CN110233501A - A kind of three-phase photovoltaic grid-connected electricity generation system low voltage traversing control method of two-stage - Google Patents
A kind of three-phase photovoltaic grid-connected electricity generation system low voltage traversing control method of two-stage Download PDFInfo
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- CN110233501A CN110233501A CN201910554217.XA CN201910554217A CN110233501A CN 110233501 A CN110233501 A CN 110233501A CN 201910554217 A CN201910554217 A CN 201910554217A CN 110233501 A CN110233501 A CN 110233501A
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- 230000005611 electricity Effects 0.000 title claims abstract description 13
- 238000002347 injection Methods 0.000 claims description 5
- 239000007924 injection Substances 0.000 claims description 5
- 238000005286 illumination Methods 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000011217 control strategy Methods 0.000 description 1
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- H02J3/383—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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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 present invention relates to a kind of three-phase photovoltaic grid-connected electricity generation system low voltage traversing control methods of two-stage, Non-MPPT algorithm including falling degree and photovoltaic plant low voltage crossing standard according to grid entry point voltage, and based on photovoltaic array realizes the low voltage crossing control of grid-connected photovoltaic system.When short trouble occurs for system, photovoltaic generating system prime reduces photovoltaic array output power using Non-MPPT operational mode, this method can not only inhibit photovoltaic generating system output short-circuit fault current, and gird-connected inverter DC voltage can be inhibited to fluctuate, to realize that photovoltaic generating system low voltage crossing controls.
Description
Technical field
The present invention relates to field of photovoltaic power generation, wear more particularly to a kind of three-phase photovoltaic grid-connected electricity generation system low-voltage of two-stage
More method.
Background technique
In photovoltaic system, for power system security, the stable operating performance for improving the photovoltaic energy containing Thief zone, photovoltaic plant
Grid-connected rule requires photovoltaic combining inverter to have fault ride-through capacity.And in existing photovoltaic generating system, it is worn with failure
More there is photovoltaic generating system gird-connected inverters need to solve the problems, such as inverter ac side overcurrent, direct current side overvoltage for ability.
Summary of the invention
In view of this, the purpose of the present invention is to provide a kind of three-phase photovoltaic grid-connected electricity generation system low voltage crossing sides of two-stage
Method can handle the short trouble problem of grid-connected photovoltaic system well.
To achieve the above object, the present invention adopts the following technical scheme:
A kind of three-phase photovoltaic grid-connected electricity generation system low-voltage ride-through method of two-stage, comprising the following steps:
Step S1: when short trouble occurs for system, grid entry point three-phase voltage u is obtainedg_N, grid entry point voltage is calculated and falls
Fall degree r；
Step S2: according to grid entry point Voltage Drop degree r and photovoltaic plant low voltage crossing requirement, obtain photovoltaic electric
The dynamic reactive electric current for injection electric system of standing；
Step S3: according to dynamic reactive electric current, required photovoltaic when inverter output rated current in failure conditions is acquired
Array output power size
Step S4: control chopper makes photovoltaic module output powerGird-connected inverter is to system amount of exports simultaneously
Fixed electric current completes the low voltage crossing of photovoltaic parallel in system.
Further, the grid entry point Voltage Drop degree r is the ratio of grid entry point voltage and voltage rating.
Further, the reactive current I of the determining photovoltaic plant injection electric systemq_setDetailed process is as follows:
As 0.2≤ug_NWhen≤0.9, Iq_set≥1.5(0.9-ug_N)IN；
Work as ug_NWhen < 0.2, Iq_set≥1.05IN；
Work as ug_NWhen > 0.9, Iq_set=0；Wherein INFor system nominal current.
Further, the output power specifically:
Wherein Iq_setThe reactive current of electric system is injected for photovoltaic plant.
Further, the step S4 specifically:
Step S41: when low voltage crossing failure occurs for system, required for calculating photovoltaic array according to step S1-S3
The power of outputSize；
Step S42: according to formulaAnd formulaCalculate the reference voltage U exported required for photovoltaic array* pv.Wherein, tref:
25℃；Sref: 1000W/m2；S, t respectively indicates input intensity of illumination, environment temperature, and a, c are temperature compensation coefficient (a=
0.025；C=0.00288), b is luminosity compensation coefficient (b=0.2), and three penalty coefficients can be according to photovoltaic material, manufacture craft
Difference is adjusted, and enhances the degree of fitting of simulation data characteristic curve and reality output curve.Isc: short circuit current；Uoc: open circuit
Voltage；Im: maximum power output electric current；Um: maximum power output voltage；
Step S43: according to formulaPhotovoltaic generating system prime Boost can be obtained to account for
Empty ratio.
Compared with the prior art, the invention has the following beneficial effects:
1, the present invention solves the problems, such as the fault traversing of grid-connected photovoltaic system using control strategy appropriate, avoids pair
The investment and use of hardware, reduce costs and are lost, while being also beneficial to the stabilization of maintenance system.
2, sampled data of the present invention is few, and algorithm is simple, and the calculating time is few, can relatively accurately track reference power.
3, tracking precision of the invention is high, and tracking speed is fast.
Detailed description of the invention
Fig. 1 is flow chart of the invention；
Fig. 2 is grid-connected photovoltaic system model applied in one embodiment of the invention；
Fig. 3 is that side voltage is exchanged in the embodiment of the present invention；
Fig. 4 is ac-side current in the embodiment of the present invention；
Fig. 5 is inverter output power in the embodiment of the present invention；
Fig. 6 is photovoltaic cell output voltage in the embodiment of the present invention；
Fig. 7 is that photovoltaic cell exports electric current in the embodiment of the present invention；
Fig. 8 is the output power from photovoltaic cells in the embodiment of the present invention；
Fig. 9 is watt current and reactive current component in the embodiment of the present invention；
Figure 10 is DC side voltage of converter in the embodiment of the present invention；
Figure 11 is structure principle chart in the embodiment of the present invention.
Specific embodiment
The present invention will be further described with reference to the accompanying drawings and embodiments.
Please referring to Fig. 1, the present invention provides a kind of three-phase photovoltaic grid-connected electricity generation system low-voltage ride-through method of two-stage, including with
Lower step:
Step S1: when short trouble occurs for system, grid entry point three-phase voltage u is obtainedg_N, grid entry point voltage is calculated and falls
Fall degree r；The grid entry point Voltage Drop degree r is the ratio of grid entry point voltage and voltage rating.
Step S2: according to grid entry point Voltage Drop degree r and photovoltaic plant low voltage crossing requirement, obtain photovoltaic electric
The dynamic reactive electric current for injection electric system of standing；
Step S3: according to dynamic reactive electric current, required photovoltaic when inverter output rated current in failure conditions is acquired
Array output power size
Step S4: control chopper makes photovoltaic module output powerGird-connected inverter is to system amount of exports simultaneously
Fixed electric current completes the low voltage crossing of photovoltaic parallel in system.
In the present embodiment, the reactive current I of the determining photovoltaic plant injection electric systemq_setDetailed process such as
Under:
As 0.2≤ug_NWhen≤0.9, Iq_set≥1.5(0.9-ug_N)IN；
Work as ug_NWhen < 0.2, Iq_set≥1.05IN；
Work as ug_NWhen > 0.9, Iq_set=0；Wherein INFor system nominal current.
Further, the output power specifically:
Wherein Iq_setThe reactive current of electric system is injected for photovoltaic plant.
In the present embodiment, the step S4 specifically:
Step S41: when low voltage crossing failure occurs for system, required for calculating photovoltaic array according to step S1-S3
The power of outputSize；
Step S42: according to formulaAnd formulaCalculate the reference voltage U exported required for photovoltaic array* pv.Wherein, tref:
25℃；Sref: 1000W/m2；S, t respectively indicates input intensity of illumination, environment temperature, and a, c are temperature compensation coefficient (a=
0.025；C=0.00288), b is luminosity compensation coefficient (b=0.2), and three penalty coefficients can be according to photovoltaic material, manufacture craft
Difference is adjusted, and enhances the degree of fitting of simulation data characteristic curve and reality output curve.Isc: short circuit current；Uoc: open circuit
Voltage；Im: maximum power output electric current；Um: maximum power output voltage；
Step S43: according to formulaPhotovoltaic generating system prime Boost can be obtained to account for
Empty ratio
In the present embodiment, as shown in Fig. 2, building the three-phase photovoltaic grid-connected hair of two-stage using MATLAB/SIMULINK software
Electric system model, grid entry point line voltage rated value are 380V, rated current 112A.Photovoltaic array peak power output is
52KW, corresponding output voltage are equal to 350V.Inverter direct-flow side is the series capacitance of two 1F, and when normal operation is maintained at
1000V, exchange side line road is the resistance of 0.001 Ω and the inductance in parallel of 0.01H.In 0.5s-0.6s, make grid entry point electric
Pressure falls 50%, the voltage of observation photovoltaic array output, the variation of electric current and output power, observe DC side voltage of converter with
And the variation of ac-side current.
As shown in figure 4, grid entry point electric current fluctuates very little during short trouble, remain unchanged substantially, exchanges the overcurrent of side
Phenomenon has obtained very good solution.As shown in figure 5, the active power of inverter output reduces, idle function during short trouble
Rate increases, and reaches the target of control.As shown in Fig. 6 to 8, during short trouble, the output voltage of photovoltaic cell reduces, output electricity
Stream increases, and whole power output reduces, and illustrates to have reached effect to the non-mppt control of chopper.As shown in figure 9, short
During the failure of road, active current reduces, and reactive current component increases, and meets wanting for photovoltaic generating system low voltage crossing
It asks.As shown in Figure 10, DC side voltage of converter fluctuates very little during short trouble, illustrates that the overpressure conditions of DC side obtain
Very good solution.
The foregoing is merely presently preferred embodiments of the present invention, all equivalent changes done according to scope of the present invention patent with
Modification, is all covered by the present invention.
Claims (5)
1. a kind of three-phase photovoltaic grid-connected electricity generation system low-voltage ride-through method of two-stage, which comprises the following steps:
Step S1: when short trouble occurs for system, grid entry point three-phase voltage u is obtainedg_N, grid entry point Voltage Drop journey is calculated
Spend r；
Step S2: according to grid entry point Voltage Drop degree r and photovoltaic plant low voltage crossing requirement, obtain photovoltaic plant note
Enter the dynamic reactive electric current of electric system；
Step S3: according to dynamic reactive electric current, required photovoltaic array when inverter output rated current in failure conditions is acquired
Output power size
Step S4: control chopper makes photovoltaic module output powerGird-connected inverter exports specified to system simultaneously
Electric current completes the low voltage crossing of photovoltaic parallel in system.
2. the three-phase photovoltaic grid-connected electricity generation system low-voltage ride-through method of a kind of two-stage according to claim 1, feature exist
In: the grid entry point Voltage Drop degree r is the ratio of grid entry point voltage and voltage rating.
3. the three-phase photovoltaic grid-connected electricity generation system low-voltage ride-through method of a kind of two-stage according to claim 1, feature exist
In: the reactive current I of the determining photovoltaic plant injection electric systemq_setDetailed process is as follows:
As 0.2≤ug_NWhen≤0.9, Iq_set≥1.5(0.9-ug_N)IN；
Work as ug_NWhen < 0.2, Iq_set≥1.05IN；
Work as ug_NWhen > 0.9, Iq_set=0；Wherein INFor system nominal current.
4. the three-phase photovoltaic grid-connected electricity generation system low-voltage ride-through method of a kind of two-stage according to claim 1, feature exist
In: the output power specifically:
Wherein Iq_setThe reactive current of electric system is injected for photovoltaic plant.
5. the three-phase photovoltaic grid-connected electricity generation system low-voltage ride-through method of a kind of two-stage according to claim 1, feature exist
In the step S4 specifically:
Step S41: when low voltage crossing failure occurs for system, output required for calculating photovoltaic array according to step S1-S3
PowerSize；
Step S42: according to the following formula
Calculate the reference voltage U exported required for photovoltaic array* pv；
Wherein, tref: 25 DEG C；Sref: 1000W/m2；S, t respectively indicates input intensity of illumination, environment temperature, and a, c are temperature-compensating
Coefficient, b are luminosity compensation coefficient, IscFor short circuit current；UocFor open-circuit voltage；ImFor maximum power output electric current；UmFor maximum
Power output voltage；
Step S43: according to formulaPhotovoltaic generating system prime Boost duty ratio can be obtained.
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Cited By (1)
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| CN111525605A (en) * | 2020-04-07 | 2020-08-11 | 北方工业大学 | Photovoltaic system low voltage ride through method and system based on variable power output control |
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Application publication date: 20190913 |