KR100934932B1 - Solar photovoltaic driving circuit - Google Patents

Abstract

PURPOSE: A solar photovoltaic driving circuit is provided to always supply a fixed voltage to an inverter by reducing difference between open voltages according to season. CONSTITUTION: A main array part(110) includes a plurality of first arrays(GA1~GH1). A first end of the first arrays is connected to a first pole of an inverter(300). An input terminal of a plurality of first switches(SA1~SH1) is connected to a second end of the first arrays. A first selecting terminal of the first switches is connected to a second pole of the inverter. A sub array part(130) includes a plurality of second arrays(GA2~GH2). The second arrays are connected to a second selecting terminal of the first switches. A plurality of second switches(SA2,SH2) is arranged between the second arrays.

Description

SOLAR PHOTOVOLTAIC DRIVING CIRCUIT}

The present invention relates to a photovoltaic drive circuit, and more particularly, to a photovoltaic drive circuit that can change the circuit according to the sensed ambient temperature.

In general, solar photovoltaic is one of solar energy generation technology. In other words, solar light energy is directly converted into electrical energy using a photoelectric converter called a solar module. It uses light in part, so it can be used even on cloudy days, making solar energy use more efficient than heat generation.

The solar power system is installed outside, not indoors. When installed outside, it is affected by the ambient temperature. In the case of the photovoltaic module, an open voltage of about 0.2V increases whenever the temperature decreases by 1 ° C based on the ambient temperature of 25 ° C. Formulating a method for obtaining the total open voltage of the array consisting of a plurality of solar modules can be expressed by the following equation (1).

Opening voltage = (36.9 V * N) + (reference temperature-sensing temperature) * 0.2 * N

Where N represents the number of photovoltaic modules connected in series to form an array. It is assumed that the open circuit voltage of one solar module is 36.9V and the reference temperature is 25 ° C.

In Korea, it is common to calculate the open circuit voltage of a module based on the external temperature of -20 ℃ in winter.In case of connecting 16 photovoltaic modules with the assumed module open circuit voltage of 36.9V in series, the ambient temperature is -20. The open circuit voltage in winter at 占 폚 is 734.4V according to Equation 1, and the open circuit voltage in summer at 35 占 폚 is 558.4V. In addition, in the winter when the ambient temperature is -20 ℃, if 18 solar modules having an open voltage of 36.9V in series, the open voltage is 826.2V by the equation (1).

However, in case of inverter converting DC voltage produced by solar module to AC voltage, there is a limit on the allowable input voltage range that can be converted. The device is in operation and cannot generate smooth power.

Therefore, the photovoltaic power generation system according to the related art has a limitation in that the voltage generation amount that can be generated through the photovoltaic module should be smaller than the allowable input voltage range of the inverter. In particular, in the summer when the temperature is high, the power generation voltage may drop. Inevitably, there is a problem that affects the power generation efficiency.

Therefore, the technical problem to be achieved by the present invention is to provide a photovoltaic drive circuit that can effectively maintain the power generation efficiency even in winter when the air temperature is low.

The solar cell driving circuit according to an embodiment of the present invention for achieving the technical problem includes a plurality of first array in which a plurality of solar modules are connected in series, the first stage of the plurality of first array Is a main array unit connected to a first pole of the inverter, an input terminal is respectively connected to a second end of the first array, and a first selection end is a plurality of first switches connected to a second pole of the inverter, And a plurality of second arrays in which the solar modules are connected in series, wherein the second array is positioned between the plurality of second arrays adjacent to the auxiliary array unit connected to the second selection terminal of the first switch, respectively. A plurality of second switches, a plurality of third switches connected between the plurality of second arrays and the second poles of the inverter, and the sensed temperatures by comparing the sensed temperatures with reference temperatures; 3 And a control unit for adjusting the switch.

When the sensed temperature is higher than the reference temperature, the controller may turn on the plurality of first switches to the second selection terminal, turn off the plurality of second switches, and turn on the third switch. .

The second array corresponding to the first array may be connected in series to each other to form a third array, and the plurality of third arrays may be connected to each other in parallel.

The controller, when the sensed temperature is lower than the reference temperature, turn on the plurality of first switches to the first selection stage, turn on the plurality of second switches, and the auxiliary switch among the plurality of third switches. The third switch connected to the solar PV module included in the first row of the array unit may be turned on.

All of the solar modules included in the auxiliary array unit may be connected in series to form a third array, and the plurality of first arrays and the third array may be connected in parallel with each other.

The total number of solar modules included in the auxiliary array unit may be equal to or greater than the number of solar modules included in the first array.

The inverter may include a plurality of inverters, and each inverter may correspond to the first array and the second array, respectively.

As described above, according to the present invention, in the photovoltaic drive circuit, by changing the circuit freely according to the ambient temperature in summer and winter, the difference in the open voltage according to the season can be reduced, so that the inverter improves constant voltage 365 days a year. Increasing the output of the inverter by increasing the voltage in the long summer, without compromising the operation of the inverter, by maximizing the average monthly increase in the annual power generation by compensating for the generation of winter during the relatively short year can do. In particular, the average voltage according to the open voltage of the photovoltaic module array can be increased in summer, thereby maximizing the power generation efficiency during the summer when the electricity is used a lot, which can be helpful for the management of national power supply in summer.

DETAILED DESCRIPTION OF THE EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

In addition, the expression that voltage is maintained throughout the specification indicates that even if the potential difference between two specific points changes over time, the change is within an allowable range in the design or the cause of the change is due to parasitic components that are ignored in the design practice of those skilled in the art. Include cases by. In addition, since the threshold voltage of a semiconductor device (transistor, diode, etc.) is very low compared to the discharge voltage, the threshold voltage is regarded as 0V and approximated.

In addition, the switch described throughout the specification includes all devices used to change the opening and closing of the electrical circuit, and may include a power control semiconductor device such as SCR, GTO thyristor, bipolar transistor, MOSFET, IGBT and the like.

1 is a block diagram of a solar power system according to an embodiment of the present invention. As shown in FIG. 1, the photovoltaic power generation system includes a photovoltaic power generation drive circuit 100, a circuit breaker 200, and an inverter unit 300. The photovoltaic driving circuit 100 converts and collects light energy incident from the sun into electrical energy, and generates a high voltage by connecting a plurality of photovoltaic modules in series. When the circuit breaker 200 is installed in the connection section between the photovoltaic drive circuit 100 and the inverter unit 300 and the voltage transmitted from the photovoltaic drive circuit 100 to the inverter unit 300 exceeds the allowable voltage. Block it. The inverter unit 300 converts electrical energy converted into direct current by the photovoltaic drive circuit 100 into alternating current energy and supplies it to various loads. In FIG. 1, the breaker 200 is illustrated as being separated from the inverter unit 300, but may be integrated with the inverter unit 300 and included in the inverter unit 300.

Hereinafter, a photovoltaic power generation driving circuit according to an embodiment of the present invention will be described in detail with reference to FIGS. 2 to 4.

2 is a circuit diagram illustrating a photovoltaic power generation driving circuit according to a first embodiment of the present invention. As shown in FIG. 2, the photovoltaic driving circuit 100 includes a main array unit 110, a first switching unit 120, an auxiliary array unit 130, a second switching unit 140, and a controller (not shown). ).

First, the main array unit 110 includes a plurality of arrays GA1, GB1, GC1,..., GG1, and GH1, and each array includes a plurality of solar modules connected in series.

According to FIG. 2, the main array unit 110 includes eight arrays, and each array includes sixteen solar modules. Taking the GA1 array as an example, sixteen solar modules A1, A2, A3, ..., A14, A15, A16 are connected in series. The solar module converts light energy incident from the sun into a direct current voltage, and according to an embodiment of the present invention, assumes an open voltage of 36.9V. Thus, when 16 solar modules with an open voltage of 36.9V are connected in series, the open voltage across an array is 590.4V, corresponding to 36.9V * 16. 2, one end of each of the arrays GA1, GB1, GC1,..., GG1, and GH1 is connected to the negative pole of the inverter unit 300.

The first switching unit 120 includes a plurality of three-way switches SA1, SB1, SC1,..., SG1, and SH1, and an input terminal of each three-way switch is connected to the other end of the main array unit 110. That is, the input terminals of the three-way switches SA1, SB1, SC1, ..., SG1, SH1 are connected to the corresponding photovoltaic modules A16, B16, C16, ..., G16, H16, respectively.

In addition, a first selection stage (shown as point 'a' in FIG. 2) of each three-way switch is connected to the inverter unit 300, and a second selection stage (shown as point 'b' in FIG. 2). Is connected to one end of the auxiliary array unit 130.

The auxiliary array unit 130 includes a plurality of arrays GA2, GB2, GC2,..., GG2, and GH2, and each array includes a plurality of solar modules connected in series. According to FIG. 2, the auxiliary array unit 130 includes eight arrays, and each array includes two solar modules. For example, two solar modules A17 and A18 are connected in series to the GA2 array.

Here, eight switches S1, S2,..., S7, and S8 are disposed between the arrays GA2, GB2, GC2,..., GG2, and GH2 included in the auxiliary array unit 130. Each of the switches S1, S2, ..., S7, S8 is alternately placed in a zigzag manner in 17 series and 18 series, so that when each of the switches S1, S2, ..., S7, S8 is turned on, All solar modules included in the array unit 130 are connected in series. That is, when the switches S1, S2, ..., S7, S8 are all turned on, the solar module is A18-A17-B17-B18-C18-C17-D17-D18-E18-E17-F17-F18-G18-G17 -H17-H18 are connected in series to form another array.

One end of the auxiliary array unit 130 is connected to the other end of the first switching unit 120. That is, each of the photovoltaic modules A17, B17, C17, ..., G17, H17 positioned at one end of the auxiliary array unit 130 has corresponding three-way switches SA1, SB1, SC1, ..., SG1, SH1. Is connected to.

The second switching unit 140 includes a plurality of switches SA2, SB2, SC2,..., SG2, and SH2, one end of each switch is connected to the other end of the auxiliary array unit 130, and the other end of the inverter unit. Connected with 300. That is, the input terminals of each of the eight switches SA2, SB2, SC2, ..., SG2, SH2 are connected to the corresponding solar modules A18, B18, C18, ..., G18, H18, respectively.

The positive pole of the inverter unit 300 is connected to the other ends of the plurality of switches SA2, SB2, SC2,..., SG2, SH2 included in the second switching unit 140, and the first switching unit 120. It is connected to the first selection terminal of the plurality of three-way switch (SA1, SB1, SC1, ..., SG1, SH1) included in. The inverter unit 300 converts the DC voltage generated from the solar modules included in the main array unit 110 and the auxiliary array unit 130 into an AC voltage.

On the other hand, the control unit senses the ambient temperature around the photovoltaic system, and corresponding to the detected temperature, the three-way switch (SA1, SB1, SC1, ..., SG1, SH1), the second included in the first switching unit 120 Controls switching of the plurality of switches SA2, SB2, SC2,..., SG2, SH2 included in the switching unit 140, and the switches S1, S2,..., S6, S7 included in the auxiliary array unit 130. do. In FIG. 2, the controller is not illustrated for convenience of description, and the controller may be included in the first switching unit 120, the auxiliary array unit 130, and the second switching unit 140.

Hereinafter, the switching operation of the controller will be described with reference to FIG. 3. 3 is a flowchart illustrating a switching control method of a controller according to an exemplary embodiment of the present invention.

First, the controller measures the atmospheric temperature around the solar power system (S310), and compares the sensed temperature with a reference temperature (S320). Here, the reference temperature is a temperature included in the range of minus 20 ° C or more and 35 ° C or less, and in the embodiment of the present invention, it may be set to about minus 20 ° C.

If the detected temperature is higher than the reference temperature, the controller switches the three-way switches SA1, SB1, SC1,..., SG1, and SH1 included in the first switching unit 120 to the second selection terminal (point 'b'). The switches S1, S2, ..., S7, S8 included in the auxiliary array unit 130 are turned off. In addition, the plurality of switches SA2, SB2,..., SG2, and SH2 included in the second switching unit 140 are turned on so that the photovoltaic power generation circuit is converted into an array of eight groups including 18 solar modules ( S330).

Therefore, the eight arrays GA1, GB1, GC1,..., GG1, GH1 included in the main array unit 110 are the eight arrays GA2, GB2, GC2,... , GG2, GH2) is connected in series. For example, sixteen solar modules A1, A2, A3, ..., A14, A15, and A16 included in the GA1 array are connected in series with two solar modules A17 and A18 included in the GA2 array. As a result, 18 solar modules are connected in series. Therefore, eight arrays of 18 solar modules connected in series are converted into a form in which the inverter unit 300 is connected in parallel.

In Equation 1, when the sensing temperature in summer is assumed to be 35 ° C. and N = 18 is substituted, the open voltage is 628.2V.

If the detected temperature is lower than the reference temperature, the controller moves the three-way switches SA1, SB1, SC1,..., SG1, and SH1 included in the first switching unit 120 to the first selection terminal (the 'a' point). The switch is turned on and the switches S1, S2,..., S7, and S8 included in the auxiliary array unit 130 are turned on. In addition, the switch SA2 is turned on among the plurality of switches included in the second switching unit 140, and the remaining seven switches SB2, SC2,..., SG2, and SH2 are turned off, and thus, 16 solar power generation circuits are provided. It is converted into a group of nine groups including the solar module (S340).

 At this time, all of the solar modules included in the auxiliary array unit 130 are connected in series, a new array (A18-A17-B17-B18-C18-C17-D17-D18-E18-E17-F17-F18-G18-G17) -H17-H18 are formed and referred to as an array IG1 for convenience of explanation.

Therefore, the eight arrays GA1, GB1, GC1,..., GG1, GH1 included in the main array unit 110 and the array IG1 generated in the auxiliary array unit 130 are connected in parallel. That is, nine arrays (GA1, GB1, GC1, ..., GG1, GH1, IG1) formed by connecting 16 solar modules in series are converted into a form in which the inverter unit 300 is connected in parallel.

In Equation 1, if the sensing temperature in winter is assumed to be minus 20 ° C and N = 16 is substituted, the open voltage is 734.4V. Therefore, the open circuit voltage is lowered by about 91.8V compared to the open circuit voltage of 826.2V when nine arrays in which 18 solar modules are connected in series at minus 20 ° C are connected in parallel.

Therefore, according to an embodiment of the present invention, the control unit switches so that the eight arrays formed by the 18 solar modules are connected in parallel in the summer when the air temperature is higher than the reference temperature, the parallel switching, 16 in the winter when the air temperature is lower than the reference temperature The solar modules are switched so that nine arrays formed in series are connected in parallel.

That is, according to the embodiment of the present invention, the size of the open voltage may be adjusted by dividing the photovoltaic power generation driving circuit including 144 photovoltaic modules into two types according to the temperature. Table 1 shows the change in the magnitude of the open voltage when implementing the PV drive circuit in two forms. Here, the magnitude of the open voltage is calculated through Equation 1.

16 1-array 9-group configuration Eight groups of 18 one arrays Number of solar modules 144 144 Winter opening pressure (-20 ℃) 734.4 V 826.2 V Summer Opening Pressure (35 ℃) 558.4 V 628.2 V

According to an embodiment of the present invention, in the summer of about 35 ℃ 18 solar modules are connected in series to form a parallel connection of eight arrays formed, in the winter of about 20 ℃ ℃ 16 solar modules are connected in series By converting the nine arrays to be connected in parallel, the seasonal difference in open voltage can be reduced to 106.2V, which is the difference between 734.4V and 628.2V.

In other words, in the case of a circuit having a 16-1 array of 9 groups regardless of temperature, the difference in seasonal open voltage is calculated as 176V corresponding to the difference between 734.4V and 558.4V. In addition, in the case of a circuit having an 18-by-1 array of 8 groups regardless of temperature, the difference in seasonal open voltage is calculated as 198V corresponding to 826.2V and 628.2V.

Therefore, according to an embodiment of the present invention, by freely changing the two types of circuit according to the sensed temperature, the difference in the open voltage according to the season can be reduced, so that the voltage fluctuation range is 365 days a year, stable power generation can do. In particular, there is an effect to maximize the power generation efficiency in summer.

4 is another circuit diagram illustrating the photovoltaic power generation driving circuit of FIG. 2. Compared with the photovoltaic drive circuit shown in FIG. 4, the auxiliary array unit 130 includes a separate array in addition to the plurality of arrays GA2, GB2, GC2,..., GG2, and GH2. The difference is that it further includes an array GI2. The GI2 array includes a plurality of solar modules I1, I2, and I3, and a switch S9 is included between the solar modules I1 and I3. The plurality of solar modules I1, I2, and I3 are preliminary modules, and may further improve the efficiency of photovoltaic power generation generated through the auxiliary array unit 130.

Therefore, when the switches S1, S2, ..., S7, S8, S9, S10 are all turned on, the solar module is A18-A17-B17-B18-C18-C17-D17-D18-E18-E17-F17-F18 -G18-G17-H17-H18-I2-I1-I3 are connected in series to form one array. Since the switching operation of the controller according to the temperature is substantially the same as in FIGS. 2 and 3, redundant descriptions thereof will be omitted.

5 is a circuit diagram illustrating a photovoltaic power generation driving circuit according to a second embodiment of the present invention. Compared with the photovoltaic drive circuit shown in FIG. 3, the photovoltaic drive circuit shown in FIG. 5 differs in the number and matrix form of the photovoltaic modules included in the main array unit 110 and the auxiliary array unit 130. have.

According to FIG. 5, the main array unit 110 includes six arrays GA1, GB1, GC1, GD1, GE1, and GF1, and each array includes 18 solar modules connected in series. The auxiliary array unit 130 includes six arrays GA2, GB2, GC2, GD2, GE2, and GF2, and each array includes three solar modules connected in series. Since the switching operation of the controller according to the temperature is substantially the same as in the first embodiment of the present invention, redundant description thereof will be omitted.

According to the second embodiment of the present invention, the size of the open voltage may be adjusted by dividing the photovoltaic driving circuit including 126 photovoltaic modules into two types according to temperature. That is, according to an exemplary embodiment of the present invention, when the atmospheric temperature is higher than the reference temperature, the control unit switches so that the six arrays in which 21 solar modules are connected in series are connected in parallel. The solar modules are switched so that the seven arrays formed in series are connected in parallel.

6 is a circuit diagram illustrating a photovoltaic power generation driving circuit according to a third embodiment of the present invention. According to FIG. 6, the photovoltaic driving circuit according to the third embodiment of the present invention uses a multistring scheme using an individual inverter for each array.

That is, the inverter unit 300 includes a plurality of inverters 301, 302,..., 307, 308, and the negative poles of the first to seventh inverters 301, 302,. It is connected to the arrays GA1, GB1, GC1, GD1, GE1, GF1, GG1. In more detail, the negative poles of the first to seventh inverters 301, 302,..., 307 are respectively connected to one ends of the corresponding solar modules A1, B1, C1, D1, E1, F1, and G1. Connected.

The positive poles of the first to seventh inverters 301, 302,..., 307 are respectively connected to the first selection terminals of the corresponding three-way switches SA1, SB1, SC1,..., SF1, SG1. And a plurality of switches SA2, SB2,..., SF2, and SG2 included in the second switching unit 140.

In addition, the negative pole of the eighth inverter 308 is connected to the switch S7 located at one end of the auxiliary array unit 130, and the positive pole of the eighth inverter 308 is included in the second switching unit 140 (SA2). )

Therefore, since the atmospheric temperature is higher than the reference temperature, the arrays GA1, GB1, GC1, ..., GF1, GG1 included in the main array unit 110 and the arrays GA2, GB2, When connected in series with GC2, ..., GF2, GF2, that is, when 21 solar modules are connected in series, the first to seventh inverters 301, 302, ..., 307 are individually connected to each enlarged array. Connected to convert a DC voltage into an AC voltage.

In addition, when the atmospheric temperature is lower than the reference temperature, all solar modules A21, A20, A19, B19, B20, ..., F21, G21, G20, and G19 included in the auxiliary array unit 130 are connected in series. The inverter 308 is connected to the array formed by the photovoltaic module included in the auxiliary array unit 130 to convert a DC voltage into an AC voltage.

As described above, according to the present invention, in the photovoltaic drive circuit, by changing the circuit freely according to the ambient temperature in summer and winter, the difference in the open voltage according to the season can be reduced, so that the inverter improves constant voltage 365 days a year. Increasing the output of the inverter by increasing the voltage in the long summer, without compromising the operation of the inverter, by maximizing the average monthly increase in the annual power generation by compensating for the generation of winter during the relatively short year can do. In particular, the average voltage according to the open voltage of the photovoltaic module array can be increased in summer, thereby maximizing the power generation efficiency during the summer when the electricity is used a lot, which can be helpful for the management of national power supply in summer.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a block diagram of a solar power system according to an embodiment of the present invention.

2 is a circuit diagram illustrating a photovoltaic power generation driving circuit according to a first embodiment of the present invention.

3 is a flowchart illustrating a switching control method of a controller according to an exemplary embodiment of the present invention.

4 is another circuit diagram illustrating the photovoltaic power generation driving circuit of FIG. 2.

5 is a circuit diagram illustrating a photovoltaic power generation driving circuit according to a second embodiment of the present invention.

6 is a circuit diagram illustrating a photovoltaic power generation driving circuit according to a third embodiment of the present invention.

Claims (7)

A plurality of first arrays in which a plurality of solar modules are connected in series, and a first end of the plurality of first arrays is connected to a first pole of an inverter; Input terminals are respectively connected to the second stage of the first array, and the first selection stage includes a plurality of first switches connected to the second pole of the inverter; A plurality of second arrays in which the plurality of photovoltaic modules are connected in series, wherein the second array includes an auxiliary array unit connected to a second selection end of the first switch; A plurality of second switches located between the plurality of adjacent second arrays, A plurality of third switches connected between the plurality of second arrays and the second poles of the inverter, and And a controller configured to adjust the plurality of first, second, and third switches by comparing the sensed temperature with a reference temperature. The method of claim 1, The control unit, And turning on the plurality of first switches to the second selection stage, turning off the plurality of second switches and turning on the third switch if the sensed temperature is higher than the reference temperature. The method of claim 2, And the second array corresponding to the first array is connected in series to each other to form a third array, and the plurality of third arrays are connected to each other in parallel. The method of claim 1, The control unit, When the sensed temperature is lower than a reference temperature, the plurality of first switches are turned on to the first selection terminal, respectively, the plurality of second switches are turned on, and a first row of the auxiliary array unit is included in the plurality of third switches. The solar power generation driving circuit for turning on the third switch connected to the solar module included in. The method of claim 4, wherein And all of the solar modules included in the auxiliary array unit are connected in series to form a third array, and the plurality of first arrays and the third array are connected to each other in parallel. The method of claim 1, The total number of photovoltaic modules included in the auxiliary array unit is equal to or greater than the number of photovoltaic modules included in the first array. The method of claim 1, The plurality of inverters may include a plurality of inverters, and first poles of the plurality of inverters may be connected to the first ends of the first array, respectively, and second poles of the first switches connected to the corresponding first arrays. A first switch and a third switch connected to the second array corresponding to the first switch, respectively, A photovoltaic drive circuit further comprising a secondary inverter having a first pole connected to the second switch connected to the last row of the auxiliary array unit and a second pole connected to the third switch connected to the first row of the auxiliary array unit. .

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