CN103176500B - Maximum power tracking method for solar cell - Google Patents
Maximum power tracking method for solar cell Download PDFInfo
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- CN103176500B CN103176500B CN201110442395.7A CN201110442395A CN103176500B CN 103176500 B CN103176500 B CN 103176500B CN 201110442395 A CN201110442395 A CN 201110442395A CN 103176500 B CN103176500 B CN 103176500B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention provides a maximum power tracking method for a solar cell. The maximum power tracking method for the solar cell comprises the following steps. A system is initialized, and an initial value of variable quantity is set. At the moment of K, an output voltage UK and an output current IK are detected, and an error value I_errorK of a current loop is calculated. Output power is PK, and an output power difference value is delta P. An output current set value Iref (K) enabling the delta P to meet the requirement of an error is obtained based on a current I_max1 which is closest to the maximum current value of the system, and the set value Iref (K) is the maximum current I_max that the system can output. The maximum power tracking method for the solar cell and a controller loop are combined closely so that charging of a rear end storage cell is effectively managed, and therefore the maximum power point of a system level can be rapidly tracked in time.
Description
Technical field
The present invention relates to solar cell control technology field, particularly a kind of by a kind of maximum power tracking method that solar power is followed the tracks of and controller efficiency combines.
Background technology
Independently solar power system is generally made up of solar cell, controller (charger), accumulator, distribution system, at present, it is substantially all by sampling solar cell output voltage, electric current that solar maximum power is followed the tracks of, by the maximal power tracing that data processing directly controls the voltage of the pulsewidth of controller or solar cell, electric current realizes sun power, but also have minority be sampling solar cell input voltage, electric current, control controller output current by process, realize maximal power tracing.But there is following defect in these schemes: 1, solar cell exports the tracking of control realization solar maximum power, the peak power of solar cell can be obtained, but be not the peak power of whole solar power system, because do not consider the nonlinear problem of the efficiency of controller itself; 2, the maximal power tracing strategy that current controller for solar adopts, do not have to integrate with the loop control strategy of controller itself, the Charge Management for rear end accumulator is conflicting, effectively can not realize the Charge Management of battery science.
Summary of the invention
The present invention is intended at least solve the technical matters existed in prior art, especially innovatively proposes a kind of solar cell maximum power tracking method.
In order to realize above-mentioned purpose of the present invention, the invention provides a kind of solar cell maximum power tracking method, it comprises the steps:
S1: initialization system, the initial value of setting variable, described variable comprises output current large disturbances amount Δ I_big, output current microvariations amount Δ I_small, power stability scope ε, current error minimal value ε 1, current error maximum value ε 2, tracking direction DirFlag;
S2: in the K moment, the output voltage U of detection control device
kwith the output current I of controller
k, calculate the error amount I_error of current flow loop
k=Iref
k-I
k, described Iref
kfor output current set-point, calculate current output power P
k=U
k× I
k, output power difference DELTA P=P
k-P
k-1;
S3: if | I_error
k| < ε 1, then get Iref
k+1=Iref
k+ Δ I_big, makes K=K+1, returns step S2, if ε is 1<|I_error
k| < ε 2, makes K=K+1, returns step S2, if | I_error
k| > ε 2, then the immediate value I_max1 of the maximum current I_max of system output is I_max1=I_ref
k-1, system enters step S4;
S4: output current set-point Iref
k=Iref
k-1+ Δ I_small × DirFlag;
S5: if Δ P> is ε, gets DirFlag=1, make K=K+1, return step S4; If Δ P<0 and | Δ P|> ε, get DirFlag=-1, make K=K+1, return step S4; If | Δ P|< ε, gets DirFlag=0, exits.According to another embodiment of the invention, solar cell maximum power tracking method of the present invention comprises the steps:
S1: initialization system, the initial value of setting variable, described variable comprises output voltage large disturbances amount Δ U_big, output voltage microvariations amount Δ U_small, power stability scope ε, voltage error minimal value ε 1, voltage error maximum value ε 2, tracking direction DirFlag;
S2: in the K moment, the output voltage U of detection control device
kwith the output current I of controller
k, calculate the error amount U_error of current voltage loop
k=Uref
k-U
k, described Uref
kfor output voltage set-point, calculate current output power P
k=U
k× I
k, output power difference DELTA P=P
k-P
k-1;
S3: if | U_error
k| < ε 1, then get Uref
k+1=Uref
k+ Δ U_big, makes K=K+1, returns step S2, if ε is 1<|U_error
k| < ε 2, makes K=K+1, returns step S2, if | U_error
k| > ε 2, then the immediate value U_max1 of the maximum voltage u_max of system output is U_max1=U_ref
k-1, system enters step S4;
S4: output voltage set-point Uref
k=Uref
k-1+ Δ U_small × DirFlag;
S5: if Δ P> is ε, gets DirFlag=1, make K=K+1, return step S4; If Δ P<0 and | Δ P|> ε, get DirFlag=-1, make K=K+1, return step S4; If | Δ P|< ε, gets DirFlag=0, exits.
The present invention proposes a kind of new MPPT (Maximum Power Point Tracking, MPPT maximum power point tracking) method realizes the energy utilization rate of solar energy photovoltaic system optimum, and the method and controller loop combine closely, the effective Charge Management having managed rear end accumulator, also solve the local peak power stable problem of current maximum power tracking method as fixed step size method, variable step disturbance observation simultaneously, system-level maximum power point can be traced in time, fast.
The present invention considers and a kind of maximized method of Energy harvesting of proposition for the system of solar cell, controller, accumulator composition.Its energy in conjunction with solar cell and the transformation efficiency of controller, by controlling the output current of controller, namely output current adopts segmentation step length changing method to find the maximum point of controller output power, or by controlling the output voltage of controller, namely output voltage adopts segmentation step length changing method to find the maximum point of controller output power, but not the maximum power point that the searching solar cell generally adopted at present exports, the method considers the transformation efficiency of controller itself, system-level maximizes power can be obtained, and the loop that control strategy can take into account self controls, and the battery charging management of rear end.This method from system integration angle give a kind of completely newly, more reasonably maximal power tracing mode, obtain the maximum power point on systemic hierarchial, and control thought incorporates control strategy and the rear end battery management of controller, makes whole control framework more terse, efficient, reasonable.
Additional aspect of the present invention and advantage will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present invention.
Accompanying drawing explanation
Above-mentioned and/or additional aspect of the present invention and advantage will become obvious and easy understand from accompanying drawing below combining to the description of embodiment, wherein:
Fig. 1 is the process flow diagram of the solar cell maximum power tracking method of the present invention first preferred implementation;
Fig. 2 is the process flow diagram of the solar cell maximum power tracking method of the present invention second preferred implementation.
Embodiment
Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Being exemplary below by the embodiment be described with reference to the drawings, only for explaining the present invention, and can not limitation of the present invention being interpreted as.
Fig. 1 is the process flow diagram of the solar cell maximum power tracking method of the present invention first preferred implementation.As seen from the figure, solar cell maximum power tracking method of the present invention comprises the steps:
The first step: initialization system, the initial value of setting variable, wherein, variable comprises output current large disturbances amount Δ I_big, output current microvariations amount Δ I_small, power stability scope ε, tracking direction DirFlag, current error minimal value ε 1, current error maximum value ε 2;
Second step: in the K moment, the output voltage U of detection control device
kwith the output current I of controller
k, calculate the error amount I_error of current flow loop
k=Iref
k-I
k, described Iref
kfor output current set-point, calculate current output power P
k=U
k× I
k, with current output power P
kdeduct the power P of previous moment
k-1, draw output power difference DELTA P=P
k-P
k-1;
3rd step: if | I_error
k| < ε 1, illustrates that current loop is stable, and current reference can also continue to add, then give output current set-point Iref
kincrease the given value of current value of an output current large disturbances amount Δ I_big as the K+1 moment, system returns second step, if ε is 1<|I_error
k| < ε 2, makes K=K+1, and system returns second step, if | I_error
k| > ε 2, illustrate that current loop is unstable, photovoltaic cell can not export so large electric current, and namely current reference cannot continue to add, and the maximum current I_max that this system can export is at I_max1=I_ref
k-1near, system enters the 4th step;
4th step: to given value of current value Iref
kincrease an output current microvariations amount Δ I_small, i.e. Iref
k=Iref
k-1+ Δ I_small × DirFlag, enters the 5th step;
5th step: if Δ P> is ε, illustrate that output power becomes large, the given value of current value in K+1 moment can also increase, and tracking direction is constant, DirFlag=1, makes K=K+1, returns the 4th step; If Δ P<0 and | Δ P|> ε, illustrates that output power diminishes, and the given value of current value in K+1 moment needs to reduce, and tracking direction needs oppositely to change, and DirFlag=-1, makes K=K+1, returns the 4th step; If | Δ P|< ε, illustrates that output power is substantially constant, and the given value of current value in K+1 moment does not need to change yet, and do not need to continue to follow the tracks of, DirFlag=0, program exits, this given value of current value Iref
knamely be the maximum current I_max that system can export.
In the present embodiment, each time interval T, again look for a maximum current point I_max, the scope of this time interval T is 1 minute-10 minutes, and in a kind of embodiment be more preferably, time interval T is 5 minutes.In the present embodiment, the time interval in K moment and K+1 moment is 50ms to 200ms.
As shown in Figure 1, as DirFlag=0, program can not exit, but each time interval T, again looking for a maximum current point I_max, when not needing to find peak power, quitting a program.
Fig. 2 is the process flow diagram of the solar cell maximum power tracking method of the present invention second preferred implementation.As seen from the figure, solar cell maximum power tracking method of the present invention comprises the steps:
The first step: initialization system, the initial value of setting variable, wherein, variable comprises output voltage large disturbances amount Δ U_big, output voltage microvariations amount Δ U_small, power stability scope ε, tracking direction DirFlag, voltage error minimal value ε 1, voltage error maximum value ε 2;
Second step: in the K moment, the output voltage U of detection control device
kwith the output current I of controller
k, calculate the error amount U_error of current voltage loop
k=Uref
k-I
k, described Uref
kfor output voltage set-point, calculate current output power P
k=U
k× I
k, with current output power P
kdeduct the power P of previous moment
k-1, draw output power difference DELTA P=P
k-P
k-1;
3rd step: if | U_error
k| < ε 1, illustrates that current loop is stable, and voltage reference can also continue to add, then give output voltage set-point Uref
kincrease the voltage given value of an output voltage large disturbances amount Δ U_big as the K+1 moment, system returns second step, if ε is 1<|U_error
k| < ε 2, makes K=K+1, and system returns second step, if | U_error
k| > ε 2, account for voltage loop is unstable, and photovoltaic cell can not export so large voltage, and namely voltage reference cannot continue to add, and the maximum voltage that this system can export is at U_max1=U_ref
k-1near, system enters the 4th step;
4th step: to voltage given value Uref
kincrease an output voltage microvariations amount Δ U_small, i.e. Uref
k=Uref
k-1+ Δ U_small × DirFlag, enters the 5th step;
5th step: if Δ P> is ε, illustrate that output power becomes large, the voltage given value in K+1 moment can also increase, and tracking direction is constant, DirFlag=1, makes K=K+1, returns the 4th step; If Δ P<0 and | Δ P|> ε, illustrates that output power diminishes, and the voltage given value in K+1 moment needs to reduce, and tracking direction needs oppositely to change, and DirFlag=-1, makes K=K+1, returns the 4th step; If | Δ P|< ε, illustrates that output power is substantially constant, and the voltage given value in K+1 moment does not need to change yet, and do not need to continue to follow the tracks of, DirFlag=0, program exits, this voltage given value Uref
knamely be the maximum voltage U_max that system can export.
In the present embodiment, each time interval T, looks for a maximum voltage point U_max again, and the scope of this time interval T is 1 minute-10 minutes, and in a kind of embodiment be more preferably, time interval T is 5 minutes.In the present embodiment, the time interval in K moment and K+1 moment is 50ms to 200ms.
As shown in Figure 1, as DirFlag=0, program can not exit, but each time interval T, again looking for a maximum voltage point U_max, when not needing to find peak power, quitting a program.
Control with the loop of controller self compatible mutually while the present invention finds solar cell peak power by adjustment control output current or adjustment control output voltage, effectively combine external characteristics and the battery management of controller.
Control of the present invention can pass through microprocessor DSP, MCU, and the digitizing energy supply control module that specialized simulation chip realizes realizes, and particular hardware comprises photovoltaic cell, DC/DC controller, accumulator, distribution system, monitoring module.
The present invention integrates front end solar cell, rear end accumulator, and by digital control chip DSP, MCU, specialized simulation chip, achieves maximal power tracing, loop controls, the control of the science of battery management.
In the description of this instructions, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, identical embodiment or example are not necessarily referred to the schematic representation of above-mentioned term.And the specific features of description, structure, material or feature can combine in an appropriate manner in any one or more embodiment or example.
Although illustrate and describe embodiments of the invention, those having ordinary skill in the art will appreciate that: can carry out multiple change, amendment, replacement and modification to these embodiments when not departing from principle of the present invention and aim, scope of the present invention is by claim and equivalents thereof.
Claims (7)
1. a solar cell maximum power tracking method, is characterized in that, comprises the steps:
S1: initialization system, the initial value of setting variable, described variable comprises output current large disturbances amount Δ I_big, output current microvariations amount Δ I_small, power stability scope ε, current error minimal value ε 1, current error maximum value ε 2, tracking direction DirFlag;
S2: in the K moment, the output voltage U of detection control device
kwith the output current I of controller
k, calculate the error amount I_error of current flow loop
k=Iref
k-I
k, described Iref
kfor output current set-point, calculate current output power P
k=U
k× I
k, output power difference DELTA P=P
k-P
k-1;
S3: if | I_error
k| < ε 1, then get Iref
k+1=Iref
k+ Δ I_big, makes K=K+1, returns step S2, if ε 1 is < | I_error
k| < ε 2, makes K=K+1, returns step S2, if | I_error
k| > ε 2, then the immediate value I_max1 of the maximum current I_max of system output is I_max1=I_ref
k-1, system enters step S4;
S4: output current set-point Iref
k=Iref
k-1+ Δ I_small × DirFlag;
S5: if Δ P > is ε, gets DirFlag=1, make K=K+1, return step S4; If Δ P < 0 and | Δ P| > ε, get DirFlag=-1, make K=K+1, return step S4; If | Δ P| < ε, gets DirFlag=0, exits.
2. solar cell maximum power tracking method as claimed in claim 1, is characterized in that, each time interval T, again looks for a maximum current point I_max.
3. a solar cell maximum power tracking method, is characterized in that, comprises the steps:
S1: initialization system, the initial value of setting variable, described variable comprises output voltage large disturbances amount Δ U_big, output voltage microvariations amount Δ U_small, power stability scope ε, voltage error minimal value ε 1, voltage error maximum value ε 2, tracking direction DirFlag;
S2: in the K moment, the output voltage U of detection control device
kwith the output current I of controller
k, calculate the error amount U_error of current voltage loop
k=Uref
k-U
k, described Uref
kfor output voltage set-point, calculate current output power P
k=U
k× I
k, output power difference DELTA P=P
k-P
k-1;
S3: if | U_error
k| < ε 1, then get Uref
k+1=Uref
k+ Δ U_big, makes K=K+1, returns step S2, if ε 1 is < | U_error
k| < ε 2, makes K=K+1, returns step S2, if | U_error
k| > ε 2, then the immediate value U_max1 of the maximum voltage U_max of system output is U_max1=U_ref
k-1, system enters step S4;
S4: output voltage set-point Uref
k=Uref
k-1+ Δ U_small × DirFlag;
S5: if Δ P > is ε, gets DirFlag=1, make K=K+1, return step S4; If Δ P < 0 and | Δ P| > ε, get DirFlag=-1, make K=K+1, return step S4; If | Δ P| < ε, gets DirFlag=0, exits.
4. solar cell maximum power tracking method as claimed in claim 3, is characterized in that each time interval T looks for a maximum voltage point U_max again.
5. the solar cell maximum power tracking method as described in claim 2 or 4, is characterized in that, the scope of described time interval T is 1 minute-10 minutes.
6. solar cell maximum power tracking method as claimed in claim 5, it is characterized in that, described time interval T is 5 minutes.
7. solar cell maximum power tracking method as claimed in claim 1 or 2, it is characterized in that, the time interval in described K moment and K+1 moment is 50ms to 200ms.
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| CN103929054A (en) * | 2013-10-29 | 2014-07-16 | 张家港智电柔性输配电技术研究所有限公司 | Soft starting method for photovoltaic grid-connected inverter |
| CN104393638B (en) * | 2014-11-12 | 2017-06-23 | 厦门拓宝科技有限公司 | The realization method and system of battery charging current optimal value in off-grid charging system |
| CN106340879A (en) * | 2016-10-27 | 2017-01-18 | 沈阳建筑大学 | Novel single-phase parallel type active power filter |
| CN112240952A (en) * | 2019-10-24 | 2021-01-19 | 北京新能源汽车技术创新中心有限公司 | Power testing method, system, computer device and storage medium |
| CN113291173A (en) * | 2021-07-02 | 2021-08-24 | 西安特锐德智能充电科技有限公司 | Charging device, method and system |
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| EP1521345A1 (en) * | 1996-08-30 | 2005-04-06 | Canon Kabushiki Kaisha | Power control apparatus for solar power generation system |
| CN101630171A (en) * | 2009-08-05 | 2010-01-20 | 华南理工大学 | Segmentation self-adapting hill climbing method and system applied for tracing maximum power of photovoltaic cell |
| CN201854045U (en) * | 2010-08-31 | 2011-06-01 | 佛山市顺德区瑞德电子实业有限公司 | Solar charging/discharging control circuit with maximum power point tracking structure |
| CN102111088A (en) * | 2010-11-24 | 2011-06-29 | 广东工业大学 | Photovoltaic power generation control system |
| CN102291050A (en) * | 2011-08-17 | 2011-12-21 | 华北电力大学（保定） | Maximum power point tracking method and device for photovoltaic power generation system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100132757A1 (en) * | 2008-12-01 | 2010-06-03 | Chung Yuan Christian University | Solar energy system |
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| EP1521345A1 (en) * | 1996-08-30 | 2005-04-06 | Canon Kabushiki Kaisha | Power control apparatus for solar power generation system |
| CN101630171A (en) * | 2009-08-05 | 2010-01-20 | 华南理工大学 | Segmentation self-adapting hill climbing method and system applied for tracing maximum power of photovoltaic cell |
| CN201854045U (en) * | 2010-08-31 | 2011-06-01 | 佛山市顺德区瑞德电子实业有限公司 | Solar charging/discharging control circuit with maximum power point tracking structure |
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