CN2762419Y

CN2762419Y - Parallel network photovoltaic inversion system

Info

Publication number: CN2762419Y
Application number: CN 200420121029
Authority: CN
Inventors: 赵斌; 李亚西; 赵栋利; 潘磊; 李峰; 姚红菊
Original assignee: Institute of Electrical Engineering of CAS
Current assignee: Beijing Corona Science and Technology Co Ltd
Priority date: 2004-12-30
Filing date: 2004-12-30
Publication date: 2006-03-01
Anticipated expiration: 2014-12-30

Abstract

The utility model relates to a parallel network photovoltaic inversion system, which is characterized in that the utility model comprises two industrial frequency transformers (7), (8) and a real-time detecting and control system of an inversion device, wherein the same kind of isolation transformer is adopted by the two industrial frequency transformers, the capacity of the transformer (7) is the same as the rated capacity of the inversion system, and the capacity of the transformer (8) is equal to 30 percent of the rated capacity of the inversion system. The two transformers (7), (8) are in parallel connection with each other, the real-time detecting and control system is mainly composed of voltage sensors (9), (10), current sensors (11), (12), an analog-digital conversion chip (16), DSP (17), etc., wherein the output of the voltage and the current sensors is connected with the analog-digital conversion chip (16) which is directly connected to a universal IO mouth of the DSP (17), and output control signals of the DSP (17) are used for controlling the connection and disconnection of contactors (3), (4), (5), (6). The transformer can always runs at higher efficiency through the utility model, therefore the efficiency of the overall system is improved, and the utility model is suitable for single-phase or three-phase systems.

Description

Grid-connected photovoltaic inverter system

Technical field

The utility model relates to the inversion system in the grid-connected photovoltaic power generation system.

Background technology

Grid-connected photovoltaic inverter system is that dc inverter that solar panel is sent becomes the amplitude with line voltage, the inversion system that frequency is all identical with phase place.It generally is that an inverter and an Industrial Frequency Transformer of being made up of power electronic device and control section thereof constitutes.Inverter mainly is that dc inverter is become to exchange, and realizes maximal power tracing control.And Industrial Frequency Transformer mainly plays the effect with inverter and electrical network isolation, so promptly can strengthen the safety of inverter, has guaranteed that again the issuable DC component of inverter can not exert an influence to electrical network.As shown in Figure 1, in general Grid-connected photovoltaic inverter system, the input side joint solar panel of inverter becomes to exchange with the dc inverter that solar panel sent, and links by transformer and electrical network then, and energy is offered electrical network.

At present the solar cell plate efficiency space of improving is very limited, so the efficient of inversion system has the decision meaning for the efficient of whole grid-connected photovoltaic power generation system, and the efficient that how to improve Grid-connected photovoltaic inverter system is just very crucial.With regard to present technology, near the efficient of grid-connected photovoltaic power generation system rated power the time has reached satisfied level, but the efficient of whole inversion system is lower when underloading.This mainly be since Industrial Frequency Transformer efficient is lower when light running causes.

The utility model content

For the Grid-connected photovoltaic inverter system that the overcomes prior art lower shortcoming of efficient when the underloading, the utility model proposes a kind of new Grid-connected photovoltaic inverter system.

The utility model is made up of an inverter and two Industrial Frequency Transformers.Wherein, inverter is identical with the inverter of existing system.The transformer that two Industrial Frequency Transformers are respectively rated capacities and the transformer of a low capacity.Parallel with one another between two transformers.When Grid-connected photovoltaic inverter system operates in underloading, adopt the transformer operation of low capacity; And adopt the transformer of rated capacity to move in other cases.Because near the efficient of transformer its nominal load can reach very high, so even the utility model has higher efficient too when underloading.

Description of drawings

Fig. 1 is the schematic diagram of prior art Grid-connected photovoltaic inverter system.

Fig. 2 is a schematic diagram of the present utility model.

Fig. 3 is the schematic diagram of real-time Detection ﹠ Controling system in the utility model.

Fig. 4 is the catenation principle figure of DSP and AD module in the utility model.

Embodiment

Below in conjunction with the drawings and specific embodiments the utility model is further described.

As shown in Figure 2, the utility model has adopted two cover transformers 7,8, also comprises the real-time Detection ﹠ Controling system of an inverter simultaneously.Wherein, two transformers 7,8 adopt same a kind of isolating transformer, but different capacitance grades is arranged: the capacity of transformer 7 is identical with the rated capacity of this inversion system, and the capacity of transformer 8 equals 30% of this inversion system rated capacity.

As shown in Figure 3, the Detection ﹠ Controling system is mainly by voltage sensor 9,10 in real time, and current sensor 11,12, modulus conversion chip 16 and DSP17 etc. partly constitute.Wherein, voltage-current sensor adopts Ke Hai company product.Voltage sensor 9,20 adopts the KVAP model, and current sensor 11,12 adopts KAV model or KAVT model.Voltage-current sensor is used to detect the output voltage and the electric current of inverter, and the output of voltage-current sensor links to each other with modulus conversion chip 16.Modulus conversion chip 16 adopts the AD7864 of AD companies, and its input range is-10V～+ 10V.

The output of modulus conversion chip 16 is directly connected to the universal I/O port of DSP17.That DSP17 adopts is the fixed DSP of American TI Company: F2812.The output control signal of DSP17 is control contactor 3,4,5,6 break-make.

As shown in Figure 4, AD7864 with the annexation of F2812 is: the IOPAn pin of F2812 is connected with the CONVST pin of AD7864, and when IOPAn produces a low level signal to the CONVST pin, AD7864 just begins to carry out analog-to-digital conversion.The IS pin of F2812 is received the chip selection signal pin CS end of AD7864-1.The R/W of F2812 and W/R pin are connected with RD and the WR pin of AD7864-1 respectively.When the WR pin received the useful signal that the W/R pin sends, the numerical data after AD7864 will change write the data field; When the R/W pin when the RD pin sends a low level signal, expression F2812 prepares from the AD7864 reading of data.Data wire D0～D15 of F2812 is connected with the data wire of AD7864 respectively, and F2812 reads in the data of AD7864 among the F2812 by these data wires.The BUSY pin of AD7864 is connected to the XINTn pin of F2812, as long as the BUSY pin of AD7864 is a high level, then the XINTn pin of F2812 also is a high level, and expression has the conversion of AD7864 not finish.

When inverter is worked, the voltage and current transducer of Detection ﹠ Controling system can detect the output voltage and the electric current of inverter in real time in real time, transducer be output as with the proportional analog quantity of the electric weight that detects, these analog quantitys are input to modulus conversion chip 16, after converting digital quantity to, be input among the DSP17 again.DSP17 according to the program of being worked out in the DSP17, can calculate the power output of inverter according to the amplitude and the phase place of input voltage and input current in real time.The value that sets in this power output and the DSP17 is compared: when DSP17 is bigger than predefined value A by the value that obtains after calculating (value A represent inverter rated power 30%), the output of its a general input/output port (IO mouth) of DSP17 control is uprised by low, this output signal is received on the auxiliary relay 18 after by a light lotus root 13, and this auxiliary relay is with direct control contactor 3 and contactor 4 conductings.This moment, inverter linked by transformer 7 and electrical network; The value that obtains after DSP17 is by calculating was than predefined value A hour (this moment, power output was at below 30% of rated power), DSP17 is by the general input/output port of another one (IO mouth) control contactor 5 and contactor 6 conductings, and this moment, inverter linked by transformer 8 and electrical network.

In actual implementation process, the phenomenon of switching repeatedly for the contactor that prevents from when the power output of inverter changes about 30%, may occur, when working control, be provided with the ring that stagnates: in contactor 3 and 4 conductings, during transformer 7 operations, if this moment, the power output of inverter reduced, then when real-time Detection ﹠ Controling system detect power output less than rated power 28% the time, DSP17 control contactor 5 and 6 conductings, contactor 3 and 4 disconnects; When contactor 5 and 6 conductings, during transformer 8 operation, if this moment inverter power output increase, then when real-time Detection ﹠ Controling system detect power output greater than rated power 32% the time, control contactor 3 and 4 conductings, contactor 5 and 6 disconnections.The phenomenon that the contactor that stagnant ring controlling schemes like this can be avoided may occurring when the power output of inverter changes about 30% effectively switches repeatedly.

The utility model makes transformer always operate in a higher efficient.Thereby make overall system efficiency also be improved.

The utility model is applicable to single-phase or three-phase system.

Claims

1, a kind of Grid-connected photovoltaic inverter system comprises inverter, Industrial Frequency Transformer, it is characterized in that comprising the real-time Detection ﹠ Controling system of two Industrial Frequency Transformers [7], [8] and an inverter; Adopt with a kind of isolating transformer two Industrial Frequency Transformers [7], [8], and the capacity of transformer [7] is identical with the rated capacity of this inversion system, and the capacity of transformer [8] equals 30% of this inversion system rated capacity; Two transformers [7], [8] are parallel with one another; The Detection ﹠ Controling system is mainly by voltage sensor [9], [10] in real time, current sensor [11], [12], modulus conversion chip [16] and DSP[17] etc. part constitute, the output of voltage-current sensor links to each other with modulus conversion chip [16], modulus conversion chip [16] is directly connected to DSP[17 again] universal I/O port, DSP[17] output control signal control contactor [3], [4], [5], the break-make of [6].

2, according to the described Grid-connected photovoltaic inverter system of claim 1, it is characterized in that described modulus conversion chip [16] AD7864 and DSP:F2812[17] annexation be: the IOPAn pin of F2812 is connected with the CONVST pin of AD7864, when IOPAn produces a low level signal to the CONVST pin, AD7864 just begins to carry out analog-to-digital conversion; The IS pin of F2812 is received the chip selection signal pin CS end of AD7864; The R/W of F2812 and W/R pin are connected with RD and the WR pin of AD7864 respectively; When the WR pin received the useful signal that the W/R pin sends, the numerical data after AD7864 will change write the data field; When the R/W pin when the RD pin sends a low level signal, expression F2812 prepares from the AD7864 reading of data; Data wire D0～D15 of F2812 is connected with the data wire of AD7864 respectively, and F2812 reads in the data of AD7864 among the F2812 by these data wires; The BUSY pin of AD7864 is connected to the XINTn pin of F2812, as long as the BUSY pin of AD7864 is a high level, then the XINTn pin of F2812 also is a high level, and expression has the conversion of AD7864 not finish.

3, according to the described Grid-connected photovoltaic inverter system of claim 1, it is characterized in that the voltage and current transducer of real-time Detection ﹠ Controling system detects the output voltage and the electric current of inverter in real time, what transducer was exported is input to modulus conversion chip [16] with the proportional analog quantity of detection electric weight, after converting digital quantity to, be input to DSP[17 again] in; DSP[17] according to the amplitude and the phase place of input voltage and input current, according to DSP[17] the interior program of being worked out, calculate the power output of inverter in real time, with this power output and DSP[17] in the value that sets compare: as DSP[17] by the value that obtains after calculating greater than predefined value A---inverter rated power 30% the time, DSP[17] output of controlling its a general input/output port (IO mouth) uprises by low, this output signal is received on the auxiliary relay [18] after by a light lotus root [13], and this auxiliary relay is with direct control contactor [3] and contactor [4] conducting; This moment, inverter linked by transformer [7] electrical network; As DSP[17] by the value that obtains after calculating during less than predefined value A, this moment, power output was at below 30% of rated power, DSP[17] logical by the general input/output port of another one (IO mouth) control contactor [5] and contactor [6], this moment, inverter linked by transformer [8] and electrical network.