Photovoltaic power generation apparatus with global maximum power output function
Technical field
The present invention relates to field of photovoltaic power generation, be specifically related to a kind of photovoltaic power generation apparatus with global maximum power output function.
Background technology
Along with the progressively exhaustion of fossil fuel, energy problem has become the significant problem of global growing interest, the frontier science and technology problem with strategic importance that China studies energetically, needs to be resolved hurrily especially.Simultaneously; Problem such as ecological deterioration, climate warming impels various countries to greatly develop the renewable energy technologies of cleaning, safety, low-carbon emission again, and wind energy, solar energy, tidal energy, geothermal energy, fuel cell, hybrid power technology etc. are all arisen at the historic moment under such background.In numerous renewable energy utilizations, solar photovoltaic generation system is the second largest generation mode that installed capacity is only second to wind generator system, has broad application prospects.The correlative study of solar photovoltaic generation system also is the research focus of academia always, all joins in the research of field of photovoltaic power generation one after another from the scholar in fields such as material, building, electric power system, electronics, control, promoting him its development and application.Power electronic technology is the core support technology of transformation of electrical energy and control as the cross discipline across electric power, electronics, control three big fields, is comprising the renewable energy source domain decisive role of solar photovoltaic generation system.The main direction of studying of power electronic technology in the solar energy power generating field comprises parallel network reverse technology, maximal power tracing, quality of power supply control, island detection etc. at present, and the subproblem of maximal power tracing just comprises the power adjustments cell design of photovoltaic cell.
As shown in Figure 1, the photovoltaic battery array of existing photovoltaic power generation apparatus generally comprises the photovoltaic cell of a plurality of series connection.As everyone knows; The physical characteristic of photovoltaic cell is determined by semi-conducting material; Its basic functional principle is a photovoltaic effect; Promptly when the irradiate light photovoltaic cell of certain energy; Semi-conducting material absorbs energy; Electron transition takes place, and the charge carrier distribution and the concentration of its inner ability conduction current change, and produce electromotive force and electric current thus.Fig. 2 is the equivalent electric circuit of photovoltaic cell, according to photovoltaic cell physical characteristic and equivalent electric circuit thereof, can set up the Mathematical Modeling of photovoltaic cell, is shown below:
V
PVcell=V
D-R
SI
PVFig. 3 is the photovoltaic battery module output characteristic curve.The output characteristic of photovoltaic cell is by environmental factor decisions such as the physical characteristic of material and illumination, temperature, humidity.The output characteristic that changed by intensity of illumination and produce changes particularly evident; Fig. 4 is the photovoltaic cell output characteristic curve under the different illumination intensity, and can be found out by the characteristic curve of Fig. 3: short circuit current increases with intensity of illumination, and peak power output increases with intensity of illumination.Given this, the research of tracing maximum power of photovoltaic cell problem just becomes the sixty-four dollar question that promotes energy conversion efficiency.So-called maximum power point (Maximum Power Point; MPP) promptly under certain solar irradiance and ambient temperature; Photovoltaic cell operates in the peak power output state; And MPPT maximum power point tracking (Maximum Power Point Tracking; MPP) be and make full use of photovoltaic cell; The load resistance of adjustment photovoltaic cell makes the photovoltaic cell operation always work near the process of maximum power point in real time.In the practical application, photovoltaic cell often is not to use separately, but forms photovoltaic array behind the polylith photovoltaic battery module series and parallel, as a whole externally power supply.The branch current of each series arm must be identical, and the series arm electric current will be limited by the photovoltaic module electric current of minimum, make photovoltaic array integral body can not bring into play maximum effect if each photovoltaic battery module characteristic differs this moment.For the photovoltaic cell of cascaded structure, local shade is a very problem of reality, i.e. illumination is blocked by other objects in the environment, and the intensity of illumination that causes each photovoltaic module of photovoltaic array to receive is different.This moment, each modular character produced tangible discrete type, and a plurality of extreme points appear in characteristic curve such as Fig. 5 and shown in Figure 6, power-voltage curve.Current soft, hardware measure all can't solve photovoltaic array maximum power output problem under the local shade condition.
Summary of the invention
The technical problem that the present invention will solve provides a kind of simple in structure, with low cost, can compensate the output current that reduces under the local shade condition automatically, realize the photovoltaic power generation apparatus with global maximum power output function of the maximum power output of photovoltaic cell monomer.
For solving the problems of the technologies described above; The technical scheme that the present invention adopts is: a kind of photovoltaic power generation apparatus with global maximum power output function; Comprise photovoltaic battery array and main convertor; Said photovoltaic battery array comprises the photovoltaic cell of a plurality of serial connections; Said photovoltaic power generation apparatus also comprises power adjusting array and AuCT; The input of said AuCT links to each other with the dc bus of photovoltaic battery array; Said power adjusting array comprises and said photovoltaic cell power adjusting unit one to one; Said power adjusting unit is in parallel with corresponding photovoltaic cell, and the input of said power adjusting unit links to each other with the output of AuCT.
Further improvement as technique scheme of the present invention:
Said power adjustments unit comprises the electron electric power change-over circuit; Control module and sampling unit; The input of said electron electric power change-over circuit links to each other with the output of AuCT; The output of said electron electric power change-over circuit is parallelly connected with the two poles of the earth of corresponding photovoltaic cell; The control end of said electron electric power change-over circuit links to each other with the output of said control module; Said sampling unit comprises the output current acquisition module; Output voltage acquisition module and battery current acquisition module; The input of said output current acquisition module links to each other with an output of electron electric power change-over circuit; The input of said output voltage acquisition module links to each other with the output of electron electric power change-over circuit; The input or the output of the input serial connection photovoltaic cell of said battery current acquisition module, the output of said output current acquisition module; The output of the output of output voltage acquisition module and battery current acquisition module links to each other with the input of said control module respectively.
Said electron electric power change-over circuit comprises transformer, derailing switch, driver module and rectification filtering module; The input side of said transformer is connected in series with derailing switch and links to each other with the output of AuCT; The control end of said derailing switch links to each other with the output of said control module through driver module, and the outlet side of said transformer is parallelly connected with the two poles of the earth of corresponding photovoltaic cell through rectification filtering module.
Said main convertor comprises control drive unit, boost module, full-bridge inverting module and voltage transformation output module; The input of said boost module links to each other with the dc bus of photovoltaic battery array respectively; The input of said full-bridge inverting module links to each other with the output of boost module, the dc bus of photovoltaic battery array respectively; The control end of said boost module, full-bridge inverting module links to each other with the output of control drive unit respectively, and the output of said full-bridge inverting module is exported electric energy through voltage transformation output module.
Be provided with high frequency ripple filtering module between said full-bridge inverting module and the voltage transformation output module, said high frequency ripple filtering module comprises inductance that is serially connected with an output of said full-bridge inverting module and the electric capacity that links to each other with said full-bridge inverting module output two electrodes respectively.
Said AuCT comprises assist control driver module, auxiliary full-bridge inverting module, boost voltage transformation output module and rectification module; The input of said auxiliary full-bridge inverting module links to each other with the dc bus of photovoltaic battery array; The control end of said auxiliary full-bridge inverting module links to each other with the output of assist control driver module, and the output of said auxiliary full-bridge inverting module links to each other with the power adjustments unit through boost voltage transformation output module, rectification module successively.
Be provided with auxiliary high frequency ripple filtering module between the output of said rectification module and the power adjustments unit, said auxiliary high frequency ripple filtering module comprises inductance that is serially connected with an output of rectification module and the electric capacity that links to each other with said rectification module output two electrodes respectively.
The present invention has following advantage:
1, photovoltaic power generation apparatus of the present invention comprises power adjusting array and AuCT; The input of AuCT links to each other with the dc bus of photovoltaic battery array; The power adjusting array comprises and said photovoltaic cell power adjusting unit one to one; The power adjusting unit is in parallel with corresponding photovoltaic cell; The output current that the compensation photovoltaic cell reduces under local shade condition; Realize the peak power output of photovoltaic cell monomer by main convertor; The invention enables photovoltaic array at each photovoltaic cell monomer characteristic disunity; Under the particularly local shade situation; Realize energy automatic equalization between each photovoltaic cell; Guarantee the peak power output under self environmental condition of arbitrary photovoltaic cell, thereby obtain maximum generating efficiency.
2; The input of power adjustments unit links to each other with the output of AuCT; Look up from electric energy transmitting side; Output to the power adjustments bus from the electric energy of photovoltaic array output through AuCT; Get back to photovoltaic module through the power adjustments unit again; Thereby form a power closed-loop feedback mechanism; This energy closed-loop structure can be according to the real-time output of photovoltaic array; Unbalanced photovoltaic module is carried out the fast uniform compensation; Thereby reach maximum power output; This incomplete structure the energy storing structure of traditional approach; Remove searching external energy source from, considered energy storage link response speed, performance index; The trouble in useful life; Has compact conformation; Volume is little, and is easy to maintenance, the advantage of good reliability.And because native system has designed a closed loop feedback on the electric energy output element, so the power adjustments unit only need adopt the Uniderectional DC-DC circuit to realize, and need not adopt complicated bi-directional DC-DC circuit, thus simplify circuit design, reduced system cost.
3, control method of the present invention is flexible, has excellent engineering operability, universality and versatility.The user is under the prerequisite that keeps original photovoltaic system structure, and only needing to increase a public AuCT, and said function can be realized in parallelly connected power adjustments unit on each photovoltaic cell simultaneously.Described universality and versatility also are embodied in the restriction that use of the present invention is not subjected to photovoltaic array quantity, space layout etc., in theory applicable to the photovoltaic array of any amount, arbitrary placement's mode, and plug and play, but quantity infinite expanding in the reasonable scope.
4, the present invention can reduce the photovoltaic system cost that generates electricity by way of merging two or more grid systems; Can improve through AuCT and power adjustments unit and can reduce generating on the basis of energy conversion efficiency indirectly and become; Effectively reduce rate for incorporation into the power network, become more feasible thereby photovoltaic system is generated electricity by way of merging two or more grid systems.
5, the present invention can prolong the useful life of photovoltaic cell.The unbalanced output of energy not only limits the energy conversion efficiency of photovoltaic cell, the useful life of further having reduced uneven part photovoltaic battery module simultaneously.Particularly the photovoltaic battery array that is covered by local shade is local, as does not have effective safeguard measure possibly cause the electric current adverse effects such as damage of pouring in down a chimney, generate heat.Behind parallel connection electronic power convertor power model and the employing advanced control algorithm, the worry of relevant issues can effectively be avoided.
6, the present invention can transform on conventional photovoltaic electricity generation system basis, and project installation is simple, and is with low cost, and use and later maintenance are convenient.
Description of drawings
Fig. 1 is the frame structure sketch map of existing photovoltaic power generation apparatus.
Fig. 2 is the equivalent electric circuit of photovoltaic cell.
Fig. 3 is the photovoltaic battery module output characteristic curve.
Fig. 4 is the photovoltaic cell output characteristic curve under the different illumination intensity.
Fig. 5 is a photovoltaic array output characteristic curve under a kind of local shade condition.
Fig. 6 is a photovoltaic array output characteristic curve under the another kind of local shade condition.
Fig. 7 is the frame structure sketch map of the embodiment of the invention.
Fig. 8 is the frame structure sketch map of embodiment of the invention power adjustments unit.
Fig. 9 is the circuit principle structure sketch map of embodiment of the invention power adjustments unit.
Figure 10 is the circuit principle structure sketch map of embodiment of the invention main convertor.
Figure 11 is the circuit principle structure sketch map of embodiment of the invention AuCT.
Marginal data: 1, photovoltaic battery array; 11, photovoltaic cell; 2, main convertor; 21, control drive unit; 22, boost module; 23, full-bridge inverting module; 24, voltage transformation output module; 25, high frequency ripple filtering module; 3, power adjustments array; 31, power adjustments unit; 311, electron electric power change-over circuit; 312, control module; 313, output current acquisition module; 314, output voltage acquisition module; 315, battery current acquisition module; 316, transformer; 317, derailing switch; 318, driver module; 319, rectification filtering module; 4, AuCT; 41, assist control driver module; 42, auxiliary full-bridge inverting module; 43, boost voltage transformation output module; 44, rectification module; 45, auxiliary high frequency ripple filtering module.
Embodiment
As shown in Figure 7; The photovoltaic power generation apparatus that the embodiment of the invention has the global maximum power output function comprises photovoltaic battery array 1 and main convertor 2; Photovoltaic battery array 1 comprises the photovoltaic cell 11 of a plurality of serial connections; Photovoltaic power generation apparatus also comprises power adjusting array 3 and AuCT 4; The input of AuCT 4 links to each other with the dc bus of photovoltaic battery array 1; Power adjusting array 3 comprises and photovoltaic cell 11 power adjusting unit 31 one to one; Power adjusting unit 31 and corresponding photovoltaic cell 11 parallel connections, the input of power adjusting unit 31 links to each other with the output of AuCT 4.
Adjusting the power of the present embodiment by the power adjusting unit 31 together with the auxiliary bus is connected to the converter 4, the DC power control bus can be in the form, the form can also be a communication, power control unit 31 was the current source output characteristics of the photovoltaic cell 11 is connected in parallel for energy compensation, power conditioning unit 31 via auxiliary converter 4 from the PV array output DC bus extract energy, photovoltaic cells for energy balance and compensation, power conditioning unit 31 for distributed real-time high maximum power tracking, appropriate compensation for energy photovoltaic modules in order to achieve maximum power output of the module, the main converter 2 for the global maximum power point tracking, power conditioning unit 31 pairs unbalanced module mechanism to achieve a balanced global maximum power output, even in the PV array In each PV module characteristics are not uniform, particularly the case of partial shadow, the photovoltaic modules to achieve energy balance automatically to ensure that any light-volt modules in their own environment under the conditions of maximum power output, in order to achieve maximum power output of the PV array globally; and implement each a maximum power output of the PV modules and the global maximum power output of the PV array at the same time, inverter output power is unbalanced process only part, minimizes the power converting part of the energy loss caused.In the present embodiment, photovoltaic cell 11 photovoltaic cells can be monocrystalline silicon photovoltaic cell, polysilicon photovoltaic cell or amorphous silicon photovoltaic battery, and the output of each photovoltaic cell is drawn, and link to each other with the output of power adjustments unit 31.
As shown in Figure 8; Power adjustments unit 31 comprises electron electric power change-over circuit 311; Control module 312 and sampling unit; The input of electron electric power change-over circuit 311 links to each other with the output of AuCT 4; The output of electron electric power change-over circuit 311 is parallelly connected with the two poles of the earth of corresponding photovoltaic cell 11; The control end of electron electric power change-over circuit 311 links to each other with the output of control module 312; Sampling unit comprises output current acquisition module 313; Output voltage acquisition module 314 and battery current acquisition module 315; The input of output current acquisition module 313 links to each other with an output of electron electric power change-over circuit 311; The input of output voltage acquisition module 314 links to each other with the output of electron electric power change-over circuit 311; The input or the output of the input serial connection photovoltaic cell 11 of battery current acquisition module 315, the output of output current acquisition module 313; The output of the output of output voltage acquisition module 314 and battery current acquisition module 315 links to each other with the input of control module 312 respectively.Electron electric power change-over circuit 311 is the DC/DC current transformer of energy one-way flow.
Electron electric power change-over circuit 311 can adopt anti-swash, normal shock, recommend, different circuits topologys such as half-bridge, full-bridge; Output voltage, the output current of control module 312 sampled power regulons; And the output current of corresponding photovoltaic cell; Regulate output current through algorithm; Make the photovoltaic module power output parallelly connected reach maximum, perhaps make the net power output (being that the photovoltaic module power output adds that power adjustments unit power output deducts power adjustments unit input power) of power adjustments unit and parallel photovoltaic module reach maximum with this power adjustments unit.
As shown in Figure 9; Electron electric power change-over circuit 311 comprises transformer 316, derailing switch 317, driver module 318 and rectification filtering module 319; The input side of transformer 316 is connected in series with derailing switch 317 and links to each other with the output of AuCT 4; The control end of derailing switch 317 links to each other with the output of control module 312 through driver module 318, and the outlet side of transformer 316 is parallelly connected with the two poles of the earth of corresponding photovoltaic cell 11 through rectification filtering module 319.
As shown in figure 10; Main convertor 2 comprises control drive unit 21, boost module 22, full-bridge inverting module 23 and voltage transformation output module 24; The input of boost module 22 links to each other with the dc bus of photovoltaic battery array 1 respectively; The input of full-bridge inverting module 23 links to each other with the output of boost module 22, the dc bus of photovoltaic battery array 1 respectively; The control end of boost module 22, full-bridge inverting module 23 links to each other with the output of control drive unit 21 respectively, and the output of full-bridge inverting module 23 is exported electric energy through voltage transformation output module 24.Main convertor 2 adopts combining inverter or separate inverter unit or the DC/DC power supply with maximal power tracing output function; Main convertor is unique device that electric energy is provided to the outside in the native system; Inner maximal power tracing (MPPT) algorithm that adopts is to obtain peak power output.Main convertor 2 is realized the tracking of photovoltaic array module global maximum power point; The MPPT maximum power point tracking and the energy output of each photovoltaic cell is realized in power adjustments unit 31; Independent operating, control strategy cooperatively interact respectively for the overall MPPT algorithm of main convertor 2 and the distributed MPPT algorithm of power adjustments unit 31; Make each photovoltaic cell 11 all be operated in maximum power point, thereby realize the maximum power output of the overall situation.In the present embodiment; Control drive unit 21 is made up of controller U1, drive circuit U2, drive circuit U3; Controller U1 adopts the TMS320F2812 or the TMS320F28035 of TI company, and drive circuit U2 adopts the IR IR2110 of company, and drive circuit U3 adopts the ONSEMICONDUCTOR MC34152 of company.Boost module 22 is that L1, D1, T5 form a boost circuit, is used for input voltage is risen to certain limit.Full-bridge inverting module 23 is that T1, T2, T3, T4 constitute a full bridge inverter, and voltage transformation output module 24 is transformer Tx1.Be provided with high frequency ripple filtering module 25 between full-bridge inverting module 23 and the voltage transformation output module 24, high frequency ripple filtering module 25 comprises inductance L 2 that is serially connected with 23 1 outputs of full-bridge inverting module and the capacitor C 2 that links to each other with full-bridge inverting module 23 outputs two electrodes respectively.The electric current of full-bridge inverting module 23 output is through L2, C2 filtering high frequency ripple, after transformer Tx1 be connected to the grid.
AuCT 4 is the DC/DC current transformer of energy one-way flow.As shown in figure 11; AuCT 4 comprises assist control driver module 41, auxiliary full-bridge inverting module 42, boost voltage transformation output module 43 and rectification module 44; The input of auxiliary full-bridge inverting module 42 links to each other with the dc bus of photovoltaic battery array 1; The control end of auxiliary full-bridge inverting module 42 links to each other with the output of assist control driver module 41, and the output of auxiliary full-bridge inverting module 42 links to each other with power adjustments unit 31 through boost voltage transformation output module 43, rectification module 44 successively.The portion of energy that AuCT 4 is exported photovoltaic battery array 1 is converted into the electric energy of low-voltage direct or form of communication, to simplify the design of power adjustments unit.The main circuit of AuCT 4 can adopt unidirectional DC/DC circuit or unidirectional DC/AC circuit, and it is constant that output voltage keeps.In the present embodiment; Assist control driver module 41 is made up of drive circuit U1 and controller U2; Controller U2 adopts the TMS320F28035 of TI company; Drive circuit U1 adopts the IR IR2110 of company; Auxiliary full-bridge inverting module 42 is that T1, T2, T3, T4 form a full bridge inverter; Boost voltage transformation output module 43 adopts high frequency transformer Lm to realize the full-wave rectifying circuit that rectification module 44 is made up of D1, D2.Be provided with auxiliary high frequency ripple filtering module 45 between the output of rectification module 44 and the power adjustments unit 31;, auxiliary high frequency ripple filtering module 45 comprises inductance L 1 that is serially connected with 44 1 outputs of rectification module and the capacitor C 1 that links to each other with rectification module 44 outputs two electrodes respectively.The electric current of auxiliary full-bridge inverting module 42 outputs through D1, D2 rectification and L1, C1 filtering, is exported a dc-isolation power supply after high frequency transformer Lm isolates.
The above only is a preferred implementation of the present invention, and protection scope of the present invention is not limited in above-mentioned execution mode, and every technical scheme that belongs to the principle of the invention all belongs to protection scope of the present invention.For a person skilled in the art, some improvement and the retouching under the prerequisite that does not break away from principle of the present invention, carried out, these improvement and retouching also should be considered as protection scope of the present invention.