CN211860011U - High-voltage photovoltaic power generation system - Google Patents

Abstract

The utility model discloses a high-pressure photovoltaic power generation system belongs to photovoltaic power generation technical field. A plurality of photovoltaic modules are connected in series to form a photovoltaic subgroup string, each photovoltaic subgroup string is connected with one electrical isolation controller, and all the electrical isolation controllers are connected in series and then connected with a photovoltaic inverter; the electric isolation controller comprises a maximum power point tracking module and an electric isolation module, and the maximum power point tracking module is connected with the electric isolation module. The utility model discloses can realize higher direct current voltage level under the condition that does not improve the withstand voltage level of photovoltaic module, avoid the series mismatch risk that long group's cluster brought simultaneously, show the lowering system cost when promoting photovoltaic system efficiency, have good application prospect.

Description

High-voltage photovoltaic power generation system

Technical Field

The utility model belongs to the technical field of photovoltaic power generation, concretely relates to high-pressure photovoltaic power generation system.

Background

The DC voltage level of the photovoltaic system is improved, so that the line loss is reduced, and the system cost is reduced. The conventional photovoltaic system can obtain a larger direct current voltage grade, such as 1000V or 1500V direct current voltage, by connecting the modules in series, but the photovoltaic modules in the string are required to have the insulation voltage resistance level of 1000V or 1500V simultaneously while obtaining 1000V direct current voltage and 1500V direct current voltage. Because no photovoltaic module with voltage-resistant grade above 1500V exists at present, and no related technical standard exists, the photovoltaic system is limited to be developed to a higher direct-current voltage grade.

Meanwhile, under the condition that the withstand voltage grade of the photovoltaic module meets the high-voltage requirement, obtaining better direct-current bus voltage means that more photovoltaic modules are required to be connected in series, and more series connection means higher series mismatch probability, so that improvement of system electric quantity is not facilitated.

Disclosure of Invention

In order to solve the existing problem, an object of the utility model is to provide a high-pressure photovoltaic power generation system has realized higher direct current voltage level under the condition that does not improve the withstand voltage level of photovoltaic module, has avoided the series mismatch risk that long group's cluster brought simultaneously, is showing the lowering system cost when promoting photovoltaic system efficiency.

The utility model discloses a following technical scheme realizes:

the utility model discloses a high-voltage photovoltaic power generation system, wherein a plurality of photovoltaic modules are connected in series to form photovoltaic sub-group strings, each photovoltaic sub-group string is connected with an electrical isolation controller, and all the electrical isolation controllers are connected in series and then are connected with a photovoltaic inverter;

the electric isolation controller comprises a maximum power point tracking module and an electric isolation module, and the maximum power point tracking module is connected with the electric isolation module.

Preferably, the number x of photovoltaic modules within a string of photovoltaic subgroups: x is more than or equal to 1 and less than or equal to [ V/V ]_oct]Wherein]For rounding symbols, V is the DC voltage level of the photovoltaic module, V_octThe maximum open circuit voltage of the photovoltaic module at the local extreme low temperature.

Preferably, the number of electrically isolated controllers y: y is more than or equal to 2 and less than or equal to [ V/V ]_oct]Wherein]For rounding symbols, V is the DC voltage level of the photovoltaic module, V_octThe maximum open circuit voltage of the photovoltaic module at the local extreme low temperature.

Preferably, the voltage to ground of any one photovoltaic module in the photovoltaic subunit string is not higher than the input voltage of the electrical isolation controller connected with the photovoltaic subunit string.

Preferably, the maximum power point tracking module is an MTTP controller.

Preferably, the electrical isolation module is an isolation circuit.

Compared with the prior art, the utility model discloses following profitable technological effect has:

the utility model discloses a high pressure photovoltaic power generation system, photovoltaic module are not directly established ties and are formed the group cluster, but establish ties earlier by a plurality of photovoltaic module and form photovoltaic subgroup cluster, and each photovoltaic subgroup cluster inserts an electrical isolation controller that has maximum power tracking and electrical isolation function, and electrical isolation controller establishes ties again and forms the photovoltaic group cluster of higher voltage, and this photovoltaic group cluster inserts the dc-to-ac converter again and carries out grid-connected electricity generation. The input side of the electrical isolation controller is decoupled from the output side with respect to ground potential, i.e., the added accumulation of ground potential on the output side of the electrical isolation controller due to the series connection with each other does not affect the ground potential of any of the sub-strings on the input side of the electrical isolation controller. The maximum power point tracking module can perform maximum power point tracking on the input photovoltaic subgroup strings, the maximum output of the photovoltaic module is guaranteed, series mismatch between the subgroup strings is eliminated, the electrical isolation module can achieve decoupling on earth potentials of an output side and an input side, and meanwhile earth voltage of the input side cannot be raised by accumulation of earth voltage of the output side. The utility model discloses can realize higher direct current voltage level under the condition that does not improve the withstand voltage level of photovoltaic module, avoid the series mismatch risk that long group's cluster brought simultaneously, show the lowering system cost when promoting photovoltaic system efficiency, have good application prospect.

Further, the number of photovoltaic modules in the photovoltaic subgroup string depends on the fact that the sum of open-circuit voltages of the photovoltaic modules in the extremely low temperature condition is not higher than the maximum input voltage of the direct current side of the inverter. Therefore, as the voltage on the dc side increases, the number of pv modules in the pv string increases in response, and the open-circuit voltage of the module increases as the ambient temperature decreases.

Further, the number of the electrical isolation controllers can be one component, or can be one photovoltaic subgroup string composed of a plurality of photovoltaic components, the voltage of any photovoltaic subgroup string is not higher than the voltage-resistant grade of the photovoltaic components, and meanwhile, cost factors are considered.

Drawings

Fig. 1 is a schematic structural diagram of a photovoltaic system according to embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a photovoltaic system according to embodiment 2 of the present invention;

fig. 3 is a schematic diagram of the structural principle of the electrical isolation controller of the present invention.

In the figure: the photovoltaic module is 1, the electrical isolation controller is 2, the maximum power point tracking module is 21, the electrical isolation module is 22, and the photovoltaic inverter is 3.

Detailed Description

The invention will be described in further detail with reference to the following drawings and specific examples, which are intended to illustrate and not to limit the invention:

the utility model discloses a high pressure photovoltaic power generation system, a plurality of photovoltaic module 1 establish ties and constitute photovoltaic subgroup cluster, photovoltaic subgroup in-cluster photovoltaic module 1's quantityx：1≤x≤[V/V_oct]Wherein, the]For rounding symbols, the integer part is taken directly. V is the DC voltage level of the photovoltaic module 1, V_octIs the maximum open circuit voltage of the photovoltaic module 1 at the local extreme low temperature. Each photovoltaic subgroup string is connected with one electrical isolation controller 2, and the voltage to ground of any photovoltaic module 1 in the photovoltaic subgroup string is not higher than the input voltage of the electrical isolation controller 2 connected with the photovoltaic subgroup string; all the electrical isolation controllers 2 are connected in series and then connected with the photovoltaic inverter 3, and the number y of the electrical isolation controllers 2 is as follows: y is more than or equal to 2 and less than or equal to [ V/V ]_oct]Wherein V is the DC voltage level of the photovoltaic module 1, V_octIs the maximum open circuit voltage of the photovoltaic module 1 at the local extreme low temperature.

As shown in fig. 3, the electrical isolation controller 2 includes a maximum power point tracking module 21 and an electrical isolation module 22, and the maximum power point tracking module 21 is connected to the electrical isolation module 22. The output positive and negative electrodes of the photovoltaic module 1 are connected to the positive and negative electrodes on the input side of the electrical isolation controller 2. The electrical isolation controller 2 includes two functional modules, a DC/DC maximum power point tracking Module (MPPT)21 and an electrical isolation module 22. Firstly, the maximum power point tracking module 21 optimizes the maximum power output point of the accessed photovoltaic module 1 through DC/DC conversion, and the optimized output is output to the electrical isolation module 22. The electrical isolation module 22 achieves voltage isolation between the output and input sides, i.e. the positive and negative potential differences of the input and output sides are related, but the earth potentials of the input and output side electrodes are independent of each other. Therefore, the output end of the photovoltaic module 1 is decoupled from the ground potential and the total voltage of the photovoltaic string. The flow direction of the electric energy inside the power supply system can be from the input side to the maximum power point tracking module 21 to the electrical isolation module 22 and then to the output side, or from the input side to the electrical isolation module 22 to the maximum power point tracking module 21 and then to the output side. The maximum power point tracking module 21 may employ an MTTP controller. The electrical isolation module 22 may employ an isolation circuit.

Example 1

As shown in fig. 1, each photovoltaic module 1 is individually connected to an electrical isolation controller 2. The electric isolation controllers 2 are mutually connected in series to form high voltage, and the high voltage is input to the direct current side of the photovoltaic inverter 3. The electric isolation controller 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. For example, the voltage isolation capability of the input side and the output side is illustrated, for example, the maximum output voltage of each photovoltaic module 1 is 40V, and the maximum output voltage after MPPT tracking by the electrical isolation controller 2 is 45V. Each photovoltaic component 1 is connected to one electrical isolation controller 2, and the total number of the photovoltaic component 1 is 50. After the 50 electric isolation controllers 2 are connected in series, the total voltage is raised to 2250V. Assuming that the cathode of the string is grounded, the voltage to ground at the cathode output side of the first electrical isolation controller 2 from the cathode is 0V, and the maximum voltage to ground at the anode output side is 45V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground of the negative electrode input side (negative electrode output side of the photovoltaic assembly 1) of the first electrical isolation controller 2 is 0V, the maximum voltage to ground of the positive electrode input side (positive electrode output side of the photovoltaic assembly 1) is 40V, the maximum voltage to ground of the negative electrode of the second electrical isolation controller 2 is 40V, and therefore the maximum voltage to ground of the positive electrode is 90V. Meanwhile, because the output side is electrically isolated from the input side, the voltage of the negative input side (negative output side of the photovoltaic assembly 1) of the second electrical isolation controller 2 to the ground is 0V, and the maximum voltage of the positive input side (positive output side of the photovoltaic assembly 1) to the ground is 40V. And in this way, the maximum voltage of the negative pole of the nth electrical isolation controller 2 to the ground is (n-1) × 45V, and the maximum voltage of the positive pole to the ground is n × 45V. Meanwhile, because the output side is electrically isolated from the input side, the voltage of the negative input side (negative output side of the photovoltaic assembly 1) of the first electrical isolation controller 2 to the ground is 0V, and the maximum voltage of the positive input side (positive output side of the photovoltaic assembly 1) to the ground is 40V. Therefore, under the system architecture, no matter how many electrically isolated controllers 2 are connected in series, the voltage to ground on the input side of each electrically isolated controller 2 is not accumulated, so that the voltage to withstand of the photovoltaic assembly 1 can be kept lower while a higher set of series direct current voltage is realized. Meanwhile, the electrical isolation controller 2 has an independent maximum power point tracking function, so that no matter how many photovoltaic assemblies 1 are contained in the string, the current mismatch among the photovoltaic assemblies 1 is eliminated by the electrical isolation controller 2, and the series mismatch problem of a long string is avoided.

Example 2

As shown in fig. 2, a plurality of photovoltaic modules 1 are connected in series and then connected to an electrical isolation controller 2. The electric isolation controllers 2 are connected in series to form higher voltage, and the higher voltage is input to the direct current side of the photovoltaic inverter 3. The electric isolation controller 2 has a maximum power point tracking function and an input side and output side voltage isolation capability. For example, the voltage isolation capability of the input side and the output side is illustrated, for example, the maximum output voltage of each photovoltaic module 1 is 40V, 20 photovoltaic modules 1 are connected in series to form a photovoltaic sub-group string with the maximum output voltage of 800V, and the output voltage is 900V after MPPT tracking by the electrical isolation controller 2. 3 photovoltaic modules 1 are respectively connected into 3 electrical isolation controllers 2, and the three electrical isolation controllers 2 are connected in series to form a group string with 2700V voltage. In this system, assuming that the negative pole of the string is grounded, the voltage to ground on the negative output side of the first electrical isolation controller 2 from the negative pole is 0V, and the maximum voltage to ground on the positive output side is 900V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground on the negative input side (negative output side of the photovoltaic subgroup string) of the first electrical isolation controller 2 is 0V, the maximum voltage to ground on the positive input side (positive output side of the photovoltaic subgroup string) is 800V, and the maximum voltage withstand requirement of any photovoltaic module 1 in the photovoltaic subgroup string does not exceed 800V. The second electrical isolation controller 2 has a negative electrode with a maximum voltage of 900V and a positive electrode with a maximum voltage of 1800V. Meanwhile, because the output side is electrically isolated from the input side, the voltage to ground of the cathode input side (cathode output side of the photovoltaic subgroup string) of the second electrical isolation controller 2 is 0V, the voltage to ground of the anode input side (anode output side of the photovoltaic subgroup string) is 800V, and the maximum voltage withstanding requirement of any photovoltaic module 1 in the photovoltaic subgroup string does not exceed 800V. By analogy, under the system architecture, no matter how many electrical isolation controllers 2 are connected in series, the voltage to ground on the input side of each electrical isolation controller 2 cannot be accumulated, so that a higher set of series direct-current voltage can be realized, and the voltage-resistant grade of the photovoltaic assembly 1 connected under each electrical isolation controller 2 does not exceed the maximum output voltage of a single photovoltaic assembly 1 by the number of series connection, so that the voltage-resistant requirement of the lower photovoltaic assembly 1 is maintained. Meanwhile, the electrical isolation controller 2 has an independent maximum power point tracking function, so that no matter how many photovoltaic assemblies 1 are contained in the string, the current mismatch among the photovoltaic assemblies 1 is eliminated by the electrical isolation controller 2, and the series mismatch problem of a long string is avoided.

It should be noted that the above description is only one of the embodiments of the present invention, and all equivalent changes made by the system described in the present invention are included in the protection scope of the present invention. The technical field of the present invention can be replaced by other embodiments described in a similar manner, without departing from the structure of the present invention or exceeding the scope defined by the claims, which belong to the protection scope of the present invention.

Claims (6)

1. A high-voltage photovoltaic power generation system is characterized in that a plurality of photovoltaic modules (1) are connected in series to form a photovoltaic subgroup string, each photovoltaic subgroup string is connected with an electrical isolation controller (2), and all the electrical isolation controllers (2) are connected in series and then connected with a photovoltaic inverter (3);

the electric isolation controller (2) comprises a maximum power point tracking module (21) and an electric isolation module (22), wherein the maximum power point tracking module (21) is connected with the electric isolation module (22).

2. The high-voltage photovoltaic power generation system according to claim 1, characterized in that the number x of photovoltaic modules (1) within a string of photovoltaic subgroups: x is more than or equal to 1 and less than or equal to [ V/V ]_oct]Wherein]For rounding symbols, V is the DC voltage level of the photovoltaic module (1), V_octIs the maximum open circuit voltage of the photovoltaic module (1) at the local extreme low temperature.

3. The high-voltage photovoltaic power generation system according to claim 1, characterized in that the number y of electrically isolated controllers (2): y is more than or equal to 2 and less than or equal to [ V/V ]_oct]Wherein]For rounding symbols, V is the DC voltage level of the photovoltaic module (1), V_octIs the maximum open circuit voltage of the photovoltaic module (1) at the local extreme low temperature.

4. The high-voltage photovoltaic power generation system according to claim 1, characterized in that the voltage to ground of any photovoltaic module (1) in the photovoltaic sub-group string is not higher than the input voltage of the galvanic isolation controller (2) connected thereto.

5. The high voltage photovoltaic power generation system of claim 1, wherein the maximum power point tracking module (21) is an MTTP controller.

6. The high voltage photovoltaic power generation system of claim 1, wherein the electrical isolation module (22) is an isolation circuit.

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