CN103064460B - MPPT (maximum power point tracking) control device and MPPT control method of photovoltaic inverter - Google Patents
MPPT (maximum power point tracking) control device and MPPT control method of photovoltaic inverter Download PDFInfo
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- CN103064460B CN103064460B CN201310001326.1A CN201310001326A CN103064460B CN 103064460 B CN103064460 B CN 103064460B CN 201310001326 A CN201310001326 A CN 201310001326A CN 103064460 B CN103064460 B CN 103064460B
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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
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- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention discloses an MPPT (maximum power point tracking) control device and an MPPT control method of a photovoltaic inverter. The MPPT control method includes the steps: A, sampling direct-current voltage Ux and direct current Ix of a direct-current side of the photovoltaic inverter, and computing input power Px of the direct-current side of the photovoltaic inverter; B, judging whether the direct-current voltage Ux is not larger than a voltage minimal value U1 or not, if so, updating the voltage minimal value U1 and corresponding input power P1 and switching to D, and otherwise switching to C; C, judging whether the direct-current voltage Ux is not smaller than a voltage maximum value U2 or not, if so, updating he voltage maximum value U2 and corresponding input power P2 and switching to the D, and otherwise switching to E; D, computing a voltage result value U; and E, sending PWM (pulse-width modulation) signals of switches in the photovoltaic inverter according to the voltage result value U. The MPPT control method is simple in sampling MPPT algorithm, easy to implement, rapid in processing, stable in control and capable of improving use efficiency of solar cells.
Description
Technical field
The present invention relates to MPPT control technology, especially relate to a kind of MPPT control device and method of the photovoltaic DC-to-AC converter based on voltage fluctuation.
Background technology
Along with expanding economy and social progress, the demand of the energy is growing, and conventional energy resources is (as coal, oil, waterpower, rock gas etc.) also more and more supply falls short of demand, therefore tapping a new source of energy is the inexorable trend of the world today, and solar cell is exactly one of main new forms of energy.But the on the low side of photovoltaic cell conversion efficiency is the bottleneck of sun power large-scale promotion application at present.The energy that how to utilize to greatest extent the sun generating chief to produce is an important directions of photovoltaic research.
Photovoltaic array output characteristics has nonlinear characteristic, and its output voltage, electric current are affected by intensity of illumination, environment temperature and loading condition.Under certain Intensity of the sunlight and environment temperature, photovoltaic array can be operated in different output voltages, but only when a certain output voltage values, the output power of photovoltaic array just can reach maximal value, at this moment the working point of photovoltaic array has just reached the peak of output power voltage curve, be referred to as maximum power point (Maximum Power Point, MPP).Therefore, in photovoltaic generating system, improve whole efficiency, an important approach is exactly to adjust in real time the working point of photovoltaic array, make it to always work near maximum power point, this process is just referred to as MPPT maximum power point tracking (Maximum Power Point Tracking, MPPT).
It is in order to use more completely solar cell that MPPT controls, and improves the utilization ratio of solar cell.Now conventional MPPT control method is method of perturbation (such as voltage disturbance method), although method of perturbation is used easily, also has 2 shortcomings: the first can allow photovoltaic DC-to-AC converter in the concussion of MPP point left and right, thereby causes energy loss, reduces the efficiency of solar cell; It two is that the disturbance step-length of common method of perturbation is difficult to determine, if step-length is too large, increases the degree of concussion, if step-length is too small, can increase the time that MPP is ordered of finding.
Summary of the invention
The problems and shortcomings that exist for prior art, in order to improve the service efficiency of solar cell, the invention provides a kind of simpler, stable photovoltaic DC-to-AC converter MPPT control device and method based on voltage fluctuation.
The present invention adopts following technical scheme to realize: a kind of MPPT control method of photovoltaic DC-to-AC converter, and it comprises step:
DC voltage Ux and the DC current Ix of A, sampling photovoltaic inverter direct-flow side, and calculate the power input Px of photovoltaic DC-to-AC converter DC side;
B, judge whether the DC voltage Ux of current sampling is not more than voltage minimal value U
1, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage minimal value U
1and voltage minimal value U
1corresponding power input P
1and proceed to D, otherwise proceed to C;
C, judge whether the DC voltage Ux of current sampling is not less than voltage maximum value U
2, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage maximum value U
2and voltage maximum value U
2corresponding power input P
2and proceed to D, otherwise proceed to E;
D, according to voltage minimal value U
1and corresponding power input P
1, voltage maximum value U
2and corresponding power input P
2calculating voltage end value U;
E, according to voltage end value U, send the pwm signal of each switch in photovoltaic DC-to-AC converter.
Wherein, step D is according to formula
calculating voltage end value U, wherein, k>0; Sign is for getting symbolic operation, when U1>U2, and sign (U
2– U
1) for negative, when U1<U2, sign (U
2– U
1) for just.
In addition, the present invention discloses a kind of MPPT control device of photovoltaic DC-to-AC converter, and it comprises:
Voltage sampling circuit and current sampling circuit, for DC voltage Ux and the DC current Ix of the photovoltaic inverter direct-flow side of sampling respectively;
The controller with AD module and PWM output module, the AD module of controller connects photovoltaic DC-to-AC converter DC side by voltage sampling circuit, current sampling circuit, and the PWM output module of controller connects each switch of inverter circuit in photovoltaic DC-to-AC converter by driving circuit;
Wherein, by controller, carried out the power input Px of following processing: A, calculating photovoltaic DC-to-AC converter DC side; B, judge whether the DC voltage Ux of current sampling is not more than voltage minimal value U
1, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage minimal value U
1and power input P corresponding to voltage minimal value U1
1and proceed to D, otherwise proceed to C; C, judge whether the DC voltage Ux of current sampling is not less than voltage maximum value U
2, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage maximum value U
2and voltage maximum value U
2corresponding power input P
2and proceed to D, otherwise proceed to E; D, according to voltage minimal value U
1and corresponding power input P
1, voltage maximum value U
2and corresponding power input P
2calculating voltage end value U; E, by controller, according to voltage end value U, by PWM output module, to driving circuit, sent the pwm signal of each switch in photovoltaic DC-to-AC converter.
Wherein, controller is according to formula
calculating voltage end value U, wherein, k>0; Sign is for getting symbolic operation, when U1>U2, and sign (U
2-U
1) for negative, when U1<U2, sign (U
2-U
1) for just.
Wherein, controller is dsp controller.
Compared with prior art, the present invention has following beneficial effect:
The present invention is that the photovoltaic DC-to-AC converter MPPT that the busbar voltage disturbance based on photovoltaic DC-to-AC converter DC side realizes controls, and this MPPT control device is simpler and easy, realizes cost lower.In addition, MPPT control method provided by the invention realizes simply, processes fast and control stable, can improve the service efficiency of solar cell.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of single-phase photovoltaic DC-to-AC converter.
Fig. 2 is that the power-balance of single-phase photovoltaic DC-to-AC converter is related to schematic diagram.
Fig. 3 is the structural representation of MPPT control device of the present invention.
Fig. 4 is the schematic flow sheet of MPPT control method of the present invention.
Fig. 5 is the pursuit path schematic diagram of maximum power point voltage-power of the present invention.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is further illustrated.
First analyze the energy flow situation in single-phase photovoltaic DC-to-AC converter.Ignore various losses (comprise inverter bridge open the light loss, passive device loss, line loss and secondary power supply etc.), as depicted in figs. 1 and 2, arrow represents the power positive dirction of regulation to the power-balance relation of system.In figure, the output power that Ppv is photovoltaic cell; Pc is the power of dc-link capacitance; UDC is DC bus-bar voltage, i.e. the output voltage of sun power electroplax; IC is the electric current on dc-link capacitance; UL is the voltage on ac filter inductance; UG is ac grid voltage; IG is ac output current; C is dc-link capacitance value; L is ac filter inductance value.According to power-balance relation, have
If line voltage and electric current are the sine wave with frequency homophase, i.e. u
g=Usinwt, i
g=Isinwt.U is line voltage amplitude; I is power network current amplitude; W is line voltage angular frequency.Substitution formula (1.1)
In formula (1.2),
Under typical photovoltaic DC-to-AC converter parameter, during steady-state operation, the myopia solution of formula (1.2) is
In formula, D is DC voltage u
dCmean value.
From formula (1.3), single-phase photovoltaic DC-to-AC converter is when steady-state operation, and DC bus-bar voltage has the fluctuation that doubles mains frequency.Under certain condition, can be as traditional interference observation, by the mode of continuous modification voltage instruction value, carry out voltage disturbance, the present invention but MPPT control is carried out in the intrinsic fluctuation that makes full use of busbar voltage voltage, can avoid like this causing unnecessary concussion near maximum power point, thereby improve the steady-state behaviour that MPPT controls.
Shown in Fig. 3, in one embodiment, the MPPT control device of realizing MPPT control method comprises: have the controller of AD module and PWM output module, such as dsp controller; The AD module of controller connects photovoltaic DC-to-AC converter DC side by voltage sampling circuit, current sampling circuit, and the PWM output module of controller connects each switch of inverter circuit in photovoltaic DC-to-AC converter (DC/AC) by driving circuit.
Shown in Fig. 4, the present invention realizes MPPT control method and comprises the steps:
Step S1, by voltage sampling circuit, the current sampling circuit of MPPT control device sample respectively the DC voltage Ux of photovoltaic inverter direct-flow side and DC bus-bar voltage uDC and the output current iDC that DC current Ix(is sun power electroplax output terminal), and by controller, calculated the power input Px=Ux*Ix of photovoltaic DC-to-AC converter DC side.
Step S2, by controller, judged DC voltage Ux(or the sampled voltage Ux of current sampling) whether be not more than voltage minimal value U
1(when DC bus-bar voltage uDC is voltage minimal value U
1time, corresponding power input P
1), if so, proceed to step S3, otherwise proceed to step S4.
Step S3, by controller by the DC voltage Ux assignment of current sampling to voltage minimal value U
1, and by power input Px assignment corresponding to DC voltage Ux to voltage minimal value U
1corresponding power input P
1, in MPPT control device, upgrade voltage minimal value U
1and corresponding power input P
1.
Step S4, by controller, further judged DC voltage Ux(or the sampled voltage Ux of current sampling) whether be not less than voltage maximum value U
2(when DC bus-bar voltage uDC is voltage maximum value U
2time, corresponding power input P
2), if so, proceed to step S5, otherwise proceed to step S7.
Step S5, by controller by the DC voltage Ux assignment of current sampling to voltage maximum value U
2, and by power input Px assignment corresponding to DC voltage Ux to voltage maximum value U
2corresponding power input P
2, in MPPT control device, upgrade voltage maximum value U
2and corresponding power input P
2.
Step S6, by controller according to formula
calculating voltage end value U.In formula, k>0; Sign, for getting symbolic operation, works as U
1>U
2time, sign (U
2-U
1) for negative, work as U
1<U
2time, sign (U
2-U
1) for just.
Step S7, by controller, according to voltage end value U, by PWM output module, to driving circuit, sent the pwm signal of each switch in photovoltaic DC-to-AC converter.
In Fig. 4, the direction of change in voltage is relevant with the symbol of each voltage, performance number, and the direction towards the increase of output power changes all the time.P
1and P
2when gap is larger, the step-length of change in voltage is just larger; P
1and P
2more hour, the step-length of change in voltage is just less for gap.When DC voltage average value reaches maximum power point, there is P
1=P
2, the voltage instruction value that now calculates gained is just DC voltage average value, therefore when stable state, can not produce unnecessary concussion.
Figure 5 shows that the voltage-power track in MPPT control procedure, and illumination is respectively 1000W/m
2and 600W/m
2time photovoltaic cell voltage-power characteristic.Adopt as seen from the figure said method can effectively find maximum power point, and in process of environmental change, follow all the time maximum power point, during stable state, do not occur unnecessary disturbance.
When power hour, the fluctuation amplitude of DC bus-bar voltage is also less, considers the precision limitation of sensor, is not enough to carry out correct calculating and judgement, now still needs to adopt extra voltage disturbance to carry out MPPT control.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any modifications of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.
Claims (3)
1. a MPPT control method for photovoltaic DC-to-AC converter, is characterized in that, comprises step:
DC voltage Ux and the DC current Ix of A, sampling photovoltaic inverter direct-flow side, and calculate the power input Px of photovoltaic DC-to-AC converter DC side;
B, judge whether the DC voltage Ux of current sampling is not more than voltage minimal value U
1, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage minimal value U
1and voltage minimal value U
1corresponding power input P
1and proceed to D, otherwise proceed to C;
C, judge whether the DC voltage Ux of current sampling is not less than voltage maximum value U
2, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage maximum value U
2and voltage maximum value U
2corresponding power input P
2and proceed to D, otherwise proceed to E;
D, according to voltage minimal value U
1and corresponding power input P
1, voltage maximum value U
2and corresponding power input P
2calculating voltage end value U;
E, according to voltage end value U, send the pwm signal of each switch in photovoltaic DC-to-AC converter;
Wherein, step D is according to formula
calculating voltage end value U, wherein, k > 0; Sign is for getting symbolic operation, when U1>U2, and sign (U
2– U
1) for negative, when U1<U2, sign (U
2– U
1) for just.
2. a MPPT control device for photovoltaic DC-to-AC converter, is characterized in that, comprising:
Voltage sampling circuit and current sampling circuit, for DC voltage Ux and the DC current Ix of the photovoltaic inverter direct-flow side of sampling respectively;
The controller with AD module and PWM output module, the AD module of controller connects photovoltaic DC-to-AC converter DC side by voltage sampling circuit, current sampling circuit, and the PWM output module of controller connects each switch of inverter circuit in photovoltaic DC-to-AC converter by driving circuit;
Wherein, by controller, carried out the power input Px of following processing: A, calculating photovoltaic DC-to-AC converter DC side; B, judge whether the DC voltage Ux of current sampling is not more than voltage minimal value U
1, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage minimal value U
1and voltage minimal value U
1corresponding power input P
1and proceed to D, otherwise proceed to C; C, judge whether the DC voltage Ux of current sampling is not less than voltage maximum value U
2, if so, power input Px corresponding to DC voltage Ux distinguished to assignment to voltage maximum value U
2and voltage maximum value U
2corresponding power input P
2and proceed to D, otherwise proceed to E; D, according to voltage minimal value U
1and corresponding power input P
1, voltage maximum value U
2and corresponding power input P
2calculating voltage end value U; E, by controller, according to voltage end value U, by PWM output module, to driving circuit, sent the pwm signal of each switch in photovoltaic DC-to-AC converter;
Wherein, controller is according to formula
calculating voltage end value U, wherein, k > 0; Sign is for getting symbolic operation, when U1>U2, and sign (U
2– U
1) for negative, when U1<U2, sign (U
2– U
1) for just.
3. the MPPT control device of photovoltaic DC-to-AC converter according to claim 2, is characterized in that, controller is dsp controller.
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| CN103744466A (en) * | 2013-12-17 | 2014-04-23 | 上海电机学院 | Photovoltaic array maximum power tracking method and device |
| CN103885522A (en) * | 2014-03-31 | 2014-06-25 | 上海电气集团股份有限公司 | Maximum power tracking method based on direct-current bus voltage control |
| CN103995561B (en) * | 2014-05-28 | 2015-12-02 | 华为技术有限公司 | A kind of maximum power point tracing method and device |
| CN109713714B (en) * | 2018-11-15 | 2020-12-25 | 华为技术有限公司 | Maximum power point tracking method and equipment |
| CN109538458B (en) * | 2019-01-10 | 2020-11-13 | 东莞市深鹏电子有限公司 | Solar water pump adjusting device and control method thereof |
| CN112379153B (en) * | 2020-10-30 | 2023-05-26 | 阳光电源股份有限公司 | Direct current oscillation detection circuit, direct current arc detection circuit and inverter |
| CN112711292B (en) * | 2021-03-29 | 2021-07-09 | 深圳黑晶光电技术有限公司 | Photovoltaic module maximum power tracking method, system and storage medium |
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| CN100508327C (en) * | 2007-06-08 | 2009-07-01 | 清华大学 | Photovoltaic three-phase grid control method for fast and steadily implementing maximal power tracing |
| CN101697423B (en) * | 2009-10-23 | 2012-04-18 | 安徽颐和新能源科技股份有限公司 | Non-active disturbance maximum power tracking method in photovoltaic grid-connected inverting system |
| CN102355003B (en) * | 2011-09-13 | 2013-10-16 | 辽宁力迅风电控制***有限公司 | Control method and device for single-phase grid-connected photovoltaic power generation system |
| CN102723740B (en) * | 2012-07-13 | 2015-02-25 | 浙江埃菲生能源科技有限公司 | Stable MPPT (Maximum Power Point Tracking) control system and method of single-stage photovoltaic inverter |
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