CN101494386A - Capacitance coupling type photovoltaic parallel system - Google Patents
Capacitance coupling type photovoltaic parallel system Download PDFInfo
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- CN101494386A CN101494386A CNA2009100370510A CN200910037051A CN101494386A CN 101494386 A CN101494386 A CN 101494386A CN A2009100370510 A CNA2009100370510 A CN A2009100370510A CN 200910037051 A CN200910037051 A CN 200910037051A CN 101494386 A CN101494386 A CN 101494386A
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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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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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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 a capacity coupling type grid-connected system, belonging to the technical field of solar energy photovoltaic utilization. The system is mainly composed of a solar cell photovoltaic array (2), a DC/AC convertor (3), an AC network (1) and a controller (4) and characterized in that a capacitor (5) and a capacitor (6) connected in series are connected on the AC network (1), and the AC output side of the DC/AC convertor is connected with the capacitor (5) in parallel. The solar cell array is used for absorbing sunlight energy that is converted into AC through the DC/AC convertor and then fed to the network through the capacitor. As adopting the parallel in structure that the capacitors are connected in series for voltage dividing, the system causes the output voltage at the AC side of the convertor to be low. Therefore, the capacity coupling type is rather suitable for the low-voltage characteristic of the photovoltaic system. Due to the little loss of the capacitors, the grid-connected system is characterized by little parallel in loss and high efficiency. Besides, as the output voltage controlling the DC/AC convertor can control the voltage at two ends of the capacitor (6), the reactive compensation power of the grid-connected system can be dynamically adjusted.
Description
Technical field
The invention belongs to the solar energy photovoltaic utilization technical field, specifically is a kind of high efficiency photovoltaic parallel in system that adopts capacitor to connect AC network and DC/AC inverter.
Background technology
Solar energy is as a kind of emerging green energy resource, and is never exhausted, pollution-free with it, be not subjected to advantages such as region resource limit, applied just rapidly.Though the solar energy power generating cost is higher, in the long term, along with development of technology, and other using energy source forms is saturated gradually, and solar energy can become main flow using energy source form after 2030, immeasurable development potentiality is arranged.
Photovoltaic parallel in system is family of developed country and commercial most popular photovoltaic system.Be connected with local power network, make the electric weight more than needed that sends all can be sold to electrical network.Then can buy from electrical network night.Now, the solar cell in the whole world about 60% is used for grid-connected system, mainly is to be used for urban architecture grid-connected photovoltaic system.The building grid-connected photovoltaic system of China still is in demonstration phase.Estimate that former China in 2010 will implement the roof plan, installs solar cell 50MWp; The year two thousand twenty will have more massive building grid-connected photovoltaic system item in the past, and the accumulative total installed capacity will reach 700MWp.The market share that expects building grid-connected photovoltaic system in 2010 will account for 17.6%, will account for 39% to the year two thousand twenty.Existing about 40,000,000,000 m of China
2Construction area, roof area 4,000,000,000 m
2, add south elevation, can utilize area to be approximately 5,000,000,000 m
2If 20% is used for installing solar cell, can adorn 100GWp.Local city and enterprise have also begun the trial of building photovoltaic power generation grid-connecting technology, and the Shenzhen has built up the photovoltaic grid-connection power plant of Asia maximum at that time, and total capacity reaches 1MWp.Cities such as Shanghai, Beijing, Nanjing, Wuxi, Baoding, Dezhou have also all started city solar energy demonstration project and action.The blank of city parallel network power generation has appearred in China, and the potentiality of grid-connected industry are unlimited.
Combining inverter is the core component and the key problem in technology of photovoltaic parallel in system.Traditional voltage source inverter (VSI) requires the voltage of DC side to be higher than AC side, and the power source voltage that is connected to the grid must be complementary with electrical network.To jumbo inverter, because DC bus-bar voltage is higher, exchanging output does not generally need transformer to boost can to reach 220V, and in, in the inverter of low capacity because direct voltage is lower, as 12V, 24V, just must the design booster circuit.Booster circuit can design the DC side at combining inverter, also can design the AC side at inverter.If the booster circuit design in DC side, promptly increases the DC boosting link between photovoltaic array and inverter, then increased the complexity of system, and the DC/DC DC voltage booster circuit can be brought supplementary load loss.In conventional, the low capacity photovoltaic combining inverter generally has transformer to boost to be incorporated into the power networks and two kinds of DC/DC high frequency boost inverter circuits.Transformer boosts and is incorporated into the power networks because transformer has certain leakage inductance, but limiting short-circuit current, thereby improved the reliability of circuit, but transformer utilization factor is low, and the ability that drives inductive load is relatively poor, and has increased the volume of system, and step-up transformer efficient is low, and price is also more expensive.Development along with power electronic technology and microelectric technique.Adopt high frequency boosting inverter technology to realize inversion, can realize the high power density inversion, the prime booster circuit of this inverter circuit adopts push-pull configuration, but operating frequency is all more than 20KHz, step-up transformer adopts the high frequency magnetic core material, thereby volume is little, in light weight, becomes high-frequency alternating current through high frequency transformer behind the high-frequency inversion, obtains high voltage direct current (general all more than 300V) through rectifier filter circuit again and realizes inversion by the power frequency inverter circuit again.Adopt this circuit structure, inverter power is improved greatly, the also corresponding reduction of the no-load loss of inverter, efficient is improved, but the shortcoming of this circuit is a complex circuit designs, reliability is lower than transformer booster circuit.
Summary of the invention
The objective of the invention is to propose to adapt in the photovoltaic parallel in system the low efficient and net mode simple in structure of photovoltaic array output voltage.For this reason, the innovation mode of the design's model use capacitance boost coupling is realized grid-connected, because the loss of electric capacity is very little, can improve the efficient of grid-connected system effectively.Adopt the capacitive coupling boosting mode to insert electrical network simultaneously and saved heavy step-up transformer, reduced the volume of grid-connected system, avoided the complicated circuit design of boosting of DC/DC high frequency simultaneously, improved the practicality of grid-connected system greatly.
The technical solution adopted in the present invention is as follows: a kind of capacitance coupling type photovoltaic parallel system, mainly comprise AC network [1], solar energy photovoltaic array [2], DC/AC converter [3], controller [4], it is characterized in that: be connected to series capacitors [5] and capacitor [6] on AC network, the interchange outlet side of DC/AC converter is in parallel with capacitor [5].Is direct current by the solar energy photovoltaic array with solar energy converting, be converted to alternating current by the DC/AC converter then, because in, low power photovoltaic array output dc voltage is lower, also lower by the alternating voltage exported behind the DC/AC converter, the alternating current of exporting behind the DC/AC converter is after capacitor [5] shunting, another part electric current is injected into electrical network by coupling capacitor [6], gives electrical network with energy feeding.Simultaneously, the capacitive reactive power that the output voltage of control DC/AC converter can control system sends to electrical network, thus realize dynamic passive compensation to the middle low power inductive load.This and net mode is simple in structure, realize that the operating frequency of capacitor is low easily, its loss is very little, therefore can realize the high-efficiency operation of photovoltaic parallel in system.
Be that capacitance coupling type photovoltaic parallel system is exported the equivalent schematic diagram of energy feeding to electrical network with photovoltaic array shown in the accompanying drawing 1.Photovoltaic array and DC/AC converter can equivalence be a controlled alternating-current voltage source, when considering photovoltaic generation mechanism, can regard big electrical network as Infinite bus system.The electric current of photovoltaic array output is converted to alternating current I through the DC/AC converter, and this electric current is remaining part I after capacitor [5] shunting
2Flow into electrical network by capacitor [6], thereby electrical power is presented to electrical network.
It shown in the accompanying drawing 2 capacitance coupling type photovoltaic parallel system is carried equivalent schematic diagram from reactive power to electrical network.Photovoltaic array and DC/AC converter can equivalence be a controlled alternating-current voltage source, and output and the synchronous alternating voltage of line voltage make the corresponding change of electric capacity on the capacitor [6], thereby change the reactive compensation capacity of grid-connected system to electrical network.
Can be connected with DC/DC converter [7] between described solar energy photovoltaic array [2] and the DC/AC converter [3], making photovoltaic parallel in system can keep DC/AC converter dc voltage when realization is followed the tracks of the peak power output of photovoltaic array is steady state value.
The DC side of described DC/AC converter [3] can be parallel with capacitor or the storage battery in order to energy storage.
Technique effect of the present invention is:
1. utilize the photovoltaic effect of solar cell that transform light energy is electric energy, the output energy of photovoltaic array is transformed into alternating current by the DC/AC converter after, give electrical network by capacitor with the energy feeding of photovoltaic array output.This and net mode is simple in structure, realize easily.
2. be connected to the grid after the series connection of capacitor [5] and capacitor [6], make the voltage of capacitor [5] lower, thereby very be suitable for the low characteristics of photovoltaic array output voltage.
3. the loss of capacitor is very little, makes the efficient height of grid-connected system.
4. the voltage that the output voltage of control DC/AC converter can control capacitor [6] two ends, thereby the reactive power compensation power of dynamic adjustments grid-connected system.
Description of drawings
Fig. 1 is that capacitance coupling type photovoltaic parallel system is exported the equivalent schematic diagram of energy feeding to electrical network with photovoltaic array;
Fig. 2 is capacitance coupling type photovoltaic parallel system is carried an equivalent schematic diagram from reactive power to electrical network;
Fig. 3 is the system configuration schematic diagram of the present invention that has the DC/DC converter;
Fig. 4 is concrete embodiment structure chart;
Fig. 5 is the control flow chart of controller;
Fig. 6 is the structural representation of three phase network capacitance coupling type photovoltaic parallel system;
Embodiment
Below in conjunction with drawings and Examples system of the present invention is described further.
Be an embodiment of system of the present invention as shown in Figure 4.It is mainly by Alternating Current Power Supply electrical network [1], solar energy photovoltaic array [2], DC/AC converter [3], controller formations such as [4], and the output of the direct current of solar energy photovoltaic array links to each other with the DC side of DC/AC converter.The invention is characterized in: be parallel with two capacitors [5] and [6] of mutual series connection on AC network, the two ends of capacitor [5] are connected in parallel on the AC side of DC/AC converter.DC/AC converter [3] is made of single-phase full bridge inverter circuit and the LC low-pass filter circuit that IGBT constitutes in this embodiment, and the LC low-pass filter circuit that is made of together inductance and electric capacity is in order to leach high frequency voltage spike and the rush of current that the action of IGBT HF switch causes.Controller [4] is a core with high performance digital signal process chip TMS320F2812, is aided with peripheral circuit and constitutes jointly.Solar cell photovoltaic array 1 adopts the HIT of Sanyo high efficiency solar cell to constitute, and is electric energy with solar energy converting; The direct current of solar energy photovoltaic array output becomes the sinusoidal ac with the line voltage same frequency after through single-phase bridge inverter circuit and the filtering of LC low-pass filter circuit, this alternating current by capacitor [5] and capacitor [6] with energy feeding to electrical network.Simultaneously, by controlling the reactive power compensation amount of grid-connected system to electrical network to the control of this alternating voltage.Controller [4] serves as the control core with the TMS320F2812 High Performance DSP, respectively the alternating voltage on the output AC voltage of the output voltage of solar energy photovoltaic array, output current, DC/AC converter and alternating current, the capacitor [5] is detected by voltage sensor and current sensor, through changing the voltage signal of the strong suitable DSP sampling of antijamming capability behind the signal conditioning circuit into, DSP carries out carrying out analyzing and processing after the A/D conversion to these signals.Accompanying drawing 5 is control flow charts of control system, at first DSP analyzes according to the A/D sampled result, detect warning messages such as whether overcurrent, overvoltage are arranged, after definite grid-connected system is working properly, begin to carry out closed-loop control, if AC network need be carried out the dynamic reactive power compensation, then increase the closed-loop control of dynamic passive compensation, control according to the reactive requirement of electrical network.Simultaneously, in order farthest to utilize solar energy, control system has been set up the closed-loop control to the maximal power tracing of photovoltaic array output power (MPPT), the output stack back of its control output and reactive power compensation closed-loop control provides by the PWM pin of pulse-width modulation (PWM) back by DSP as total output of control system.Pwm pulse opens and closure it by the IGBT in the photoelectricity isolation rear drive single-phase bridge inverter circuit by predetermined rule, thereby makes the voltage waveform of DC/AC converter output expection.Also be provided with the island effect trace routine in the control system, when photovoltaic parallel in system generation island effect, stop the output of photovoltaic parallel in system, shut down processing.TMS320F2812 provides keyboard and LCD MODULE interface, the parameter of controller can be set easily, the running status that shows photovoltaic parallel in system simultaneously, pass through serial communication interface, DSP can send to computer etc. with the service data of grid-connected system, is convenient to focusing on and managing of data.
As one embodiment of the present invention, can between solar energy photovoltaic array [2] and DC/AC converter [3], set up the DC/DC converter, when being carried out maximal power tracing, the solar energy photovoltaic array can keep DC/AC converter dc voltage to remain unchanged.At this moment, DSP exports other one group of pwm pulse and controls the break-make of power device among the DC/DC and realize MPPT control to photovoltaic array.
As one embodiment of the present invention, DC/AC converter using three-phase inverter, the output three-phase alternating voltage, by three group capacitors [5] and capacitor [6] energy feeding is gone in the three phase network, three capacitors [5] can connect to star-like, as shown in Figure 6, also can be the delta connection mode.The capacitance coupling type photovoltaic parallel of three-phase can be regarded the combination of three single-phase capacitance couplings and net mode as.Single-phase capacitance manifold type photovoltaic parallel in system may extend to heterogeneous application.
Claims (3)
1, a kind of capacitance coupling type photovoltaic parallel system, mainly comprise AC network [1], solar energy photovoltaic array [2], DC/AC converter [3], controller [4], it is characterized in that: be connected to series capacitors [5] and capacitor [6] on AC network [1], the interchange outlet side of DC/AC converter is in parallel with capacitor [5].
2, capacitance coupling type photovoltaic parallel system according to claim 1 is characterized in that being connected with DC/DC converter [7] between described solar energy photovoltaic array [2] and the DC/AC converter [3].
3, capacitance coupling type photovoltaic parallel system according to claim 1, the DC side parallel that it is characterized in that described DC/AC converter [3] has capacitor or the storage battery in order to energy storage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CNA2009100370510A CN101494386A (en) | 2009-02-02 | 2009-02-02 | Capacitance coupling type photovoltaic parallel system |
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| CNA2009100370510A CN101494386A (en) | 2009-02-02 | 2009-02-02 | Capacitance coupling type photovoltaic parallel system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103001189A (en) * | 2012-11-05 | 2013-03-27 | 冶金自动化研究设计院 | Converter overvoltage and overcurrent fault alarming protective circuit |
| KR101848973B1 (en) * | 2010-05-02 | 2018-05-28 | 멜리토 인코포레이티드 | Energy storage system, method of capturing electrical energy from lightning, and method of generating electricity |
| CN108406043A (en) * | 2018-04-20 | 2018-08-17 | 吴忠市中心电焊机有限公司 | Photovoltaic welding machine |
-
2009
- 2009-02-02 CN CNA2009100370510A patent/CN101494386A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101848973B1 (en) * | 2010-05-02 | 2018-05-28 | 멜리토 인코포레이티드 | Energy storage system, method of capturing electrical energy from lightning, and method of generating electricity |
| CN103001189A (en) * | 2012-11-05 | 2013-03-27 | 冶金自动化研究设计院 | Converter overvoltage and overcurrent fault alarming protective circuit |
| CN108406043A (en) * | 2018-04-20 | 2018-08-17 | 吴忠市中心电焊机有限公司 | Photovoltaic welding machine |
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Open date: 20090729 |