CN106774606B - A kind of global MPPT method and apparatus under uneven illumination is even - Google Patents
A kind of global MPPT method and apparatus under uneven illumination is even Download PDFInfo
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Abstract
The invention discloses a kind of global MPPT method and apparatus of uneven illumination under even, judging that different illumination conditions region occurs in photovoltaic array, when thering are the local shades to block, unlike existing whole scan mode scans entire characteristic curve to obtain global maximum power point, but short circuit current near the maximum power point in each illumination condition region is scanned in a jumped fashion, find the maximum value in the maximum power point in each illumination condition region, after finding global maximum power point again, conventional MPPT maximum power point tracking algorithm is performed.The present invention can help operation maintenance personnel to position shade failure rapidly while raising photovoltaic system generating efficiency is realized, further improve power station O＆M efficiency and whole power benefit.
Description
Technical field：
The present invention relates to maximum power point of photovoltaic power generation system tracking technique field, under more particularly to a kind of uneven illumination
Global maximum power point tracking method.
Background technology：
In photovoltaic generating system, MPPT (i.e. MPPT maximum power point tracking) be always the key problem most paid close attention to of researcher it
One, but in actual operation, since provisional caused by dust, trees, building etc. or regular local shades block, Yi Jitong
The multiple local shades of Shi Fasheng block that the uneven illumination to be formed is even to happen occasionally and commonly exist.Local shades and uneven illumination
Even to cause photovoltaic array output voltage mismatch and hot spot phenomenon, this not only causes the power loss of photovoltaic generating system, very
Become the serious system failure and safety problem to upgrading.In order to avoid hot spot phenomenon, light occurs in photovoltaic array in practical application
Every piece of photovoltaic module bypass diode all in parallel is lied prostrate in array, the corresponding photovoltaic module when local shades occur and block
Bypass diode is connected, and makes photovoltaic array output P-V curves that multi-peak be presented.
(conventional MPPT methods referred to herein refer to that such as perturbation observation method, incremental conductance method are or not conventional MPPT methods
Consider the method for local shades) photovoltaic array operating point may be made to sink into local peaking and global maximum power can not be traced into
Point, so as to cause power loss.
Currently for multi-peak phenomenon under uneven illumination using mainly whole scan method and based on the intelligence such as population
Algorithm.
The intelligent algorithms such as population are still immature at present, and algorithm is excessively complicated, it is difficult to realize on the microprocessor.
Whole scan method needs to scan entire P-V or I-V characteristic curve to find global maximum power point, tracking institute
The time of cost is very long, and photovoltaic generation power is caused to waste, and practical value is not high.
Invention content
Global MPPT methods under a kind of uneven illumination of present invention offer is even, for solving, whole scan method efficiency is low to be caused
The problem of photovoltaic generation power wastes.Meanwhile additionally provide a kind of uneven illumination it is even under global MPPT devices.
A kind of global MPPT methods under uneven illumination is even, step are as follows：
1) photovoltaic system is diagnosed, judges whether the region for two or more different illumination intensities occur, institute
It states each intensity of illumination and corresponds to a kind of illumination condition；
2) when judging the region of two or more different illumination intensities occur, discrete selection reference voltage, really
The corresponding short circuit current of fixed each reference voltage, every a kind of illumination condition is distinguished according to short circuit current, according to reference voltage and right
The calculation of short-circuit current answered goes out the approximate maximum power under every a kind of illumination condition；
3) according to per the approximate maximum power under a kind of illumination condition, the overall situation is determined by comparing with the mode for applying disturbance
Maximum power point；
4) routine MPPT methods are performed in the global maximum power point.
Further, in the step 2), selected reference voltage expression formula is：Y+a*x*Voc_sin, wherein
Voc_sin is the open-circuit voltage of 1 piece of photovoltaic module, and x is the photovoltaic module quantity for belonging to same illumination condition, y be from low pressure to
High pressure, all photovoltaic module quantity before current reference voltage value；A is coefficient, and a*Voc_sin represents a block assembly maximum work
The crest voltage of rate point.
Further, in the step 2), it is described every a kind of illumination condition is distinguished according to short circuit current means be：From
Low pressure detects the short circuit current under two adjacent reference voltages to high pressure, if the variation of short circuit current is more than setting ratio,
Judge that corresponding two component is in inhomogeneous illumination condition, if the variation of short circuit current is not above setting ratio, judge
Corresponding two component is in similar illumination condition.
Further, in the step 1), the mode diagnosed to photovoltaic system is：When detect power voltage change
Rate | Δ P/ Δs V | during more than μ 1, and power variation, beyond limiting, judgement illumination condition change leads to photovoltaic generating system work(
Rate is mutated；At this moment the ratio of I_first and I_last is detected, I_first is that photovoltaic array exports 1 block assembly peak value electricity
Electric current during pressure, electric current when I_last is photovoltaic array output N-1 block assembly open-circuit voltages, when the ratio is more than μ 2, judgement
There is different illumination conditions region in photovoltaic array.N is the photovoltaic module quantity of photovoltaic array；μ 1, μ 2 are corresponding coefficient.
Further, in the step 2), the approximate maximum power per class illumination condition is by under every class illumination condition
Each reference voltage obtain the maximum value of power with corresponding calculation of short-circuit current.
Further, in the step 3), determine that the mode of global maximum power point includes：
Maximum value is selected in the approximate maximum power of every class illumination condition as approximate global maximum power Pm_old；With low
High pressure is pressed onto as forward direction；
First, peak power Pm, j are traced into using part MPPT under -1 class illumination condition of jth>=2, Pm with it is described near
Higher value is relatively taken like global maximum power Pm_old, is denoted as constant power conic constant Pm_new；The part MPPT is one
The maximum power point tracing method carried out under class illumination condition；
Then, the positive disturbance since the corresponding voltages of peak power Pm under -1 class illumination condition of jth, finds mutation and arrives
The voltage reference value of jth class illumination condition, and record the short circuit current Iscj of jth class illumination condition；
Then with constant power conic constant Pm_new divided by jth class short circuit current Iscj, an obtained voltage reference value；
If the output current value of the voltage reference value corresponding points is more than θ * Iscj, and P-V slopes of curve are just, then with local MPPT at this
It continues to execute, finds the peak power under jth class illumination condition, otherwise continue unidirectional positive disturbance, find+1 class illumination item of jth
Part short circuit current；
If the constant power conic constant Pm_new divided by jth class short circuit current Iscj, obtained voltage reference value are more than
Voltage value is set, then is terminated and using constant power curve Pm_new as global maximum power.
Further, the voltage reference value of mutation to the jth class illumination condition is characterized in：The voltage reference value is in
Partial power's minimum, P-V slopes are become just by negative.
Further, before the step 3), approximate global maximum power Pm_old and Pm_mppt is compared,
If Pm_old promotes amplitude more than μ 3, step 3) is performed；Pm_mppt is the maximum power recorded before fault diagnosis, and μ 3 is phase
The coefficient answered.
The present invention also provides a kind of global MPPT device of uneven illumination under even, including：
Diagnostic module：Photovoltaic system is diagnosed, judges whether two or more different illumination intensities occur
Region, each intensity of illumination correspond to a kind of illumination condition；
Scan the module of all kinds of illumination conditions：When judging the region of two or more different illumination intensities occur,
Discrete selection reference voltage determines the corresponding short circuit current of each reference voltage, and every a kind of illumination is distinguished according to short circuit current
Condition goes out the approximate maximum power under every a kind of illumination condition according to reference voltage and corresponding calculation of short-circuit current；
Determine the module of global maximum power point：According to the approximate maximum power under every a kind of illumination condition, by comparing
Global maximum power point is determined with the mode for applying disturbance；
Maximal power tracing module：Routine MPPT methods are performed in the global maximum power point.
Further, in the module of all kinds of illumination conditions of scanning, selected reference voltage expression formula is：y+a*
X*Voc_sin, wherein Voc_sin are the open-circuit voltage of 1 piece of photovoltaic module, and x is the photovoltaic module number for belonging to same illumination condition
Amount, y are all photovoltaic module quantity before current reference voltage value from low pressure to high pressure；A is coefficient, and a*Voc_sin is represented
One block assembly maximum power point crest voltage.
Further, it is described that every a kind of light is distinguished according to short circuit current in the module of all kinds of illumination conditions of scanning
Means according to condition are：From low pressure to high pressure, the short circuit current under two adjacent reference voltages is detected, if the change of short circuit current
It is more than setting ratio to change, then judges that corresponding two component is in inhomogeneous illumination condition, if the variation of short circuit current is not super
Setting ratio is crossed, then judges that corresponding two component is in similar illumination condition.
Further, in the module of all kinds of illumination conditions of scanning, the approximate maximum power per class illumination condition is logical
It crosses and obtains the maximum value of power with corresponding calculation of short-circuit current per each reference voltage under class illumination condition.
Further, in the module of the determining global maximum power point, determine that the mode of global maximum power point includes：
Maximum value is selected in the approximate maximum power of every class illumination condition as approximate global maximum power Pm_old；With low
High pressure is pressed onto as forward direction；
First, peak power Pm, j are traced into using part MPPT under -1 class illumination condition of jth>=2, Pm with it is described near
Higher value is relatively taken like global maximum power Pm_old, is denoted as constant power conic constant Pm_new；The part MPPT is one
The maximum power point tracing method carried out under class illumination condition；
Then, the positive disturbance since the corresponding voltages of peak power Pm under -1 class illumination condition of jth, finds mutation and arrives
The voltage reference value of jth class illumination condition, and record the short circuit current Iscj of jth class illumination condition；
Then with constant power conic constant Pm_new divided by jth class short circuit current Iscj, an obtained voltage reference value；
If the output current value of the voltage reference value corresponding points is more than θ * Iscj, and P-V slopes of curve are just, then with local MPPT at this
It continues to execute, finds the peak power under jth class illumination condition, otherwise continue unidirectional positive disturbance, find+1 class illumination item of jth
Part short circuit current；The θ is setting coefficient；
If the constant power conic constant Pm_new divided by jth class short circuit current Iscj, obtained voltage reference value are more than
Voltage value is set, then is terminated and using constant power curve Pm_new as global maximum power.
Further, the voltage reference value of mutation to the jth class illumination condition is characterized in：The voltage reference value is in
Partial power's minimum, P-V slopes are become just by negative.
Further, in the diagnostic module, the mode diagnosed to photovoltaic system is：
When detecting power voltage change rate | Δ P/ Δs V | during more than μ 1, and power variation judges light beyond limiting
Photovoltaic generating system power is caused to be mutated according to condition change；At this moment the ratio of I_first and I_last, I_ are detected
First is electric current when photovoltaic array exports 1 block assembly crest voltage, and I_last is photovoltaic array output N-1 block assembly open circuits
Electric current during voltage, when the ratio is more than μ 2, there is different illumination conditions region in judgement photovoltaic array；N is photovoltaic array
Photovoltaic module quantity；μ 1, μ 2 are corresponding coefficient.
Further, before the module for performing the determining global maximum power point, by approximate global maximum power Pm_
Old is compared with Pm_mppt, if Pm_old promotes amplitude more than μ 3, performs the module for determining global maximum power point；
Pm_mppt is the maximum power recorded before fault diagnosis, and μ 3 is corresponding coefficient.
The present invention is judging that different illumination conditions region occurs in photovoltaic array, that is, when thering are the local shades to block, unlike
Existing whole scan mode scans entire characteristic curve to obtain global maximum power point, but scans in a jumped fashion each
Short circuit current near the maximum power point in illumination condition region, finds the maximum in the maximum power point in each illumination condition region
Value is quickly found out the conventional MPPT maximum power point tracking algorithm of execution after global maximum power point.
Further, with reference to the relationship feature of constant power curve and peak point current Im and short circuit current Isc, can quickly,
Accurately find global maximum power point.
The present invention method not only can quickly, accurately track global maximum power point, but also can be to photovoltaic array operating status
Diagnostic analysis is carried out with shade failure.Shade Analysis on Fault Diagnosis is realized simultaneously in global MPPT tracking process, improves photovoltaic system
While generating efficiency of uniting, operation maintenance personnel can also be made to position shade failure rapidly by monitoring system, further improve O＆M
Efficiency and whole power benefit.
The present invention realizes scanning by discrete selection reference voltage and uses constant power curve global maximum power point
Tracking is, it can be achieved that photovoltaic system quickly and accurately traces into global maximum power point, and carries out shade fault diagnosis in this process
Analysis, thus with stronger research significance and use value.
Description of the drawings：
Fig. 1 is main program flow chart；
Fig. 2 is shade fault diagnosis subroutine flow chart；
Fig. 3 tracks subroutine flow chart for global maximum power point；
Fig. 4 is that the citing of the even global MPPT algorithm of uneven illumination tracks process schematic.
Specific embodiment
The main idea of the present invention is：Judging that different illumination conditions region occurs in photovoltaic array, that is, there are local shades
When blocking, unlike existing whole scan mode scans entire characteristic curve to obtain global maximum power point, but with jump
Mode scan the maximum power point in each illumination condition region short circuit current nearby, find the maximum work in each illumination condition region
Maximum value in rate point, then correlation technique find global maximum power point, perform conventional MPPT maximum power point tracking algorithm later
.
It is specifically described with reference to Fig. 1-Fig. 4.The method of the present invention is realized in a software form, in photovoltaic
It is performed in the control system in power station, the specific implementation of software has very much, and the present invention without introducing one by one.It only provides below
A kind of realization method, i.e. software are divided into main program, shade fault diagnosis subprogram and global maximum power point tracking subprogram.Figure
1st, Fig. 2, Fig. 3 are the flow chart of main program, shade fault diagnosis subprogram and global maximum power point tracking subprogram respectively.Figure
4 tops are divided into the tracking process I-V characteristic curve of example, and lower part is divided into the tracking process P-V characteristic curves of example.
First, main program
As shown in Figure 1, main program carries out conventional maximal power tracing first, shade failure is performed after corresponding conditions are met
Diagnostic subroutine performs global maximum power point tracking subprogram after meeting corresponding conditions, and GMPP represents global maximum work in figure
Rate point.
Main program carries out conventional MPPT maximum power point tracking first, when detecting power voltage change rate | Δ P/ Δs V | be more than
During a certain value μ 1, and power variation can determine that illumination condition change causes photovoltaic generating system power to occur beyond limiting
Mutation.At this moment the ratio of detection I_first and I_last is needed, I_first is that photovoltaic array (sets photovoltaic array by N block groups
Part is in series) 1 block assembly crest voltage of output when electric current (1 block assembly crest voltage in the present embodiment, takes 1 block assembly to open
The 80% of road voltage, hereafter will be explained in), electric current when I_last is photovoltaic array output N-1 block assembly open-circuit voltages, when
The ratio is more than μ 2, can determine that at least two kinds of different illumination conditions regions (having local shades to block) occurs in photovoltaic array, together
The timing of Shi Ruguo fault diagnosises is more than to limit, and will also call shade fault diagnosis subprogram.
It should be noted that is provided in the judgment step that above-mentioned local shades block is that one kind judges whether part occur
The adhoc approach of shadow occlusion, this method can judge that local shades block according to above-mentioned limited information.Certainly, it is of the invention
Do not repel it is other kinds of judge whether the mode that local shades block occur, such as by different information, criterion and into
The method that row judges.
After performing shade fault diagnosis subprogram, when being diagnosed to be the region there are different illumination intensity, additionally it is possible to obtain
Global maximum power approximation Pm_old (concrete mode will introduce below), by global maximum power approximation Pm_old with adjusting
It is compared with the maximum power Pm_mppt recorded before fault diagnosis, if Pm_old promotes amplitude more than μ 3, carries out the overall situation
MPPT maximum power point tracking subprogram tracks subprogram by global maximum power point, finds global maximum power point GMPP.If
Pm_old promotes amplitude and is no more than μ 3, then illustrates that promotion amplitude is very limited, it is not necessary that global maximum power point tracking is carried out, after
It is continuous to perform conventional maximal power tracing.
2nd, shade fault diagnosis subprogram
Short circuit current near each maximum power point is scanned with jumping mode, there are more than 2 short circuit currents when being diagnosed to be
Section, and compare after diagnosis that power P m_mppt promotes amplitude more than μ 3 before the diagnosis of maximum power Pm_old ratio, it can carry out
Global maximum power point tracks subprogram, otherwise returns to routine MPPT tracking.After global maximum power point is traced into, to return
To conventional MPPT track algorithms.
" jumping mode scanning ", is several reference voltages of discrete selection from low pressure to high pressure, the selection of reference voltage
80% neighbouring positions of the maximum power point crest voltage Vm in open-circuit voltage Voc is utilized, and peak point current Im is about short circuit electricity
Flow the 90% of Isc.
Fig. 2 is relevant program circuit, is directed to initialization section and according to above-mentioned maximum power point crest voltage Vm
In 80% neighbouring position of open-circuit voltage Voc, and 90% part judged that peak point current Im is about short circuit current Isc,
Due in Fig. 2 variable it is more (such as x, y, i etc. are counters, be local variable；Num_Isc, Num_Vol [k], Isc [k] are complete
Office's variable, defines referring to Fig. 2 bottom left sections), in order to be easier to understand those skilled in the art, below according to the flow of Fig. 2,
It is illustrated by taking Fig. 4 as an example.
Such as Fig. 4, first, selection reference voltage Vref is 0.8*Voc_sin, even if photovoltaic array output voltage is 0.8*
Voc_sin, Voc_sin are the open-circuit voltage of monolithic photovoltaic module, detect output current Isc [1] at this time, peak point current Im1
Approximation takes the short circuit current Im1 ≈ 0.9*Isc [1] under first kind illumination condition as.
Then, it is 2*0.8*Voc_sin to choose reference voltage Vref, and detection output current is Isc [2].If | Isc
[2]-Isc[1]|/|Isc[1]|<10%, then it is assumed that the 2nd block assembly is consistent with the 1st block assembly output short circuit current, i.e., in phase
Under same illumination condition.
Figure 4, it is seen that all very close Isc1 of the corresponding electric currents of 0.8*Voc_sin and 2*0.8*Voc_sin, because
This 2nd block assembly and the 1st block assembly belong to identical illumination condition.And when reference voltage Vref is 3*0.8*Voc_sin, it is right
Induced current Isc [3] is drop dramatically to Isc2 hereinafter, declining by a big margin, | Isc [3]-Isc [2] |/| Isc [2] |>10%, therefore,
Judge the 3rd block assembly and the 2nd piece is not belonging to identical illumination condition, that is, the situation that component is bypassed occur.
When then choosing reference voltage, reference pair is selected to answer Vref=(y+0.8*x) * Voc_sin, (y >=1, x >=1),
The sum of all components number before y is represented；X is component block number under the conditions of current light.
In Fig. 4, judge the 3rd block assembly and the 2nd piece is not belonging to identical illumination condition, give up the ginseng of 3*0.8*Voc_sin
Voltage is examined, reference voltage Vref is selected to record the short circuit current of corresponding second class illumination condition for (2+0.8) * Voc_sin,
Then reference voltage is selected as (2+0.8*2) * Voc_sin, and reselection reference voltage is (2+0.8*3) * Voc_sin, then sends out again
Reveal existing different illumination conditions.Therefore give up the reference voltage of (2+0.8*3) * Voc_sin, select reference voltage as (4+0.8) *
Voc_sin；And so on.The termination condition of fault diagnostic program be reference work voltage Vref be more than 90% open-circuit voltage or
Output current I is less than the short circuit current Isc [1] under 5% most high light conditions.
As shown in figure 4, it may finally judge that the component in first kind illumination condition is 2 pieces, in the second class illumination
Condition is 2 pieces, is 1 piece in third class illumination condition, is 1 piece in the 4th class illumination condition.Above-mentioned 1st piece, the 2nd
Block, the 3rd block assembly are intended merely to facilitate understanding, do not refer to series sequence or the position of series component really.
Due to having recorded corresponding reference voltage and short circuit current under every class illumination condition, every class light can be calculated
The corresponding maximum power according under the conditions of, such as m1 in Fig. 4, m2, m3, m4 points are the maximum power point under various illumination conditions, corresponding
Maximum power, voltage difference Pm [1], Vm [1], Pm [2], Vm [2], Pm [3], Vm [3], Pm [4], Vm [4].Then again each
A maximum value is selected under class illumination condition in corresponding maximum power, using the maximum value as approximate global maximum power Pm_old,
Corresponding voltage is Vm_old.
Certainly, since the reference voltage of selection is limited, corresponding power points is also limited, therefore above-mentioned Pm [1], Vm [1], Pm
[2], Vm [2], Pm [3], Vm [3], the maximum power of the not necessarily real each illumination condition of Pm [4], Vm [4], only
Approximate maximum power under each illumination condition, therefore can not be by directly relatively determining global maximum power point.It also needs to lead to
It crosses following global maximum power point tracking subprogram and just can determine that real, accurate global maximum power point.
In above-mentioned shade fault diagnosis subprogram, when difference can assert that two block assemblies are in same illumination within 10%
Under the conditions of.The difference of near short circuit electric current is more than 10% twice up to date, it is believed that begins with illumination different residing for component.Make
For other embodiment, 10%, which can also be changed to other, can characterize the value of different illumination boundary, such as 8%, 13% etc..
In above-mentioned shade fault diagnosis subprogram, maximum power point crest voltage Vm is near the 80% of open-circuit voltage Voc
Position, and peak point current Im is about short circuit current Isc90%, this be experience setting, as other embodiment, such as may be used also
To be designed as the other values near Vm80%, such as 75%, 78%, 81%, 85% etc.；Similarly 90% may be designed in it is attached
Near other values.
In above-mentioned shade fault diagnosis subprogram, when selecting reference voltage, there is no select 0.8*Voc_sin until N*
0.8*Voc_sin is the maximum power point in order to which the reference voltage of selection is made to be more suitable for each illumination condition.
3rd, global maximum power point tracking subprogram
It is about the 90% of short circuit current Isc that global maximum power point, which tracks subprogram also with peak point current Im, with
And realize reference voltage jump tracking using constant power curve.
It forms with reference to judgement above and photovoltaic array can be seen that according to output characteristics I-V curve and be divided into 4 perseverances
Determine short circuit current section, there are 4 and have peak point m1, m2, m3, m4.
As shown in Figure 3, Figure 4.Pm_new=Pm_old is enabled, part MPPT (offices are used first under first kind illumination condition
Portion MPPT is the maximum power point tracing method carried out under certain a kind of illumination condition, identical with conventional MPPT modes, herein
It repeats no more；) trace into peak power Pm, compare Pm and Pm_new sizes, update Pm_new for Pm with it is larger in Pm_new
Value.Then it is disturbed from first kind illumination crest voltage forward direction, finds current break to the voltage reference value of the second class illumination condition,
It is noteworthy characterized by the Voltage Reference in partial power's minimum, P-V slopes are become just by negative, and electric current is second to record herein
The short circuit current Iscj of class illumination condition.Then the constant Pm_new divided by the second class short circuit current Iscj of constant power curve are used,
Output voltage reference value after being jumped.Compare the corresponding output current value of voltage reference value after jumping, if its value is more than
θ * Iscj and P-V slopes are that just, program returns to part MPPT and continues to execute, and otherwise return to positive disturbance, searching third class illumination
Conditional short circuit current.Overall situation MPPT track algorithms above are carried out successively.Global maximum power point can be thus quickly found out.Entirely
The termination condition of office's MPPT maximum power point tracking subprogram is that reference voltage Vref is more than 0.9*Voc.After program has performed, it can obtain
Obtain the global maximum power point of the even multi-peak of uneven illumination.
Specifically, setting Vref=Vm [1] first, enables Pm_new=Pm_old, using normal under first kind illumination condition
Rule MPPT traces into approximate peak power P m [1], compares Pm [1] and Pm_new sizes, is updated to Pm_new higher values therein.
Then from the positive disturbances of the voltage Vm [1] of S1 positions (as shown in figure 3, disturbance quantity is Δ V, the magnitude relationship of Δ V to algorithm time
Length can be arranged as required to), reaching the positive S2 positions of P-V slopes of curve change, (for S2 into partial power's minimum, power is electric
Slope is pressed to be become just by negative), measurement obtains Isc2, takes the short circuit current Isc2 that reference voltage is Pm_new divided by S2 positions, reference
Voltage Vref jumps to q1 positions, measures the current value under the reference voltage, which is more than θ * Isc2 and the P-V of the point is bent
Line slope is just, program return part MPPT tracking is found maximum power Pm and (found near under the second class illumination condition again
Like peak power Pm [2]), it is compared with Pm_new, Pm_new is updated to higher value.From fig. 4, it can be seen that part MPPT
Tracking continues positive disturbance always to q2 positions, and by the short circuit current Isc3 of Pm_new divided by q2 positions, reference voltage Vref is jumped
It jumps to t1 positions (corresponding current Isc4), t1 positions corresponding voltage is more than 0.9*Voc, then global maximum power point tracking subprogram
Terminate, it is the corresponding reference voltages of global maximum power point Pm_new (this example is Vm [2]) to obtain GMPP, and by photovoltaic array work
Make point to stablize on the global peak point.Voc is photovoltaic array open-circuit voltage.Program knot is can be seen that from above-mentioned concrete instance
Shu Shi, the GMPP of acquisition are the peak value Pm [2] under corresponding second class illumination condition.
Wherein, it if q1 positions are unsatisfactory for being more than θ * Isc2 and the P-V slopes of curve are positive double condition, carries out unidirectional
Positive perturbation process, directly disturbance to q2 positions omit part MPPT tracking Pm [2] processes.
Global maximum power point tracking is to select a maximum global maximum power point in multiple peak values.As
Other embodiment can also have other modes to find this global maximum power point, such as can be directly attached in Pm_old
Closely disturbed to obtain the global maximum power point, certain this mode is equivalent to the mode of above-described embodiment, precision compared with
It is low.
After finding global maximum power point GMPP, on global maximum power point GMPP, conventional maximum power point is performed
Track algorithm.
μ 1, μ 2, μ 3 and θ in above-described embodiment need, by experiment or actual operating data, to set with reference to concrete engineering
It is fixed.Wherein μ 3 can select 10%, μ2Its calculated value is recorded according to operational process.Global maximum power point tracks subprogram
In the optional 0.8-0.9 of θ coefficients between, generally choose 0.85.
Specific embodiment of the present invention is presented above, but the present invention is not limited to described embodiment.
Under the thinking provided in the present invention, to the skill in above-described embodiment by the way of being readily apparent that those skilled in the art
Art means are converted, are replaced, are changed, and play the role of with the present invention in relevant art means it is essentially identical, realize
Goal of the invention it is also essentially identical, the technical solution formed in this way is finely adjusted above-described embodiment to be formed, this technology
Scheme is still fallen in protection scope of the present invention.
Claims (8)
1. a kind of global MPPT methods under uneven illumination is even, which is characterized in that step is as follows：
1) photovoltaic system is diagnosed, judges whether the region for two or more different illumination intensities occur, Mei Geguang
A kind of illumination condition is corresponded to according to intensity；
2) when judging the region of two or more different illumination intensities occur, discrete selection reference voltage determines each
The corresponding short circuit current of reference voltage distinguishes every a kind of illumination condition according to short circuit current, according to reference voltage and corresponding
Calculation of short-circuit current goes out the approximate maximum power under every a kind of illumination condition；
3) it according to per the approximate maximum power under a kind of illumination condition, is determined by comparing with the mode for applying disturbance global maximum
Power points；
4) routine MPPT methods are performed in the global maximum power point；
Reference voltage expression formula is：Y+a*x*Voc_sin, wherein Voc_sin are the open-circuit voltage of 1 piece of photovoltaic module, and x is belongs to
The photovoltaic module quantity of same illumination condition, y are all photovoltaic module numbers before current reference voltage value from low pressure to high pressure
Amount；A is coefficient, and a*Voc_sin represents a block assembly maximum power point crest voltage.
The global MPPT methods under 2. a kind of uneven illumination according to claim 1 is even, which is characterized in that the step 2)
In, it is described every a kind of illumination condition is distinguished according to short circuit current means be：From low pressure to high pressure, two adjacent ginsengs are detected
The short circuit current under voltage is examined, if the variation of short circuit current is more than setting ratio, judges that corresponding two component is in inhomogeneity
Illumination condition, if the variation of short circuit current be more than no setting ratio, judge that corresponding two component is in similar illumination
Condition.
The global MPPT methods under 3. a kind of uneven illumination according to claim 1 is even, which is characterized in that the step 2)
In, the approximate maximum power per class illumination condition is by each reference voltage under every class illumination condition and corresponding short circuit current meter
Calculation obtains the maximum value of power.
The global MPPT methods under 4. a kind of uneven illumination according to claim 1 is even, which is characterized in that the step 1)
In, the mode diagnosed to photovoltaic system is：When detecting power voltage change rate | Δ P/ Δs V | during more than μ 1, and work(
For rate variable quantity beyond limiting, judgement illumination condition change causes photovoltaic generating system power to be mutated；At this moment I_ is detected
The ratio of first and I_last, I_first are electric currents when photovoltaic array exports 1 block assembly crest voltage, and I_last is photovoltaic
Array exports electric current during N-1 block assembly open-circuit voltages, and when the ratio is more than μ 2, different illumination items occurs in judgement photovoltaic array
Part region；N is the photovoltaic module quantity of photovoltaic array；μ 1, μ 2 are corresponding coefficient.
The global MPPT methods under 5. a kind of uneven illumination according to claim 1 is even, which is characterized in that the step 3)
In, determine that the mode of global maximum power point includes：
Maximum value is selected in the approximate maximum power of every class illumination condition as approximate global maximum power Pm_old；It is arrived with low pressure
High pressure is forward direction；
First, peak power Pm, j are traced into using part MPPT under -1 class illumination condition of jth>=2, Pm with it is described approximate complete
Office maximum power Pm_old relatively takes higher value, is denoted as constant power conic constant Pm_new；The part MPPT is in a kind of light
The maximum power point tracing method carried out according under the conditions of；
Then, the positive disturbance since the corresponding voltages of peak power Pm under -1 class illumination condition of jth finds mutation to jth
The voltage reference value of class illumination condition, and record the short circuit current Iscj of jth class illumination condition；
Then with constant power conic constant Pm_new divided by jth class short circuit current Iscj, an obtained voltage reference value；It if should
The output current value of voltage reference value corresponding points is more than θ * Iscj, and P-V slopes of curve are just, then to be continued with local MPPT at this
It performs, finds the peak power under jth class illumination condition, otherwise continue unidirectional positive disturbance, it is short to find+1 class illumination condition of jth
Road electric current；The θ is setting coefficient；
If the constant power conic constant Pm_new divided by jth class short circuit current Iscj, obtained voltage reference value is more than setting
Voltage value then terminates and using constant power curve Pm_new as global maximum power.
The global MPPT methods under 6. a kind of uneven illumination according to claim 5 is even, which is characterized in that the mutation is arrived
The voltage reference value of jth class illumination condition is characterized in：The voltage reference value is in partial power's minimum, P-V slopes by
Negative change is just.
The global MPPT methods under 7. a kind of uneven illumination according to claim 5 is even, which is characterized in that in the step
3) before, approximate global maximum power Pm_old and Pm_mppt is compared, if Pm_old promotes amplitude more than μ 3, is held
Row step 3)；Pm_mppt is the maximum power recorded before fault diagnosis, and μ 3 is corresponding coefficient.
8. a kind of global MPPT devices under uneven illumination is even, which is characterized in that including：
Diagnostic module：Photovoltaic system is diagnosed, judges whether the region for two or more different illumination intensities occur,
Each intensity of illumination corresponds to a kind of illumination condition；
Scan the module of all kinds of illumination conditions：It is discrete when judging the region of two or more different illumination intensities occur
Selection reference voltage, determine the corresponding short circuit current of each reference voltage, every a kind of illumination condition distinguished according to short circuit current,
Approximate maximum power under every a kind of illumination condition is gone out according to reference voltage and corresponding calculation of short-circuit current；
Determine the module of global maximum power point：According to the approximate maximum power under every a kind of illumination condition, by comparing and apply
The dynamic mode of scrambling determines global maximum power point；
Maximal power tracing module：Routine MPPT methods are performed in the global maximum power point；
Reference voltage expression formula is：Y+a*x*Voc_sin, wherein Voc_sin are the open-circuit voltage of 1 piece of photovoltaic module, and x is belongs to
The photovoltaic module quantity of same illumination condition, y are all photovoltaic module numbers before current reference voltage value from low pressure to high pressure
Amount；A is coefficient, and a*Voc_sin represents a block assembly maximum power point crest voltage.
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| CN107508543B (en) * | 2017-07-24 | 2019-06-04 | 北方工业大学 | The normal structure and its power optimization method of characteristic mismatch photovoltaic group string |
| CN107340799B (en) * | 2017-08-29 | 2019-01-18 | 潍坊学院 | A kind of maximum power point of photovoltaic array tracking based on shadow Detection |
| CN107704012B (en) * | 2017-10-31 | 2019-09-13 | 中国科学院广州能源研究所 | Photovoltaic DC-to-AC converter maximum power tracking method under a kind of non-uniform irradiation |
| CN110515418B (en) * | 2019-08-12 | 2020-11-13 | 全球能源互联网研究院有限公司 | Method for determining and tracking global maximum power point of photovoltaic system |
| CN111061331A (en) * | 2019-12-31 | 2020-04-24 | 内蒙古工业大学 | Photovoltaic maximum power control system and method |
| CN112104323B (en) * | 2020-09-27 | 2023-05-23 | 晟高能源科技(江苏)有限公司 | MPPT controller suitable for photovoltaic module parallel system |
| CN112327999B (en) * | 2020-11-02 | 2022-03-11 | 东南大学 | Photovoltaic rapid detection and accurate diagnosis method based on maximum power point tracking data |
| CN113359940B (en) * | 2021-07-02 | 2022-05-17 | 吉林建筑大学 | Maximum power point tracking method and system of photovoltaic array |
| CN113517718B (en) * | 2021-08-13 | 2024-06-25 | 阳光电源股份有限公司 | Photovoltaic group series-parallel mismatch optimization method, power equipment and photovoltaic system |
| CN113746314B (en) * | 2021-11-03 | 2022-02-22 | 杭州禾迈电力电子股份有限公司 | Photovoltaic inverter and starting control method |
| CN113949102B (en) * | 2021-11-22 | 2024-04-12 | 阳光电源股份有限公司 | Global maximum power point tracking method, power optimizer and photovoltaic inverter |
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