CN106774612A - Photovoltaic maximum power tracking method based on gradient method extremum search under local shades - Google Patents
Photovoltaic maximum power tracking method based on gradient method extremum search under local shades Download PDFInfo
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Abstract
The invention discloses the photovoltaic maximum power tracking method based on gradient method extremum search under a kind of local shades, set up the photovoltaic array model that photovoltaic cell string is composed in parallel, by setting the illumination value in photovoltaic array relevant sub-module, the local shades situation in actual photovoltaic array is simulated；Given initial voltage, the extremum search of Preset Time is carried out using gradient method extremum search, determine whether to search partial power's extreme value by judging search two power differences of similar time point of processing completion time used for them, if searching partial power's extreme value, then update initial voltage and search for next partial power's extreme value, otherwise extension search time continues search for the corresponding partial power's extreme value of the initial voltage.The present invention is by changing initial voltage, the power peak near different initial voltages is searched out using gradient method extremum seeking algorithm, peak-peak is relatively obtained finally by multiple peak values, the maximum power point of the photovoltaic array that there are local shades can be accurately obtained.
Description
Technical field
The invention belongs to technical field of photovoltaic power generation, more specifically, it is related to be based on gradient method under a kind of local shades
The photovoltaic maximum power tracking method of extremum search.
Background technology
Photovoltaic generation is a kind of principal mode that electric energy is converted into using solar energy, is also the important composition of regenerative resource
Part, is that global energy consumption supply is made that outstanding contributions.The quality of photovoltaic generating system is decided by its core --- photovoltaic
The utilization ratio of battery.Research has shown that, only when photovoltaic cell is always worked near its maximum power point, its utilization rate is
Highest can be reached, so as to improve the performance of photovoltaic generating system.Therefore many traditional maximum photovoltaic power point tracking MPPT controls
Algorithm processed is widely utilized, and to trace into the maximum power point of photovoltaic cell, and makes photovoltaic system under the dotted state
Work, so as to improve photovoltaic efficiency.
But for photovoltaic cell utilization rate, it is not only relevant with its own structure, also with intensity of illumination, environment temperature
It is relevant etc. factor.Particularly when photovoltaic cell is uneven by intensity of illumination, the effect of local shades can be produced, so as to cause power
There is the situation of multiple peak values, have a great impact for its energy conversion rate.And traditional MPPT control algolithms acquiescence is only deposited
In a power peak, there is limitation for the photovoltaic maximal power tracing under local shades, it is therefore desirable to propose it is new with
Track method.
The content of the invention
It is an object of the invention to overcome the deficiencies in the prior art, there is provided searched based on gradient method extreme value under a kind of local shades
The photovoltaic maximum power tracking method of rope, sets up photovoltaic array model, by constantly changing the initial of photovoltaic array model voltage
Point carries out extremum search, accurately to realize the photovoltaic maximal power tracing under local shades.
For achieving the above object, under local shades of the present invention based on gradient method extremum search photovoltaic peak power with
Track method is comprised the following steps：
S1：The photovoltaic array model that photovoltaic cell string is composed in parallel is set up, by setting the illumination value in relevant sub-module,
Local shades situation in the actual photovoltaic array of simulation, using voltage as photovoltaic array model input, power is used as photovoltaic gust
The output of row model；
S2：Set the initial voltage v of gradient method extremum search0；
S3：With initial voltage v0As photovoltaic array mode input, a length of t when being carried out using gradient method extremum seeking algorithm
The extremum search of+m, records the power P of the photovoltaic array model at moment ttWith the power P of moment t+mt+m, t and m is according to reality
The time parameter that border situation is set；The specific steps of gradient method extremum seeking algorithm include：
S3.1：Make system initial estimation voltage
S3.2：By estimated voltageIt is added with disturbance R (t), obtains voltage
S3.3：Voltage v is input into photovoltaic array model, corresponding power P is obtained, unstable ripple is filtered off by wave filter
Shape, the power stablized
S3.4：By powerIt is multiplied with disturbance Q (t), obtains signal
S3.5：By Δ P, device obtains signal after filteringIt is integrated after being multiplied by a constant coefficient K, wherein K ＞ 0,
In estimated voltage pointPlace searches out next estimation iteration pointI.e.OrderReturn to step S3.2；
S4：Judge whether | Pt+m-Pt| ＜ μ, μ represent predetermined threshold value, μ ＞ 0, if it is, by Pt+mEnter as current extreme value
Row record, while its corresponding voltage v is recorded, into step S7, otherwise into step S5；
S5：Extend the search time of gradient method extremum seeking algorithm, search time of extension represents the extension time for τ+m, τ
Parameter, records the power P of time instant τ in this extension search timeτWith the power P of time instant τ+mτ+m；
S6：Judge whether | Pτ+m-Pτ| ＜ μ, if it is, by Pτ+mRecorded as current extreme value, while it is right to record its
The voltage v for answering, into step S7, otherwise return to step S5；
S7：Make initial voltage v0=v0+ h, return to step S3, h represent that initial point updates step-length；
During step S3 to step S7 circulations are performed, parameter is terminated to search and is monitored, once reach search terminate
Condition, then extremum search terminate, record all extreme values in select maximum as photovoltaic system maximum power point, according to
Its corresponding photovoltaic array voltage is controlled to photovoltaic array.
The photovoltaic maximum power tracking method based on gradient method extremum search, sets up photovoltaic cell under local shades of the present invention
The photovoltaic array model of connection in series-parallel composition, by setting the illumination value in photovoltaic array relevant sub-module, simulates actual photovoltaic battle array
Local shades situation in row；Given initial voltage, the extremum search of Preset Time is carried out using gradient method extremum search, is passed through
Judge search two power differences of similar time point of processing completion time used for them to determine whether to search partial power's extreme value, if search
To partial power's extreme value, then update initial voltage and search for next partial power's extreme value, otherwise extension search time continues search for
The corresponding partial power's extreme value of the initial voltage.
There is the situation of multimodal extreme value for the photovoltaic array that there are local shades in the present invention, propose to be based on gradient method extreme value
Search photovoltaic maximum power tracking method, by changing initial voltage, at the beginning of searching out difference using gradient method extremum seeking algorithm
Power peak near beginning voltage, so as to avoid being trapped in some local peaking, finally by the comparing to multiple peak values
To peak-peak, the maximum power point of photovoltaic array can be accurately obtained.By simulating, verifying it can be found that the present invention is one
Double loop system, can accurately search the corresponding extreme value of different input initial voltages, and search speed is fast, good stability.
Brief description of the drawings
Fig. 1 is the specific reality of the photovoltaic maximum power tracking method based on gradient method extremum search under local shades of the present invention
Apply mode flow chart；
Fig. 2 is gradient method extremum seeking algorithm schematic diagram in the present invention；
Fig. 3 is the p-v package module figures of photovoltaic array model in the present embodiment；
Fig. 4 is p-v package module schematic internal views in the present embodiment；
Fig. 5 is photovoltaic array simulation local shades environmental simulation figure；
Photovoltaic array I-v curve maps when Fig. 6 is two peak；
Photovoltaic array p-v curve maps when Fig. 7 is two peak；
V-t curve maps under extremum seeking algorithm when Fig. 8 is two peak；
P-t curve maps under extremum seeking algorithm when Fig. 9 is two peak；
Photovoltaic array I-v curve maps when Figure 10 is three peak；
Photovoltaic array p-v curve maps when Figure 11 is three peak；
V-t curve maps under extremum seeking algorithm when Figure 12 is three peak；
P-t curve maps under extremum seeking algorithm when Figure 13 is three peak.
Specific embodiment
Specific embodiment of the invention is described below in conjunction with the accompanying drawings, so as to those skilled in the art preferably
Understand the present invention.Requiring particular attention is that, in the following description, when known function and design detailed description perhaps
When can desalinate main contents of the invention, these descriptions will be ignored herein.
Embodiment
Fig. 1 is the specific reality of the photovoltaic maximum power tracking method based on gradient method extremum search under local shades of the present invention
Apply mode flow chart.As shown in figure 1, the photovoltaic maximal power tracing side based on gradient method extremum search under local shades of the present invention
The specific steps of method include：
S101：Set up photovoltaic array model：
Initially set up the photovoltaic array model that photovoltaic cell string is composed in parallel, by setting photovoltaic array relevant sub-module in
Illumination value, simulate the local shades situation in actual photovoltaic array, using voltage as photovoltaic array model input, power work
It is the output of photovoltaic array model.
S102：Setting initial voltage：
Set the initial voltage v of gradient method extremum search0。
S103：Gradient method extremum search：
With initial voltage v0As photovoltaic array mode input, a length of t+m when being carried out using gradient method extremum seeking algorithm
Extremum search, record moment t photovoltaic array model power PtWith the power P of moment t+mt+m, t and m is according to reality
The time parameter that situation is set.
Fig. 2 is gradient method extremum seeking algorithm schematic diagram in the present invention.As shown in Fig. 2 gradient method extremum seeking algorithm
Detailed process is comprised the following steps：
S201：Make system initial estimation voltageThat is photovoltaic array model voltage
S202：Input disturbance is processed：
By estimated voltageIt is added with disturbance R (t), obtains voltage
The disturbance expression used in the present embodiment for：
R (t)=a (l1cos(W(t))+l2Sin (W (t)))=aLTδ(t) (1)
Wherein, δ (t)=[cos (W (t)), sin (W (t))]TRepresent the disturbance of Blang's unit circle, L=[l1 l2]TBe often to
Amount, l1＞ 0, l2＞ 0 and a ＞ 0 are design parameters.
S203：Obtain correspondence power：
Voltage v is input into photovoltaic array model, corresponding power P is obtained, unstable waveform is filtered off by wave filter, obtained
To the power of stabilization
S204：Power disturbance treatment：
By powerIt is multiplied with disturbance, obtains signal
Q (t) is disturbed in the present embodiment to be represented by：
Q (t)=l1cos(W(t))+l2sin(W(t)) (2)
S205：Find next estimation iteration point：
By Δ P, device obtains signal after filteringIt is integrated after being multiplied by a constant coefficient K, wherein K ＞ 0, is being estimated
PointPlace searches out next estimation iteration pointI.e.OrderReturn to step S202.
S104：Judge whether that search obtains local extremum：
By the power P for comparing moment ttWith the power P of moment t+mt+mDifference whether be that can determine that less than predetermined threshold value
Whether search obtains local extremum, that is, judge whether | Pt+m-Pt| ＜ μ, μ represent predetermined threshold value, are a positive number for very little, i.e. μ
＞ 0, if it is, by Pt+mRecorded as current extreme value, while record its corresponding voltage v, into step S107, otherwise
Into step S104.Obviously, m is a shorter time interval.
S105：Extension search time：
If not searching current initial point v also0Corresponding extreme value, then need to extend searching for gradient method extremum seeking algorithm
Rope time, search time of extension represents extension time parameter for τ+m, τ, records the work(of time instant τ in this extension search time
Rate PτWith the power P of time instant τ+mτ+m。
S106：Judge whether extension search searches for and obtain local extremum：
It is similar with step S104, by the power P for comparing time instant τ in extension search timeτWith the power P of time instant τ+mτ+m
Difference whether be that can be determined whether that search obtains local extremum less than predetermined threshold value, that is, judge whether | Pτ+m-Pτ| ＜ μ, if
It is, by Pτ+mRecorded as current extreme value, while recording its corresponding input voltage v, into step S107, otherwise returned
Step S105.
It can be seen that, if from initial voltage v0Start timing as the initial input of gradient method extremum search, can enter first
The extremum search of a length of t+m during row, if search also may proceed to carry out the extremum search of duration τ+m, with such less than extreme value
Push away, the search of a length of τ+m when extending every time, always search is gone down.
S107：Update initial voltage：
Make initial voltage v0=v0+ h, return to step S103, h represent that initial point updates step-length, is set according to actual conditions
Put.
It can be seen that, step S103 to step S107 forms a circulation, and lasting search obtains each extreme value of system.In step
During rapid S103 to step S107 circulations are performed, parameter is terminated to search and is monitored, once reach search termination condition, then pole
Value search terminates, and maximum is selected in all extreme values of record as the maximum power point of photovoltaic system, corresponding according to its
Photovoltaic array voltage is controlled to photovoltaic array.
In general, search end parameter could be arranged to two kinds, and a kind of is the overall operation of multimodal extremum search method
Time, i.e., the total runtime of multimodal extremum search method is recorded using a timer, when total runtime reaches
Predetermined threshold value, then multimodal extremum search terminate；A kind of is the value of current initial point, if i.e. initial point v0Beyond preset range,
Then multimodal extremum search terminates.User can select to be sentenced using which kind of search termination condition according to the situation of real system
It is fixed.
In order to illustrate feasibility of the invention and correctness, separately below by theory deduction and simulating, verifying two ways
To be analyzed explanation to technical scheme.
The present invention uses gradient method extremum search when peak power point search is carried out to each initial input voltage
Algorithm, the method initial voltage given for can be carried out from closed loop cycle by continuous iteration, so as to search to
Determine the power peak near initial voltage, the detailed process that it is proved is as follows.
Equation below can be reduced to for photovoltaic system：
Wherein subscript round dot represents derivation, and P is the power of photovoltaic system.
U=η (x, v) is defined, v ∈ R, v are the voltage of photovoltaic system, so system equation can be expressed as：
There is extreme point in it, when having it is assumed hereinafter that setting up：
Assuming that 1：Existence function r:R→RmSo that during and if only if x=r (v), f (x, η (x, v))=0 sets up；
Assuming that 2：For arbitrary v ∈ R, equalization point x=r (v) of system (4) is to restrain stabilization with exponential form.
Assuming that 3：There is v*∈ R cause that following formula is set up：
Wherein, gor is Second Order Continuous differentiable function.
It is therefore assumed that power P=g (r (v)) is in v=v*There is local extremum at place.
The extremum search method based on gradient method according to Fig. 2 understands that its system equation is as follows：
Wherein, h1＞ 0, h2＞ 0, respectively filter parameter, s represent Laplace operator.
Define error variance：Can obtain：
χ (t)=W (σ t) is defined, σ represents time scale variable, can obtain system equation：
WhereinSubscript r is used for formula (8) and formula
(10) the identical variable in makes a distinction.
According to assuming 3, have：
L (0)=0,
It is by equalization system equation is obtained after system (10) equalization：
The equalization point of wherein θ=t/ σ, and system (12)Meet：
Assuming thatForm meetDefinition
Bringing the formula that equalization point met into has：
Can obtainParameter：Therefore
It is hereby achieved that：
To sum up, the equalization point of system (12)For：
After solving the Jacobian matrix of system (12), the equalization point shown in formula (15) is brought into matrix, can obtain：
WillIt is lower triangular matrix by line translation, has：
Thatch criterion is tieed up from Hall, ifIt is stable then needCan be obtained by Taylor expansionAnd known H ＜ 0, K, a,Therefore In parameter a
A very small value, thus system (12) can be with stable convergence to equalization point at.So far demonstrate given to any one
Initial point, can by gradient method extremum seeking algorithm stabilization the extreme value searched near it.
The photovoltaic maximum power tracking method based on gradient method extremum search is by comparing two under local shades of the present invention
Whether the difference of similar time point power is less than a threshold values to judge whether to search the power peak near the initial voltage, if
Search, then increase initial voltage every time after h as new initial voltage.By updating the value of initial voltage, realize to many
The search of individual power peak, peak-peak is relatively obtained by multiple power peaks, so as to be accurately obtained in the presence of multiple
The maximum power point of photovoltaic array of power peak, realizes maximal power tracing.
In order to prove technique effect of the invention, simulating, verifying is carried out using a specific photovoltaic system.This implementation
In order to set up the Utility Simulation Model of photovoltaic array in example, under the Simulink environment of Matlab softwares, using match dimension LDK light
Volt component sets up the photovoltaic array model that photovoltaic cell string is composed in parallel.Fig. 3 is the p-v envelopes of photovoltaic array model in the present embodiment
Dress module map.As shown in figure 3, the T of PV modules input represents real-time environment temperature, S represents real-time intensity of illumination.This is imitated
In true checking, the short circuit current I under standard test condition STC can be provided the user according to photovoltaic cell production firmsc, open
Road voltage Uoc, peak power Pm, maximum power point voltage Um, maximum power point electric current ImTo set up simulation model.Fig. 4 is this reality
Apply p-v package module schematic internal views in example.As shown in figure 4, set photovoltaic system parameter being：Um=37.9, Im=5.16, Uoc
=45.3, Isc=5.54.Fig. 5 is photovoltaic array simulation local shades environmental simulation figure.As shown in figure 5, photovoltaic array is by six pieces
PV modules are made up of series-parallel form, while in order to avoid mismatching phenomenon as far as possible in photovoltaic generation, suppress hot spot effect,
Bypass diode and blocking diode are both increased in each photovoltaic module, mismatching phenomenon brings between reaching reduction photovoltaic module
The purpose of energy loss, but because the addition of diode increased the complexity of photovoltaic array output characteristics, p-v curves can be caused
There is the situation of multi-peak, so as to complicate the search of global maximum power point.
The environment of photovoltaic cell local shades is simulated in the present embodiment by the illumination S values of changing section PV modules, is made
Obtain photovoltaic array and the situation of multimodal occur.By T unification be set to 25, first by illumination S be respectively set to 200lux and
1000lux.Photovoltaic array I-v curve maps when Fig. 6 is two peak.As shown in fig. 6, due to being provided with two kinds of different illumination values, its
I-v figures have two ladders.Photovoltaic array p-v curve maps when Fig. 7 is two peak.As shown in fig. 7, its p-v figure has two peak values, first
The voltage of individual peak value is about 78.88, and correspondence power is about 819.22, and the voltage of second peak value is about 114.28, correspondence power
About 710.56.
Power peak search is carried out to the photovoltaic array model of above photovoltaic system using the inventive method, wherein each parameter
Set as follows：Initial voltage v0=10, initial value updates step-length h=20, search time parameter t=20, m=1, extension time ginseng
Number τ=6, judgment threshold μ=0.4 of local extremum, search termination condition is using the total runtime t for searching forAlways=100.
V-t curve maps under extremum seeking algorithm when Fig. 8 is two peak.P-t curves under extremum seeking algorithm when Fig. 9 is two peak
Figure.As shown in Figure 8, when initial voltage is set in 10,30,50, the corresponding magnitude of voltage of power peak that it is searched exists
78.10 or so, when initial voltage is set in 70, it searches the corresponding magnitude of voltage of power peak 115.31 or so.And phase
Corresponding performance number is as shown in figure 8, when initial voltage is set in 10,30,50, the power peak that it is searched is 814.51
Left and right, when initial voltage is set in 70, the power peak that it is searched is 711.97 or so.Can by the result of Fig. 8 and Fig. 9
Know, be may search for two peak values for photovoltaic array module with the inventive method, the corresponding voltage of first peak value is about
78.10, correspondence power is about 814.51, and the corresponding voltage of second peak value is about 115.31, and correspondence power is about 711.97.Table
1 is two peak-data analytical tables.
Table 1
As shown in Table 1, with the inventive method to the mistake of the result of photovoltaic array block search simulation result with itself
Difference illustrates that the inventive method can accurately search each power peak of photovoltaic array module, by comparing within 1%
The size of each power peak, you can determine global maximum power peak value.
To further illustrate the feasibility of the inventive method, three kinds of different illumination are set in photovoltaic array Mathematical Modeling
Value, respectively 500lux, 100lux and 800lux.Photovoltaic array I-v curve maps when Figure 10 is three peak.As shown in Figure 10, due to
There is provided three kinds of different illumination values, its I-v figure has three ladders.Photovoltaic array p-v curve maps when Figure 11 is three peak.Such as Figure 11
Shown, its p-v figure has three power peaks, and the corresponding voltage of first peak value is about 38.96, and correspondence power is about 354.54,
The corresponding voltage of second peak value is about 75.53, and correspondence power is about 611.66, and the 3rd corresponding voltage of peak value is about
112.98, correspondence power is about 646.16.
Similarly, power peak search is carried out to the photovoltaic array model of above photovoltaic system using the inventive method, its
In each parameter setting it is as follows：Initial voltage v0=2, initial value updates step-length h=40, search time parameter t=30, m=1, prolongs
Long-time parameter τ=6, judgment threshold μ=0.2 of local extremum, search termination condition is using the total runtime t for searching forAlways
=100.
V-t curve maps under extremum seeking algorithm when Figure 12 is three peak.P-t curves under extremum seeking algorithm when Figure 13 is three peak
Figure.As shown in Figure 12, when initial voltage is set in 2, it searches the corresponding magnitude of voltage of power peak 38.59 or so, when
When initial voltage is set in 42, the corresponding magnitude of voltage of power peak that it is searched 74.57 or so, when initial voltage is set in
When 82, the corresponding magnitude of voltage of power peak that it is searched is 113.36 or so.And corresponding performance number is as shown in figure 12, when
When initial voltage is set in 2,355.68 or so, when initial voltage is set in 42, it is searched the performance number that it is searched
Performance number 608.57 or so, when initial voltage is set in 82, the performance number that it is searched is 646.46 or so.By Figure 12
Understood with the result of Figure 13, be may search for three power peaks for above-mentioned photovoltaic array module with the inventive method, the
The corresponding voltage of one peak value is about 38.59, and correspondence power is about 355.68, and the corresponding voltage of second peak value is about 74.57,
Correspondence power is about 608.57, and the 3rd corresponding voltage of peak value is about 113.36, and correspondence power is about 646.46.Table 2 is three
Peak-data analytical table.
Table 2
As shown in Table 2, with the inventive method to the mistake of the result of photovoltaic array block search simulation result with itself
Within 2%, further illustrating the inventive method can accurately search each power peak of photovoltaic array module to difference,
By the size of relatively more each power peak, you can determine global maximum power peak value.
Although being described to illustrative specific embodiment of the invention above, in order to the technology of the art
Personnel understand the present invention, it should be apparent that the invention is not restricted to the scope of specific embodiment, to the common skill of the art
For art personnel, as long as various change is in appended claim restriction and the spirit and scope of the present invention for determining, these
Change is it will be apparent that all utilize the innovation and creation of present inventive concept in the row of protection.
Claims (3)
1. the photovoltaic maximum power tracking method of gradient method extremum search is based under a kind of local shades, it is characterised in that including
Following steps：
S1：The photovoltaic array model that photovoltaic cell string is composed in parallel is set up, by setting the illumination value in relevant sub-module, simulation
Local shades situation in actual photovoltaic array, using voltage as photovoltaic array model input and output, power as photovoltaic battle array
The output of row model；
S2：Set the initial voltage v of gradient method extremum search0；
S3：With initial voltage v0As photovoltaic array mode input, a length of t+m when being carried out using gradient method extremum seeking algorithm
Extremum search, records the power P of the photovoltaic array model at moment ttWith the power P of moment t+mt+m, t and m is according to actual feelings
The time parameter that condition is set；The specific steps of gradient method extremum seeking algorithm include：
S3.1：Make system initial estimation voltage
S3.2：By estimated voltageIt is added with disturbance R (t), obtains voltage
S3.3：Voltage v is input into photovoltaic array model, corresponding power P is obtained, unstable waveform is filtered off by wave filter,
The power stablized
S3.4：By powerIt is multiplied with disturbance Q (t), obtains signal
S3.5：By Δ P, device obtains signal after filteringIt is integrated after being multiplied by a constant coefficient K, wherein K ＞ 0, is being estimated
EnumerationPlace searches out next estimation iteration pointI.e.OrderReturn to step S3.2；
S4：Judge whether | Pt+m-Pt| ＜ μ, μ represent predetermined threshold value, μ ＞ 0, if it is, if it is, by Pt+mAs current extreme value
Recorded, while its corresponding voltage v is recorded, into step S7, otherwise into step S5；
S5：Extend the search time of gradient method extremum seeking algorithm, the search time of extension is τ+m, and τ represents that the extension time joins
Number, records the power P of time instant τ in this extension search timeτWith the power P of time instant τ+mτ+m；
S6：Judge whether | Pτ+m-Pτ| ＜ μ, if it is, by Pτ+mRecorded as current extreme value, while recording its corresponding electricity
Pressure v, into step S7, otherwise return to step S5；
S7：Make initial voltage v0=v0+ h, return to step S3, h represent that initial point updates step-length；
During step S3 to step S7 circulations are performed, parameter is terminated to search and is monitored, once search termination condition is reached,
Then extremum search terminates, and maximum is selected in all extreme values of record as the maximum power point of photovoltaic system, right according to its
The photovoltaic array voltage answered is controlled to photovoltaic array.
2. photovoltaic maximum power tracking method according to claim 1, it is characterised in that the search terminates parameter use
The total runtime of multimodal extremum search method, i.e., when total runtime reaches predetermined threshold value, then extremum search terminates.
3. photovoltaic maximum power tracking method according to claim 1, it is characterised in that the search terminates parameter use
The value of initial point, if i.e. initial point x0Beyond preset range, then extremum search terminates.
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| CN110262618A (en) * | 2019-06-19 | 2019-09-20 | 电子科技大学 | A kind of photovoltaic peak power tracking method based on no steady oscillation extremum search |
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| DE102005032864A1 (en) * | 2005-07-14 | 2007-01-25 | Sma Technologie Ag | Photovoltaic-generator maximum power output finding method, involves switching-off regulation of inverter to charge and discharge generator, and switching-on regulation to transfer operating point from stable into unstable state |
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