CN102315799A - DSP-based MPPT control method of solar energy photovoltaic grid-connected inverter - Google Patents

DSP-based MPPT control method of solar energy photovoltaic grid-connected inverter Download PDF

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Publication number
CN102315799A
CN102315799A CN201110215368A CN201110215368A CN102315799A CN 102315799 A CN102315799 A CN 102315799A CN 201110215368 A CN201110215368 A CN 201110215368A CN 201110215368 A CN201110215368 A CN 201110215368A CN 102315799 A CN102315799 A CN 102315799A
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China
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voltage
current
dsp
mppt
control
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CN201110215368A
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Chinese (zh)
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王久学
张卫强
蒋金涛
胡建平
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宁波大学
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Publication of CN102315799A publication Critical patent/CN102315799A/en

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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion systems, e.g. maximum power point trackers

Abstract

The invention relates to a digital signal processor (DSP)-based maximum power point tracking (MPPT) control method of a solar energy photovoltaic grid-connected inverter. The method is realized by a hardware portion and a software portion, wherein the hardware portion and the software portion contain a voltage sampling circuit and a current sampling circuit. Besides, the method is characterized in that: the voltage sampling circuit and the current sampling circuit are respectively corresponded to a preset charging voltage and a preset charging current of a sampling storage battery; an obtained voltage value and an obtained current value are input into a pin of a controller and are provided for usage of a program algorithm; a disturbance step length of each time is changed by the program algorithm to control an output power of a solar energy photovoltaic array; it is needed for MPPT to carrying out sampling on the preset charging voltage and the preset current of the storage battery timely and accurately; the preset charging voltage is multiplied by the preset current to obtain a preset charging power; on the basis of comparison between the preset charging power and a charging power of a front time, a duty ratio of PWM is adjusted, so that a photovoltaic battery always works with a maximum power point. The method has advantages of simple structure, few detected parameters, fast speed, and high accuracy and the like. Besides, an output power of an array is tended to be maximum by continuous disturbance, so that the solar energy can be utilized to the greatest extent.

Description

MPPT control method based on the solar photovoltaic interconnected inverter of DSP
 
Technical field
The invention belongs to grid-connected power generation system control technology field, specifically, relate to MPPT control method based on the solar photovoltaic interconnected inverter of DSP.
Background technology
Solar energy is a kind of regenerative resource of clean and effective, and in recent years, solar energy power generating becomes an emerging energy industry and develops rapidly.In solar grid-connected technical field of power generation; Usually the direct current power that needs to use solar photovoltaic interconnected inverter that each photovoltaic module of solar cell is sent convert to and electrical network with the output AC electric power of homophase frequently, also to realize each photovoltaic module is carried out the optimization of electric power output simultaneously.But photovoltaic cell is a non-linear power, and its output voltage and electric current not only receive light intensity and Influence of Temperature, and is determined by the character and the situation of load.The power output of photovoltaic cell is constantly to change like this, if the working point is in the maximum power point place, the electric energy that it produced just is fully utilized, and on the contrary, the efficient of whole solar photovoltaic grid-connection system just reduces, and causes the waste of resource.If can make the solar cell photovoltaic array when extraneous environment change, can also be in maximum power point constantly, so just can utilize solar energy to greatest extent.
Traditional solar inverter maximum power control method is " a voltage disturbance method ".The voltage disturbance ratio juris is that through the power output of this photovoltaic arrays and power ratio last time confirming to increase still is to reduce the photovoltaic cell operating voltage.If power increases, photovoltaic cell voltage is kept original voltage disturbance direction; Power reduces, and voltage is disturbance round about then.Disturbance, observation and comparison through repeatedly make the photovoltaic cell power output arrive the maximum power point place, realize MPPT.But there is defective in this method, i.e. the step-length of disturbance is immutable.When step-length is provided with when long, just be difficult to arrive accurately maximum power point; When too short, the time that arrives maximum power point is oversize, and this has reduced the efficient of system equally.
Summary of the invention
The present invention's purpose is the defective that overcomes traditional solar inverter maximum power control method, on the basis of original " voltage disturbance method ", improves, and proposes the MPPT control method based on the solar photovoltaic interconnected inverter of DSP.
The technical scheme that the present invention solves the problems of the technologies described above is: based on the MPPT control method of the solar photovoltaic interconnected inverter of DSP; It realizes hardware components and software section through comprising voltage sampling circuit and current sampling circuit; Wherein: current charging voltage and the charging current of the corresponding respectively sampling storage battery of described voltage sampling circuit and current sampling circuit; In the pin with the voltage and current value input controller that obtains; Offer programmed algorithm and use, change disturbance step-length each time, control photovoltaic array output power through programmed algorithm; Described MPPT need sample timely and accurately storage battery current charging voltage and charging current; Both multiply each other and obtain current charge power; Compare with the charge power of previous moment, regulate the duty ratio of PWM, make photovoltaic cell always work in maximum power point.
MPPT control method based on the solar photovoltaic interconnected inverter of DSP; It is characterized in that: the hardware components of described MPPT; Microcontroller adopts the MC68HC08SR12 microprocessor; Use the output current and the output voltage of A/D module samples power supply, regulate the PWM duty ratio then, finally realize the maximum power output of photovoltaic cell.
MPPT control method based on the solar photovoltaic interconnected inverter of DSP is characterized in that: described voltage collection circuit, adopt optocoupler PC817 and three-terminal voltage-stabilizing pipe TLA31 to match.TLA3l is a kind of voltage-stabiliser tube able to programme, and when the secondary output voltage Uout of transformer changed, the output voltage of optocoupler changed thereupon, and A/D can sample current charging voltage.
MPPT control method based on the solar photovoltaic interconnected inverter of DSP; It is characterized in that: described current acquisition circuit; Voltage to sampling resistor Rsam two ends is sampled; And use the amplification of differential type operational amplifier to output to the A/D sampling end of MCU, thereby obtain the current value in the main circuit.Because signal demand is accurately sampled, and and isolated from power, linear optical coupling HCNR200 therefore used.In addition, the electricity consumption of single-chip microcomputer and peripheral circuit can be directly isolated transformation through storage battery and obtained, and system need not external power source, and is very convenient.
MPPT control method based on the solar photovoltaic interconnected inverter of DSP is characterized in that: described software section, and it is adjustable producing the time interval of interrupting, the initial stage is shorter, can approach maximum power point rapidly; Later stage is longer, and anti-locking system vibrates near maximum power point.Disconnected for anti-locking system erroneous judgement, each control ratio all carries out 3 times, when 3 times results are consistent, just implements corresponding control strategies, otherwise resampling relatively.
MPPT control method based on the solar photovoltaic interconnected inverter of DSP is characterized in that realizing that the software flow of MPPT is following:
At first make photovoltaic array work in a certain definite magnitude of voltage, disturbed sun cell output voltage value (UPV+Δ U1) then, the variation of measuring power output is again compared with the performance number before the disturbance.If output power value increases, represent that then perturbation direction is correct, can to same direction with+Δ U2 is step-length disturbance again; By that analogy; When just beginning, the desirable a little bigger value of disturbance step-length is in more and more near maximum power point; Can be suitable reduce the disturbance step-length, come to reach accurately the maximum power point place; If the performance number after the disturbance reduces, then to coming near maximum power point with different disturbance step-lengths in the other direction.
The beneficial effect of foregoing invention scheme is:
1, this new MPPT control method is improved tradition " voltage disturbance method ", through algorithm routine adjustment disturbance step-length, reaches the solar energy photovoltaic array maximum power point under the environment at this moment sooner more accurately; This method has simple in structure; Measured parameter is few, and speed is fast, numerous advantages such as accuracy height.
2, through adjusting at interval the break period to Control Parameter sampling, and each controlling of sampling relatively carries out 3 times, guaranteed the precision of control, realizes maximum using solar energy.
3, the electricity consumption of single-chip microcomputer and peripheral circuit can be directly isolated transformation through storage battery and obtained, and system need not external power source, and is very convenient.
Description of drawings
Fig. 1 is the control circuit principle of MPPT;
Fig. 2 is a voltage collection circuit schematic diagram provided by the invention;
Fig. 3 is current acquisition circuit theory diagrams provided by the invention;
Fig. 4 is a software control flow chart provided by the invention.
Embodiment
Below in conjunction with accompanying drawing and embodiment the MPPT control method of the solar photovoltaic interconnected inverter that the present invention is based on DSP is carried out detailed explanation.
DSP (digital signal processor) is a kind of microprocessor of uniqueness, is the device of handling bulk information with digital signal.Its operation principle is to receive analog signal, converts 0 or 1 digital signal into.Again digital signal is made amendment, deletes, strengthened, and in the other system chip, return analogue data or actual environment form to the numerical data decipher.It is not only programmable, and the speed of service can reach the per second number with ten million bar complicated order program in fact the time, considerably beyond general purpose microprocessor, is the computer chip that becomes more and more important in the digitalized electron world.Its powerful data-handling capacity and the high speed of service are two the most commendable big characteristics.
The full name of MPPT controller " MPPT maximum power point tracking " (Maximum Power Point Tracking; Be called for short MPPT) so-called MPPT maximum power point tracking; Promptly be meant the generating voltage that controller can the detecting real-time solar panels; And follow the trail of ceiling voltage current value (VI), make system with the highest efficient to charge in batteries.The MPPT control system is a kind of operating state of logical economize on electricity gas module, makes photovoltaic panel can export the electrical system of more electric energy.Maximum power point mainly receives the influence of ambient temperature and sun light intensity.Under the constant situation of sun light intensity, along with the rising of temperature, the open circuit voltage of photovoltaic cell reduces, and peak power output decreases.When temperature-resistant, when sun light intensity increased, the open circuit voltage of photovoltaic cell was constant basically.Short circuit current significantly increases, and peak power output significantly increases.Because the photovoltaic cell system receives influence of various factors such as light intensity, temperature, angle of incidence of sunlight, among its output voltage U b, output current Ib and internal resistance R also are in and do not stop changing.Have only the dynamic change of using the DC/DC converter to realize load, could guarantee photovoltaic cell Maximum Power Output all the time.
MPPT need sample timely and accurately storage battery current charging voltage and charging current.Both multiply each other and obtain current charge power, compare with the charge power of previous moment, regulate the duty ratio of PWM, make photovoltaic cell always work in maximum power point.The MPPT control circuit is made up of the BOOST booster circuit.Schematic diagram such as Fig. 1.Because the output characteristic of photovoltaic cell is non-linear, and amplitude of variation is bigger, so use the single-ended flyback converter.This converter adds isolating transformer by buck-boost converter deduces, and direct current output can be provided simply efficiently, is widely used in the switchette power supply about power 100W.Controller works in the discontinuous current pattern.Wherein, microcontroller adopts the MC68HC08SR12 microprocessor, uses the output current and the output voltage of A/D module samples power supply, regulates the PWM duty ratio then, finally realizes the maximum power output of photovoltaic cell.Voltage collection circuit is matched by optocoupler PC817 and three-terminal voltage-stabilizing pipe TLA31 and forms.TLA3l is a kind of voltage-stabiliser tube able to programme, and when the secondary output voltage Uout of transformer changed, the output voltage of optocoupler changed thereupon, and A/D can sample current charging voltage.Its circuit diagram such as Fig. 2.Current sampling circuit such as Fig. 3.By it the voltage at sampling resistor Rsam two ends is sampled, and use the amplification of differential type operational amplifier to output to the A/D sampling end of MCU, thereby obtain the current value in the main circuit.Because signal demand is accurately sampled, and and isolated from power, linear optical coupling HCNR200 therefore used.In addition, the electricity consumption of single-chip microcomputer and peripheral circuit can be directly isolated transformation through storage battery and obtained, and system need not external power source, and is very convenient.
Because the variation of sun light intensity and ambient temperature is a process slowly, so parameter sampling need not high real-time, whenever separated several seconds, once sampling can meet the demands.It is adjustable producing the time interval of interrupting, and the initial stage is shorter, can approach maximum power point rapidly; Later stage is longer, and anti-locking system vibrates near maximum power point.Disconnected for anti-locking system erroneous judgement, each control ratio all carries out 3 times, when 3 times results are consistent, just implements corresponding control strategies, otherwise resampling has relatively so just guaranteed the normal operation of system to greatest extent.Fig. 4 illustrates the software flow of realizing MPPT.At first make photovoltaic array work in a certain definite magnitude of voltage, disturbed sun cell output voltage value (UPV+Δ U1) then, the variation of measuring power output is again compared with the performance number before the disturbance.If output power value increases, represent that then perturbation direction is correct, can to same direction with+Δ U2 is step-length disturbance again; By that analogy; When just beginning, the desirable a little bigger value of disturbance step-length is in more and more near maximum power point; Can be suitable reduce the disturbance step-length, come to reach accurately the maximum power point place; If the performance number after the disturbance reduces, then to coming near maximum power point with different disturbance step-lengths in the other direction.

Claims (8)

1. based on the MPPT control method of the solar photovoltaic interconnected inverter of DSP; It realizes hardware components and software section through comprising voltage sampling circuit and current sampling circuit; It is characterized in that: current charging voltage and the charging current of the corresponding respectively sampling storage battery of described voltage sampling circuit and current sampling circuit; In the pin with the voltage and current value input controller that obtains; Offer programmed algorithm and use, change disturbance step-length each time, control photovoltaic array output power through programmed algorithm; Described MPPT need sample timely and accurately storage battery current charging voltage and charging current; Both multiply each other and obtain current charge power; Compare with the charge power of previous moment, regulate the duty ratio of PWM, make photovoltaic cell always work in maximum power point.
2. the MPPT control method of the solar photovoltaic interconnected inverter based on DSP according to claim 1 is characterized in that the software flow of realizing MPPT is:
At first make photovoltaic array work in a certain definite magnitude of voltage;
Disturbed sun cell output voltage value (UPV+Δ U1) then;
Measure the variation of power output again, compare with the performance number before the disturbance; If output power value increases, represent that then perturbation direction is correct, can to same direction with+Δ U2 is step-length disturbance again, by that analogy, if the performance number after the disturbance reduces, then to coming near maximum power point with different disturbance step-lengths in the other direction.
3. the MPPT control method of the solar photovoltaic interconnected inverter based on DSP according to claim 1; It is characterized in that: in the hardware components of described MPPT; Microcontroller adopts the MC68HC08SR12 microprocessor, uses the output current voltage of A/D module samples power supply and regulates the PWM duty ratio.
4. the MPPT control method of the solar photovoltaic interconnected inverter based on DSP according to claim 3 is characterized in that: described voltage collection circuit adopts optocoupler PC817 and three-terminal voltage-stabilizing pipe TLA31 to match.
5. the MPPT control method of the solar photovoltaic interconnected inverter based on DSP according to claim 3, it is characterized in that: described current acquisition circuit is to the voltage sample at sampling resistor Rsam two ends; Use the differential type operational amplifier to amplify the A/D sampling end that outputs to MCU to sampled data, obtain the current value in the main circuit.
6. the MPPT control method of the solar photovoltaic interconnected inverter based on DSP according to claim 5 is characterized in that: described current acquisition circuit uses linear optical coupling HCNR200.
7. the MPPT control method of the solar photovoltaic interconnected inverter based on DSP according to claim 1 is characterized in that: the time interval that described software section Control Parameter sampling is interrupted is adjustable, and the initial stage is shorter, approaches maximum power point rapidly; Later stage is longer, and anti-locking system vibrates near maximum power point.
8. the MPPT control method of the solar photovoltaic interconnected inverter based on DSP according to claim 1 is characterized in that: described software section Control Parameter each control ratio of sampling more all carries out 3 times, and 3 unanimities are as a result then implemented corresponding control.
CN201110215368A 2011-07-29 2011-07-29 DSP-based MPPT control method of solar energy photovoltaic grid-connected inverter CN102315799A (en)

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Cited By (6)

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CN102856960A (en) * 2012-09-25 2013-01-02 广东易事特电源股份有限公司 Simplified storage battery charge MPPT (maximum power point tracking) control circuit
CN103019293A (en) * 2012-11-29 2013-04-03 宁波大学 Maximum power point tracking method for rapidly self-adapting step length of photovoltaic array
CN103296694A (en) * 2013-04-17 2013-09-11 江苏博纬新能源科技有限公司 Multi-channel MPPT link capable of being freely combined and used for photovoltaic grid-connected inverter
ES2421857R1 (en) * 2012-03-02 2013-11-05 Circutor S A "photovoltaic equipment and procedure for controlling such photovoltaic equipment"
CN103441566A (en) * 2013-09-12 2013-12-11 重庆大学 System and method for supplying power cooperatively by mains supply, photovoltaic cell and energy storage battery
CN103592602A (en) * 2012-08-18 2014-02-19 费晓凯 Photovoltaic cell output power sensor

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CN101599724A (en) * 2009-07-24 2009-12-09 中环(中国)工程有限公司 A kind of MPPT control device and method that is used for solar photovoltaic generation system
CN102005553A (en) * 2010-10-13 2011-04-06 张文迅 Accumulator intelligent constant-temperature cabinet for maximal power point tracking wind-photovoltaic hybrid powered base station

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US6046919A (en) * 1998-03-30 2000-04-04 Sanyo Electric Co., Ltd. Solar power generating device
US7248946B2 (en) * 2004-05-11 2007-07-24 Advanced Energy Conversion, Llc Inverter control methodology for distributed generation sources connected to a utility grid
CN101599724A (en) * 2009-07-24 2009-12-09 中环(中国)工程有限公司 A kind of MPPT control device and method that is used for solar photovoltaic generation system
CN102005553A (en) * 2010-10-13 2011-04-06 张文迅 Accumulator intelligent constant-temperature cabinet for maximal power point tracking wind-photovoltaic hybrid powered base station

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2421857R1 (en) * 2012-03-02 2013-11-05 Circutor S A "photovoltaic equipment and procedure for controlling such photovoltaic equipment"
CN103592602A (en) * 2012-08-18 2014-02-19 费晓凯 Photovoltaic cell output power sensor
CN102856960A (en) * 2012-09-25 2013-01-02 广东易事特电源股份有限公司 Simplified storage battery charge MPPT (maximum power point tracking) control circuit
CN103019293A (en) * 2012-11-29 2013-04-03 宁波大学 Maximum power point tracking method for rapidly self-adapting step length of photovoltaic array
CN103019293B (en) * 2012-11-29 2014-06-25 宁波大学 Maximum power point tracking method for rapidly self-adapting step length of photovoltaic array
CN103296694A (en) * 2013-04-17 2013-09-11 江苏博纬新能源科技有限公司 Multi-channel MPPT link capable of being freely combined and used for photovoltaic grid-connected inverter
CN103296694B (en) * 2013-04-17 2016-10-05 江苏博纬新能源科技有限公司 A kind of multichannel for photovoltaic combining inverter can free modular MPPT system
CN103441566A (en) * 2013-09-12 2013-12-11 重庆大学 System and method for supplying power cooperatively by mains supply, photovoltaic cell and energy storage battery
CN103441566B (en) * 2013-09-12 2016-07-06 重庆大学 The collaborative electric power system of a kind of civil power, photovoltaic cell and energy-storage battery and method

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Application publication date: 20120111