CN207819856U - A photovoltaic array IV characteristic curve scanning and parameter identification system - Google Patents

Abstract

The utility model discloses an IV characteristic curve scanning and parameter identification system of a photovoltaic array, which comprises a data acquisition module, a photovoltaic array IV characteristic curve scanning module, a storage module and a display module, and the data acquisition module samples the temperature and illuminance of the photovoltaic array , and transmit it to the photovoltaic array IV characteristic curve scanning module through a low-power wireless sensor network, scan the IV characteristic curve, detect and store the output current and voltage of the array; convert the scanned IV curve into a standard condition (STC) IV curve, IV curve fitting, accurate identification of photovoltaic model parameters. The system of the utility model can be carried outdoors to assist inspectors to manually detect the photovoltaic array, and can also be placed in the combiner box and connected with the host computer to realize real-time online component-level and component-level distributed photovoltaic array IV curve scanning .

Description

A photovoltaic array IV characteristic curve scanning and parameter identification system

technical field

The utility model relates to the technical field of photovoltaic power generation array detection, in particular to an IV characteristic curve scanning and parameter identification system of a photovoltaic array.

Background technique

As the core of the photovoltaic power generation system, the photovoltaic panel is a power generation device that must be in the outdoor environment for a long time. Therefore, in practical applications, the performance of photovoltaic panels will not only decline with the increase of service life, but also be affected by harsh natural environments and cause failures. The existence of faults will cause low-efficiency operation of the entire system and accelerate the damage of photovoltaic panels. In severe cases, it may even cause fires, cause social property losses, and endanger human life. The collection, modeling, parameter extraction, and parameter analysis and classification of characteristic voltage and current data of photovoltaic arrays in various complex environments are the basis for rapid fault detection, ensuring the safety of photovoltaic power generation systems, evaluating system performance, and improving solar cell manufacturing processes .

In recent years, many scholars at home and abroad have made in-depth research on the testing technology of the I-V characteristic curve of photovoltaic arrays. Most of the scholars mainly use the following test methods: variable power resistor test method, variable electronic load test method and dynamic Capacitor charging test method. The variable power resistor test method is to change the resistance value of the resistor manually, and use the current and voltmeter to manually read the current and voltage data at the same time, and arrange the collected data in time series to obtain the volt-ampere of the photovoltaic module. characteristic curve. The principle of this method is simple, but the test process is cumbersome, time-consuming and labor-intensive, manual control cannot make the resistance value of the resistor change continuously and accurately, and the accuracy and smoothness of the obtained I-V curve are low. The variable electronic load method uses power transistors (such as IGBTs and MOSFETs) operating in the linear region as variable loads, and changes the conduction degree of the transistors by controlling the gate drive voltage. Through continuous sampling, the I-V of photovoltaic modules can be accurately obtained. characteristic curve. However, due to the limitation of the safe working area, the power transistor can only withstand high power consumption for a few milliseconds. It is only suitable for low-power photovoltaic module I-V curve measurement. For the I-V measurement application of photovoltaic arrays, the power transistor is easy to burn out. Therefore, the robustness of variable electronic load schemes based on power transistors is very limited.

Once the I-V curve is obtained, some simple PV array electrical parameters (including open circuit voltage (Voc), short circuit current (Isc), maximum power point voltage (Vmpp) and current (Impp) and fill factor (FF) etc. can be easily extracted ), combined with the measured temperature and illuminance, it is indeed very convenient to check the operating status of the photovoltaic array. However, for the improvement of front-end solar cell production process, how to reduce the cost of photovoltaic power generation, more detailed evaluation of photovoltaic array performance, and deeper and more convenient photovoltaic array fault diagnosis, in addition to these simple electrical parameters, photovoltaic internal model parameters are also required. However, photovoltaic modules currently on the market often do not provide these internal parameters. Therefore, photovoltaic model parameter identification has received more and more attention from scholars at home and abroad in recent years.

At present, domestic research on I-V curve testers based on capacitance solutions (especially portable products) is still relatively weak, while some foreign products have high prices, and these testers do not provide the function of extracting photovoltaic internal model parameters, and these Internal parameters are of great significance for further research on photovoltaic power generation systems.

Contents of the invention

Aiming at the deficiencies of the prior art, the utility model proposes an IV characteristic curve scanning and parameter identification system of a photovoltaic array, which controls the charging of the electrolytic capacitor by controlling the conduction of the IGBT, and completes the discharge of the electrolytic capacitor by controlling the solid state relay. After obtaining the I-V characteristic curve of the photovoltaic array, the controller is directly used to realize the parameter identification of the photovoltaic array model in the embedded platform, which provides effective support for the further realization of portable photovoltaic fault diagnosis.

To achieve the above purpose, the technical solution of the present invention is: a photovoltaic array IV characteristic curve scanning and parameter identification system, including a data acquisition module, a photovoltaic array IV characteristic curve scanning module, a storage module and a display module;

The data acquisition module is connected with the photovoltaic array IV characteristic curve scanning module for measuring the temperature and illuminance of the photovoltaic array;

The photovoltaic array IV characteristic curve scanning module includes a first controller, a voltage sensor for measuring the array voltage and a current sensor for measuring the array current connected to the first controller, and one end of the current sensor is output through a diode and the array The other end of the current sensor is connected to the collector of a first IGBT, the positive electrode of a capacitor and one end of a first resistor, and the gate of the first IGBT is connected to a second resistor and a first resistor in turn. The drive optocoupler is connected to the first controller, the negative pole of the capacitor is connected to the collector of a second IGBT and the first output terminal of a solid state relay, and the second output terminal of the solid state relay is connected to the other end of the first resistor connected, the input end is connected to the first controller, the gate of the second IGBT is connected to the first controller through a third resistor and a second drive optocoupler in turn, the emitter of the first IGBT, the array output Both the cathode and the emitter of the second IGBT are grounded;

The storage module and the display module are respectively connected to the first controller.

Further, the data acquisition module includes an illumination sensor, a temperature sensor and a second controller, the illumination sensor and the temperature sensor are respectively connected to the second controller, and the second controller is connected to the first controller via wireless Transceiver for data transmission.

Further, the model of the wireless transceiver is nRF24L01.

Further, the models of the first controller and the second controller are TMS320F28335.

Further, the storage module is a USB flash drive.

Further, it also includes a host computer connected to the first controller through a UART interface.

Further, the photovoltaic array IV characteristic curve scanning module is installed at the combiner box.

Further, the data acquisition module and the photovoltaic array IV characteristic curve scanning module are powered by a rechargeable polymer lithium battery.

Further, the models of the first IGBT and the second IGBT are IRGP4066PbF.

Further, the models of the first driving optocoupler and the second driving optocoupler are TLP350.

Compared with the prior art, the utility model has beneficial effects:

(1) The system can be carried outdoors to assist inspectors in manual detection of photovoltaic arrays, and can also be placed in a combiner box to realize real-time online component-level and component-level distributed photovoltaic array I-V curve scanning;

(2) The electrolytic capacitor is charged and discharged by using IGBT and solid state relay, which can be charged quickly and discharged cleanly.

Description of drawings

Fig. 1 is the structural block diagram of the photovoltaic array IV characteristic curve scanning and parameter identification system of the utility model;

Fig. 2 is a program flow chart of the photovoltaic array IV characteristic curve scanning and parameter identification system of the utility model.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

As shown in Figure 1, a photovoltaic array IV characteristic curve scanning and parameter identification system includes a data acquisition module, a photovoltaic array IV characteristic curve scanning module, a storage module and a display module;

The data acquisition module is connected with the photovoltaic array IV characteristic curve scanning module for measuring the temperature and illuminance of the photovoltaic array;

The photovoltaic array IV characteristic curve scanning module includes a first controller, a voltage sensor for measuring the array voltage and a current sensor for measuring the array current connected to the first controller, and one end of the current sensor is output through a diode and the array The other end of the current sensor is connected to the collector of a first IGBT, the positive electrode of a capacitor and one end of a first resistor, and the gate of the first IGBT is connected to a second resistor and a first resistor in turn. The drive optocoupler is connected to the first controller, the negative pole of the capacitor is connected to the collector of a second IGBT and the first output terminal of a solid state relay, and the second output terminal of the solid state relay is connected to the other end of the first resistor connected, the input end is connected to the first controller, the gate of the second IGBT is connected to the first controller through a third resistor and a second drive optocoupler in turn, the emitter of the first IGBT, the array output Both the cathode and the emitter of the second IGBT are grounded;

The storage module and the display module are respectively connected to the first controller.

The data acquisition module includes an illumination sensor, a temperature sensor and a second controller, the illumination sensor and the temperature sensor are respectively connected to the second controller, and the second controller is connected to the first controller through a wireless transceiver. data transmission.

The wireless transceiver model is nRF24L01.

The models of the first controller and the second controller are TMS320F28335.

The storage module is a U disk.

It also includes a host computer connected to the first controller through a UART interface.

The photovoltaic array IV characteristic curve scanning module is installed at the combiner box.

The data acquisition module and the photovoltaic array IV characteristic curve scanning module are powered by a rechargeable polymer lithium battery.

Photovoltaic array IV characteristic curve scanning module adopts TMS320F28335 microprocessor as the main controller, adopts series-parallel combination of large-capacity electrolytic capacitor as variable load, and adopts a single high withstand voltage and high current IGBT power tube (model IRGP4066PbF) as capacitor charging The switch adopts non-contact, high-sensitivity solid-state relay (SSR) as the discharge switch of the capacitor, adopts the color liquid crystal module with a resolution of 480*272 as the display module, adopts the serial U disk module as the data storage module, and adopts the isolation type The Hall current sensor detects the array current, adopts precision resistor voltage divider to detect the array voltage, and uses a polymer lithium battery as the power supply of the module. Arranging the collected voltage and current in an orderly manner constitutes the I-V characteristic curve, and at the same time through the STC correction formula, the I-V curve under the STC condition is obtained.

The models of the first IGBT and the second IGBT are IRGP4066PbF.

The models of the first driving optocoupler and the second driving optocoupler are TLP350.

This system can not only be placed at the combiner box to test the photovoltaic array in real time through the host computer data management center, thereby improving the detection efficiency, but also can be carried outdoors to assist the inspectors to manually detect the photovoltaic array, which is very important for improving the power generation of photovoltaic power plants Efficiency and maintenance efficiency play an important role. The program flow chart of the system work is shown in Figure 2.

The specific embodiments described above have described the purpose, technical solutions and achievements of the present utility model in detail. It should be understood that the above descriptions are only specific embodiments of the present utility model and are not intended to limit the utility model. , Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (10)

1. IV characteristic curve scanning and parameter identification system of a kind of photovoltaic array, it is characterized in that, comprise data acquisition module, photovoltaic array IV characteristic curve scanning module, storage module and display module; The data acquisition module is connected with the photovoltaic array IV characteristic curve scanning module for measuring the temperature and illuminance of the photovoltaic array; The photovoltaic array IV characteristic curve scanning module includes a first controller, a voltage sensor for measuring the array voltage and a current sensor for measuring the array current connected to the first controller, and one end of the current sensor is output through a diode and the array The other end of the current sensor is connected to the collector of a first IGBT, the positive electrode of a capacitor and one end of a first resistor, and the gate of the first IGBT is connected to a second resistor and a first resistor in turn. The drive optocoupler is connected to the first controller, the negative pole of the capacitor is connected to the collector of a second IGBT and the first output terminal of a solid state relay, and the second output terminal of the solid state relay is connected to the other end of the first resistor connected, the input end is connected to the first controller, the gate of the second IGBT is connected to the first controller through a third resistor and a second drive optocoupler in turn, the emitter of the first IGBT, the array output Both the cathode and the emitter of the second IGBT are grounded; The storage module and the display module are respectively connected to the first controller. 2. IV characteristic curve scanning and parameter identification system according to claim 1, is characterized in that, described data acquisition module comprises illuminance sensor, temperature sensor and second controller, and described illuminance sensor and temperature sensor are connected with second controller respectively. The controllers are connected, and data transmission is performed between the second controller and the first controller through a wireless transceiver. 3. The IV characteristic curve scanning and parameter identification system according to claim 2, wherein the model of the wireless transceiver is nRF24L01. 4. The IV characteristic curve scanning and parameter identification system according to claim 2, wherein the models of the first controller and the second controller are TMS320F28335. 5. The IV characteristic curve scanning and parameter identification system according to claim 1, wherein the storage module is a U disk. 6. The IV characteristic curve scanning and parameter identification system according to claim 1, further comprising a host computer connected to the first controller through a UART interface. 7. The IV characteristic curve scanning and parameter identification system according to claim 6, wherein the photovoltaic array IV characteristic curve scanning module is installed at the combiner box. 8. The IV characteristic curve scanning and parameter identification system according to claim 1, wherein the data acquisition module and the photovoltaic array IV characteristic curve scanning module are powered by a rechargeable polymer lithium battery. 9. The IV characteristic curve scanning and parameter identification system according to claim 1, wherein the models of the first IGBT and the second IGBT are IRGP4066PbF. 10. The IV characteristic curve scanning and parameter identification system according to claim 1, wherein the model of the first driving optocoupler and the second driving optocoupler is TLP350.