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, the problem such as ecological deterioration, climate warming impels again various countries to greatly develop the renewable energy technologies of cleaning, safety, low-carbon emission, and wind energy, solar energy, tidal energy, geothermal energy, fuel cell, Technology of Hybrid Electric Vehicle etc. all arise 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 is also the study hotspot of academia always, all joins in one after another the research of field of photovoltaic power generation from the scholar in the fields such as material, building, electric power system, electronics, control, promoting him its development and application.Power electronic technology as the cross discipline across electric power, electronics, control three large fields, is the core support technology of transformation of electrical energy and control, plays conclusive effect at the renewable energy source domain that comprises solar photovoltaic generation system.Present power electronic technology comprises parallel network reverse technology, maximal power tracing, quality of power supply control, isolated island detection etc. in the main direction of studying in solar energy power generating field, and the subproblem of maximal power tracing just comprises the power adjustments Unit 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 photovoltaic effect, namely when the light of certain energy shines photovoltaic cell, semi-conducting material absorbs energy, electron transition occurs, and charge carrier distribution and the concentration of its within conduction current change, and produce thus electromotive force and electric current.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 determined by environmental factors 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 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) namely 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 take full advantage of photovoltaic cell, adjust in real time the load resistance of photovoltaic cell, make the photovoltaic cell operation always work near the process of maximum power point.In practical application, photovoltaic cell is not often to use separately, but forms photovoltaic array after polylith photovoltaic battery module series and parallel, as a whole supplying power for outside.The branch current of each series arm must be identical, if this moment, each photovoltaic battery module characteristic differed, the series arm electric current will be lived by the photovoltaic module current limit of minimum, make photovoltaic array integral body can not bring into play maximum effect.For the photovoltaic cell of cascaded structure, local shade is a very real problem, i.e. illumination is blocked by other objects in environment, and the intensity of illumination that causes each photovoltaic module of photovoltaic array to receive is different.This moment, each modular character produced obvious discrete type, characteristic curve as shown in Figure 5 and Figure 6, a plurality of extreme points appear in power-voltage curve.Current soft and hardware measure all can't solve photovoltaic array maximum power output problem under local shade condition.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of simple in structure, with low cost, the photovoltaic power generation apparatus with global maximum power output function of the output current that reduces under can auto-compensation local shade condition, the maximum power output of realizing the photovoltaic cell monomer.
for solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of photovoltaic power generation apparatus with global maximum power output function, comprise photovoltaic battery array and main convertor, described photovoltaic battery array comprises the photovoltaic cell of a plurality of serial connections, described photovoltaic power generation apparatus also comprises power adjustments array and AuCT, the input of described AuCT is connected with the dc bus of photovoltaic battery array, described power adjustments array comprises and described photovoltaic cell power adjustments unit one to one, described power adjustments unit is in parallel with corresponding photovoltaic cell, the input of described power adjustments unit is connected with the output of AuCT.
As further improvement in the technical proposal of the present invention:
described power adjustments unit comprises the electron electric power change-over circuit, control module and sampling unit, the input of described electron electric power change-over circuit is connected with the output of AuCT, the output of described electron electric power change-over circuit is in parallel with the two poles of the earth of corresponding photovoltaic cell, the control end of described electron electric power change-over circuit is connected with the output of described control module, described sampling unit comprises the output current acquisition module, output voltage acquisition module and battery current acquisition module, the input of described output current acquisition module is connected with an output of electron electric power change-over circuit, the input of described output voltage acquisition module is connected with the output of electron electric power change-over circuit, input or the output of the input serial connection photovoltaic cell of described battery current acquisition module, the output of described output current acquisition module, the output of the output of output voltage acquisition module and battery current acquisition module is connected with the input of described control module respectively.
Described electron electric power change-over circuit comprises transformer, derailing switch, driver module and rectification filtering module, the input side of described transformer is connected in series with derailing switch and is connected with the output of AuCT, the control end of described derailing switch is connected with the output of described control module by driver module, and the outlet side of described transformer is in parallel with the two poles of the earth of corresponding photovoltaic cell by rectification filtering module.
Described main convertor comprises controls driver element, boost module, full-bridge inverting module and voltage transformation output module, the input of described boost module is connected with the dc bus of photovoltaic battery array respectively, the input of described full-bridge inverting module is connected with the output of boost module, the dc bus of photovoltaic battery array respectively, the control end of described boost module, full-bridge inverting module is connected with the output of controlling driver element respectively, and the output of described full-bridge inverting module is exported electric energy by voltage transformation output module.
Be provided with high frequency ripple filtering module between described full-bridge inverting module and voltage transformation output module, described high frequency ripple filtering module comprises the inductance that is serially connected with an output of described full-bridge inverting module and the electric capacity that is connected with described full-bridge inverting module output two electrodes respectively.
Described AuCT comprises auxiliary driver module, auxiliary full-bridge inverting module, boost voltage transformation output module and the rectification module controlled, the input of described auxiliary full-bridge inverting module is connected with the dc bus of photovoltaic battery array, the control end of described auxiliary full-bridge inverting module is connected with the auxiliary output of controlling driver module, and the output of described auxiliary full-bridge inverting module passes through successively boost voltage transformation output module, rectification module and is connected with the power adjustments unit.
Be provided with auxiliary high frequency ripple filtering module between the output of described rectification module and power adjustments unit, described auxiliary high frequency ripple filtering module comprises the inductance that is serially connected with an output of rectification module and the electric capacity that is connected with described rectification module output two electrodes respectively.
The present invention has following advantage:
1, photovoltaic power generation apparatus of the present invention comprises power adjustments array and AuCT, the input of AuCT is connected with the dc bus of photovoltaic battery array, the power adjustments array comprises and described photovoltaic cell power adjustments unit one to one, the power adjustments unit is in parallel with corresponding photovoltaic cell, the output current that the compensation photovoltaic cell reduces under local shade condition, realize the maximum power output of photovoltaic cell monomer by main convertor, the invention enables photovoltaic array at each photovoltaic cell monomer characteristic disunity, particularly in local shade situation, realize energy automatic equalization between each photovoltaic cell, guarantee arbitrary photovoltaic cell maximum power output under self environmental condition, thereby obtain maximum generating efficiency.
2, the input of power adjustments unit is connected with the output of AuCT, look up from delivery of electrical energy 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, having removed the searching external energy from originates, consider energy storage link response speed, performance index, the trouble in useful life, has compact conformation, volume is little, easy to maintenance, the advantage that reliability is strong.And designed a closed loop feedback on the electric energy output element due to native system, so the power adjustments unit only need adopt the Uniderectional DC-DC circuit to realize, and do not need to adopt complicated bi-directional DC-DC circuit, thus simplify circuit design, reduced system cost.
3, control method of the present invention is flexible, has good 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 power adjustments in parallel unit on each photovoltaic cell, can realize described function 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 by AuCT and power adjustments unit and can indirectly reduce generating on the basis of energy conversion efficiency 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 extend 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.The photovoltaic battery array that is particularly covered by local shade is local, as does not have effective safeguard measure may cause the electric current adverse effects such as damage of pouring in down a chimney, generate heat.After electronic power convertor power model in parallel and 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, use and later maintenance convenient.
Description of drawings
Fig. 1 is the frame structure schematic diagram 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 different illumination intensity.
Fig. 5 is photovoltaic array output characteristic curve under a kind of local shade condition.
Fig. 6 is photovoltaic array output characteristic curve under another kind of local shade condition.
Fig. 7 is the frame structure schematic diagram of the embodiment of the present invention.
Fig. 8 is the frame structure schematic diagram of embodiment of the present invention power adjustments unit.
Fig. 9 is the circuit principle structure schematic diagram of embodiment of the present invention power adjustments unit.
Figure 10 is the circuit principle structure schematic diagram of embodiment of the present invention main convertor.
Figure 11 is the circuit principle structure schematic diagram of embodiment of the present invention AuCT.
Marginal data: 1, photovoltaic battery array; 11, photovoltaic cell; 2, main convertor; 21, control driver element; 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, the auxiliary driver module of controlling; 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 present 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 adjustments array 3 and AuCT 4, the input of AuCT 4 is connected with the dc bus of photovoltaic battery array 1, power adjustments array 3 comprises and photovoltaic cell 11 power adjustments unit 31 one to one, power adjustments unit 31 and corresponding photovoltaic cell 11 parallel connections, the input of power adjustments unit 31 is connected with the output of AuCT 4.
the power adjustments unit 31 of the present embodiment is common to be connected with AuCT 4 by the power adjustments buses, the power adjustments bus can be the direct current form, it can be also form of communication, power adjustments unit 31 is the current source output characteristic, carry out energy compensating in parallel with photovoltaic cell 11, power adjustments unit 31 is exported the dc bus extracting energy through AuCT 4 from photovoltaic array, be used for balancing energy and the compensation of photovoltaic cell, power adjustments unit 31 carries out the higher distributed maximal power tracing of real-time, for corresponding photovoltaic module for compensating electric energy to reach the maximum power output of this module, main convertor 2 carries out global maximum power to be followed the tracks of, carry out realizing on balanced mechanism global maximum power output in the unbalanced module in 31 pairs of unit of power adjustments, even at photovoltaic array at each photovoltaic module characteristic disunity, particularly in local shade situation, realize energy automatic equalization between each photovoltaic module, guarantee arbitrary photovoltaic module maximum power output under self environmental condition, thereby realize the output of photovoltaic array global maximum power, and when realizing the output of each photovoltaic module maximum power output and photovoltaic array global maximum power, current transformer is only processed uneven part in power output, has at utmost reduced the energy loss that the power conversion link is brought.In the present embodiment, photovoltaic cell 11 photovoltaic cells can be monocrystalline silicon photovoltaic cell, polysilicon photovoltaic cells or amorphous silicon photovoltaic battery, and the output of each photovoltaic cell is drawn, and are connected 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 is connected with the output of AuCT 4, the output of electron electric power change-over circuit 311 is in parallel with the two poles of the earth of corresponding photovoltaic cell 11, the control end of electron electric power change-over circuit 311 is connected 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 is connected with an output of electron electric power change-over circuit 311, the input of output voltage acquisition module 314 is connected with the output of electron electric power change-over circuit 311, 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 is connected 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, the different circuit topologies 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, by algorithm regulation output electric current, make the photovoltaic module power output in parallel with this power adjustments unit 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.
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 is connected with the output of AuCT 4, the control end of derailing switch 317 is connected with the output of control module 312 by driver module 318, and the outlet side of transformer 316 is by the two poles of the earth parallel connection of rectification filtering module 319 with corresponding photovoltaic cell 11.
As shown in figure 10, main convertor 2 comprises controls driver element 21, boost module 22, full-bridge inverting module 23 and voltage transformation output module 24, the input of boost module 22 is connected with the dc bus of photovoltaic battery array 1 respectively, the input of full-bridge inverting module 23 is connected 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 is connected with the output of controlling driver element 21 respectively, and the output of full-bridge inverting module 23 is exported electric energy by 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 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, 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 the distributed MPPT algorithm of the overall MPPT algorithm of main convertor 2 and power adjustments unit 31 respectively, make each photovoltaic cell 11 be operated in maximum power point, thereby realize the maximum power output of the overall situation.In the present embodiment, controlling driver element 21 is comprised of controller U1, drive circuit U2, drive circuit U3, controller U1 adopts 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 consist of 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 voltage transformation output module 24, high frequency ripple filtering module 25 comprises the inductance L 2 that is serially connected with 23 1 outputs of full-bridge inverting module and the capacitor C 2 that is connected with full-bridge inverting module 23 output two electrodes respectively.The electric current of full-bridge inverting module 23 outputs is by L2, C2 filtering high frequency ripple, and Tx1 is connected to the grid finally by transformer.
AuCT 4 is the DC/DC current transformer of energy one-way flow.As shown in figure 11, AuCT 4 comprises auxiliary driver module 41, auxiliary full-bridge inverting module 42, boost voltage transformation output module 43 and the rectification module 44 controlled, the input of auxiliary full-bridge inverting module 42 is connected with the dc bus of photovoltaic battery array 1, the control end of auxiliary full-bridge inverting module 42 is connected with the auxiliary output of controlling driver module 41, and the output of auxiliary full-bridge inverting module 42 passes through successively boost voltage transformation output module 43, rectification module 44 and is connected with power adjustments unit 31.AuCT 4 is converted into the portion of energy of photovoltaic battery array 1 output 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, the auxiliary driver module 41 of controlling is comprised 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 comprised of D1, D2.Be provided with auxiliary high frequency ripple filtering module 45 between the output of rectification module 44 and power adjustments unit 31,, auxiliary high frequency ripple filtering module 45 comprises the inductance L 1 that is serially connected with 44 1 outputs of rectification module and the capacitor C 1 that is connected with rectification module 44 output two electrodes respectively.The electric current of auxiliary full-bridge inverting module 42 outputs by D1, D2 rectification and L1, C1 filtering, is exported a DC-isolation power supply after high frequency transformer Lm isolation.
The above is only the preferred embodiment 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 improvements and modifications of carrying out under the prerequisite that does not break away from principle of the present invention, these improvements and modifications also should be considered as protection scope of the present invention.