WO2017000910A1

WO2017000910A1 - Photovoltaic electricity generation system and method of operating same to perform photovoltaic electricity generation

Info

Publication number: WO2017000910A1
Application number: PCT/CN2016/088093
Authority: WO
Inventors: 江红胜; 曹晓宁; 庄波; 温志伟
Original assignee: 中民新能投资有限公司
Priority date: 2015-07-01
Filing date: 2016-07-01
Publication date: 2017-01-05
Also published as: CN104953945A; CN104953945B; CN205430161U

Abstract

The disclosed embodiments provide a photovoltaic electricity generation system, the photovoltaic electricity generation system (100) comprising: an electricity conversion apparatus (120), having a first input (121) and a second input (122); and a DC module (110), the DC module (110) comprising: a bus bar (150); and an upper bridge unit (130) and a lower bridge unit (140) sharing the bus bar (150) and mutually connected in parallel with respect to the bus bar (150); and a circuit formed between the upper bridge unit (130) and the bus bar (150) and a circuit formed between the lower bridge unit (140) and the bus bar (150) capable of respectively generating DC electrical energy according to incident light respectively received thereby. The present disclosure further provides a method of operating the above photovoltaic electricity generation system in order to perform photovoltaic electricity generation. The disclosed photovoltaic system and electricity generation method of the embodiments can enable independent control of photovoltaic modules comprised in mutually independent control circuits according to sunlight or a state of the photovoltaic module, thereby markedly advancing the efficiency of photovoltaic electricity generation.

Description

Photovoltaic power generation system and method of operating the same for photovoltaic power generation

Technical field

The present disclosure relates to photovoltaic power generation and, in particular, to independently controlled photovoltaic power generation systems and methods.

Background technique

Photovoltaic power generation is a technology that directly converts light energy into electrical energy by utilizing the photovoltaic effect of the semiconductor interface. Photovoltaic panels or photovoltaic panels typically output direct current and convert the direct current from the photovoltaic panel to a stable, different voltage direct current output as needed through a DC-to-DC converter coupled thereto. Thereafter, via the electrical conversion device, the direct current can be converted to alternating current to access the grid or to power the home.

Since different photovoltaic panels may be in different physical environments, the output voltage or current of each photovoltaic panel may be quite different. For example, for a large-area photovoltaic module, some of its photovoltaic panels may be blocked by buildings, trees, or other objects at certain times, and thus such physical environment weakens the electrical output performance of the photovoltaic panels. In addition, due to the difference in age, different photovoltaic panels may have different degrees of aging, which also has an impact on the electrical output performance of the photovoltaic panel. All of the above may reduce the efficiency of photovoltaic power generation.

Summary of the invention

It is an object of the present disclosure to provide a photovoltaic power generation system and a method of operating the same that improve photovoltaic power generation efficiency.

According to an aspect of the disclosure, a photovoltaic power generation system is provided. The photovoltaic power generation system includes: an electrical conversion device having a first input and a second input; and a direct current module including: a bus bar; and an upper bridge unit and a lower bridge unit that share the bus bars and are connected in parallel with each other with respect to the bus bars, The circuit formed by the upper bridge unit and the busbar is And the circuit formed by the lower bridge unit and the busbar generates DC power according to the respective received incident light energy.

A photovoltaic power generation system formed in accordance with the present disclosure utilizes circuits that do not interfere with each other to generate independent direct current. Since the upper bridge unit and the lower bridge unit have a common bus bar for each DC module, the solution of the present disclosure can select the withstand voltage for the upper bridge unit and the lower bridge unit compared to the scheme for using one conversion circuit for the same number of photovoltaic panels. Low power devices reduce costs while improving the efficiency of photovoltaic power generation.

According to an embodiment of the present disclosure, the upper bridge unit may include: an upper bridge DC-DC converter having an upper bridge input and an upper bridge output and an upper bridge filter capacitor connected between the upper bridge output and the bus, the upper bridge The output is connected to a first input of the electrical conversion device; and the upper bridge photovoltaic component is capable of generating a DC output from the received light energy, the positive output of the upper bridge photovoltaic component being coupled to the upper bridge input and the negative output of the upper bridge photovoltaic component Connect to the bus.

According to an embodiment of the present disclosure, the lower bridge unit may include: a lower bridge DC-DC converter having a lower bridge input and a lower bridge output and a lower bridge filter capacitor connected between the lower bridge output and the bus, the lower bridge output being a second input connected to the electrical conversion device; and a lower bridge photovoltaic component capable of generating a DC output from the received light energy, a negative output of the lower bridge photovoltaic component being connected to the lower bridge input and a positive output of the lower bridge photovoltaic component being connected to the busbar .

According to an embodiment of the present disclosure, the upper bridge photovoltaic component may include a plurality of photovoltaic panels connected in series.

According to an embodiment of the present disclosure, the lower bridge photovoltaic component may include a plurality of photovoltaic panels connected in series.

According to an embodiment of the present disclosure, the direct current module may include a plurality of upper bridge units connected in parallel with respect to the bus bars and a plurality of lower bridge units connected in parallel with respect to the bus bars. In this way, different numbers of upper and lower bridge units can be accessed in one DC module as needed, and DC power can be generated independently of each other.

According to an embodiment of the present disclosure, the photovoltaic power generation system may include a plurality of DC modules connected in parallel to the first input and the second input of the electrical conversion device. In this way, Multiple DC modules can be connected to one electrical conversion device as needed, and the number of upper and lower bridge units of each DC module can also be different. Therefore, the configuration according to an embodiment of the present disclosure realizes flexible photovoltaic power generation, and the photovoltaic power generation output power in units of each of the upper and lower bridge units of each of the direct current modules can be optimized without affecting each other.

According to an embodiment of the present disclosure, the electrical conversion apparatus may further include a bus input that is connected to the bus input.

According to an embodiment of the present disclosure, both the upper bridge DC-DC converter and the lower bridge DC-DC converter may be boost type DC-DC converters.

According to an embodiment of the present disclosure, each of the upper-bridge DC-DC converter and the lower-bridge DC-DC converter may include: an energy storage inductor, providing an upper bridge input at the first end; and a power switch a tube connected between the second end of the energy storage inductor and the bus bar; and a freewheeling diode connected between the second end of the energy storage inductor and the upper bridge output or the lower bridge output.

According to an embodiment of the present disclosure, the photovoltaic power generation system may further include a controller that receives at least one of a voltage and a current from an upper bridge input, a lower bridge input, an upper bridge output, and a lower bridge output, and according to the received The upper bridge DC-DC converter and the lower bridge DC-DC converter are controlled by at least one of voltage and current.

According to an embodiment of the present disclosure, the controller may be a maximum power point tracking MPPT controller. In this way, each controller can detect in time when the output power of the circuit is significantly smaller, and determine whether to continue the maximum power point tracking of the photovoltaic components in the upper or lower bridge unit as needed, thereby reducing the photovoltaic components. Negative effects of current or power mismatch with electrical switching equipment.

According to an embodiment of the present disclosure, the electrical conversion device may include at least one of an inverter, a battery, and a direct current electrical device.

According to another aspect of the present disclosure, there is provided a method of operating a photovoltaic power generation system as described above for photovoltaic power generation, comprising: initializing an electrical conversion device and a direct current module; measuring a bus voltage on the bus, on an upper bridge output Bridge output voltage and the lower bridge output voltage on the lower bridge output; the difference between the upper bridge output voltage and the bus voltage and the lower bridge The absolute value of the difference between the output voltage and the bus voltage is compared with a preset voltage threshold, and if the absolute value of the difference is less than the preset voltage threshold, the maximum of both the upper bridge DC-DC converter and the lower bridge DC-DC converter is performed. Power point following control, if the absolute value of the difference is greater than the preset voltage threshold, maximum power point following control is performed on one of the upper bridge DC-DC converter and the lower bridge DC-DC converter.

The photovoltaic system and the power generation method according to various embodiments of the present disclosure enable the photovoltaic panels to be individually controlled in the control circuits independent of each other according to the conditions of the sunlight or the photovoltaic panel, thereby significantly improving the efficiency of photovoltaic power generation.

DRAWINGS

The above and other objects, features and advantages of the embodiments of the present invention will become more <RTIgt; In the figures, various embodiments of the present disclosure are described by way of example and not limitation

FIG. 1 illustrates a structural schematic diagram of a photovoltaic power generation system in accordance with an embodiment of the present disclosure;

2 illustrates a further structural schematic of a photovoltaic power generation system in accordance with an embodiment of the present disclosure;

3 illustrates a schematic circuit diagram of a DC module in a photovoltaic power generation system in accordance with an embodiment of the present disclosure;

4 illustrates a method of operating a photovoltaic power generation system for photovoltaic power generation, in accordance with an embodiment of the present disclosure.

detailed description

The principles of the present disclosure will now be described with reference to various exemplary embodiments illustrated in the drawings. It is to be understood that the description of the embodiments is only to be understood by those skilled in the art, and is not intended to limit the scope of the disclosure in any way. It should be noted that similar or identical reference numerals may be used in the drawings where possible, and similar or identical reference numerals may indicate similar or identical functions. Those skilled in the art will readily recognize the description from the following Alternative embodiments of the structures and methods described herein may be employed without departing from the principles of the invention described herein.

FIG. 1 illustrates a structural schematic of a photovoltaic power generation system 100 in accordance with an embodiment of the present disclosure. Photovoltaic power generation system 100 is a system for converting energy in received sunlight into electrical energy. Typically such systems include electrical conversion device 120 to distribute the generated electrical energy to different applications. The electrical conversion device 120 of the present application can be a variety of different devices. For example, electrical conversion device 120 can include a battery or battery pack to store such electrical energy by converting electrical energy to chemical energy. Alternatively, the electrical conversion device 120 can include an inverter to convert the generated direct current to alternating current to power the input device or input to the grid. The electrical conversion device 120 can also include a battery and an inverter, for example, for charging the battery during daytime sunshine and using the stored energy in the battery for further AC power distribution when there is no sunlight at night. . In some cases, the electrical conversion device 120 can also be a direct current electrical device that converts electrical energy to mechanical energy, such as a direct current motor.

Photovoltaic power generation system 100 also includes a DC module 110 that is coupled to and provides DC power to electrical conversion device 120. It should be understood that although only one DC module 110 is shown in FIG. 1, in other embodiments, multiple DC modules 110 may be associated with a common input terminal of the electrical conversion device 120 (ie, the first input 121 and The second input 122, and optional bus input 123) are connected in parallel. The DC module 110 is configured to receive light from the outside that is incident on a photovoltaic panel, such as a photovoltaic panel, and convert it to a DC output having an appropriate voltage and current to the electrical conversion device 120.

As shown in FIG. 1, the DC module 110 includes a bus bar 150, an upper bridge unit 130 and a lower bridge unit 140 that share the bus bar 150 and are connected in parallel with each other with respect to the bus bar 150. The circuit formed by the upper bridge unit 130 and the bus bar 150 and the circuit formed by the lower bridge unit 140 and the bus bar 150 generate DC power according to the respective received incident light energy. The DC power generated by the upper bridge unit 130 is delivered to the first input of the electrical conversion device 120 via the upper bridge output 135. The DC power generated by the lower bridge unit 140 is delivered to the second input of the electrical conversion device 120 via the lower bridge output 145. Bus 150 can be powered as needed The gas is connected to the bus input 123 of the electrical conversion device 120 or is not connected to the bus input 123. Since the connection of busbar 150 to electrical conversion device 120 is optional and not necessary, in FIG. 2, the connection of busbar 150 to busbar input 123 of electrical conversion device 120 is indicated by dashed lines.

FIG. 2 illustrates a further structural schematic of a photovoltaic power generation system 100 in accordance with an embodiment of the present disclosure. The upper bridge unit 130 includes an upper bridge photovoltaic component 131 and an upper bridge DC-DC converter 132, and the lower bridge unit 140 includes a lower bridge photovoltaic component 141 and a lower bridge DC-DC converter 142. Each of the upper bridge photovoltaic component 131 and the lower bridge photovoltaic component 141 can include a single photovoltaic panel for converting the energy of the optical radiation into electrical energy. The photovoltaic panel can be in the form of a panel made of semiconductor (or commonly referred to as a solar cell) or any other suitable form. Moreover, in some other embodiments, multiple photovoltaic panels may also be included in each of the upper or lower bridge

photovoltaic modules

131, 141. The negative pole of the upper bridge photovoltaic component 131 can be connected to the busbar 150. Thus, the positive pole of the upper bridge photovoltaic component 131 can be connected to the upper bridge DC-DC converter 131 via the upper bridge input 134. Accordingly, the anode of the lower bridge photovoltaic component 141 can be connected to the bus 150, and thus, the cathode of the lower bridge photovoltaic component 141 can be connected to the lower bridge DC-DC converter 141 via the lower bridge input 144.

The upper bridge DC-DC converter 132 may include a power device (not shown) that modulates the current and voltage of the DC power to be output, thereby passing the upper bridge output 135 of the upper bridge DC-DC converter 132 and the electrical conversion device 120. The first input 121 forms a better fit with the electrical conversion device 120. Accordingly, the lower bridge DC-DC converter 142 may also include a power device (not shown) that modulates the current and voltage of the DC power to be output, thereby passing the lower bridge output 145 of the lower bridge DC-DC converter 142 and The second input 122 of the electrical conversion device 120 forms a better fit with the electrical conversion device 120.

The upper bridge DC-DC converter 132 includes an upper bridge filter capacitor 133 that is bridged between the upper bridge output 135 and the bus 150. Accordingly, the lower bridge DC-DC converter 142 also includes a lower bridge filter capacitor 143 that is bridged between the lower bridge output 145 and the bus 150. The bus bar 150 may in one embodiment be electrically connected to the bus input 123 of the electrical conversion device 120 (provided the electrical conversion device provides a bus input terminal), but in another implementation In an example, the bus bar 150 may not form a direct connection to the electrical conversion device 120. Therefore, the bus bar 150 and the electrical conversion device 120 are indicated by broken lines in FIG.

It should be understood that although the embodiment shown in FIG. 2 shows only one upper bridge unit 130 and one lower bridge unit 140, in other embodiments there may be one or more upper bridge units 130 and one or more Lower bridge unit 140. For example, a plurality of upper or lower units that are the same or different (eg, different configurations of photovoltaic modules, different configurations of DC-DC converters, etc.) may be connected in parallel with respect to bus 150 and have their respective upper bridge outputs coupled to electrical The first input 121 of the device 120 is converted. Similarly, a plurality of identical or different lower bridge units can be connected in parallel with respect to bus 150 and have their respective lower bridge outputs coupled to second input 122 of electrical conversion device 120. The number of upper bridge unit 130 and lower bridge unit 140 may be the same or different. Moreover, the term "unit" as used in an upper bridge unit or a lower bridge unit does not exclude the possibility of including several components or elements therein, for example, a "unit" according to an embodiment of the present disclosure may include, for example, a photovoltaic module and Multiple components such as a transformer.

As described above with reference to FIG. 1, there may be multiple DC modules 110 connected to the same electrical conversion device 120. Thus, the nth DC module is indicated by a square in the lower portion of Fig. 2, and the n-2 DC modules in the middle are omitted in Fig. 2. The configuration and configuration in each DC module may be the same or different (eg, the number of upper bridge units, the number of lower bridge units, the composition of the photovoltaic components, the configuration of the DC-DC converter, etc.). Each of the upper or each lower bridge units of each of the direct current modules can be independently controlled, thereby ensuring that the efficiency of power generation for each of the photovoltaic modules can be individually optimized, thereby increasing the overall power generation efficiency of the system. Furthermore, since more than one DC module 110 is optional and not necessary, in FIG. 2, the connection of the nth DC module 110 to the electrical conversion device 120 is indicated by a broken line. The description of the independent control can be explained below with reference to a simplified circuit diagram of a DC module 110 of FIG.

FIG. 3 illustrates a schematic circuit diagram of a DC module 110 in a photovoltaic power generation system 100 in accordance with an embodiment of the present disclosure. For the upper bridge unit 130, an upper bridge photovoltaic component 131 (not shown in FIG. 3) may be bridged between the first bus end point 151 of the busbar 150 and the first upper bridge end point 134, and in this example the upper bridge The positive electrode of the photovoltaic module 131 is Connected to the first upper bridge end 134, the negative pole is connected to the first bus end point 151. The upper bridge filter capacitor 133 is bridged between the upper bridge output 135 and the second bus terminal 152. In addition, the upper bridge DC-DC converter 132 can include an upper bridge energy storage inductor 136, an upper bridge freewheeling diode 137, and an upper bridge power switch tube 138. The upper bridge auxiliary diode 139 can be connected across the upper bridge power switch tube 138 (connected in anti-parallel mode) for protection.

Similarly, for the lower bridge unit 140, a lower bridge photovoltaic component 141 (not shown in FIG. 3) may be bridged between the first bus end 151 and the first lower bridge end 144 of the bus 150, and in this example The cathode of the mid-lower bridge photovoltaic module 141 is connected to the first lower bridge end 144, the anode of which is connected to the first bus terminal 151. The lower bridge filter capacitor 143 is bridged between the lower bridge output 145 and the second bus terminal 152. In addition, the lower bridge DC-DC converter 142 can include a lower bridge energy storage inductor 146, a lower bridge freewheeling diode 147, and a lower bridge power switch tube 148. The lower bridge auxiliary diode 149 can be bridged across the lower bridge power switch 148 (connected in anti-parallel mode) for protection. Due to the different orientation of the photovoltaic modules, the direction of the directional components (eg, power switch tubes, diodes, etc.) in the upper bridge unit 130 may be different from the direction of the directional components in the lower bridge unit 140, as in FIG. Shown in .

Although only one of the components is shown in FIG. 3, it should be understood that the present disclosure does not limit the number of such components. These components may be of different types or types. For example, the upper bridge power switch 138 may be in the form of an insulated gate bipolar transistor (IGBT) or other power switch component capable of implementing a corresponding control/switching function.

In one embodiment, as shown in FIG. 3, controller 160 receives electrical signals from first upper bridge terminal 134, first lower bridge terminal 144, upper bridge output 135, and lower bridge output 145, such as an upper bridge input voltage V. _I1 , upper bridge input current I _i1 , lower bridge input voltage V _i2 , lower bridge input current I _i2 , upper bridge output voltage V _{o1 ,} and lower bridge output voltage V _o2 . The controller 160 is capable of independent control of the upper bridge power switch 138 and the lower bridge power switch 148 to which it is coupled by collecting and analyzing these electrical signals by devices such as processors within the controller 160. For example, in one embodiment, controller 160 can be a maximum power point tracking (MPPT) controller. The MPPT controller can perform maximum power point tracking for each upper bridge unit or each lower bridge unit of each DC module, and control each of the upper bridge power switch tube 138 and the lower bridge power switch tube 148, respectively. In this manner, the DC voltages and currents at the upper bridge output 135 and the lower bridge output 145 can be optimally matched to the electrical switching device 120 for each upper bridge unit and each lower bridge unit. The highest power generation efficiency.

It should be understood that although the upper bridge DC-DC converter 132 and the lower bridge DC-DC converter 142 in the embodiment of FIG. 3 are both boost type converters, the present disclosure does not include a DC-DC converter. The type is limited to this. For example, a buck DC-DC converter or a more complicated circuit connection may be included as needed to achieve different effects, such as a multi-channel parallel boost converter circuit, a push-pull converter circuit, and a single-phase full-bridge transform. Circuits, etc. In the case of having a plurality of upper bridge units 130 or a plurality of lower bridge units 140, each of the upper bridge units 130 or each of the lower bridge units 140 may employ different types of conversion circuits and are individually controlled by the controller 160. Moreover, although FIG. 3 shows only one controller 160, multiple controllers may be used as needed for controlling different upper bridge units 130 or lower bridge units 140.

FIG. 4 illustrates a method of operating photovoltaic power generation system 100 for photovoltaic power generation, in accordance with an embodiment of the present disclosure. First, at block 401, the electrical conversion device and the respective DC modules can be initialized to stabilize the voltage value on the bus. At block 402, the bus voltage on bus 150 as shown in FIG. 2 or FIG. 3, the upper bridge output voltage on the upper bridge output 135, and the lower bridge output voltage on the lower bridge output 145 can be measured in real time.

At block 403, the difference between the upper bridge output voltage and the bus voltage is subtracted from the difference between the lower bridge output voltage and the bus voltage, and then the absolute value of the resulting difference is compared to a predetermined threshold. If the absolute value of the difference is less than the threshold, indicating that the voltage difference between the upper bridge output 135 and the lower bridge output 145 is relatively small, then at block 404, the upper bridge DC-DC converter and the lower bridge DC-DC converter are continued. Both perform maximum power point following control. If the difference absolute value is greater than the threshold, indicating that the voltage difference between the upper bridge output 135 and the lower bridge output 145 is relatively large, meaning that it is possible that one photovoltaic component does not produce good electrical power well, then at block 405 only the upper bridge One of the DC-DC converter and the lower-bridge DC-DC converter performs maximum power point following control.

It should be understood that although the method illustrated in FIG. 4 only shows an example employing two DC-DC converters, there may be more converters throughout the system (eg, in different DC modules or different upper bridges). In the unit or in the lower bridge unit). In the case where multiple converters need to be measured (monitored), compared, and controlled, various statistical methods can be used to perform the comparison step in 403. For example, if the output voltage of a converter differs from the average value of the output voltages of all of the converters by more than a predetermined threshold, the step of 405 is performed without MPPT control of the converter having a small voltage. Otherwise, the step 404 is performed to continue MPPT control for all of the converters. Then return to step 403 for real-time monitoring and control. Such monitoring and control methods enable the efficiency of the electrical power output of the entire photovoltaic power generation system to be maintained at a good level in real time without attenuating the performance of the overall system due to the environmental impact of individual photovoltaic panels.

Although the claims in the present application have been made in terms of specific combinations of features, it should be understood that the scope of the present disclosure also includes any novel features disclosed herein that are either explicit or implicit or any of the novel features or features Combination, whether or not it relates to the same solution in any claim as currently claimed. The Applicant hereby informs that the new claims may be formulated into these features and/or combinations of these features in the course of the review of the present application or any further application derived therefrom.

Claims

A photovoltaic power generation system (100) comprising:

An electrical conversion device (120) having a first input (121) and a second input (122);

A DC module (110), the DC module (110) includes:

Busbar (150);

An upper bridge unit (130) and a lower bridge unit (140) that share the bus bars (150) and are connected in parallel with each other with respect to the bus bars (150), the upper bridge unit (130) and the bus bar (150) are formed The circuit and the circuit formed by the lower bridge unit (140) and the bus bar (150) respectively generate DC power according to the respective received incident light energy.
The photovoltaic power generation system of claim 1 wherein said upper bridge unit (130) comprises:

An upper bridge DC-DC converter (132) having an upper bridge input (134) and an upper bridge output (135) and an upper bridge filter spanning between the upper bridge output (135) and the bus (150) a capacitor (133), the upper bridge output (135) being coupled to the first input (121) of the electrical conversion device (120);

An upper bridge photovoltaic component (131) capable of generating a DC output from the received light energy, a positive output of the upper bridge photovoltaic component (131) being coupled to the upper bridge input (134) and the upper bridge photovoltaic component (131) The negative output of the ) is connected to the bus bar (150).
The photovoltaic power generation system of claim 2 wherein said lower bridge unit (140) comprises:

a lower bridge DC-DC converter (142) having a lower bridge input (144) and a lower bridge output (145) and a lower bridge filter spanning between the lower bridge output (145) and the bus (150) a capacitor (143), the lower bridge output (145) being coupled to the second input (122) of the electrical conversion device (120);

A lower bridge photovoltaic component (141) capable of producing a DC output from the received light energy, a negative output of the lower bridge photovoltaic component (141) being coupled to the lower bridge input (144) and the lower bridge photovoltaic component (141) The positive output of the ) is connected to the bus bar (150).
The photovoltaic power generation system of claim 2 wherein said upper bridge photovoltaic component (131) comprises a plurality of photovoltaic panels connected in series.
The photovoltaic power generation system of claim 3 wherein said lower bridge photovoltaic component (141) comprises a plurality of photovoltaic panels connected in series.
The photovoltaic power generation system according to claim 1, wherein said direct current module (110) includes a plurality of said upper bridge unit (130) connected in parallel with respect to said bus bar (150) and a plurality of said bus bars ( 150) The lower bridge unit (140) connected in parallel.
The photovoltaic power generation system according to claim 1, wherein said photovoltaic power generation system comprises a plurality of said first input (121) and said second input (122) connected in parallel to said electrical conversion device (120) DC module (110).
The photovoltaic power generation system of claim 1 wherein said electrical conversion device (120) further comprises a bus input (123), said bus (150) being coupled to said bus input (123).
The photovoltaic power generation system according to claim 8, wherein each of said upper bridge DC-DC converter (132) and said lower bridge DC-DC converter (142) comprises:

An energy storage inductor (136, 146) providing the upper bridge input (134) at a first end;

a power switch tube (138, 148) connected across the second end of the energy storage inductor (136, 146) and the bus bar (150);

A freewheeling diode (137, 147) is coupled between the second end of the energy storage inductor (136, 146) and the upper bridge output (135) or the lower bridge output (145).
A photovoltaic power generation system according to any one of claims 3 to 9, further comprising a controller (160) receiving the upper bridge input (134), the lower bridge input (144) At least one of a voltage and a current of the upper bridge output (135) and the lower bridge output (145), and the upper bridge according to at least one of the received voltage and current A DC-DC converter (132) and the lower bridge DC-DC converter (142) are controlled.
A photovoltaic power generation system according to claim 10, wherein said controller (160) is the maximum power point tracking MPPT controller.
The photovoltaic power generation system according to any one of claims 1 to 9, wherein the electrical conversion device (120) comprises at least one of an inverter, a battery, and a direct current electrical device.
A method of operating a photovoltaic power generation system according to any one of claims 3 to 11 for photovoltaic power generation, comprising:

Initializing the electrical conversion device (120) and the direct current module (110);

Measuring a bus voltage on the bus (150), an upper bridge output voltage on the upper bridge output (135), and a lower bridge output voltage on the lower bridge output (145);

Comparing an absolute value of a difference between the upper bridge output voltage and the bus voltage and a difference between the lower bridge output voltage and the bus voltage to a preset voltage threshold, and

If the absolute value of the difference is less than the preset voltage threshold, performing maximum power point following control on both the upper bridge DC-DC converter (132) and the lower bridge DC-DC converter (142),

If the absolute value of the difference is greater than the preset voltage threshold, performing maximum power point following on one of the upper bridge DC-DC converter (132) and the lower bridge DC-DC converter (142) control.