CN110377099A - A kind of photovoltaic module invariable power electricity-generating method - Google Patents

A kind of photovoltaic module invariable power electricity-generating method Download PDF

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Publication number
CN110377099A
CN110377099A CN201910564932.1A CN201910564932A CN110377099A CN 110377099 A CN110377099 A CN 110377099A CN 201910564932 A CN201910564932 A CN 201910564932A CN 110377099 A CN110377099 A CN 110377099A
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power
photovoltaic
mould group
mpp
point
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朱殷晓
文辉清
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Xian Jiaotong Liverpool University
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Xian Jiaotong Liverpool University
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/66—Regulating electric power
    • G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
    • 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)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

The invention discloses a kind of photovoltaic module invariable power electricity-generating method, photovoltaic mould splits is two operating modes: MPPT mode and CPG mode: if the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is big, photovoltaic mould group enters CPG mode, works in two power limitation point LPPA、LPPAThe middle lesser power points LPP of voltageA, the output power P of current photovoltaic mould grouppvWith PlimitEqual, working region corresponds to constant current area；If the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is small or equal, then in photovoltaic mould group MPPT mode, work in corresponding maximum power point MPP, i.e., in CPG mode embed an adaptive MPPT mode, to work point carry out self-control.Photovoltaic module invariable power electricity-generating method of the invention, in conjunction with MPPT mode and CPG mode, self-control can be carried out to work point, further increase photovoltaic system permeability in power grid, can autonomous soft readjustment photovoltaic mould group generated energy, solves the problems, such as to load or power grid will face overload.

Description

A kind of photovoltaic module invariable power electricity-generating method
Technical field
The present invention relates to photovoltaic art, in particular to a kind of photovoltaic module invariable power electricity-generating method.
Background technique
Photovoltaic system (Photovoltaic System, PVS) is always maintained at the trend of growth in the past few years and will Play the part of important role in following energy mix power grid.As shown in Figure 1, can be directlyed adopt in current most of PVS DC-DC converter is adjusted in maximum power point tracking (Maximum Power Point Tracking, MPPT) technology, so The maximization of power, which exports, to be realized to photovoltaic mould group afterwards.And the DC-AC inverter of the second level mainly passes through inversion control, by DC- The direct current of DC converter output terminal is changed into exchange and boosts to the demand of matched load or grid side.However, some PVS has in the hybrid power system of height ratio, since PVS is easy to be effected by environmental factors, it is assumed that load or power grid Power demand be consistent, if PVS whole day keep maximum output operation, load or power grid will be easy to face the feelings of overload Condition.Photovoltaic system permeability in power grid in order to further increase is capable of the algorithm of autonomous soft readjustment photovoltaic mould group generated energy Limitation output power be can be used to come the problems such as solving overload.
It is assumed that power invariability required for present load and being expressed as Plimit, according to photovoltaic mould group in different illumination intensity Under power vs. voltage (P-V) characteristic curve, in power limitation PlimitLower photovoltaic mould group has two kinds of working conditions as shown in Figure 2: If the value P of the maximum power point (Maximum Power Point, MPP) of photovoltaic mould groupmppCompare PlimitValue it is big, then photovoltaic Mould group can work in power limitation point (Limiting Power Point, LPP), the output power P of current photovoltaic mould grouppvWith PlimitIt is equal；If PmppValue be less than or equal to PlimitValue, then then to need to operate in current MPP point most for photovoltaic mould group It is likely to reduced the deficiency of energy supply, the output power P of current photovoltaic mould grouppvWith PmppIt is equal.It is formulated are as follows:
In invariable power power generation (Constant Power Generation, CPG) algorithm, according to P-V curve characteristic, when PmppGreater than PlimitWhen, photovoltaic mould group can work two possible operating points LPP, that is, work in LPP as shown in Figure 2AOr LPPBPoint is to guarantee current photovoltaic output power PpvWith power limitation PlimitIt is equal.
Summary of the invention
Object of the present invention is to: a kind of photovoltaic module invariable power electricity-generating method is provided, in conjunction with MPPT mode and CPG mode, Self-control can be carried out to work point, solve the problems, such as that load or power grid will face overload.
The technical scheme is that
A kind of photovoltaic module invariable power electricity-generating method, photovoltaic mould splits are two operating modes: MPPT mode and CPG mould Formula:
If the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is big, photovoltaic mould group enters CPG Mode works in two power limitation point LPPA、LPPAThe middle lesser power points LPP of voltageA, the output work of current photovoltaic mould group Rate PpvWith PlimitEqual, working region corresponds to constant current area；
If the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is small or equal, then photovoltaic mould It in group MPPT mode, works in corresponding maximum power point MPP, i.e., embeds an adaptive MPPT mode in CPG mode, it is right The point that works carries out self-control.
Preferably, when photovoltaic module work is in the case where CPG mode, to the available power P of photovoltaic mould groupaviEstimated It calculates, according to the characteristic of photovoltaic module, the voltage V of MPP pointmppIt is estimated with following formula:
Vmpp=kvocVoc, 0.7 < kvoc<0.8
Wherein, kvocIt is a constant, VocIt is the operating voltage that power is zero.
Preferably, when the operating point of photovoltaic mould group is located at constant current area, according to corresponding to constant current area any two points Electric current and voltage calculate slope g corresponding to this straight line；It is further estimated according to the slope g being calculated current The short circuit current I of photovoltaic mould group under illuminationscValue, and then find out MPP point corresponding current Impp:
Wherein, kIscFor a constant, I, V respectively indicate the electric current and voltage value measured, and subscript n and n-1 are respectively indicated For a current and upper measurement period；
The available power P of photovoltaic mould group so at this timeaviIt is expressed as
Pavi=VmppImpp。
Preferably, according to PlimitValue, determine the corresponding quiescent potential V of photovoltaic mould groupref, according to following formula to ginseng Voltage is examined to be adjusted
Preferably, the step of invariable power electricity-generating method includes:
Before S1, system work, first to the operating mode of system and to PlimitIt is preset；
S2, to the output voltage V of photovoltaic mould groupnWith output electric current InIt is sampled and records correlation values；
Operating mode set by S3, judgement system, even Flag are equal to zero, CPG algorithm and do not start, and keep maximum power Operation；If Flag is not zero, CPG algorithm is activated, according to PlimitAnd PaviValue carry out automatic adjusument；
S4, when system is in CPG algorithm state of activation, calculate the maximum power P of photovoltaic mould groupavi；Compare PlimitAnd Pavi Value result determine CPG activation pattern under photovoltaic mould group operational mode: if PmppCompare PlimitValue, then work in algorithm The CPG mode set；It is on the contrary then work in MPPT mode.
Preferably, no matter whether CPG algorithm activates, and algorithm work recycles each time in LPP point or MPP point after activation Reference voltage V laterrefIt will update, then further adjust the work point of photovoltaic mould group.
The invention has the advantages that
Photovoltaic module invariable power electricity-generating method of the invention can be to work point in conjunction with MPPT mode and CPG mode Carry out self-control, further increase photovoltaic system permeability in power grid, can autonomous soft readjustment photovoltaic mould group generated energy, Solve the problems, such as that load or power grid will face overload.
Detailed description of the invention
The invention will be further described with reference to the accompanying drawings and embodiments:
Fig. 1 is the structure and control block diagram of twin-stage type photovoltaic system；
Fig. 2 is the power vs. voltage curve figure of two kinds of working conditions of invariable power power generation；
Fig. 3 is photovoltaic i-v curve specificity analysis figure；
Fig. 4 is invariable power power generation algorithm flow chart；
Fig. 5 is invariable power electricity generation system topological diagram；
Fig. 6 is the result current curve diagram of invariable power electricity-generating method.
Specific embodiment
Photovoltaic module invariable power electricity-generating method of the invention, photovoltaic mould splits be two operating modes: MPPT mode and CPG mode:
If the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is big, photovoltaic mould group enters CPG Mode, work two power limitation point LPP in Fig. 2A、LPPAThe middle lesser power points LPP of voltageA, current photovoltaic mould group it is defeated Power P outpvWith PlimitEqual, working region corresponds to constant current area in corresponding diagram 3；
If the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is small or equal, then photovoltaic mould It in group MPPT mode, works in corresponding maximum power point MPP, i.e., embeds an adaptive MPPT mode in CPG mode, it is right The point that works carries out self-control.
When photovoltaic module work is in the case where CPG mode, to the available power P of photovoltaic mould groupaviIt is estimated, according to The characteristic of photovoltaic module, the voltage V of MPP pointmppIt is estimated with following formula:
Vmpp=kvocVoc, 0.7 < kvoc<0.8
Wherein, kvocIt is a constant, VocIt is the operating voltage that power is zero.
When the operating point of photovoltaic mould group is located at constant current area, according to electric current corresponding to constant current area any two points and electricity Pressure, calculates slope g corresponding to this straight line；The light under current light is further estimated according to the slope g being calculated The short circuit current I of Fu Mo groupscValue, and then find out MPP point corresponding current Impp:
Wherein, kIscFor a constant, I, V respectively indicate the electric current and voltage value measured, and subscript n and n-1 are respectively indicated For a current and upper measurement period；
The available power P of photovoltaic mould group so at this timeaviIt is expressed as
Pavi=VmppImpp。
According to PlimitValue, determine the corresponding quiescent potential V of photovoltaic mould groupref, according to following formula to reference voltage into Row adjustment
As shown in figure 4, the step of invariable power electricity-generating method, includes:
Before S1, system work, first to the operating mode of system and to PlimitIt is preset；
S2, to the output voltage V of photovoltaic mould groupnWith output electric current InIt is sampled and records correlation values；
Operating mode set by S3, judgement system, even Flag are equal to zero, CPG algorithm and do not start, and keep maximum power Operation；If Flag is not zero, CPG algorithm is activated, according to PlimitAnd PaviValue carry out automatic adjusument；
S4, when system is in CPG algorithm state of activation, calculate the maximum power P of photovoltaic mould groupavi；Compare PlimitAnd Pavi Value result determine CPG activation pattern under photovoltaic mould group operational mode: if PmppCompare PlimitValue, then work in algorithm The CPG mode set；It is on the contrary then work in MPPT mode.
No matter whether CPG algorithm activates, ginseng of the algorithm work in LPP point or MPP point, after recycling each time after activation Examine voltage VrefIt will update, then further adjust the work point of photovoltaic mould group.
As shown in figure 5, the system topological that generates electricity of photovoltaic module invariable power of the invention includes a photovoltaic module, one Boost converter, a current sensor, a voltage sensor, constant voltage loads and one for loading CPG algorithm Controller.Result corresponding to system is as shown in Figure 6: (a) in the case where lighting change, which can be according to the P of estimationavi Value carry out automatic adjusument；(b)PlimitIn the case where change, which can be according to PlimitChange adjust operating point Position.
The above embodiments merely illustrate the technical concept and features of the present invention, and its object is to allow person skilled in the art It cans understand the content of the present invention and implement it accordingly, it is not intended to limit the scope of the present invention.It is all to lead according to the present invention The modification for wanting the Spirit Essence of technical solution to be done, should be covered by the protection scope of the present invention.

Claims (6)

1. a kind of photovoltaic module invariable power electricity-generating method, which is characterized in that photovoltaic mould splits is two operating modes: MPPT mode And CPG mode:
If the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is big, photovoltaic mould group enters CPG mould Formula works in two power limitation point LPPA、LPPAThe middle lesser power points LPP of voltageA, the output power of current photovoltaic mould group PpvWith PlimitEqual, working region corresponds to constant current area；
If the power P of the maximum power point of photovoltaic mould groupmppThan power limitation PlimitValue it is small or equal, then photovoltaic mould group In MPPT mode, works in corresponding maximum power point MPP, i.e., an adaptive MPPT mode is embedded in CPG mode, to work Make point and carries out self-control.
2. photovoltaic module invariable power electricity-generating method according to claim 1, which is characterized in that
When photovoltaic module work is in the case where CPG mode, to the available power P of photovoltaic mould groupaviIt is estimated, according to photovoltaic The characteristic of module, the voltage V of MPP pointmppIt is estimated with following formula:
Vmpp=kvocVoc, 0.7 < kvoc<0.8
Wherein, kvocIt is a constant, VocIt is the operating voltage that power is zero.
3. photovoltaic module invariable power electricity-generating method according to claim 2, which is characterized in that
When the operating point of photovoltaic mould group is located at constant current area, according to electric current corresponding to constant current area any two points and voltage, Calculate slope g corresponding to this straight line；The photovoltaic mould under current light is further estimated according to the slope g being calculated The short circuit current I of groupscValue, and then find out MPP point corresponding current Impp:
Impp=kIscIsc=kIsc(In-gVn), 0.78 < kIsc<0.92,
Wherein, kIscFor a constant, I, V respectively indicate the electric current and voltage value measured, and subscript n and n-1 are expressed as working as A preceding and upper measurement period；
The available power P of photovoltaic mould group so at this timeaviIt is expressed as
Pavi=VmppImpp。
4. photovoltaic module invariable power electricity-generating method according to claim 3, which is characterized in that
According to PlimitValue, determine the corresponding quiescent potential V of photovoltaic mould groupref, reference voltage is adjusted according to following formula It is whole
5. photovoltaic module invariable power electricity-generating method according to claim 4, which is characterized in that the step of invariable power electricity-generating method Suddenly include:
Before S1, system work, first to the operating mode of system and to PlimitIt is preset；
S2, to the output voltage V of photovoltaic mould groupnWith output electric current InIt is sampled and records correlation values；
Operating mode set by S3, judgement system, even Flag are equal to zero, CPG algorithm and do not start, and keep maximum power fortune Row；If Flag is not zero, CPG algorithm is activated, according to PlimitAnd PaviValue carry out automatic adjusument；
S4, when system is in CPG algorithm state of activation, calculate the maximum power P of photovoltaic mould groupavi；Compare PlimitAnd PaviValue Result determine CPG activation pattern under photovoltaic mould group operational mode: if PmppCompare PlimitValue, then work built in algorithm CPG mode；It is on the contrary then work in MPPT mode.
6. photovoltaic module invariable power electricity-generating method according to claim 5, which is characterized in that no matter whether CPG algorithm swashs It is living, reference voltage V of the algorithm work in LPP point or MPP point, after recycling each time after activationrefWill update, then into The work point of one step section photovoltaic mould group.
CN201910564932.1A 2019-06-27 2019-06-27 A kind of photovoltaic module invariable power electricity-generating method Pending CN110377099A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116736929A (en) * 2023-06-26 2023-09-12 浙江大学 Photovoltaic string global maximum power point tracking method and system based on region segmentation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116736929A (en) * 2023-06-26 2023-09-12 浙江大学 Photovoltaic string global maximum power point tracking method and system based on region segmentation
CN116736929B (en) * 2023-06-26 2024-05-28 浙江大学 Photovoltaic string global maximum power point tracking method and system based on region segmentation

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