WO2021017234A1

WO2021017234A1 - Method and system for monitoring attenuation of performance of photovoltaic assembly

Info

Publication number: WO2021017234A1
Application number: PCT/CN2019/114562
Authority: WO
Inventors: 董颖华; 张军军; 吴福保; 秦昊; 李红涛; 秦筱迪
Original assignee: 中国电力科学研究院有限公司; 国家电网有限公司
Priority date: 2019-08-01
Filing date: 2019-10-31
Publication date: 2021-02-04
Also published as: CN112311326A

Abstract

A system and method for monitoring the attenuation of the performance of a photovoltaic assembly, the method comprising: on the basis of a standard test environment, acquiring the starting powers of a plurality of monitored photovoltaic assemblies; respectively mounting the plurality of monitored photovoltaic assemblies according to a plurality of set angles, and testing power data of each of the monitored photovoltaic assemblies; and calculating performance attenuation data of each of the monitored photovoltaic assemblies on the basis of the starting power and power data of each of the monitored photovoltaic assemblies.

Description

Attenuation monitoring method and system for photovoltaic module performance

This disclosure claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 201910707487.X on August 1, 2019, and the entire content of the above application is incorporated into this disclosure by reference.

Technical field

This article relates to the field of photovoltaic module testing, such as a method and system for monitoring the degradation of photovoltaic module performance.

Background technique

Photovoltaic modules are an important part of the photovoltaic power generation system, and their function is to convert sunlight energy into DC electrical energy for output.

The important parameters of photovoltaic modules are: open circuit voltage, short circuit current, maximum power point voltage, maximum power point current, maximum power, etc. When the photovoltaic module is exposed to the sun, its external current-voltage characteristic curve is called the IV curve. As the external resistance of the photovoltaic module increases, its voltage changes from 0 to open circuit voltage, and the corresponding current changes from short-circuit current to 0. Among them, The maximum value of the voltage multiplied by the corresponding current is the maximum power. The voltage and current at this point are called the maximum power point voltage and the maximum power point current.

In actual use, meteorological factors such as actual solar irradiance, temperature and wind speed on site determine the external output power of photovoltaic modules. At the same time, due to the characteristics of the photovoltaic module material, the output power of the photovoltaic module will decay with the use time during use, that is, under the same weather conditions, the output power of the same photovoltaic module after years of use is much lower than when it was first put into use. Performance will gradually decay.

In the method for testing the performance of photovoltaic modules in the related art, the full cycle power detection of the photovoltaic modules is not performed, and thus the attenuation performance of the photovoltaic modules cannot be accurately evaluated.

Summary of the invention

This article provides a photovoltaic module performance degradation monitoring method and system, which can solve the problem of the lack of full cycle power detection of photovoltaic modules in related technologies, and thus the inability to accurately evaluate photovoltaic module degradation performance.

The technical solutions provided in this article are:

A method for monitoring the degradation of photovoltaic module performance, including:

Obtain the initial power of multiple monitored photovoltaic modules based on a standard test environment;

Installing a plurality of the monitored photovoltaic modules at multiple set angles, and testing the power data of each of the monitored photovoltaic modules;

Calculate performance degradation data of each monitored photovoltaic component based on the initial power of each monitored photovoltaic component and the power data of each monitored photovoltaic component.

A degradation monitoring system for photovoltaic module performance, the system comprising: a plurality of current-voltage test modules, and a monitoring control module;

Each of the current-voltage test modules is respectively connected to a monitored photovoltaic component, and each of the current-voltage test modules is configured to test the power data of the monitored photovoltaic component in an outdoor environment;

The monitoring control module is connected to each of the current-voltage test modules, and the monitoring control module is configured to control each of the current-voltage test modules to collect power data at a set frequency outdoors, and is also configured to collect power data according to The initial power of each of the monitored photovoltaic components and the power data of each of the monitored photovoltaic components are used to calculate performance degradation data of each of the monitored photovoltaic components.

Description of the drawings

FIG. 1 is a flowchart of a method for monitoring degradation of photovoltaic module performance according to an embodiment of the present invention;

Figure 2 is a flow chart of degradation monitoring of photovoltaic module performance according to an embodiment of the present invention;

Fig. 3 is a structural diagram of a system for monitoring the performance degradation of photovoltaic modules according to an embodiment of the present invention.

Detailed ways

The content of this article will be further explained below in conjunction with the drawings and examples of the specification.

Example 1:

This embodiment provides a method for monitoring the degradation of photovoltaic module performance, and the method flowchart is shown in FIG. 1.

The steps are as follows: select four empirical monitoring angles according to the latitude and longitude of the empirical site and the best inclination angle of local photovoltaic module installation; before the modules are monitored, use the mobile photovoltaic module STC test platform to perform initial power calibration on the monitored components; The IV curve (ie: current-voltage characteristic curve) on-line tester of the transformer and photovoltaic module performs online monitoring of the module, and finally evaluates the attenuation performance of the module based on the monitoring result.

It is understandable that "I-V" is the abbreviation of "current-voltage" in English.

This article includes the following steps:

1) Random sampling of the tested photovoltaic modules for photovoltaic modules that need empirical monitoring, and 16 of each type of photovoltaic module for empirical monitoring;

2) Before the empirical monitoring, electroluminescence (EL) test is performed on the tested photovoltaic modules on the demonstration platform site, that is, EL test, to ensure the integrity and quality of each tested photovoltaic module;

3) After passing the EL test, use the AAA-level analog light source to perform the initial power calibration of the tested photovoltaic module on the demonstration platform site, and use the calibration result as the initial value P _{or of the} photovoltaic module power attenuation, and retain the original test data;

4) At the site, 4 kinds of angles are used to install the tested photovoltaic modules, the 4 angles are: 0°, 45°, actual latitude and set angle, and 4 tested modules are installed at each inclination angle.

The set angle can be the best inclination angle for photovoltaic module power generation.

The actual latitude may be a latitude angle determined according to the local latitude.

It should be noted that, in some embodiments, in the field, the measured photovoltaic module can be installed at various angles. The various angles can include: 0°, 45°, actual latitude and set angle, and each inclination angle is installed More than 4 tested components in the same batch.

5) After the modules are installed, firstly connect the photovoltaic module output positive and negative poles to the input terminal of the photovoltaic module I-V online test device, and connect the output terminal of the photovoltaic module I-V online test device to the DC side of the single-phase micro-inverter;

6) Connect the AC output side of each single-phase micro-inverter to converge in parallel to form three-phase electricity and then merge it into the grid;

7) Set the host computer to regularly send test commands to the photovoltaic module I-V online test device, and upload the test results and photovoltaic module power generation parameters to the host computer, and at the same time obtain meteorological information such as irradiation, temperature, and wind speed at that moment;

8) According to the outdoor empirical monitoring results, adopt the method specified in the standard IEC60891 to transform the empirical test results of photovoltaic modules to STC conditions;

9) Calculate the outdoor attenuation performance of the photovoltaic module η _pv according to the initial power calibration of the photovoltaic module to P _or and the empirical monitoring result P _de of the photovoltaic module:

10) According to the installation angle of the tested photovoltaic module and its attenuation, the outdoor performance of the photovoltaic module can be analyzed under different angles.

Example 2:

This embodiment provides a method for monitoring the degradation of photovoltaic module performance.

It should be noted that Embodiment 1 is an example of specific implementation steps of the method provided herein, and Embodiment 2 is an example of steps of a test performed according to the method provided herein.

Selection of photovoltaic modules: 16 modules are selected according to each model. The demonstration platform has a total of 240 modules monitored.

At the site, the photovoltaic module mobile testing platform is used to perform EL testing on the extracted photovoltaic modules to ensure that the tested components are free from cracks and other faults. If the module detects cracks, the tested photovoltaic modules need to be replaced.

Place the photovoltaic modules that have passed the EL test on the module test rack, and use AAA-level analog light sources to calibrate the initial power of all tested components, and record the calibration results of each module, according to model, serial number, nominal value, and test station Record the results.

Install the photovoltaic module with the initial power calibration on the photovoltaic bracket. The bracket has 4 angles: 0°, 45°, local latitude and the best inclination angle of photovoltaic module power generation. Each inclination angle is installed with 4 tested modules.

After the modules are installed, firstly connect the photovoltaic module output positive and negative poles to the input terminal of the photovoltaic module I-V online testing device, and connect the output terminal of the photovoltaic module I-V online testing device to the DC side of the single-phase micro-inverter.

The AC output of each individual micro-inverter is converged in parallel to form a three-phase power and then merged into the grid.

Set the I-V curve test time interval according to the upper computer, perform online I-V curve test on the photovoltaic module, and upload the test results to the upper computer.

According to the initial power of the photovoltaic module and the empirical monitoring result of the module, the outdoor performance degradation of the photovoltaic module is evaluated and the test result is obtained.

In some embodiments, the method includes:

Installing a plurality of the monitored photovoltaic modules according to a plurality of set angles, and testing the power data of each of the monitored photovoltaic modules;

In some embodiments, the standard test environment is: an irradiance of 1000 W/m ² , a component temperature of 25° C., and an air quality of 1.5.

In some embodiments, the multiple set angles include but are not limited to:

0°, 45°, actual latitude and set inclination.

In some embodiments, the testing the power data of each of the monitored photovoltaic components includes:

Collect current-voltage data (ie: I-V data) of each of the monitored photovoltaic components at a set frequency;

The power data of each monitored photovoltaic component is acquired based on the current-voltage data of each monitored photovoltaic component.

In some embodiments, the performance degradation data is calculated by the following formula:

Wherein, η _pv is the performance degradation data of the monitored photovoltaic component, P _or is the initial power of the monitored photovoltaic component, and P _de is the power data of the monitored photovoltaic component.

In some embodiments, before the obtaining the initial power of a plurality of monitored photovoltaic modules based on a standard test environment, the method further includes:

The photovoltaic module is turned on with reverse-biased direct current, and based on the judgment result that the photovoltaic module is not turned on, it is determined that the photovoltaic module does not have a hidden crack gate; based on the judgment result of the photovoltaic module is turned on, it is determined that the photovoltaic module has a hidden crack Gate

Screen out a set number of photovoltaic modules that do not have hidden breaking grids as the monitored photovoltaic modules.

Example 3:

This embodiment provides a degradation monitoring system for photovoltaic module performance, and the system structure diagram is shown in FIG. 2.

The system includes:

Multiple I-V test modules, monitoring and control modules;

Each I-V test module is respectively connected to a monitored photovoltaic module, and is configured to test the power data of the monitored photovoltaic module in an outdoor environment;

The monitoring control module is connected to all IV test modules, is configured to control the IV test module to collect power data at a set frequency outdoors, and is also configured to calculate the performance degradation of each monitored photovoltaic module according to the initial power and power data data.

It should be noted that, before the test, the initial power of the monitored photovoltaic module can be tested in a standard test environment.

The system further includes: a plurality of single-phase micro inverters;

Each single-phase micro-inverter is respectively connected to a monitored photovoltaic component, and is configured to integrate the monitored photovoltaic component into the power grid.

The monitoring control module includes: an attenuation data calculation sub-module;

The attenuation data calculation sub-module is connected to the I-V test module;

The attenuation data calculation submodule is configured to calculate performance attenuation data according to the initial power and the power data.

The attenuation data calculation submodule calculates the performance attenuation data by using the following formula:

In some embodiments, the system includes: a plurality of current-voltage test modules (ie: I-V test modules), a monitoring control module;

The monitoring control module is connected to each of the current-voltage test modules, and the monitoring control module is configured to control each of the current-voltage test modules to collect power data at a set frequency outdoors, and is also configured to collect power data according to The initial power of each of the monitored photovoltaic components and the power data of each of the monitored photovoltaic components are calculated to calculate the performance degradation data of each of the monitored photovoltaic components.

In some embodiments, the system further includes: a plurality of single-phase micro-inverters;

Each of the single-phase microinverters is respectively connected to a monitored photovoltaic component, and each of the single-phase microinverters is configured to integrate the monitored photovoltaic component into the power grid.

In some embodiments, the monitoring control module includes: an attenuation data calculation sub-module;

The attenuation data calculation sub-module is connected to each of the current-voltage test modules;

The attenuation data calculation sub-module is configured to calculate the power data of each monitored photovoltaic component according to the initial power of each monitored photovoltaic component and the power data of each monitored photovoltaic component Performance degradation data.

In some embodiments, the attenuation data calculation submodule is configured to calculate the performance attenuation data by using the following formula:

Obviously, the described embodiments are part of the embodiments in this document, rather than all of the embodiments. Based on the embodiments herein, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of this text.

Those skilled in the art should understand that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, this application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

This application is described with reference to flowcharts and/or block diagrams of methods, equipment (systems), and computer program products according to the embodiments of this application. It should be understood that each process and/or block in the flowchart and/or block diagram, and the combination of processes and/or blocks in the flowchart and/or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing equipment to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing equipment are generated It is a device that realizes the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing equipment to work in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction device. The device implements the functions specified in one process or multiple processes in the flowchart and/or one block or multiple blocks in the block diagram.

These computer program instructions can also be loaded on a computer or other programmable data processing equipment, so that a series of operation steps are executed on the computer or other programmable equipment to produce computer-implemented processing, so that the computer or other programmable equipment is executed The instructions provide steps for implementing functions specified in a flow or multiple flows in the flowchart and/or a block or multiple blocks in the block diagram.

Compared with related technologies, this solution obtains the initial power of all monitored photovoltaic modules based on a standard test environment; installs the monitored photovoltaic modules at multiple set angles, and tests the power data of the monitored photovoltaic modules; Calculate performance degradation data of the monitored photovoltaic module based on the initial power and the power data. This solution realizes the full cycle power calibration of the photovoltaic module by testing the initial power of the photovoltaic module under test, making the test of the attenuation performance more accurate. In addition, by installing and arranging the photovoltaic modules to be tested at different set angles, the test is more practical and meets the outdoor attenuation performance monitoring requirements of photovoltaic modules at different angles.

Claims

A method for monitoring the degradation of photovoltaic module performance, including:

Obtain the initial power of multiple monitored photovoltaic modules based on a standard test environment;

Installing a plurality of the monitored photovoltaic modules according to a plurality of set angles, and testing the power data of each of the monitored photovoltaic modules;

Calculate the performance degradation data of each monitored photovoltaic component based on the initial power of each monitored photovoltaic component and the power data of each monitored photovoltaic component.
The method of claim 1, wherein the standard test environment is: an irradiance of 1000 W/m 2 , a component temperature of 25° C., and an air quality of 1.5.
The method of claim 1, wherein the plurality of set angles includes:

0°, 45°, actual latitude and set inclination.
The method of claim 1, wherein the testing the power data of each of the monitored photovoltaic modules includes:

Collect current-voltage data of each monitored photovoltaic module at a set frequency;

The power data of each monitored photovoltaic component is acquired based on the current-voltage data of each monitored photovoltaic component.
The method of claim 1, wherein the performance degradation data is calculated by the following formula:

Wherein, η pv is the performance degradation data of the monitored photovoltaic component, P or is the initial power of the monitored photovoltaic component, and P de is the power data of the monitored photovoltaic component.
The method according to claim 1, before obtaining the initial power of a plurality of monitored photovoltaic modules based on a standard test environment, the method further comprises:

The photovoltaic module is turned on with reverse-biased direct current, and based on the judgment result that the photovoltaic module is not conductive, it is determined that the photovoltaic module does not have a hidden cracking grid; based on the judgment result of the photovoltaic module being turned on, the photovoltaic module is determined There are hidden cracks;

Screen out a set number of photovoltaic modules that do not have hidden breaking grids as the monitored photovoltaic modules.
A degradation monitoring system for photovoltaic module performance, the system comprising: a plurality of current-voltage test modules, and a monitoring control module;

Each of the current-voltage test modules is respectively connected to a monitored photovoltaic component, and each of the current-voltage test modules is configured to test the power data of the monitored photovoltaic component in an outdoor environment;

The monitoring control module is connected to each of the current-voltage test modules, and the monitoring control module is configured to control each of the current-voltage test modules to collect power data at a set frequency outdoors, and is also configured to collect power data according to The initial power of each of the monitored photovoltaic components and the power data of each of the monitored photovoltaic components are calculated to calculate the performance degradation data of each of the monitored photovoltaic components.
The system of claim 7, further comprising: a plurality of single-phase micro inverters;

Each of the single-phase micro-inverters is respectively connected to a monitored photovoltaic component, and each of the single-phase micro-inverters is configured to integrate the monitored photovoltaic component into the power grid.
8. The system of claim 7, wherein the monitoring control module comprises: an attenuation data calculation sub-module;

The attenuation data calculation sub-module is connected to each of the current-voltage test modules;

The attenuation data calculation sub-module is configured to calculate the power data of each monitored photovoltaic component according to the initial power of each monitored photovoltaic component and the power data of each monitored photovoltaic component Performance degradation data.
The system according to claim 9, wherein the attenuation data calculation sub-module is configured to calculate the performance attenuation data by the following formula:

Wherein, η pv is the performance degradation data of the monitored photovoltaic component, P or is the initial power of the monitored photovoltaic component, and P de is the power data of the monitored photovoltaic component.