CN108983861A - Optimal power point-tracking method when generation part shading grid-connected based on photovoltaic multi-electrical level inverter - Google Patents
Optimal power point-tracking method when generation part shading grid-connected based on photovoltaic multi-electrical level inverter Download PDFInfo
- Publication number
- CN108983861A CN108983861A CN201810716291.2A CN201810716291A CN108983861A CN 108983861 A CN108983861 A CN 108983861A CN 201810716291 A CN201810716291 A CN 201810716291A CN 108983861 A CN108983861 A CN 108983861A
- Authority
- CN
- China
- Prior art keywords
- voltage
- shading
- illumination
- point
- intensity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- 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
Landscapes
- 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 optimal power point-tracking methods when a kind of generation part shading grid-connected based on photovoltaic multi-electrical level inverter, this method comprises: carrying out the measurement of voltage and current to the photo-voltaic power supply of several basic concatenation units of the multi-electrical level inverter；Calculate total output power；The reference voltage for changing H bridge DC side, compares and calculates optimal output power；Corresponding voltage value is the reference voltage of H bridge DC side.Part shading is divided to two groups of situations, can use conventional method optimizing under equilibrium state；Under non-equilibrium state, according to the principle that COS distance is constant, the electric power output voltage for the unit that do not shade is looked in characteristic circle, and calculates the power supply output reference voltage of shading unit, to calculate the voltage minimum of OPPT output.System can will restore rapidly normal condition in the minimum voltage value stable operation, and after locally shading.The characteristics of present invention is according to topological structure, the stabilization transition of system and recovery rapidly when realizing part shading.
Description
Technical field
The present invention relates to photovoltaic multi-electrical level inverter technical fields, and in particular to one kind is based on photovoltaic multi-electrical level inverter simultaneously
Optimal power point when part shading occurs for net tracks (Optimum Power Point Tracking, OPPT) method.
Background technique
Many scholars are dedicated to MPPT maximum power point tracking when part shading occurs for photovoltaic array, and propose and much seek
Excellent algorithm.MPPT under conventional topologies structure will each piece of photovoltaic panel in consideration system specific output power, thus work as certain
Local shading has occurred in one piece of photovoltaic panel, and output power will reduce, for total output power, original voltage etc.
The corresponding power of grade is also no longer maximum power point MPP, and local MPP will become two by one.
If it is a large amount of photovoltaic plate serioparallel, then the probability that multimodal occurs will greatly increase, overall situation MPP is found
Complexity can also be multiplied therewith.For all photovoltaic inverter grid-connected systems, the output voltage of MPPT is adjusted, due to
System reaches new steady s tate and is also required to certain time, thus can not obtain corresponding power at once.So as population
Algorithm (PSO), group hunting optimization algorithm (GSO) etc. is this kind of to be needed to obtain great amount of samples data, is screened out from it optimal value again
Algorithm will time-consuming amount it is very big, be not suitable for putting into actual motion, even if the later period is obtained using intensified learning (RL)
MPP, the complexity of algorithm itself be not also low.There are also the algorithm of many dynamic optimizations, it is dedicated to adjusting step-size in search, shortens and reach
It the time of maximum power point and avoids falling into local optimum, but repeatedly carries out the voltage adjustment of big step-length, also can make system not
Stablize, and system reaches stable when will also extend.The optimization of these algorithms is all directed to reduce searching times, not
There is the reason of further investigation multimodal occurs and how to reduce peak value.
Summary of the invention
The purpose of the present invention is to solve drawbacks described above in the prior art, provide a kind of based on photovoltaic multi-level inverse conversion
The characteristics of optimal power point-tracking method when the grid-connected generation part of device is shaded, this method is according to topological structure, realize part
The stabilization transition of system and recovery rapidly when shading.
The purpose of the present invention can be reached by adopting the following technical scheme that:
A kind of optimal power point-tracking method when generation part shading grid-connected based on photovoltaic multi-electrical level inverter, it is described
Optimal power point-tracking method includes the following steps:
S1, the photo-voltaic power supply output voltage v for acquiring each concatenation unitpvnWith output electric current ipvn；
S2, the total output power of photo-voltaic power supply is calculatedWherein N indicates the quantity of concatenation unit；
S3, judge whether to shade, if do not shaded, determine reference voltage variation range, controlled by MPPT
Method searches for maximum power point as optimal solution；
S4, if it happens shade, judge whether each concatenation unit shading degree is identical, if shading degree is identical,
Maximum power point is searched for as optimal solution by MPPT control method；
If S5, shading degree are different, that is, unbalanced part shading occurs, only considers that one and only one unit occurs
Shading, finds the value in characteristic circle, constant by COS distance, finds the corresponding output voltage reference value of shading unit；
S6, total output voltage reference value, the output as OPPT are calculated.
Further, the step S2 includes:
S201, it is pre-processed according to voltage and current serial data of the sampling density to the photo-voltaic power supply of acquisition, selection is suitable
The window of size divides serial data；
S202, the value that most representational data are used to represent the period is filtered out in each wicket.
Further, the method for most representational data is filtered out such as in each wicket in the step S202
Under:
The median of selected window or the average value of selected window are used as most representational data.
Further, the step S3 includes:
S301, determine reference voltage variation range, will it is grid-connected needed for minimum inverter voltage as OPPT output voltage lower limit；
S302, the front and back variation for comparing photo-voltaic power supply voltage in basic unit, judge whether to shade；
When part shading occurs for S303, hypothesis, the intensity of illumination of the tandem photovoltaic plate in each concatenation unit is the same,
I.e. maximum power point always only one, based on this it is assumed that changing the shading degree of photo-voltaic power supply in all units, calculateOPPT output voltage limit is determined with MPPT method for searching；
S304, the intensity of illumination by changing simultaneously all basic units determine under some intensity of illumination, there is maximum
Output power, when intensity of illumination reduce when, output power also reduces therewith；When intensity of illumination increases, output power also subtracts
Small, this maximum power point is denoted as Pm(Im, Vm)。
Further, the step S4 process is as follows:
When the part shading balanced, the photo-voltaic power supply shading situation in each concatenation unit is identical, considers in unit
Voltage range where peak value number that series-parallel photovoltaic is likely to occur and each peak value, determines in feasible voltage range most
Voltage range where high-power point, then searched in the voltage range with MPPT method for searching, the local optimum found is made
For global optimum.
Further, the MPPT method for searching is perturbation observation method.
Further, the step S5 includes:
S501, choose a concatenation unit carry out shading experiment, only change its intensity of illumination, and allow other concatenation units all
In most suitable intensity of illumination；
S502, the intensity of illumination difference according to shading unit, the output voltage of each concatenation unit is also different, and do not shade electricity
The output voltage of pressure can rise automatically, and rise to a particular value, and setting intensity of illumination changes step-length, measure corresponding electricity
Pressure value；
S503, the above-mentioned voltage value of fitting, obtain fitting function, this is that a center of circle is C (- NIm, Vm), radius is (N+
1)ImCircle, point Pm(Im, Vm) it is used as maximum power point, it is denoted as reference point, intensity of illumination is defined and is lower than PmCorresponding intensity of illumination
Part shading occurs for photovoltaic panel, connects origin O and Pm, straight lineThe as variation range of shading elements reference voltage；
S504, when uneven part shading occurs, it is corresponding to find non-shading cell voltage value on the circle for being C in the center of circle
Point crosses the point and makees straight line parallel in y-axis, withIntersection point be the shading unit output voltage reference value.
The present invention has the following advantages and effects with respect to the prior art:
(1) the invention proposes OPPT controller, have under the topological structure and only one OPPT controller, Er Qie
It all supports to use most traditional MPPT control method when balance or uneven part shading.
(2) when unbalanced part shading occurs, it was found that cell voltage of not shading changing rule is one special
Circle proposes that COS distance chooses OPPT output voltage minimum, need to only allow system to run in minimum, can both stablize transition.
Detailed description of the invention
Fig. 1 is real topology and control algolithm schematic diagram of the invention, is research with the topological structure of 4 concatenation units
Object；
Fig. 2 is the relational graph of inverter direct-flow side output power and output voltage of the invention；
Fig. 3 is in 4 concatenation units of the invention, and three blocks of tandem photovoltaic plates occur to be likely to occur when the shading of part in certain level-one
Voltage, electric current and power different situations schematic diagram；Wherein, Fig. 3 (a) indicates to occur 3 MPP, Fig. 3 occur when the shading of part
(b) it indicates to occur to occur when the shading of part 2 MPP, Fig. 3 (c) indicates to occur only one MPP when the shading of part；
Fig. 4 be single-stage photovoltaic array under different illumination intensity i.e. under different output current, electricity that peak value is fallen in
Press interval graph；
Fig. 5 is that changed power when the shading of part occurs for a certain concatenation unit, and is reached by control voltage and current
The output power balance chart of every level-one, it is known that output power at different levels is P when normal operation0, when part shading occurs, shade unit
Output power fall to P1', by controlling voltage and current so that the unit that shades reaches its own maximum power point P1；
Fig. 6 is when single-stage occurs locally to shade, and cell voltage of not shading rises regular schematic diagram, wherein Fig. 6 (a) definition
The circle is characterized circle, changes the intensity of illumination of shading unit, and voltage will change along characteristic circle, and it is true that Fig. 6 (b) introduces COS distance
Surely the reference value of shading unit output voltage；
Fig. 7 is under 4 concatenation unit grid connection topology structures, and when part shading occurs for inversion unit, output voltages at different levels are surveyed
Value and reference value schematic diagram；Wherein Fig. 7 (a) is the photo-voltaic power supply output voltage schematic diagram of shading unit, and Fig. 7 (b) is not shade
The photo-voltaic power supply output voltage schematic diagram of unit；
Fig. 8 is under 4 concatenation unit grid connection topology structures, and when part shading occurs for inversion unit, network voltage and electric current are real
Measured value schematic diagram；
Fig. 9 is inverter output voltage schematic diagram, wherein Fig. 9 (a) is a certain list under 4 concatenation unit grid connection topology structures
When part shading occurs for member, inverter output voltage measured value schematic diagram, Fig. 9 (b) show inverter under normal illumination and exports
Voltage measured value schematic diagram；
Optimal power point when Figure 10 is generation part shading grid-connected based on photovoltaic multi-electrical level inverter disclosed by the invention
The flow chart of tracking.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art
Every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
Embodiment
OPPT is simply introduced below.
OPPT, i.e. optimal power point track (Optimum Power Point Tracking, OPPT) abbreviation OPPT algorithm.
The difference of OPPT and traditional MPPT maximum power point tracking (Maximum Power Point Tracking, MPPT) is, equally
It is to find maximum power point, OPPT is that lower selection global optimum is constrained according to physical condition, this solution is not necessarily the overall situation most
High-power point.The characteristics of this algorithm, is, without spending a large amount of resource to look for the global optimum of power increment very little.
As shown in Figure 1, this topological structure is a kind of switching tube --- diode cascade multilevel inverter, by forward and backward
Grade converter is in series, and the front stage converter is by N number of switching tube --- and diode cascade is constituted, specially full-control type
Electronic power switch S1nType diode D is not controlled1nIt is connected in series.
The rear class converter is single-phase full bridge inverter circuit, is specially made of 4 full-control type power electronic switches
Single-phase full bridge inverter circuit, by full-control type power electronic switch S21、S23Series connection obtains bridge arm 1, S22、S24Be connected in series bridge arm
2, the output of inverter is connected with five rank RLC filters.
In the present embodiment, N selection 4, i.e. concatenation unit number are 4.In each concatenation unit, photo-voltaic power supply is by three
The photovoltaic panel of block model Trina Solar TSM-250PA05.08 is connected in series.Filter is five rank LC filters, right
The topological structure of title can realize the two-way flow of energy.Electrical network parameter is 110V, 60Hz, connects two loads 1 and 2.
Entire control flow includes: the voltage value and electric current of photo-voltaic power supply in OPPT acquisition inverter direct-flow side concatenation unit
Value, the inverter direct-flow side reference voltage being calculated by OPPT；Network voltage is acquired, is obtained by PLL phaselocked loop current
Collected network voltage and electric current are passed through Park Transformation (Park Transformation) by electric voltage frequency, defeated together with OPPT
Reference voltage out, together be sent into PWM generator in, final output duty ratio with sinusoidal variations square wave, to control direct current
Switching tube in the concatenation unit of side.
Wherein, the process of OPPT control is as shown in Fig. 10, comprising the following steps:
S1, the photo-voltaic power supply output voltage v for acquiring each concatenation unitpvnWith output electric current ipvn；
S2, the total output power of photo-voltaic power supply is calculatedWherein N indicates the quantity of concatenation unit；
Step S2 process is as follows:
S201, it is pre-processed according to voltage and current serial data of the sampling density to the photo-voltaic power supply of acquisition, selection is suitable
The window of size divides serial data；
S202, the value that most representational data are used to represent the period is filtered out in each wicket, for the sake of simplicity,
What is generally chosen is median.
According to the fluctuation of the error of sampling and system, window size can be suitably selected, is averaged substitution.Usual situation
Under, when systematic comparison is stablized, it can not also pre-process.
S3, judge whether to shade, if do not shaded, reference voltage variation range is determined, by traditional
MPPT control method searches for maximum power point as optimal solution；
Step S3 process is as follows:
S301, the variation range for determining reference voltage, will it is grid-connected needed for minimum inverter voltage as under OPPT output voltage
Limit；
S302, the front and back variation for comparing photo-voltaic power supply voltage in basic unit, judge whether to shade；
When part shading occurs for S303, hypothesis, the intensity of illumination of the tandem photovoltaic plate in each concatenation unit is the same,
I.e. maximum power point always only one.Based on this it is assumed that changing the shading degree of photo-voltaic power supply in all units, calculateWith traditional MPPT method for searching, such as perturbation observation method, OPPT output voltage limit is determined.
S304, the intensity of illumination by changing simultaneously all basic units, can determine under some intensity of illumination, have
Maximum output power.When intensity of illumination reduces, output power also reduces therewith；When intensity of illumination increases, output power
Also reduce.This maximum power point is denoted as Pm(Im,Vm)。
Wherein it is determined that the variation range of reference voltage, can measure institute by the intensity of illumination of each concatenation unit of change
The voltage and current for having photovoltaic array in unit to export, calculates its output power, and to voltage and power relation carry out described point and
Fitting.
There are three pieces of photovoltaic panel series connection in each concatenation unit, when the same voltage value obtains maximum power, three pieces
The intensity of illumination of photovoltaic panel is the same, obtains maximum power.Therefore, output power model is carried out in the intensity of illumination for changing concatenation unit
When enclosing calculating, only consider that three pieces of photovoltaic panel intensities of illumination are identical.
As shown in Fig. 2, lateral curve refers to, under some intensity of illumination, changes OPPT output voltage, measure direct current
Side output power, and draw out voltage --- power curve.4 intensities of illumination are chosen in figure to be emulated, and 4 electricity are obtained
Pressure --- power curve.It can be seen from the figure that the selection of OPPT voltage has bound.Longitudinal curve expression is not being shared the same light
The position occurred according to maximum power point under intensity.It as seen from the figure, is not directly proportional between intensity of illumination and maximum power, and
It is to have a most suitable intensity of illumination, the maximum power point under this intensity of illumination is exactly Pm.Research below is no more than
The voltage class.
S4, if it happens shade, judge whether each concatenation unit shading degree is identical, if shading degree is identical,
The same S3 of optimizing mode；
The step is specific as follows: the photo-voltaic power supply shading situation when part shading balanced, in each concatenation unit
It is identical.Consider the voltage range where series-parallel photovoltaic is likely to occur in unit peak value number and each peak value, in conjunction with
Step S301 determines the voltage range in feasible voltage range where maximum power point, then in the range with perturbation observation method
It searches, the local optimum found is as global optimum.
In this topological structure, it is assumed that three pieces of photovoltaic panel parameters of each concatenation unit are the same, and are passed through
Change its respective intensity of illumination, so that changing it exports electric current.This three pieces of photovoltaic panels are in different intensity of illumination (output electricity
Stream) under, the number of peak value be also it is different, MPP is possible to fall in any one peak value.Such as Fig. 3 (a), Fig. 3 in Fig. 3
(b), shown in Fig. 3 (c), this is relationship when part shading occurs between one of which voltage, electric current and power.
Assuming that there are three peak values, then:
1, three voltage ranges [0, v1]、[v1, v2] and [v2, v3] width be equal；
2, the electric current in three voltage ranges is all constant；
3,1., 2. and 3. three local optimums are respectively labeled as；
1., 2. and 3. corresponding [0, v1]、[v1, v2] and [v2, v3]。
If the power of the maximum power point of each peak value is the same, critical condition is
I1·V1=I2·V2=I3·V3 (1)
Wherein, I1、I2And I3The corresponding size of current of three voltage ranges is respectively indicated, and has I1=aI, I2=bI, I3
=cI；V1=1.5V2=3V3。
Then available
aIV1=bIV2=cIV3 (2)
Wherein, a=b+x, b=c+y, c=z.
Then it can be obtained with summary and induction:
According to the relationship between above-mentioned electric current, it can soon judge which voltage range maximum power point falls in.With
When as part shading occurs, search voltage initial value can be quickly adjusted.
In practical applications, as shown in figure 3, the number for peak value occur is not quite similar.Thus specially mark, such as Fig. 3 (a)
Shown, when one and only one peak value, 1. MPP is labeled as；As shown in Fig. 3 (b), when there are two peak values, high voltage
1. the MPP of grade is labeled as, 2. low-voltage-grade is labeled as.As shown in Fig. 3 (c), when there are two peak values, voltage levels
MPP be labeled as 1., the MPP of medium voltate grade is that 2., 3. low-voltage-grade is.
Three pieces of photovoltaic panel intensities of illumination (1000W/m from complete darkness to all light respectively is set2), according to this three pieces of photovoltaic panels
1., 2. and 3. corresponding output electric current and the place MPP section, can draw MPP voltage range distribution map.As shown in figure 4, three seats
Parameter respectively indicates the output electric current of three pieces of photovoltaic panels, and the point of three kinds of shapes of intermediate three kinds of colors represents 3 voltage class sections.
Wherein, the side's of being expressed as point when MPP falls in 1. section falls in 2. section and is expressed as dot, falls in 3. section and is expressed as triangulation point.By
Assume that three pieces of photovoltaic panels are duplicate in previous, therefore three reference axis are symmetrized in turn, constitute a square.It can
Square point occupies the overwhelming majority, and is located at the centre of entire square volume graphic；Dot is located remotely from three of square origin
Vertex；Triangulation point is located at close to three vertex of square origin.
The corresponding actual conditions of Fig. 4 are: when the degree that three pieces of photovoltaic panels generations are locally shaded is more close, MPP is always
Fall in 1. section；When wherein there is one piece of photovoltaic panel that more serious part shading occurs, MPP can fall in 2. section；When wherein
When having two pieces of photovoltaic panels that more serious part shading occurs, MPP can fall in 3. section.Thus we can be according to electric after shading
Flow relation finds out rapidly which section MPP falls in, and carries out voltage adjustment.
For grid-connected system, in order to grid-connected smooth, MPPT Initial Voltage Value is always arranged higher, therefore electricity
Pressure is searched actually from high voltage toward low-voltage transition, therefore the MPP for falling in 1. section can be found with conventional method.It falls in
3. 2. needing to carry out primary voltage adjustment, then searched with conventional method when section.
It is worth noting that, voltage class is all too low, is unsatisfactory for inverter direct current when MPP is appeared in 2. and when 3. section
The requirement of side minimum voltage, and the performance number of global optimum and the local optimum in 1. section are not much different at this time, therefore not
It needs also carry out voltage adjustment.
In being incorporated into the power networks, change the reference value of DC side voltage of converter, that is, when changing MPPT output voltage reference value, electricity
Net needs the regular hour to get to stablize.Therefore in actual motion, the algorithm of big step-length modification voltage value is needed repeatedly simultaneously
It is not applicable.Benefit using conventional method is to can simplify calculation amount, is facilitated on code migrating to chip.And this power points at
For optimal power point OPP.
If S5, shading degree are different, that is, unbalanced part shading occurs, only considers that one and only one unit occurs
Shading, finds the value in characteristic circle, constant by COS distance, finds the corresponding output voltage reference value of shading unit；
Step S5 process is as follows:
S501, choose a concatenation unit carry out shading experiment, only change its intensity of illumination, and allow other concatenation units all
In most suitable intensity of illumination.
S502, the intensity of illumination difference according to shading unit, the output voltage of each concatenation unit are also different.Do not shade electricity
The output voltage of pressure can rise automatically, and rise to a particular value.Intensity of illumination is set and changes step-length, measures corresponding electricity
Pressure value.
S503, these voltage values are fitted, obtain fitting function, this is that a center of circle is C (- NIm,Vm), radius is (N+
1)ImCircle, point Pm(Im,Vm) it is used as maximum power point, it is denoted as reference point.It defines intensity of illumination and is lower than PmCorresponding intensity of illumination
Part shading occurs for photovoltaic panel.Connect origin O and Pm, straight lineThe as variation range of shading elements reference voltage.
S504, when uneven part shading occurs, find the corresponding point of non-shading cell voltage value on circle C, cross and be somebody's turn to do
Point makees straight line parallel in y-axis, withIntersection point be the shading unit output voltage reference value.
This topological structure have the shortcomings that one it is obvious, for each concatenation unit, the power of output, which must balance, just may be used
To operate normally, otherwise system will collapse.As soon as voltage-power characteristic according to photovoltaic panel is a Convex Functions, also mean
The same performance number can correspond to two voltage values.It can be by the regulation of voltage come so that these units are still kept
Balance.As shown in figure 5, original output power at different levels is all P0, when part shading occurs for a certain unit, power curve meeting
Decline, in order to enable power-balance, the unit that do not shade just must boosted output voltages.MPPT search result is desirable to shading unit
Energy Maximum Power Output, i.e. changed power are P0→P1'→P1.Therefore it can be controlled separately the output voltage of voltage shading unit
From V0→V1'→V1, the output voltage of the unit that do not shade is from V0→V2'→V2.When actual motion, due to the limit of cascading topological structure
System, electric current are clamped, and the actual output current for the unit that shades can not measure, and in other words, the maximum power for the unit that shades can not be straight
It connects to obtain.But its voltage change rule follows above-mentioned conclusion, therefore can take voltage is measured and is adjusted from
And reach power-balance.Control voltage only needs to control the output voltage of MPPT.
When part shading occurs, the output voltage for the unit that shades can decline automatically, and the output voltage for the unit that do not shade can be certainly
It is dynamic to rise.By observation it is found that the output voltage for the unit that do not shade can rise to a particular value and keep in this voltage value
Stable operation.The intensity of illumination for changing shading unit, can measure the size of this particular value under different illumination.
When testing photovoltaic panel characteristic, change intensity of illumination, from 250W/m2Change to 1000W/m2.When intensity of illumination is
750W/m2When, photovoltaic panel output power is maximum, and the output power of photovoltaic panel can all be reduced by increasing or reduce intensity of illumination.Cause
Corresponding voltage is V under this intensity of illuminationmax, corresponding electric current is Imax.This point is denoted as maximum power point Pmax(Im,Vm)。
The intensity of illumination for changing shading unit, from 250W/m2Change to 750W/m2, obtain the output of one group of unit that do not shade
Voltage particular value, by fitting it is found that it is (- 4I that these particular values, which are distributed in a center of circle,m,Vm), radius is 5ImFeature
On circle, shown in matched curve such as Fig. 6 (a), what abscissa indicated is electric current, and what ordinate indicated is voltage.
When part shading occurs, the voltage for the unit that do not shade is all a definite value, therefore calculates the output voltage of OPPT
It is exactly the power supply output reference voltage for calculating shading unit.As shown in Fig. 6 (b), when part shading occurs, the electricity for the unit that do not shade
Pressure rises to B point, and due to current-clamp, the voltage for the unit that shades at this time can only be in the straight line parallel with y-axisUpper variation.For
Keep selected voltage value and Pmax(Im,Vm) characteristic close, introduce COS distance: connection origin O and Pmax(Im,Vm) simultaneously
Point A is met at circle, thenWithIntersection point be point C.The COS distance of point C and point A is 1, i.e. the COS distance of point B and point C
Cos ∠ BOC and point B is equal with point A distance cos ∠ BOA.The point C is the output voltage reference value of required shading unit.
The voltage reference value of each unit is added up, the output voltage minimum of as OPPT.When the part that equal extent occurs
When shading, system will be in the minimum stable operation of OPPT output voltage.When different degrees of part shading occurs, according to institute
Current value is surveyed,Middle corresponding selection voltage value.Particularly, since the minimum of OPPT output voltage must not be lower than inverter
DC voltage minimum, therefore when OPPT minimum is excessively small, it will require run according to inverter direct-flow side minimum voltage.
By simulating, verifying, it was demonstrated that when part shading occurs for a certain unit, according to the selected reference of rule described in Fig. 6 (b)
Voltage, system can stable operations.The method of selected reference voltage is not unique, determines shading elements reference electricity by COS distance
Pressure is one of method the most simple and feasible.
Control effect is to provide a total reference as shown in fig. 7, reference value for the four concatenation units output voltage
Value.It averagely arrives after every level-one as predicted value shown in Fig. 7 (a) and 7 (b).In Fig. 7 (a), the photovoltaic voltage for the unit that shades is sharply
Decline, in Fig. 7 (b), the voltage for the unit that do not shade rises, and changing rule follows Fig. 5.To guarantee voltage inverter DC side
Voltage stabilization, need to control the electric power output voltage in unit, choose suitable working voltage.Although at this time not
The unit that shades is not the maximum power point operated under traditional sense, but its output power can't be reduced too much, but also
It is able to maintain the power-balance of each concatenation unit.
When illuminance abrupt variation, the voltage and current changing rule of grid side is as shown in Figure 8.Grid side voltage is not substantially by shadow
It rings, electric current can change steadily, until reaching new stationary value.In practice, illumination is continuous and slowly varying, therefore system
The impact being subject to is smaller, and change procedure can be more stable.
When the power supply power supply imbalance of each unit, although ill operation, filtering when because of inversion can be eliminated
Inductive discharge bring due to voltage spikes in device.When being that part shading occurs for a certain unit shown in Fig. 9 (a), inverter output electricity
It is compacted measured value, is inverter output voltage measured value under normal illumination shown in Fig. 9 (b).It can be seen that the voltage of Fig. 9 (a) does not have
There is spike.It can be considered to increase level-one lower wattage power supply to eliminate spike.
In conclusion prime cascaded switch pipe in the present invention --- diode transformer is connected with rear class inverter circuit,
The more level staircase waveforms that can realize near sinusoidal well, simplify the complexity of power cell system topological structure, dispersion
A large amount of series-parallel, the appearance of reduction power multi-peak of photovoltaic panel, reduction search number.It is sent out in the present invention by seeking full unit
The changing rule of voltage and power when the shading of part occurs for raw part shading and a unit, reduces the quantity of MPPT controller,
It is reduced to no matter cascade number is how many by one MPPT controller of level-one, has and only one controller, this improved MPPT
Controller is known as OPPT controller.
S6, total output voltage reference value, the output as OPPT are calculated.
The above embodiment is a preferred embodiment of the present invention, but embodiments of the present invention are not by above-described embodiment
Limitation, other any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present invention,
It should be equivalent substitute mode, be included within the scope of the present invention.
Claims (7)
1. optimal power point-tracking method when a kind of generation part shading grid-connected based on photovoltaic multi-electrical level inverter, feature exist
In the optimal power point-tracking method includes the following steps:
S1, the photo-voltaic power supply output voltage v for acquiring each concatenation unitpvnWith output electric current ipvn；
S2, the total output power of photo-voltaic power supply is calculatedWherein N indicates the quantity of concatenation unit；
S3, judge whether to shade, if do not shaded, determine reference voltage variation range, pass through MPPT control method
Maximum power point is searched for as optimal solution；
S4, if it happens shade, judge whether each concatenation unit shading degree is identical, if shading degree is identical, passes through
MPPT control method searches for maximum power point as optimal solution；
If S5, shading degree are different, that is, unbalanced part shading occurs, only considers that one and only one unit hides
Yin finds the value in characteristic circle, constant by COS distance, finds the corresponding output voltage reference value of shading unit；
S6, total output voltage reference value, the output as OPPT are calculated.
2. it is according to claim 1 based on photovoltaic multi-electrical level inverter it is grid-connected generation part shading when optimal power point with
Track method, which is characterized in that the step S2 includes:
S201, it is pre-processed according to voltage and current serial data of the sampling density to the photo-voltaic power supply of acquisition, selects suitable size
Window divide serial data；
S202, the value that most representational data are used to represent the period is filtered out in each wicket.
3. it is according to claim 1 based on photovoltaic multi-electrical level inverter it is grid-connected generation part shading when optimal power point with
Track method, which is characterized in that the method for filtering out most representational data in each wicket in the step S202
It is as follows:
The median of selected window or the average value of selected window are used as most representational data.
4. it is according to claim 1 based on photovoltaic multi-electrical level inverter it is grid-connected generation part shading when optimal power point with
Track method, which is characterized in that the step S3 includes:
S301, determine reference voltage variation range, will it is grid-connected needed for minimum inverter voltage as OPPT output voltage lower limit；
S302, the front and back variation for comparing photo-voltaic power supply voltage in basic unit, judge whether to shade；
When part shading occurs for S303, hypothesis, the intensity of illumination of the tandem photovoltaic plate in each concatenation unit is the same, i.e., most
High-power point always only one, based on this it is assumed that changing the shading degree of photo-voltaic power supply in all units, calculateOPPT output voltage limit is determined with MPPT method for searching；
S304, the intensity of illumination by changing simultaneously all basic units are determined under some intensity of illumination, are had maximum defeated
Power out, when intensity of illumination reduces, output power also reduces therewith；When intensity of illumination increases, output power also reduces, this
A maximum power point is denoted as Pm(Im,Vm)。
5. it is according to claim 1 based on photovoltaic multi-electrical level inverter it is grid-connected generation part shading when optimal power point with
Track method, which is characterized in that the step S4 process is as follows:
When the part shading balanced, the photo-voltaic power supply shading situation in each concatenation unit is identical, considers that string is simultaneously in unit
Voltage range where peak value number that the photovoltaic of connection is likely to occur and each peak value, determines maximum work in feasible voltage range
Voltage range where rate point, then searched in the voltage range with MPPT method for searching, the local optimum found is as complete
Office's optimal value.
6. optimal power when generation part shading grid-connected based on photovoltaic multi-electrical level inverter according to claim 4 or 5
Point-tracking method, which is characterized in that the MPPT method for searching is perturbation observation method.
7. it is according to claim 1 based on photovoltaic multi-electrical level inverter it is grid-connected generation part shading when optimal power point with
Track method, which is characterized in that the step S5 includes:
S501, choose a concatenation unit carry out shading experiment, only change its intensity of illumination, and allow other concatenation units all in
Most suitable intensity of illumination；
S502, the intensity of illumination difference according to shading unit, the output voltage of each concatenation unit is also different, and do not shade voltage
Output voltage can rise automatically, and rise to a particular value, and setting intensity of illumination changes step-length, measure corresponding voltage
Value；
S503, the above-mentioned voltage value of fitting, obtain fitting function, this is that a center of circle is C (- NIm,Vm), radius is (N+1) Im
Circle, point Pm(Im,Vm) it is used as maximum power point, it is denoted as reference point, intensity of illumination is defined and is lower than PmCorresponding intensity of illumination is light
It lies prostrate plate and part shading occurs, connect origin O and Pm, straight lineThe as variation range of shading elements reference voltage；
S504, when uneven part shading occurs, find the corresponding point of non-shading cell voltage value on the circle for being C in the center of circle,
It crosses the point and makees straight line parallel in y-axis, withIntersection point be the shading unit output voltage reference value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810716291.2A CN108983861B (en) | 2018-07-03 | 2018-07-03 | Optimal power point tracking method based on local shading of grid-connected photovoltaic multi-level inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810716291.2A CN108983861B (en) | 2018-07-03 | 2018-07-03 | Optimal power point tracking method based on local shading of grid-connected photovoltaic multi-level inverter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108983861A true CN108983861A (en) | 2018-12-11 |
| CN108983861B CN108983861B (en) | 2020-02-18 |
Family
ID=64536544
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810716291.2A Active CN108983861B (en) | 2018-07-03 | 2018-07-03 | Optimal power point tracking method based on local shading of grid-connected photovoltaic multi-level inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108983861B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110502057A (en) * | 2019-07-05 | 2019-11-26 | 北京空间飞行器总体设计部 | A kind of spacecraft solar power adjustment module current equalizing method without current detecting |
| CN110782365A (en) * | 2019-09-26 | 2020-02-11 | 中国神华能源股份有限公司国华电力分公司 | Parameter optimization interval configuration method and device, electronic equipment and storage medium |
| CN114115431A (en) * | 2021-11-30 | 2022-03-01 | 浙江佳乐科仪股份有限公司 | Photovoltaic power generation maximum power tracking method and system |
| CN114142526A (en) * | 2021-12-17 | 2022-03-04 | 深圳市中旭新能源有限公司 | Photovoltaic power generation system with series conversion stage voltage optimization control |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102136734B (en) * | 2010-09-08 | 2013-01-02 | 上海岩芯电子科技有限公司 | Method for tracing maximum power point of photovoltaic miniature grid-connected inverter |
| CN103455081A (en) * | 2013-08-19 | 2013-12-18 | 西安理工大学 | Maximum power point tracking method based on disturbance observation |
| EP3005521A1 (en) * | 2013-05-28 | 2016-04-13 | Alessandro Caraglio | Device and method for optimization of power harvested from solar panels |
| CN106787729A (en) * | 2017-02-08 | 2017-05-31 | 广西大学 | The control system and method for photovoltaic array delivery efficiency are improved under a kind of local shades |
| CN107563489A (en) * | 2017-07-25 | 2018-01-09 | 华南理工大学 | Photovoltaic array powerinjected method method under local shades based on Chaos particle swarm optimization algorithm |
| CN107704012A (en) * | 2017-10-31 | 2018-02-16 | 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 |
-
2018
- 2018-07-03 CN CN201810716291.2A patent/CN108983861B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102136734B (en) * | 2010-09-08 | 2013-01-02 | 上海岩芯电子科技有限公司 | Method for tracing maximum power point of photovoltaic miniature grid-connected inverter |
| EP3005521A1 (en) * | 2013-05-28 | 2016-04-13 | Alessandro Caraglio | Device and method for optimization of power harvested from solar panels |
| CN103455081A (en) * | 2013-08-19 | 2013-12-18 | 西安理工大学 | Maximum power point tracking method based on disturbance observation |
| CN106787729A (en) * | 2017-02-08 | 2017-05-31 | 广西大学 | The control system and method for photovoltaic array delivery efficiency are improved under a kind of local shades |
| CN107563489A (en) * | 2017-07-25 | 2018-01-09 | 华南理工大学 | Photovoltaic array powerinjected method method under local shades based on Chaos particle swarm optimization algorithm |
| CN107704012A (en) * | 2017-10-31 | 2018-02-16 | 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 |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110502057A (en) * | 2019-07-05 | 2019-11-26 | 北京空间飞行器总体设计部 | A kind of spacecraft solar power adjustment module current equalizing method without current detecting |
| CN110782365A (en) * | 2019-09-26 | 2020-02-11 | 中国神华能源股份有限公司国华电力分公司 | Parameter optimization interval configuration method and device, electronic equipment and storage medium |
| CN114115431A (en) * | 2021-11-30 | 2022-03-01 | 浙江佳乐科仪股份有限公司 | Photovoltaic power generation maximum power tracking method and system |
| CN114115431B (en) * | 2021-11-30 | 2023-05-30 | 浙江佳乐科仪股份有限公司 | Photovoltaic power generation maximum power tracking method and system |
| CN114142526A (en) * | 2021-12-17 | 2022-03-04 | 深圳市中旭新能源有限公司 | Photovoltaic power generation system with series conversion stage voltage optimization control |
| CN114142526B (en) * | 2021-12-17 | 2024-05-07 | 深圳市中旭新能源有限公司 | Photovoltaic power generation system with series conversion stage voltage optimized control |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108983861B (en) | 2020-02-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108983861A (en) | Optimal power point-tracking method when generation part shading grid-connected based on photovoltaic multi-electrical level inverter | |
| Jeon et al. | Least power point tracking method for photovoltaic differential power processing systems | |
| Radjai et al. | Implementation of a modified incremental conductance MPPT algorithm with direct control based on a fuzzy duty cycle change estimator using dSPACE | |
| Mohammed et al. | A novel hybrid maximum power point tracking technique using perturb & observe algorithm and learning automata for solar PV system | |
| Du et al. | A novel solar panel optimizer with self-compensation for partial shadow condition | |
| US9142960B2 (en) | Constraint weighted regulation of DC/DC converters | |
| Hossain et al. | Design and implementation of MPPT controlled grid connected photovoltaic system | |
| WO2011082184A2 (en) | Power point tracking | |
| CN104953945B (en) | High efficiency photovoltaic generating system and electricity-generating method | |
| Tsao et al. | Distributed max power point tracking for photovoltaic arrays | |
| Pathak et al. | Reduced oscillations based perturb and observe solar maximum power point tracking scheme to enhance efficacy and speed of a photovoltaic system | |
| Radjai et al. | The new FLC-variable incremental conductance MPPT with direct control method using Cuk converter | |
| Ali et al. | Optimization of PV model using fuzzy-neural network for DC-DC converter systems | |
| KR20210125834A (en) | Differential Power Processor for Improving Performance of Photovoltaic Systems with Multiple Photovoltaic Modules Connected in Series and power control apparatus using the same | |
| KR102599736B1 (en) | Differential power processing unit with state of health and by-pass circuit for the serial connected pv module | |
| Salam et al. | Partial shading in building integrated PV system: Causes, effects and mitigating techniques | |
| Tsang et al. | PLL-less single stage grid-connected photovoltaic inverter with rapid maximum power point tracking | |
| CN116882105A (en) | Method for analyzing boundaries of power supply modes of large-scale photovoltaic access AC/DC power distribution network | |
| Radjai et al. | Fuzzy logic variable step of p&o MPPT with direct control method using cuk converter | |
| CN106300327B (en) | A kind of topological structure and control method that distribution MPPT and centralization MPPT is changeable | |
| CN108988379A (en) | Based on the grid-connected varying index novel Integration Reset Control strategy method of photovoltaic multi-electrical level inverter | |
| Kanakasabapathy | Multistring seven-level inverter for standalone photovoltaic systems | |
| Wang et al. | Dynamic characteristics analysis of distributed PV plants with panel-level DC optimizers under severe partial shading conditions | |
| KR20210142217A (en) | Power control method to minimize loss of Power Conditioning System | |
| CN105227045A (en) | A kind of Optimization Design of photovoltaic DMPPT system maximal power tracing region |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CB03 | Change of inventor or designer information | ||
| CB03 | Change of inventor or designer information |
Inventor after: Wu Qinghua Inventor after: Lin Biyuan Inventor after: Wang Lei Inventor before: Wu Qinghua Inventor before: Lin Biyuan Inventor before: Wang Lei |