730 U CN 201420093730U CN 203734325 U CN203734325 U CN 203734325U
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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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Abstract
The utility model discloses a photovoltaic grid-connected power generation system. The system comprises a plurality of photovoltaic battery arrays, a plurality of maximum power point tracking devices, a confluence unit and a grid-connected inverter, wherein the plurality of maximum power point tracking devices are connected with the plurality of photovoltaic battery arrays in a one-to-one correspondence mode, the grid-connected inverter comprises a chopper assembly unit and an inverter unit which are electrically connected in sequence; the chopper assembly unit comprises a first switching tube and an energy consumption resistor connected between DC buses of the grid-connected inverter in series; and the grid-connected inverter further comprises an inverter control unit. Implementation of the photovoltaic grid-connected power generation system has the beneficial effects that the first switching tube of the chopper assembly unit is controlled to be conducted when faults such as low-voltage rid through or high-voltage ride through of a power grid occur to result in boosting of voltage of the DC bus, and the voltage of the DC bus is reduced through discharging of the energy consumption resistor, thereby enabling the DC bus to return to normal quickly, and ensuring reliable running of the overall photovoltaic grid-connected power generation system.
Description
Technical field
The utility model relates to photovoltaic generating system field, more particularly, relates to a kind of grid-connected photovoltaic system.
Background technology
In order to promote the efficiency of photovoltaic generating system, there is a kind of grid-connected photovoltaic system as shown in Figure 1, a connect MPPT maximum power point tracking (MPPT) device of each photovoltaic battery array branch road, comprises DC/DC booster circuit in this device.MPPT maximum power point tracking (MPPT) device is followed electrification component and is disperseed to be installed to different positions, the direct current input of combining inverter is delivered in the output of multiple MPPT devices after the cable of long-distance or bus-bar converge, then by the combining inverter power output that is connected to the grid.Owing to comprising DC/DC booster circuit in MPPT maximum power point tracking (MPPT) device, after being raised, the operating voltage of photovoltaic battery array output delivers to the DC input voitage of combining inverter, carry out grid-connectedly thereby make combining inverter can export higher alternating voltage, its output current is also reduced greatly.Therefore reduced the cost of combining inverter, and after output current reduces, the line loss of copper bar and cable also reduces greatly.In addition, adopt after the electricity generation system shown in Fig. 1, include many group MPPT trace points for every 500kW, can reduce the energy output loss that the difference of photovoltaic cell component or the difference of environment cause.
But; for the grid-connected photovoltaic system shown in Fig. 1, the operating voltage of combining inverter DC side is higher, passes through once low-voltage crossing or high pressure that line voltage occurs; more easily cause producing the overvoltage protection of DC bus, thereby affect the reliability of whole photovoltaic generating system.
Utility model content
The technical problems to be solved in the utility model is, cause grid-connected inverter direct current bus voltage too high and DC bus overvoltage protection easily occurs once the fault such as pass through for the above-mentioned generation electrical network low-voltage crossing of prior art or high pressure, thereby affect the defect of whole grid-connected photovoltaic system reliability, a kind of grid-connected photovoltaic system is provided, comprises several photovoltaic battery arrays, several maximum power point tracking devices that connect one to one with described some photovoltaic battery arrays respectively, unit and combining inverter conflux; Each in described several maximum power point tracking devices all with described in the unit that confluxes be connected, the described unit that confluxes is connected with described combining inverter, the described unit that confluxes is for by an integrated multi-channel DC remittance road direct current output, then is to be input in electrical network after alternating current by described combining inverter by DC inverter;
Wherein, described combining inverter comprises the chopper assembly unit and the inversion unit that are electrically connected successively; Described chopper assembly unit comprises the first switching tube and the energy consumption resistor between the DC bus that is connected in series in described combining inverter;
Described combining inverter also comprises an inverter control unit, described inverter control unit is for sampling the DC bus-bar voltage of described combining inverter, and in described DC bus-bar voltage during higher than the first predeterminated voltage, control described the first switching tube conducting and in the DC bus-bar voltage of described inverter during lower than the second predeterminated voltage, control described the first switching tube and turn-off.
In above-mentioned grid-connected photovoltaic system, described inverter control unit comprises the first control subelement, the second control subelement, wherein:
Described first controls son in the time of described the first switching tube conducting and described electrical network generation low-voltage crossing, controls described inversion unit and provides capacitive reactive power support for described electrical network;
Described second controls subelement in the time that described the first switching tube conducting and described electrical network generation high pressure pass through, and controls described inversion unit and provides perceptual reactive power support for described electrical network.
In above-mentioned grid-connected photovoltaic system, described inverter control unit comprises that the 3rd controls subelement, and the described the 3rd controls subelement for DC bus-bar voltage is carried out to closed-loop control so that DC bus-bar voltage is stabilized in the 3rd predeterminated voltage.
In above-mentioned grid-connected photovoltaic system, described chopper assembly unit also comprises the second switch pipe being connected in parallel with described energy consumption resistor.
In above-mentioned grid-connected photovoltaic system, described the first switching tube comprises IGBT, thyristor, metal-oxide-semiconductor; Described second switch pipe comprises IGBT, the metal-oxide-semiconductor with fly-wheel diode, the diode with fly-wheel diode.
In above-mentioned grid-connected photovoltaic system, described inversion unit is three phase full bridge circuit.
In above-mentioned grid-connected photovoltaic system, described combining inverter also comprises the filter unit being connected with described inversion unit, and described filter unit is LC filter unit.
In above-mentioned grid-connected photovoltaic system, described maximum power tracking device comprises a Boost booster circuit.
Implement grid-connected photovoltaic system of the present utility model, there is following beneficial effect: the inverter direct-flow side in grid-connected photovoltaic system increases chopper assembly unit, while making DC bus-bar voltage at combining inverter higher than the first predeterminated voltage, by the first switching tube conducting in inverter control unit control chopper assembly unit, energy on DC bus is released by energy consumption resistor, thereby reduces DC bus-bar voltage.And in DC bus-bar voltage during lower than the second predeterminated voltage, inverter control unit control the first switching tube turn-offs.In the time that the faults such as electrical network generation low pressure or high pressure pass through cause DC bus-bar voltage to raise, the first switching tube conducting, inverter control unit can support to line voltage (electrical network generation low-voltage crossing) or slacken (electrical network generation high pressure passes through) and reduce DC bus-bar voltage.Therefore can fast and stable DC bus-bar voltage in the time of the faults such as electrical network generation low-voltage crossing or high pressure pass through, ensure the reliability service of photovoltaic generating system, give full play to advantage and the potential of parallel network power generation.
Brief description of the drawings
Below in conjunction with drawings and Examples, the utility model is described in further detail, in accompanying drawing:
Fig. 1 is existing grid-connected photovoltaic system structure chart;
Fig. 2 is the grid-connected photovoltaic system structure chart of the utility model embodiment;
Fig. 3 is the structure chart of combining inverter the first embodiment in Fig. 2;
Fig. 4 is the structure chart of combining inverter the second embodiment in Fig. 2;
Fig. 5 is the structure chart of maximum power point tracking device in Fig. 2;
Fig. 6 is the parallel network power generation control flow chart of the utility model embodiment;
Embodiment
Understand for technical characterictic of the present utility model, object and effect being had more clearly, now contrast accompanying drawing and describe embodiment of the present utility model in detail.
As shown in Figure 2, the grid-connected photovoltaic system of the utility model embodiment comprises several photovoltaic battery arrays 201, several maximum power point tracking devices 202 that connect one to one with some photovoltaic battery arrays respectively, unit 203 and combining inverter 204 conflux; The array that photovoltaic battery array 201 is made up of multiple photovoltaic cells, also multiple photovoltaic battery arrays form, and this is not restricted.
Each in several maximum power point tracking devices is all connected with the unit 203 that confluxes; The unit 203 that confluxes is connected with combining inverter 204, and the unit 203 that confluxes is for by an integrated multi-channel DC remittance road direct current output, then is to be input in electrical network after alternating current by combining inverter 204 by DC inverter.
Fig. 3 is the concrete structure figure of combining inverter in Fig. 2, comprises the chopper assembly unit 2041, inversion unit 2042 and the filter unit 2043 that are electrically connected successively; Wherein, chopper assembly unit 2041 comprises the switching tube Q1 and the energy consumption resistor R that are connected in series between combining inverter DC bus (positive direct-current bus 2044 and negative DC bus 2045).This combining inverter also comprises an inverter control unit (not shown).Relatively existing grid-connected photovoltaic system, the utility model embodiment increases by a chopper assembly unit 2041 in combining inverter DC side.
In the utility model embodiment, inverter control unit sampling DC bus-bar voltage, usually by inverter control unit, DC bus-bar voltage being carried out to closed-loop control makes it be stabilized in the 3rd predeterminated voltage, particularly, inverter control unit can be realized by the switching tube of controlling inversion unit 2042.In the time that line voltage generation low-voltage crossing or high pressure such as pass through at the fault, can cause DC bus-bar voltage fluctuation and exceed the first predeterminated voltage, switching tube Q1 conducting in now inverter control unit control chopper assembly unit, energy on DC bus is released by energy consumption resistor R, prevents that DC bus-bar voltage from further raising.Afterwards, if DC bus-bar voltage lower than the second predeterminated voltage, in inverter control unit control chopper assembly unit switching tube Q1 turn-off.Usually, the value of magnitude of voltage < first predeterminated voltage of magnitude of voltage < second predeterminated voltage of the 3rd predeterminated voltage, taking 1MW photovoltaic grid-connected inverting system as example, the value of the first predeterminated voltage can be set as 880V, the value of the second predeterminated voltage can be set as 820V, and the value of the 3rd predeterminated voltage can be set as 800V.
Above-mentioned inverter control unit can further comprise the first control subelement, the second control subelement and the 3rd control subelement, in the time that electrical network generation low-voltage crossing or high pressure such as pass through at the fault, easily cause DC bus-bar voltage to raise, therefore in the time of switching tube Q1 conducting and electrical network generation low-voltage crossing, control subelement control inversion unit by first in inverter control unit and promote line voltage for electrical network provides capacitive reactive power support; In the time that switching tube Q1 conducting and electrical network generation high pressure pass through, controlling subelement control inversion unit by second in inverter control unit provides perceptual reactive power support to reduce line voltage for electrical network.Therefore the chopper assembly unit in the utility model combining inverter is mainly used in the time that the DC bus-bar voltage of combining inverter raises extremely, conducting by control switch pipe Q1 and shutoff and in the time of switching tube conducting for electrical network provides capacitive reactive power support (electrical network generation low-voltage crossing) or perceptual reactive power support (electrical network generation high pressure passes through) with fast reducing DC bus-bar voltage, then control subelement by the 3rd and DC bus-bar voltage is carried out to closed-loop control DC bus-bar voltage be finally stabilized in the 3rd predeterminated voltage.
In the present embodiment, chopper assembly unit 2041 comprises switching tube Q1 and energy consumption resistor R, and switching tube Q1 can be any one in IGBT or the IGBT with fly-wheel diode, thyristor, metal-oxide-semiconductor, contactor.
As shown in Figure 4, chopper assembly unit 2041 also comprises the switching tube Q2 being connected in parallel with energy consumption resistor R, and switching tube Q2 can be any one in the IGBT with fly-wheel diode, metal-oxide-semiconductor, the diode with fly-wheel diode.
In the present embodiment, switching tube Q2 maintains not conducting, makees diode and uses, in the time that chopper assembly unit need to be opened work, inverter control unit sends a control signal driving switch pipe Q1 conducting, and the energy of positive direct-current bus is released through switching tube Q1 and energy consumption resistor R; In the time that chopper assembly unit need to quit work, inverter control unit control switch pipe Q1 turn-offs, the energy storing in energy consumption resistor R and lead-in inductance carries out afterflow through the diode of switching tube Q2, prevent to turn-off overvoltage and damage device, because of in large electric current and HF switch, resistive element also can present certain perception, the wire of contact resistance also can present certain perception simultaneously, the electric current of on-off switching tube inductance can not cut off immediately, afterflow path must be provided, otherwise can on resistance or DC bus, produce high pressure and burn device.
In the present embodiment, inversion unit 2042 is three phase full bridge circuit, and filter unit 2043 is LC filter circuit.
As shown in Figure 5, in the present embodiment, maximum power tracking device 202 comprises a Boost booster circuit 2021 and control unit 2022.
Fig. 6 is the parallel network power generation control flow chart of the utility model embodiment, and based on the combining inverter shown in Fig. 2, its control method comprises the steps:
S1: inverter control unit is sampled to the DC bus-bar voltage of combining inverter;
S2: inverter control unit is controlled the switching tube Q1 conducting in chopper assembly unit in the DC bus-bar voltage sampling during higher than the first predeterminated voltage, to prevent that DC bus-bar voltage from further raising; Or
The switching tube Q1 that inverter control unit is controlled during lower than the second predeterminated voltage in the DC bus-bar voltage sampling in chopper assembly unit turn-offs;
In the time that electrical network generation low-voltage crossing or high pressure such as pass through at the fault, easily cause the rising of grid-connected inverter direct current bus voltage.Therefore in step S2, DC bus-bar voltage, higher than the first predeterminated voltage, also comprises step after the switching tube Q1 conducting in inverter control unit control chopper assembly unit:
S3: inverter control unit, in the time of electrical network generation low-voltage crossing, is controlled the three-phase bridge arm switch pipe in inversion unit, for electrical network provides capacitive reactive power support; Or
Inverter control unit, in the time that electrical network generation high pressure passes through, is controlled three-phase bridge arm switch pipe in inversion unit and is provided perceptual reactive power support for electrical network.
In step S3, inverter control unit supports (when low-voltage crossing) or slackens (when high pressure passes through) by controlling inversion unit the DC bus-bar voltage that reduces combining inverter to line voltage, thus the DC bus-bar voltage of further fast and stable combining inverter.
In the time of normal work, it is stable that DC bus-bar voltage need to keep, and therefore control method is further comprising the steps of:
S4: DC bus-bar voltage is carried out to closed-loop control to inverter control unit so that DC bus-bar voltage is stabilized in the 3rd predeterminated voltage.
Usually, the value of magnitude of voltage < first predeterminated voltage of magnitude of voltage < second predeterminated voltage of the 3rd predeterminated voltage, taking 1MW photovoltaic grid-connected inverting system as example, the value of the first predeterminated voltage can be set as 880V, the value of the second predeterminated voltage can be set as 820V, and the value of the 3rd predeterminated voltage can be set as 800V.
By reference to the accompanying drawings embodiment of the present utility model is described above; but the utility model is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; instead of restrictive; those of ordinary skill in the art is under enlightenment of the present utility model; not departing from the scope situation that the utility model aim and claim protect, also can make a lot of forms, within these all belong to protection of the present utility model.
Claims (8)
1. a grid-connected photovoltaic system, is characterized in that, comprises several photovoltaic battery arrays, several maximum power point tracking devices that connect one to one with described some photovoltaic battery arrays respectively, unit and combining inverter conflux; Each in described several maximum power point tracking devices all with described in the unit that confluxes be connected, the described unit that confluxes is connected with described combining inverter, the described unit that confluxes is for by an integrated multi-channel DC remittance road direct current output, then is to be input in electrical network after alternating current by described combining inverter by DC inverter;
Wherein, described combining inverter comprises the chopper assembly unit and the inversion unit that are electrically connected successively; Described chopper assembly unit comprises the first switching tube and the energy consumption resistor between the DC bus that is connected in series in described combining inverter;
Described combining inverter also comprises an inverter control unit, described inverter control unit is for sampling the DC bus-bar voltage of described combining inverter, and in described DC bus-bar voltage during higher than the first predeterminated voltage, control described the first switching tube conducting and in the DC bus-bar voltage of described inverter during lower than the second predeterminated voltage, control described the first switching tube and turn-off.
2. grid-connected photovoltaic system according to claim 1, is characterized in that, described inverter control unit comprises the first control subelement, the second control subelement, wherein:
Described first controls subelement in the time of described the first switching tube conducting and described electrical network generation low-voltage crossing, controls described inversion unit and provides capacitive reactive power support for described electrical network;
Described second controls subelement in the time that described the first switching tube conducting and described electrical network generation high pressure pass through, and controls described inversion unit and provides perceptual reactive power support for described electrical network.
3. grid-connected photovoltaic system according to claim 2, it is characterized in that, described inverter control unit comprises that the 3rd controls subelement, and the described the 3rd controls subelement for DC bus-bar voltage is carried out to closed-loop control so that DC bus-bar voltage is stabilized in the 3rd predeterminated voltage.
4. grid-connected photovoltaic system according to claim 1, is characterized in that, described chopper assembly unit also comprises the second switch pipe being connected in parallel with described energy consumption resistor.
5. grid-connected photovoltaic system according to claim 4, is characterized in that, described the first switching tube comprises IGBT, thyristor, metal-oxide-semiconductor; Described second switch pipe comprises IGBT, the metal-oxide-semiconductor with fly-wheel diode, the diode with fly-wheel diode.
6. grid-connected photovoltaic system according to claim 1, is characterized in that, described inversion unit is three phase full bridge circuit.
7. grid-connected photovoltaic system according to claim 1, is characterized in that, described combining inverter also comprises the filter unit being connected with described inversion unit, and described filter unit is LC filter unit.
8. grid-connected photovoltaic system according to claim 1, is characterized in that, described maximum power tracking device comprises a Boost booster circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201420093730.6U CN203734325U (en) | 2014-02-28 | 2014-02-28 | Photovoltaic grid-connected power generation system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201420093730.6U CN203734325U (en) | 2014-02-28 | 2014-02-28 | Photovoltaic grid-connected power generation system |
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| CN203734325U true CN203734325U (en) | 2014-07-23 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103825299A (en) * | 2014-02-28 | 2014-05-28 | 深圳市长昊机电有限公司 | Grid-connected photovoltaic power generation system and control method thereof |
| CN104377732A (en) * | 2014-11-21 | 2015-02-25 | 南车株洲电力机车研究所有限公司 | DC bus distributed MPPT photovoltaic power generation system |
| CN104734603A (en) * | 2015-03-20 | 2015-06-24 | 三峡大学 | All-independent parallel type photovoltaic power generation device |
-
2014
- 2014-02-28 CN CN201420093730.6U patent/CN203734325U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103825299A (en) * | 2014-02-28 | 2014-05-28 | 深圳市长昊机电有限公司 | Grid-connected photovoltaic power generation system and control method thereof |
| CN104377732A (en) * | 2014-11-21 | 2015-02-25 | 南车株洲电力机车研究所有限公司 | DC bus distributed MPPT photovoltaic power generation system |
| CN104734603A (en) * | 2015-03-20 | 2015-06-24 | 三峡大学 | All-independent parallel type photovoltaic power generation device |
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Granted publication date: 20140723 Termination date: 20210228 |