CN114825420A

CN114825420A - Photovoltaic power generation system, dust monitoring device and detection method

Info

Publication number: CN114825420A
Application number: CN202110128346.XA
Authority: CN
Inventors: 汪建强; 舒震寰; 万松; 张彦忠
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2021-01-29
Filing date: 2021-01-29
Publication date: 2022-07-29

Abstract

The application provides a photovoltaic power generation system, a dust monitoring device and a detection method, and relates to the technical field of photovoltaic power generation. The photovoltaic power generation system comprises a dust monitoring device and a power converter. The input end of the power converter is used for connecting the photovoltaic group string; the power converter is used for sending the electric parameter detection data of the photovoltaic string to the dust monitoring device; the dust monitoring device is used for determining a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, and determining the dust adhesion degree of the target photovoltaic string according to electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, wherein the standard photovoltaic string is a clean photovoltaic string, namely the standard photovoltaic string has no dust adhesion or only a small amount of dust adhesion. By means of the scheme, the hardware cost and the maintenance cost of dust monitoring are reduced.

Description

Photovoltaic power generation system, dust monitoring device and detection method

Technical Field

The application relates to the technical field of photovoltaic power generation, in particular to a photovoltaic power generation system, a dust monitoring device and a detection method.

Background

Photovoltaic power generation is a technology for converting light energy into electrical energy by utilizing the photovoltaic effect of a semiconductor interface. The photovoltaic Module (PV Module) is used as a core component in a photovoltaic power generation system and is used for converting light energy into electric energy, so that the maintenance of the photovoltaic Module directly influences the power generation amount of the photovoltaic power generation system. The photovoltaic power generation system is arranged on the photovoltaic power station.

The dust adhesion degree is an important factor influencing the power generation performance of the photovoltaic module, when the dust adhesion is serious, the power generation amount of the photovoltaic module can be seriously reduced, and the photovoltaic module needs to be maintained and cleaned at the moment. Therefore, the dust adhesion degree of the photovoltaic module in the current photovoltaic power generation system is accurately monitored, so that the photovoltaic module is maintained in time, and the method has important significance for improving the power generation capacity of the photovoltaic power generation system.

The current dust monitoring scheme is that a standard photovoltaic module and a comparison photovoltaic module are arranged near a photovoltaic power station, the standard photovoltaic module and the comparison photovoltaic module are both in the same specification as the photovoltaic module used by the photovoltaic power station, the standard photovoltaic module is maintained to be in a high cleanliness state, the comparison photovoltaic module carries out natural dust deposition, the output parameters of the two groups of photovoltaic modules are monitored, and when the difference of the output parameters of the two groups of photovoltaic modules reaches a certain threshold value, an alarm is given, namely the photovoltaic modules of the photovoltaic power station are prompted to be maintained and cleaned currently.

However, since the photovoltaic power generation station is built in an open scene, the influence of dust on the photovoltaic power generation station is complex, and the deposition speeds of dust on the surfaces of the photovoltaic modules at different positions are obviously different, so that in order to improve the accuracy of warning, the dust detection scheme needs to set multiple groups of standard photovoltaic modules and control photovoltaic modules at different positions, and the hardware cost and the maintenance cost are increased.

Disclosure of Invention

In order to solve the problems, the application provides a photovoltaic power generation system, a dust monitoring device and a detection method, and hardware cost and maintenance cost required by dust monitoring are reduced.

In a first aspect, the present application provides a photovoltaic power generation system comprising: dust monitoring devices and power converters. The input end of the power converter is connected with the photovoltaic group string. The power converter is used for acquiring the electric parameter detection data of the photovoltaic string and sending the electric parameter detection data of the photovoltaic string to the dust monitoring device. The dust monitoring device is used for determining a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, and determining the dust attachment degree of the target photovoltaic string according to electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string. The standard photovoltaic string is a clean photovoltaic string, namely, the standard photovoltaic string has no dust adhesion or only has inevitable small dust adhesion. And the target photovoltaic string is the detected photovoltaic string.

According to the dust monitoring device of the photovoltaic power generation system, the standard photovoltaic string and the target photovoltaic string are determined from the photovoltaic strings connected with the photovoltaic power generation system, the photovoltaic strings required by dust monitoring are prevented from being additionally and independently arranged, and the hardware cost and the maintenance cost are reduced. The dust monitoring device acquires electric parameter detection data of the photovoltaic group string sent by the power converter, and determines the dust adhesion degree of the target photovoltaic group string according to the electric parameter detection data respectively corresponding to the standard photovoltaic group string and the target photovoltaic group string. When the target photovoltaic string is distributed around the standard photovoltaic string, the deposition speed of the surface dust is similar because the positions of the target photovoltaic string and the standard photovoltaic string are similar, and therefore the accuracy of the monitoring result of the dust adhesion degree of the target photovoltaic string is improved.

In one possible implementation, the electrical parameter detection data includes current-voltage curve scan data and output performance data, the output performance data including at least one of output voltage, output current, output power, or power generation per unit time.

In a possible implementation manner, the dust monitoring device is configured to screen out a failed photovoltaic string from the standard photovoltaic string and the target photovoltaic string according to current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determine a dust adhesion degree of the target photovoltaic string according to a ratio of output performance data of the target photovoltaic string to output performance data of the standard photovoltaic string.

For the photovoltaic module that breaks down, its electrical parameter detection data is unusual, if utilize the electrical parameter detection data of trouble photovoltaic group cluster to carry out the detection of dust adhesion degree, can lead to the erroneous judgement, through the screening to trouble photovoltaic group cluster, avoided because the erroneous judgement that photovoltaic group cluster trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

Based on the above comparison method, the skilled person can also derive other similar comparison methods, for example, the dust adhesion degree of the target pv group string is determined by using the difference between the output performance data of the standard pv group string and the output performance data of the target pv group string.

In one possible implementation, the electrical parameter sensing data includes current-voltage curve sweep data. At the moment, the dust monitoring device determines the difference of the open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to the current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determines the dust attachment degree of the target photovoltaic string according to the difference of the open-circuit voltages.

When the open-circuit voltage of the photovoltaic module is reduced, the phenomenon of dust adhesion of the photovoltaic module is represented.

In one possible implementation, the power converter is further configured to send fault information indicating a faulty photovoltaic string to the dust monitoring device according to the current-voltage curve scan data of the photovoltaic string. And the dust monitoring device screens out the photovoltaic string with faults from the standard photovoltaic string and the target photovoltaic string according to the fault information.

Through the screening of the photovoltaic string that breaks down, avoided because the erroneous judgement that photovoltaic string trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

In one possible implementation, the electrical parameter detection data includes output performance data, and the dust monitoring device determines the dust adhesion degree of the target photovoltaic string according to a ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

In one possible implementation, the output performance data is at least one of an output voltage, an output current, an output power, or an amount of power generated per unit time.

In one possible implementation, the power converter further sends fault information indicating the faulty photovoltaic string to the dust monitoring device according to the current-voltage curve scan data of the photovoltaic string. And the dust monitoring device screens out the photovoltaic string with faults from the standard photovoltaic string and the target photovoltaic string according to the fault information. Through the screening of the photovoltaic string that breaks down, avoided because the erroneous judgement that photovoltaic string trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

In one possible implementation, the power converter is at least one of a photovoltaic inverter, a dc combiner box, or a photovoltaic optimizer. The photovoltaic inverter is a group-series inverter and comprises a DC-DC converter and a DC-AC converter two-stage power converter, and the direct current combiner box and the photovoltaic optimizer are DC-DC converters.

In a second aspect, the present application further provides a dust monitoring device, where the dust monitoring device is configured to receive electrical parameter detection data of a photovoltaic string sent by a power converter of a photovoltaic power generation system, determine the electrical parameter detection data of the photovoltaic string, and determine the dust adhesion degree of a target photovoltaic string according to electrical parameter detection data corresponding to a standard photovoltaic string and the target photovoltaic string, respectively. The standard photovoltaic string is a clean photovoltaic string, that is, a photovoltaic module without dust adhesion or only inevitably adhered with a small amount of dust.

By utilizing the dust monitoring device, the additional arrangement of a photovoltaic module required by dust monitoring is avoided, the hardware cost and the maintenance cost are reduced, and the accuracy of the dust adhesion degree monitoring result of the target photovoltaic group string distributed around the standard photovoltaic group string is improved. In addition, this dust monitoring device can also get rid of the influence of photovoltaic group cluster of trouble to dust adhesion degree monitoring result, has further promoted the accuracy of dust adhesion degree monitoring result.

In one possible implementation mode, the dust monitoring device scans data according to current-voltage curves respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and screens out the photovoltaic string with a fault from the standard photovoltaic string and the target photovoltaic string; and determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string. Through the screening of the photovoltaic string that breaks down, avoided because the erroneous judgement that photovoltaic string trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

In one possible implementation, the electrical parameter sensing data includes current-voltage curve sweep data. The dust monitoring device determines the difference of the open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to the current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determines the dust attachment degree of the target photovoltaic string according to the difference of the open-circuit voltages.

In a possible implementation manner, the dust monitoring device receives fault information which is sent by the power converter and used for indicating a faulty photovoltaic string, and screens out the faulty photovoltaic string from the standard photovoltaic string and the target photovoltaic string according to the fault information. Through the screening to trouble photovoltaic group cluster, avoided because the erroneous judgement that photovoltaic group cluster trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

In one possible implementation, the electrical parameter sensing data includes output performance data. And the dust monitoring device determines the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

In one possible implementation, the output performance data includes at least one of an output voltage, an output current, an output power, or an amount of power generated per unit time.

In a possible implementation manner, the dust monitoring device is further configured to receive fault information sent by the power converter and used for indicating a faulty photovoltaic string, and screen out the faulty photovoltaic string from the standard photovoltaic string and the target photovoltaic string according to the fault information. Through the screening of the photovoltaic string that breaks down, avoided because the erroneous judgement that photovoltaic string trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

In a third aspect, the present application further provides a power converter applied to a photovoltaic power generation system, the power converter including an input interface and a controller. Wherein, input interface is used for connecting the photovoltaic group cluster. The controller determines a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, and determines the dust adhesion degree of the target photovoltaic string according to electrical parameter detection data corresponding to the standard photovoltaic string and the target photovoltaic string respectively, wherein the standard photovoltaic string is a clean photovoltaic string, namely the standard photovoltaic string has no dust adhesion or only has inevitable small dust adhesion.

When the power converter is used for detecting the dust adhesion degree, the additional arrangement of a photovoltaic module required by dust monitoring is avoided, the hardware cost and the maintenance cost are reduced, the dust adhesion degree of the target photovoltaic string is determined according to the electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string by acquiring the electrical parameter detection data of the photovoltaic string, and the accuracy of the dust adhesion degree monitoring result of the target photovoltaic string distributed around the standard photovoltaic string is improved. In addition, the power converter can also eliminate the influence of the failed photovoltaic string on the monitoring result of the dust adhesion degree, and the accuracy of the dust adhesion degree monitoring result is further improved.

In one possible implementation manner, the controller is configured to screen out a faulty photovoltaic string from the standard photovoltaic string and the target photovoltaic string according to current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string; and determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string. Through the screening of the photovoltaic string that breaks down, avoided because the erroneous judgement that photovoltaic string trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

In one possible implementation, the electrical parameter sensing data includes current-voltage curve sweep data. The controller determines the difference of the open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to the current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determines the dust attachment degree of the target photovoltaic string according to the difference of the open-circuit voltages.

In one possible implementation, the controller screens out malfunctioning photovoltaic strings from the standard photovoltaic string and the target photovoltaic string according to the current-voltage curve scan data of the photovoltaic strings. Through the screening of the photovoltaic string that breaks down, avoided because the erroneous judgement that photovoltaic string trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

In one possible implementation, the power converter is at least one of a photovoltaic inverter, a dc combiner box, or a photovoltaic optimizer. The photovoltaic inverter is a group string inverter and comprises a DC-DC converter and a DC-AC converter, and the direct current combiner box and the photovoltaic optimizer are DC-DC converters.

In a fourth aspect, the present application further provides a method for detecting a dust adhesion degree, which is applied to a photovoltaic power generation system, and the method includes the following steps:

acquiring electrical parameter detection data of the photovoltaic string;

determining a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, wherein the standard photovoltaic string is a clean photovoltaic string;

and determining the dust attachment degree of the target photovoltaic string according to the electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string.

In a possible implementation manner, determining the dust adhesion degree of the target photovoltaic string according to electrical parameter detection data corresponding to the standard photovoltaic string and the target photovoltaic string respectively includes:

screening out the photovoltaic string with faults from the standard photovoltaic string and the target photovoltaic string according to current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string;

and determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

In a possible implementation manner, the electrical parameter detection data includes current-voltage curve scanning data, and the determining of the dust adhesion degree of the target photovoltaic string according to the electrical parameter detection data corresponding to the standard photovoltaic string and the target photovoltaic string respectively includes:

and determining the difference of the open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to the current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determining the dust attachment degree of the target photovoltaic string according to the difference of the open-circuit voltages.

In one possible implementation, the method further includes:

determining fault information of a fault photovoltaic group string according to current-voltage curve scanning data of the photovoltaic group string;

and screening out the photovoltaic string with the fault from the standard photovoltaic string and the target photovoltaic string according to the fault information.

In a possible implementation manner, the electrical parameter detection data includes output performance data, and the determining of the dust adhesion degree of the target photovoltaic string according to the electrical parameter detection data corresponding to the standard photovoltaic string and the target photovoltaic string respectively includes:

In one possible implementation, the method further includes:

By utilizing the method for detecting the dust attachment degree, the standard photovoltaic string and the target photovoltaic string are determined from the photovoltaic strings connected with the photovoltaic power generation system, the photovoltaic string required by dust monitoring is prevented from being additionally and independently arranged, and the hardware cost and the maintenance cost are reduced. When the target photovoltaic string is distributed around the standard photovoltaic string, the deposition speed of the surface dust is similar because the positions of the target photovoltaic string and the standard photovoltaic string are similar, and the accuracy of the monitoring result of the dust adhesion degree of the target photovoltaic string is improved. Through the screening of the photovoltaic string that breaks down, avoided because the erroneous judgement that photovoltaic string trouble arouses, promoted the accuracy of dust adhesion degree monitoring result.

Drawings

FIG. 1 is a schematic diagram of an exemplary centralized inverter-based photovoltaic power generation system provided herein;

FIG. 2 is a schematic diagram of an exemplary string inverter based photovoltaic power generation system provided herein;

fig. 3 is a schematic diagram of an exemplary string inverter provided in an embodiment of the present application;

fig. 4 is a schematic diagram of an exemplary photovoltaic power generation system based on a centralized inverter and an MPPT boost combiner box according to the present disclosure;

FIG. 5 is a schematic view of an exemplary MPPT boost combiner box provided herein;

FIG. 6 is a schematic diagram of an exemplary photovoltaic power generation system based on a photovoltaic optimizer and string inverters as provided herein;

FIG. 7 is a schematic view of a photovoltaic power generation system provided by an embodiment of the present application;

FIG. 8 is a first schematic view of dust monitoring provided by an embodiment of the present application;

fig. 9 is a second schematic diagram of dust monitoring provided in the embodiment of the present application;

FIG. 10 is a schematic view of a dust monitoring apparatus according to an embodiment of the present disclosure;

FIG. 11 is a schematic diagram of a power converter provided in an embodiment of the present application;

fig. 12 is a flowchart of a method for detecting a dust adhesion degree according to an embodiment of the present application.

Detailed Description

In order to make those skilled in the art better understand the technical solutions provided in the embodiments of the present application, an application scenario of the technical solutions provided in the present application is first described below.

The photovoltaic power generation system based on the concentrated inverter is first explained below.

Referring to fig. 1, a schematic diagram of an exemplary centralized inverter-based photovoltaic power generation system is provided.

The photovoltaic power generation system includes a photovoltaic unit 10, a dc combiner box 11, a centralized inverter 12, and a transformer 14.

Wherein each photovoltaic unit 10 comprises one or more photovoltaic modules. The photovoltaic module is a direct current power supply formed by packaging solar cells in series or in parallel and is used for converting light energy into electric energy.

When the photovoltaic unit 10 includes a plurality of photovoltaic modules, the plurality of photovoltaic modules may form a photovoltaic string by connecting the positive and negative electrodes in series end to form the photovoltaic unit 10; a plurality of photovoltaic modules may also be connected in series to form a plurality of photovoltaic strings, which are then connected in parallel to form the photovoltaic unit 10.

The centralized inverter 12 includes a Direct Current (DC) -Alternating Current (AC) circuit, which may also be referred to as an inverter circuit, for inverting a DC power input from at least one DC combiner box 11 into an AC power. The power of the centralized inverter 12 is relatively large, so the centralized inverter 12 is generally arranged in a machine room or a container 13 by adopting a rack type design. A centralized inverter with power of more than 500kW is generally adopted in a photovoltaic power station.

The ac power output by the centralized inverter 12 is transformed by a transformer 14 and then is input into an ac power grid 15.

The following describes a photovoltaic power generation system based on a string inverter.

Referring to fig. 2, a schematic diagram of an exemplary string inverter based photovoltaic power generation system is provided.

The photovoltaic power generation system includes photovoltaic units 10, string inverters 16, ac combiner boxes 17, and transformers 14.

The dc side of the string inverter 16 is connected to one or more photovoltaic units 10, and in practical applications, the dc side of the string inverter 11 is generally connected to a plurality of photovoltaic units 10.

The implementation of the string inverter is described in detail below.

Referring to fig. 3, the figure is a schematic diagram of an exemplary string inverter provided in an embodiment of the present application.

The power of the string inverter 16 is smaller than that of a centralized inverter, and the power is mostly designed in an outdoor modular manner, and the string inverter includes two power conversion circuits, wherein the first stage is a DC-DC circuit 161 and a general booster circuit, and the second stage is a DC-AC circuit 121, i.e., an inverter circuit.

The string inverter 16 may include a plurality of DC-DC circuits 161, positive output ports of the plurality of DC-DC circuits 161 are connected in parallel to the positive input port on the DC side of the DC-AC circuit 121, and negative output ports of the plurality of DC-DC circuits 161 are connected in parallel to the negative input port on the DC side of the DC-AC circuit 121.

The AC outlet of the DC-AC circuit 121 is the output of the string inverter 16.

Each of the DC-DC circuits 161 is connected to at least one of the photovoltaic units 10, a positive input port of each of the DC-DC circuits 161 is connected to a positive electrode of the photovoltaic unit 10, and a negative input port of each of the DC-DC circuits 161 is connected to a negative electrode of the photovoltaic unit 10.

Alternating current output by the multi-path group string type inverter 16 is collected after passing through the alternating current header box 12, and then is connected to an alternating current power grid 15 after being transformed by the transformer 14.

A photovoltaic power generation system based on a centralized inverter and a Maximum Power Point Tracking (MPPT) boost combiner box, which is also called a distributed photovoltaic power generation system, is described below.

Referring to fig. 4, the figure is a schematic view of an exemplary photovoltaic power generation system based on a centralized inverter and an MPPT boost combiner box provided in the present application.

The photovoltaic power generation system is also referred to as a distributed photovoltaic power generation system.

The illustrated photovoltaic power generation system includes photovoltaic units 10, MPPT boost combiner boxes 18, a centralized inverter 21, and a transformer 14.

The MPPT boost combiner box 18 is a boost converter, and is specifically described below with reference to the drawings.

Referring to fig. 5, the figure is a schematic diagram of an exemplary MPPT boost combiner box provided herein.

MPPT boost combiner box 20 generally includes at least two DC-DC circuits 161. Wherein each DC-DC circuit 161 is connected to at least one of the photovoltaic units 10. The positive input port of each DC-DC circuit 161 is connected to the positive pole of the photovoltaic unit 10 and the negative input port of the DC-DC circuit 161 is connected to the negative pole of the photovoltaic unit 10.

The positive output port of each DC-DC circuit 161 is connected in parallel to the positive pole of the output DC bus, and the negative output port of each DC-DC circuit 161 is connected in parallel to the negative pole of the output DC bus.

The positive and negative poles of the dc bus are respectively used as the positive and negative output ports of the MPPT boost combiner box 20, and are respectively connected to the positive and negative input ports of the subsequent centralized inverter 12 via dc cables.

The centralized inverter 12 is used to convert a single or multiple DC inputs connected in parallel to each other at the DC side into an AC output, and generally employs DC-AC single-stage power conversion. The ac power output by the centralized inverter 21 is input to the ac grid 15 via the transformer 14.

The centralized inverter 12 is generally electrically distant from the photovoltaic unit 10, and is usually designed as an outdoor cabinet or integrated as an outdoor module.

Referring to fig. 6, a schematic diagram of an exemplary photovoltaic power generation system based on a photovoltaic optimizer and string inverter is provided.

The illustrated photovoltaic power generation system includes a photovoltaic unit 10, a photovoltaic optimizer 30, a string inverter 16, a transformer 14, and an ac power grid 15.

The photovoltaic optimizer 30 is a DC-DC converter, and an input side of the DC-DC converter is connected to the photovoltaic unit 10, and an output side of the DC-DC converter is connected to the group string inverter in a series connection manner, so as to increase or decrease an output voltage of the photovoltaic unit.

The photovoltaic optimizer 30 includes a DC-DC circuit that is a BUCK (BUCK) circuit, a BOOST (BOOST) circuit, or a BUCK-BOOST circuit. The positive input port of the DC-DC circuit is connected to the positive pole of the photovoltaic unit 10 and the negative input port of the DC-DC circuit is connected to the negative pole of the photovoltaic unit 10.

The positive pole of the DC-DC circuit is connected with the positive pole of the output direct current bus and is used as a positive output port of the photovoltaic optimizer 30; the negative pole of the DC-DC circuit is connected to the negative pole of the output DC bus as the negative output port of the photovoltaic optimizer 30.

A photovoltaic power generation system employing photovoltaic optimizers 30 typically connects a plurality of photovoltaic optimizers 30 in series to form a sub-string.

For example, N photovoltaic optimizers are connected in series end to end, that is, the positive output port of the ith photovoltaic optimizer is connected to the negative output port of the (i-1) th photovoltaic optimizer, the negative output port of the ith photovoltaic optimizer is connected to the positive output port of the (i + 1) th photovoltaic optimizer, and i is 2, 3, …, N-1. And a positive output port of the 1 st photovoltaic optimizer is used as a positive output port of the photovoltaic optimizer sub-string, and a negative output port of the Nth photovoltaic optimizer is used as a negative output port of the photovoltaic optimizer sub-string. And the output end of the sub-string of the photovoltaic optimizer is connected with the input end of the rear-stage device through a direct-current cable.

The alternating current output by the string inverter 16 is input into an alternating current power grid 15 after passing through a transformer 14.

For the photovoltaic power generation systems of the types, dust shielding is an important factor influencing the power generation performance of the photovoltaic modules, the field operation environment of the photovoltaic power generation system is complex, and the deposition speeds of dust on the surfaces of the photovoltaic modules at different positions are obviously different, so that the accuracy of the alarm of the current dust detection scheme is poor, and an accurate maintenance guidance suggestion is difficult to provide for a user.

In order to solve the problems, the application provides a photovoltaic power generation system, a dust monitoring device and a detection method, hardware cost and maintenance cost of dust monitoring are reduced, a standard photovoltaic string and a target photovoltaic string are determined in the photovoltaic string, the standard photovoltaic string is periodically cleaned and maintained, the target photovoltaic string is a selected detected string, then electric parameter detection data of the photovoltaic string are collected through a power converter, dust adhesion degree of the target photovoltaic string is determined according to the electric parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and accuracy of dust adhesion degree monitoring on the target photovoltaic string distributed around the standard photovoltaic string can be improved by adjusting the selected standard photovoltaic string.

The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

The terms "first", "second", and the like in the following description of the present application are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated.

In the present application, unless expressly stated or limited otherwise, the term "coupled" is to be construed broadly, e.g., "coupled" may be a fixed connection, a removable connection, or an integral part; may be directly connected or indirectly connected through an intermediate.

The embodiment of the application provides a photovoltaic power generation system, which is specifically described below with reference to the accompanying drawings.

Referring to fig. 7, the figure is a schematic view of a photovoltaic power generation system provided in an embodiment of the present application.

The illustrated photovoltaic power generation system includes: a photovoltaic string 101, a power converter 102 and a dust monitoring device 103.

Wherein, the input end of the power converter 102 is used for connecting the photovoltaic string 101.

The photovoltaic string 101 is used for converting light energy into direct current and transmitting the direct current to the power converter.

The power converter 102 is used for transmitting the electrical parameter detection data of the photovoltaic string 101 to the dust monitoring device.

In some embodiments, the power converter 102 may be a DC-DC converter, such as a boost combiner box as shown in fig. 5, or a photovoltaic optimizer as shown in fig. 6.

In other embodiments, the power converter 102 may be a DC-AC converter, such as the string inverter shown in FIG. 3.

The embodiment of the present application does not limit the specific type of the power converter 102. The output of the power converter 102 is connected to the post-stage system 104.

The dust monitoring device 103 may be an electronic computer or a server in a central control room of the photovoltaic power generation system, that is, the dust monitoring device 103 is an upper computer of the power converter 102, and has a data processing function.

Referring to fig. 8, the figure is a schematic diagram of a dust monitoring range provided in the embodiment of the present application.

The dust monitoring device 103 determines a standard photovoltaic string 201 and a target photovoltaic string 202 among all photovoltaic strings to which the power converter is connected.

The standard photovoltaic string is a reference standard, and is a clean photovoltaic string, that is, no dust adheres to the standard photovoltaic string, or only a small amount of dust inevitably adheres to the standard photovoltaic string (the influence of the small amount of dust on the standard photovoltaic string is negligible). The standard photovoltaic string is periodically cleaned and maintained to maintain a clean state. The embodiment of the application does not limit the selection number and distribution of the standard photovoltaic string.

In some embodiments, to reduce the effort to maintain and clean standard photovoltaic strings, a standard photovoltaic module may select several strings of photovoltaic strings that are collectively distributed together.

In other embodiments, in order to more accurately reflect the effect of dust adhesion on the photovoltaic system, the standard photovoltaic module may select a plurality of strings distributed discretely, for example, the plurality of strings may be arranged at a certain sequential interval.

In still other embodiments, the standard pv modules may be set or adjusted according to the distribution environment of the pv power generation system, such as selecting pv strings at edge locations of the pv power generation system, or pv strings at center locations, or in combination with wind direction conditions of the environment.

The target pv strings are selected strings to be detected, and the number of the target pv strings is not specifically limited in the embodiment of the present application. In some embodiments, the other photovoltaic strings of the photovoltaic string that remain after the standard photovoltaic string are removed are the target photovoltaic string.

See also the schematic view of dust monitoring shown in fig. 9.

At this time, the target photovoltaic string 202 is a photovoltaic string distributed around the standard photovoltaic string 201, and the deposition speeds of the dust on the surfaces of the target photovoltaic string 202 and the standard photovoltaic string 201 are close to each other, so that the accuracy of dust monitoring can be improved.

The dust monitoring device 103 determines the dust adhesion degree of the target photovoltaic string by using the electrical parameter detection data corresponding to the standard photovoltaic string and the target photovoltaic string respectively acquired from each power converter 102, thereby monitoring the dust adhesion state of the target photovoltaic string.

In summary, according to the dust monitoring device of the photovoltaic power generation system, the standard photovoltaic string and the target photovoltaic string are determined from the photovoltaic strings connected with the photovoltaic power generation system, so that the additional arrangement of photovoltaic modules required for dust monitoring is avoided, and the hardware cost and the maintenance cost are reduced. Collecting electric parameter detection data of the photovoltaic string through a power converter, and determining the dust adhesion degree of the target photovoltaic string according to the electric parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string. And the accuracy of the monitoring result of the dust adhesion degree of the target photovoltaic string distributed around the standard photovoltaic string is improved.

The following specifically describes a specific principle of the photovoltaic power generation system for monitoring the dust adhesion degree.

In one possible implementation, the electrical parameter sensing data sent by the power converter to the dust monitoring device includes current-voltage curve sweep data and output performance data.

For a photovoltaic module, under the condition that environmental factors such as temperature and illumination intensity are constant, the output current of the photovoltaic module changes along with the output voltage thereof, and can be drawn as a current-voltage curve (i.e., "IV curve"). The power converter acquires IV curve scanning data through an IV curve scanning technology and sends the IV curve scanning data to the dust monitoring device.

The power converter may also obtain output performance data of the photovoltaic string, the output performance data including at least one of an output voltage, an output current, an output power, or a power generation amount per unit time.

After the dust monitoring device acquires the electrical parameter detection data sent by the power converter, firstly, current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string are utilized, and the photovoltaic string with a fault is screened out from the standard photovoltaic string and the target photovoltaic string. For the photovoltaic module with a fault, if the electrical parameter detection data of the photovoltaic module string with the fault is used for detecting the dust adhesion degree, the false judgment can be caused, for example, the output voltage of the photovoltaic module string is reduced due to the fault, and the false judgment is that the output voltage of the photovoltaic module string is reduced due to the serious dust adhesion degree.

The dust monitoring device then determines the degree of dust attachment of the target photovoltaic string based on the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

The dust monitoring device determines the severity of dust attachment based on a threshold value of the ratio. The following examples are given.

In some embodiments, when the ratio ranges from (0.9, 1), the dust adhesion degree characterizing the target photovoltaic string at this time is low, and the cleaning and maintenance of the target photovoltaic string may not be performed at this time;

when the ratio range is (0.8, 0.9), representing that the target photovoltaic string has a certain degree of dust adhesion, but the influence on the output performance is low, and cleaning and maintenance of the target photovoltaic string can be omitted;

when the ratio range is (0, 0.8), the target photovoltaic string is characterized to have serious dust adhesion, the output performance of the photovoltaic string is seriously influenced, and the target photovoltaic string needs to be cleaned and maintained.

The above examples are merely illustrative, and the specific operation and maintenance strategy is related to the actual situation of the photovoltaic power generation system, for example, affected by the conditions of loss of power generation, electricity price, cost of cleaning and maintenance (manpower cost, equipment cost, material cost, etc.), and the like.

The corresponding relation between the ratio and the dust attachment degree can be calibrated in advance, and is stored in a memory of the dust monitoring device in a data table mode and called when detection is to be carried out.

It is understood that, based on the above comparison manners, those skilled in the art may also derive other similar comparison manners, for example, a ratio of the output performance data of the standard photovoltaic string to the output performance data of the target photovoltaic string is used to determine the dust adhesion degree of the target photovoltaic string, where the ratio is greater than or equal to 1, and a larger ratio indicates that the dust adhesion degree is about severe; for another example, the dust adhesion degree of the target pv string may be determined by using a difference between the output performance data of the standard pv string and the output performance data of the target pv string, where the larger the difference is, the more serious the dust adhesion is.

In another possible implementation, the electrical parameter detection data sent by the power converter to the dust monitoring device is current-voltage curve sweep data. The current-voltage curve scanning data comprises open-circuit voltage of the photovoltaic string, namely voltage at two ends of the photovoltaic string in an open-circuit state, and when the open-circuit voltage of the photovoltaic module is reduced, the photovoltaic module is represented to have a dust adhesion phenomenon.

At the moment, the dust monitoring device determines the difference of the open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to the current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determines the dust attachment degree of the target photovoltaic string according to the difference of the open-circuit voltages.

The open-circuit voltage of the standard photovoltaic string is used as a standard, in some embodiments, a standard photovoltaic module with a significantly reduced open-circuit voltage may be determined as a faulty photovoltaic module, an average value of the open-circuit voltages of the remaining normal standard photovoltaic modules is used as a reference value, and the open-circuit voltages of the remaining target photovoltaic strings are compared with the reference value of the open-circuit voltage of the standard photovoltaic module to determine the dust adhesion degree of the target photovoltaic string, which is exemplified below.

In some embodiments, a ratio of an open circuit voltage of the target photovoltaic string to a reference value is obtained.

When the ratio range is (0.9, 1), representing that the dust adhesion degree of the target photovoltaic string is low at the moment, the target photovoltaic string can not be cleaned and maintained at the moment;

It is understood that, based on the above comparison manners, those skilled in the art may also derive other similar comparison manners, for example, a ratio of the reference value to the target photovoltaic string is used to determine the dust adhesion degree of the target photovoltaic string, where the ratio is greater than or equal to 1, and the larger the ratio is, the dust adhesion degree is about serious; for another example, the dust adhesion degree of the target photovoltaic string may be determined by using a difference between the reference value and the open-circuit voltage of the target photovoltaic string, and the larger the difference is, the more serious the dust adhesion is.

In yet another possible implementation, the electrical parameter detection data sent by the power converter to the dust monitoring device is output performance data. At this time, the output performance data is at least one of output voltage, output current, output power or power generation amount per unit time corresponding to the photovoltaic module. The output performance of the photovoltaic module may be reduced with the severity of the dust adhesion degree, and thus the dust adhesion degree may be judged using the output performance.

The dust monitoring device determines the dust adhesion degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string, which is exemplified below.

For example, in some embodiments, when the ratio is in the range of (0.8, 1), the dust adhesion degree characterizing the target photovoltaic string at this time is low, and cleaning and maintenance of the target photovoltaic string may not be performed at this time;

when the ratio range is (0.6, 0.8), representing that the target photovoltaic string has a certain degree of dust adhesion, but the influence on the output performance is low, and cleaning and maintenance can not be performed on the target photovoltaic string at this time;

when the ratio range is (0, 0.6), the target photovoltaic string is characterized to have serious dust adhesion, the output performance of the photovoltaic string is seriously influenced, and the target photovoltaic string needs to be cleaned and maintained.

It is understood that, based on the above comparison manners, those skilled in the art can also derive other similar equivalent comparison manners, for example, a ratio of the output performance data of the standard photovoltaic string to the output performance data of the target photovoltaic string is used to determine the dust adhesion degree of the target photovoltaic string, where the ratio is greater than or equal to 1, and the larger the ratio is, the dust adhesion degree is about severe; for another example, the dust adhesion degree of the target pv string may be determined by using a difference between the output performance data of the standard pv string and the output performance data of the target pv string, where the larger the difference is, the more serious the dust adhesion is.

Further, in order to remove the influence of the failed photovoltaic string on the dust adhesion detection result, the power converter further determines the failed photovoltaic string according to the current-voltage curve scanning data of the photovoltaic string, and sends the fault information for indicating the failed photovoltaic string to the dust monitoring device.

And after receiving the fault information, the dust monitoring device screens out the photovoltaic string with the fault from the standard photovoltaic string and the target photovoltaic string according to the fault information.

The power converter in the above description is connected to the photovoltaic group in series, and the power converter may be specifically a boost combiner box, a photovoltaic inverter, or a photovoltaic optimizer, and the embodiment of the present application is not particularly limited.

In summary, according to the dust monitoring device of the photovoltaic power generation system, the standard photovoltaic string and the target photovoltaic string are determined from the photovoltaic strings connected with the photovoltaic power generation system, so that the additional arrangement of photovoltaic modules required for dust monitoring is avoided, and the hardware cost and the maintenance cost are reduced. Collecting electric parameter detection data of the photovoltaic string through a power converter, and determining the dust adhesion degree of the target photovoltaic string according to the electric parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string. And the accuracy of the monitoring result of the dust adhesion degree of the target photovoltaic string distributed around the standard photovoltaic string is improved. In addition, this dust monitoring device can also get rid of the influence of photovoltaic group cluster of trouble to dust adhesion degree monitoring result, has further promoted the accuracy of dust adhesion degree monitoring result.

Based on the photovoltaic power generation system provided by the above embodiment, the embodiment of the present application further provides a dust monitoring device, which is specifically described below with reference to the accompanying drawings.

Referring to fig. 10, the figure is a schematic view of a dust monitoring apparatus according to an embodiment of the present application.

The illustrated dust monitoring device 103 may be an electronic computer or a server in a central control room of the photovoltaic power generation system, that is, the dust monitoring device 103 is an upper computer of the power converter 102 and has a data processing function.

The dust monitoring apparatus 103 comprises at least one processor 1031, and at least one memory 1032 and a bus 1033 connected to the processor 1031.

The processor 1031 and the memory 1032 communicate with each other via the bus 1033, and the processor 1031 is configured to invoke the program instructions in the memory 1032 to further monitor the dust attachment degree.

The memory 1032 may comprise volatile memory in a computer readable medium, such as Read Only Memory (ROM) or flash memory (flash RAM), for example, and/or non-volatile memory, including at least one memory chip. The memory is an example of a computer-readable medium.

Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device.

The dust monitoring device 103 is specifically configured to receive electrical parameter detection data of a photovoltaic string sent by a power converter 102 of the photovoltaic power generation system, determine electrical parameter detection data of the photovoltaic string, and determine a dust adhesion degree of a target photovoltaic string according to electrical parameter detection data corresponding to a standard photovoltaic string and the target photovoltaic string, respectively.

This will be explained in detail below.

For a photovoltaic module, under the condition that environmental factors such as temperature and illumination intensity are constant, the output current of the photovoltaic module changes with the output voltage thereof and can be drawn as a current-voltage curve (i.e., "IV curve"). The power converter acquires IV curve scan data through an IV curve scan technique and transmits the IV curve scan data to the dust monitoring device.

The power converter may also obtain output performance data of the photovoltaic string, the output performance data including at least one of an output voltage, an output current, an output power, or an amount of power generated per unit time.

The dust monitoring device then determines the degree of dust attachment of the target photovoltaic string based on the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string. The dust monitoring device determines the severity of dust attachment based on a threshold value of the ratio.

The open-circuit voltage of the standard photovoltaic group string is used as a standard, in some embodiments, a standard photovoltaic module with obviously reduced open-circuit voltage can be determined as a faulty photovoltaic module, an average value of the open-circuit voltages of the remaining normal standard photovoltaic modules is used as a reference value, and the open-circuit voltages of the remaining target photovoltaic group strings are compared with the reference value of the open-circuit voltage of the standard photovoltaic module to determine the dust adhesion degree of the target photovoltaic group string.

And the dust monitoring device determines the dust adhesion degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

The dust adhesion degree corresponds to a specific operation and maintenance strategy, and the operation and maintenance strategy is related to the actual situation of the photovoltaic power generation system, for example, affected by conditions such as loss of power generation, electricity price, cost of cleaning and maintenance (manpower cost, equipment cost, material cost, and the like).

The power converter in the above description may be specifically a boost combiner box, a photovoltaic inverter, or a photovoltaic optimizer, and the embodiments of the present application are not particularly limited.

In summary, the dust monitoring device determines the standard photovoltaic string and the target photovoltaic string from the photovoltaic strings connected with the photovoltaic power generation system, thereby avoiding additional arrangement of photovoltaic modules required for dust monitoring and reducing hardware cost and maintenance cost. Collecting electric parameter detection data of the photovoltaic string through a power converter, and determining the dust adhesion degree of the target photovoltaic string according to the electric parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string. And the accuracy of the monitoring result of the dust adhesion degree of the target photovoltaic string distributed around the standard photovoltaic string is improved. In addition, this dust monitoring device can also get rid of the influence of photovoltaic group cluster of trouble to dust adhesion degree monitoring result, has further promoted the accuracy of dust adhesion degree monitoring result.

The embodiment of the present application further provides a power converter, which is described in detail below with reference to the accompanying drawings.

Referring to fig. 11, a schematic diagram of a power converter according to an embodiment of the present application is shown.

The illustrated power converter 102 includes an input interface and controller 1021.

The input interface of the power converter 102 is used to connect the photovoltaic string 101. The power converter 102 includes a plurality of sets of input interfaces, each set including a positive input interface (identified as IN + IN the figure) and a negative input interface (identified as IN-IN the figure).

The controller 1021 is configured to determine a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, and determine a dust adhesion degree of the target photovoltaic string according to electrical parameter detection data corresponding to the standard photovoltaic string and the target photovoltaic string, where the standard photovoltaic string is a clean photovoltaic string, that is, no dust adhesion, or only a small amount of dust inevitably adheres (the small amount of dust has a negligible effect on the standard photovoltaic string).

This will be explained in detail below.

In one possible implementation, the electrical parameter sensing data acquired by the power converter includes current-voltage curve sweep data and output performance data.

For a photovoltaic module, under the condition that environmental factors such as temperature and illumination intensity are constant, the output current of the photovoltaic module changes along with the output voltage thereof, and can be drawn as a current-voltage curve (i.e., "IV curve"). The power converter acquires IV curve scan data via an IV curve scan technique.

Then, the controller 1021 firstly screens out the photovoltaic string with a fault from the standard photovoltaic string and the target photovoltaic string by using the current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string. For the photovoltaic module with a fault, if the electrical parameter detection data of the photovoltaic module string with the fault is used for detecting the dust adhesion degree, the false judgment can be caused, for example, the output voltage of the photovoltaic module string is reduced due to the fault, and the false judgment is that the output voltage of the photovoltaic module string is reduced due to the serious dust adhesion degree.

The controller 1021 then determines the degree of dust attachment for the target photovoltaic string based on the ratio of the output performance data for the target photovoltaic string to the output performance data for the standard photovoltaic string. Specifically, the controller 1021 determines the severity of dust attachment based on a threshold value of the ratio.

The corresponding relation between the ratio and the dust attachment degree can be calibrated in advance, and is stored in a storage module of the controller in a data table mode and called when detection is to be carried out.

In another possible implementation, the electrical parameter detection data acquired by the controller 1021 is current-voltage curve scan data. The current-voltage curve scanning data comprises open-circuit voltage of the photovoltaic string, namely voltage at two ends of the photovoltaic string in an open-circuit state, and when the open-circuit voltage of the photovoltaic module is reduced, the photovoltaic module is represented to have a dust adhesion phenomenon.

At this time, the controller 1021 determines the difference between the open-circuit voltages of the target pv string and the standard pv string according to the current-voltage curve scan data corresponding to the standard pv string and the target pv string, and determines the dust adhesion degree of the target pv string according to the difference between the open-circuit voltages.

The corresponding relation between the ratio and the dust attachment degree can be calibrated in advance, and is stored in a storage module of 1021 in a data table mode and called when detection is to be carried out.

In yet another possible implementation, the electrical parameter detection data acquired by the controller 1021 is output performance data. At this time, the output performance data is at least one of output voltage, output current, output power or power generation amount per unit time corresponding to the photovoltaic module. The output performance of the photovoltaic module may be reduced with the severity of the dust adhesion degree, and thus the dust adhesion degree may be judged using the output performance.

The controller 1021 determines the degree of dust attachment of the target photovoltaic string based on the ratio of the output performance data of the target photovoltaic string and the output performance data of the standard photovoltaic string.

The correspondence between the above ratio and the dust attachment degree may be calibrated in advance, and stored in the storage module of the controller 1021 in the form of a data table, and called when detection is to be performed.

Further, in order to remove the influence of the failed photovoltaic string on the dust adhesion detection result, the controller 1021 determines the failed photovoltaic string according to the current-voltage curve scanning data of the photovoltaic string, and screens out the failed photovoltaic string from the standard photovoltaic string and the target photovoltaic string.

The controller 1021 may be an Application Specific Integrated Circuit (ASIC), a Programmable Logic Device (PLD), a Digital Signal Processor (DSP), or a combination thereof. The PLD may be a Complex Programmable Logic Device (CPLD), a Field-Programmable Gate Array (FPGA), a General Array Logic (GAL), or any combination thereof, and the embodiment of the present invention is not limited thereto.

The power converter in the above description of the embodiment of the present application may specifically be a boost combiner box, a photovoltaic inverter, or a photovoltaic optimizer, and the embodiments of the present application are not specifically limited, and the subsequent systems respectively connected correspondingly are not described herein again.

In summary, the controller of the power converter determines the standard photovoltaic string and the target photovoltaic string from the photovoltaic strings connected to the photovoltaic power generation system, avoids additionally arranging a photovoltaic module required for dust monitoring, reduces hardware cost and maintenance cost, determines the dust adhesion degree of the target photovoltaic string by acquiring electrical parameter detection data of the photovoltaic string and according to the electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and improves the accuracy of a dust adhesion degree monitoring result of the target photovoltaic string distributed around the standard photovoltaic string. In addition, the power converter can also eliminate the influence of the failed photovoltaic string on the monitoring result of the dust adhesion degree, and the accuracy of the dust adhesion degree monitoring result is further improved.

Based on the above embodiments, the embodiments of the present application further provide a method for detecting a dust attachment degree, which is specifically described below with reference to the accompanying drawings.

Referring to fig. 12, it is a flowchart of a method for detecting a dust adhesion degree according to an embodiment of the present application.

The method comprises the following steps:

s1201: and acquiring electrical parameter detection data of the photovoltaic string.

S1202: and determining a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, wherein the standard photovoltaic string is a clean photovoltaic string.

The standard photovoltaic string is maintained in a clean state by means of regular cleaning, with no dust adhering to the standard photovoltaic string, or only a small amount of dust adhering to the standard photovoltaic string (the influence of the small amount of dust on the standard photovoltaic string is negligible).

S1203: and determining the dust attachment degree of the target photovoltaic string according to the electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string.

In one possible implementation, the acquired electrical parameter detection data includes current-voltage curve scan data and output performance data.

For a photovoltaic module, under the condition that environmental factors such as temperature and illumination intensity are constant, the output current of the photovoltaic module changes along with the output voltage thereof, and can be drawn as a current-voltage curve (i.e., "IV curve"). IV curve scan data is acquired by an IV curve scan technique.

Meanwhile, the power converter can also acquire output performance data of the photovoltaic string, wherein the output performance data comprises at least one of output voltage, output current, output power or power generation amount per unit time.

And then, respectively scanning data by using current-voltage curves corresponding to the standard photovoltaic string and the target photovoltaic string, and screening out the photovoltaic string with a fault from the standard photovoltaic string and the target photovoltaic string. For the photovoltaic module with a fault, if the electrical parameter detection data of the photovoltaic module string with the fault is used for detecting the dust adhesion degree, the false judgment can be caused, for example, the output voltage of the photovoltaic module string is reduced due to the fault, and the false judgment is that the output voltage of the photovoltaic module string is reduced due to the serious dust adhesion degree.

And determining the dust adhesion degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string. Specifically, the severity of dust adhesion is determined based on a threshold value of the ratio.

The corresponding relation between the ratio and the dust attachment degree can be calibrated in advance, stored in a data table mode and called when detection is to be carried out.

In another possible implementation, the acquired electrical parameter detection data is current-voltage curve scan data. The current-voltage curve scanning data comprises open-circuit voltage of the photovoltaic string, namely voltage at two ends of the photovoltaic string in an open-circuit state, and when the open-circuit voltage of the photovoltaic module is reduced, the photovoltaic module is represented to have a dust adhesion phenomenon.

In this case, S1203 specifically includes: and determining the difference of the open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to the current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determining the dust attachment degree of the target photovoltaic string according to the difference of the open-circuit voltages.

In yet another possible implementation, the acquired electrical parameter detection data is output performance data. At this time, the output performance data is at least one of output voltage, output current, output power or power generation amount per unit time corresponding to the photovoltaic module. The output performance of the photovoltaic module may be reduced with the severity of the dust adhesion degree, and thus the dust adhesion degree may be judged using the output performance.

In this case, S1203 specifically includes: and determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

Furthermore, in order to remove the influence of the failed photovoltaic string on the dust adhesion detection result, the failed photovoltaic string can be determined according to the current-voltage curve scanning data of the photovoltaic string, and the failed photovoltaic string is screened out from the standard photovoltaic string and the target photovoltaic string.

By utilizing the method provided by the embodiment of the application, the standard photovoltaic string and the target photovoltaic string are determined from the photovoltaic strings connected with the photovoltaic power generation system, the photovoltaic string required by dust monitoring is prevented from being additionally and independently arranged, and the hardware cost and the maintenance cost are reduced. When the target photovoltaic string is distributed around the standard photovoltaic string, the deposition speed of the surface dust is similar because the positions of the target photovoltaic string and the standard photovoltaic string are similar, and therefore the accuracy of the monitoring result of the dust adhesion degree of the target photovoltaic string is improved.

It should be understood that in the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" for describing an association relationship of associated objects, indicating that there may be three relationships, e.g., "a and/or B" may indicate: only A, only B and both A and B are present, wherein A and B may be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In addition, some or all of the units and modules may be selected according to actual needs to achieve the purpose of the solution of the embodiment. One of ordinary skill in the art can understand and implement without inventive effort.

The foregoing is directed to embodiments of the present application and it is noted that numerous modifications and adaptations may be made by those skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.

Claims

1. A photovoltaic power generation system, characterized in that the photovoltaic power generation system comprises: dust monitoring devices and power converters; wherein, the first and the second end of the pipe are connected with each other,

the input end of the power converter is used for connecting the photovoltaic string;

the power converter is used for sending the electric parameter detection data of the photovoltaic string to the dust monitoring device;

the dust monitoring device is used for determining a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, and determining the dust adhesion degree of the target photovoltaic string according to electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, wherein the standard photovoltaic string is a clean photovoltaic string.

2. The photovoltaic power generation system of claim 1, wherein the electrical parameter detection data comprises current-voltage curve sweep data and output performance data, the output performance data comprising at least one of:

output voltage, output current, output power or generated energy per unit time.

3. The photovoltaic power generation system according to claim 2, wherein the dust monitoring device is specifically configured to screen out a faulty pv string from the standard pv string and the target pv string according to current-voltage curve scan data respectively corresponding to the standard pv string and the target pv string; and determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

4. The photovoltaic power generation system of claim 1, wherein the electrical parameter detection data comprises current-voltage curve sweep data;

the dust monitoring device is specifically configured to determine a difference between open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, and determine a dust attachment degree of the target photovoltaic string according to the difference between the open-circuit voltages.

5. The photovoltaic power generation system of claim 4, wherein the power converter is further configured to send fault information indicating a faulty photovoltaic string to the dust monitoring device according to the current-voltage curve scan data of the photovoltaic string;

and the dust monitoring device is also used for screening out the photovoltaic string with the fault from the standard photovoltaic string and the target photovoltaic string according to the fault information.

6. The photovoltaic power generation system of claim 1, wherein the electrical parameter detection data comprises output performance data;

and the dust monitoring device is used for determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

7. The photovoltaic power generation system of claim 6, wherein the output performance data comprises at least one of:

output voltage, output current, output power or generated energy per unit time.

8. The photovoltaic power generation system according to claim 6 or 7, wherein the power converter is further configured to send fault information indicating a faulty photovoltaic string to the dust monitoring device according to the current-voltage curve scanning data of the photovoltaic string;

9. The photovoltaic power generation system of claim 1, wherein the power converter is at least one of:

a photovoltaic inverter, a dc combiner box, or a photovoltaic optimizer.

10. The dust monitoring device is characterized by being used for receiving electric parameter detection data of a photovoltaic group string sent by a power converter of a photovoltaic power generation system, determining the dust adhesion degree of the target photovoltaic group string according to the electric parameter detection data respectively corresponding to the standard photovoltaic group string and the target photovoltaic group string, wherein the standard photovoltaic group string is a clean photovoltaic group string.

11. The dust monitoring device according to claim 10, wherein the electrical parameter detection data includes current-voltage curve scan data and output performance data, the output performance data including at least one of an output voltage, an output current, an output power, or an amount of power generation per unit time.

12. The dust monitoring device according to claim 11, wherein the dust monitoring device is specifically configured to screen out a failed pv string from the standard pv string and the target pv string according to current-voltage curve scan data respectively corresponding to the standard pv string and the target pv string; and determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

13. The dust monitoring device of claim 10, wherein the electrical parameter detection data comprises current-voltage curve sweep data;

14. The dust monitoring device of claim 13, further configured to receive fault information sent by the power converter to indicate a faulty pv string, and to screen out the faulty pv string from the standard pv string and the target pv string according to the fault information.

15. A dust monitoring device according to claim 10, in which the electrical parameter sensing data comprises output performance data;

16. The dust monitoring apparatus of claim 15, wherein the output performance data comprises at least one of:

output voltage, output current, output power or generated energy per unit time.

17. The dust monitoring device according to claim 15 or 16, further configured to receive fault information sent by the power converter and indicating a faulty pv string, and to screen out the faulty pv string from the standard pv string and the target pv string according to the fault information.

18. A power converter is applied to a photovoltaic power generation system and comprises an input interface and a controller;

the input interface is used for connecting the photovoltaic group string;

the controller is used for determining a standard photovoltaic string and a target photovoltaic string in the photovoltaic string, and determining the dust adhesion degree of the target photovoltaic string according to electrical parameter detection data respectively corresponding to the standard photovoltaic string and the target photovoltaic string, wherein the standard photovoltaic string is a clean photovoltaic string.

19. The power converter of claim 18, wherein the electrical parameter sensing data comprises current-voltage curve sweep data and output performance data, the output performance data comprising at least one of:

output voltage, output current, output power or generated energy per unit time.

20. The power converter according to claim 19, wherein the controller is specifically configured to screen out a faulty pv string from the standard pv string and the target pv string according to current-voltage curve scan data corresponding to the standard pv string and the target pv string, respectively; and determining the dust attachment degree of the target photovoltaic string according to the ratio of the output performance data of the target photovoltaic string to the output performance data of the standard photovoltaic string.

21. The power converter of claim 18, wherein said electrical parameter sensing data comprises current-voltage curve sweep data;

the controller is specifically configured to determine a difference between open-circuit voltages of the target photovoltaic string and the standard photovoltaic string according to current-voltage curve scan data corresponding to the standard photovoltaic string and the target photovoltaic string, and determine a dust adhesion degree of the target photovoltaic string according to the difference between the open-circuit voltages.

22. The power converter of claim 21, wherein the controller is further configured to screen the standard pv string and the target pv string for malfunctioning strings based on current-voltage curve scan data of the pv strings.

23. The power converter of claim 18, wherein the power converter is at least one of:

a photovoltaic inverter, a dc combiner box, or a photovoltaic optimizer.

24. A method for detecting a degree of dust adhesion, the method comprising:

acquiring electrical parameter detection data of the photovoltaic string;

25. The method of claim 24, wherein the electrical parameter detection data comprises current-voltage curve sweep data and output performance data, the output performance data comprising at least one of:

output voltage, output current, output power or generated energy per unit time.

26. The method according to claim 24, wherein the determining the degree of dust adhesion of the target pv string according to the electrical parameter detection data corresponding to the standard pv string and the target pv string respectively comprises:

screening out the photovoltaic string with the fault from the standard photovoltaic string and the target photovoltaic string according to current-voltage curve scanning data respectively corresponding to the standard photovoltaic string and the target photovoltaic string;

27. The method according to claim 24, wherein the electrical parameter detection data includes current-voltage curve scan data, and the determining the dust adhesion degree of the target pv group string according to the electrical parameter detection data corresponding to the standard pv group string and the target pv group string respectively includes:

and determining the difference of the open-circuit voltages of the target photovoltaic group string and the standard photovoltaic group string according to the current-voltage curve scanning data respectively corresponding to the standard photovoltaic group string and the target photovoltaic group string, and determining the dust attachment degree of the target photovoltaic group string according to the difference of the open-circuit voltages.

28. The detection method according to claim 27, further comprising:

determining fault information of the fault photovoltaic group string according to the current-voltage curve scanning data of the photovoltaic group string;

and screening out the photovoltaic group strings with faults from the standard photovoltaic group strings and the target photovoltaic group strings according to the fault information.

29. The method according to claim 24, wherein the electrical parameter detection data includes output performance data, and the determining the dust adhesion degree of the target pv group string according to the electrical parameter detection data corresponding to the standard pv group string and the target pv group string respectively includes:

30. The detection method of claim 29, wherein the output performance data comprises at least one of the following

Output voltage, output current, output power or generated energy per unit time.

31. The detection method according to claim 29 or 30, further comprising: