CN103048599A - Characteristic test device for photovoltaic cell - Google Patents

Abstract

A photovoltaic battery characteristic testing device, the light intensity sensor and the photovoltaic battery panel to be tested are placed outdoors; the temperature sensor is closely attached to the back of the photovoltaic battery panel. The negative terminal of the charging capacitor is grounded, and the positive terminal is connected to the common pin of the SPDT switch. One end of the discharge resistor is grounded, and the other end is connected to a select pin of the SPDT switch. The positive pole of the photovoltaic cell to be tested is connected to another selection pin of the SPDT switch, and the negative pole of the photovoltaic cell to be tested is grounded. One end of the Hall current sensor is sleeved on the positive output wire of the photovoltaic cell, and the other end is connected to an oscilloscope probe. The voltage probe that comes with the oscilloscope is connected in parallel between the positive and negative poles of the photovoltaic cell. The light intensity sensor is placed outdoors near the photovoltaic cell to be tested, and the light intensity sensor and the photovoltaic cell to be tested are located at the same angle to receive light. The signals received by the above sensors are sent to the oscilloscope for display.

Description

A photovoltaic cell characteristic testing device

technical field

The invention relates to a photovoltaic battery testing device. the

Background technique

Photovoltaic cells have a constant current output within a certain output voltage range, and generate a maximum power point at a specific voltage value close to the voltage inflection point, as shown in Figure 1. In order to obtain the voltage-current curve of photovoltaic cells, the traditional method usually connects a sliding rheostat at the output end, and obtains several voltage-current coordinate points by changing the resistance value, and then establishes a coordinate axis to draw the voltage-current curve. If you want to obtain a continuously changing curve, you need an automatically changing resistance, and then require the use of motor control, and the control and testing methods are very cumbersome. Because of this, traditional test equipment is often expensive. Moreover, most of the existing voltage-current curve testing instruments are used for testing above 50 kilowatts, and the unit price of similar products ranges from tens of thousands to hundreds of thousands of yuan, such as the IV400 tester developed by Italy HT Company. There are almost no VI curve testing instruments for small photovoltaic arrays and single solar panels. the

Chinese patent CN201010046547.7 "Photovoltaic grid-connected inverter with photovoltaic array IV test function and test method" discloses a photovoltaic grid-connected inverter with photovoltaic array voltage-current test function, which consists of the inverter main circuit and System controller constitutes, as shown in Figure 5. The main circuit of the inverter adopts a voltage-type inverter, including single-phase and three-phase grid-connected systems. It is characterized in that: a current sensor CT1 for measuring the input current of the photovoltaic array is set between the input port of the photovoltaic array and the filter capacitor C1; Set the DC bus voltage sensor VT1 for measuring the voltage at the filter capacitor C1 terminal; set a DC circuit breaker K1 at the output port of the photovoltaic array, and the total output current of the photovoltaic array is input into the photovoltaic grid-connected inverter, DC Bus voltage sensor VT1 and current sensor CT1. This invention is suitable for conventional grid-connected inverter systems, and can conveniently test the voltage-current characteristics of photovoltaic arrays, but cannot be flexibly applied to the voltage-current characteristics test of a single photovoltaic cell. the

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the traditional photovoltaic cell voltage-current testing instrument, which is high in cost and unable to flexibly test the output characteristics of a single photovoltaic cell, and propose a photovoltaic cell characteristic testing device. The invention can realize accurate measurement of the voltage, current and power of the photovoltaic cell, and provides a data basis for further realizing maximum power point tracking (MPPT). The invention can also detect the temperature and light in real time, and then measure the electrical characteristics of photovoltaic cells under different working conditions. the

The device of the invention includes a charging capacitor, a discharging resistor, a single pole double throw switch, a light intensity sensor, a temperature sensor, a Hall current sensor, a light intensity signal processing module, a temperature signal processing module, a power conversion module, an oscilloscope and the like. The light intensity sensor is used to measure the amount of radiation received by the photovoltaic cell to be tested. The light intensity sensor and the photovoltaic cell panel to be tested are placed outdoors together, and the light intensity sensor is placed near the photovoltaic cell to be tested. The temperature sensor is attached to the back of the photovoltaic panel and is used to measure the operating temperature of the photovoltaic cell. The light intensity signal processing module is used to amplify and filter the light intensity signal generated by the light intensity sensor, its input end is connected to the light intensity sensor, and the output end of the light intensity signal processing module is connected to an oscilloscope. The input end of the temperature signal processing module is connected to the temperature sensor, and the output end of the temperature signal processing module is connected to an oscilloscope to amplify and filter the temperature signal generated by the temperature sensor. The power conversion module is a rectifier, its input terminal is directly connected to the 220V AC power grid, and finally outputs 24V DC power through the rectification circuit, voltage stabilization circuit and filter circuit inside the power conversion module, and the 24V DC power supply is connected to the power supply of the current sensor The pin supplies power to it, and the 24V DC power supply is also connected to the power supply pin of the signal amplifier in the temperature signal processing module to supply power to the temperature signal processing module. The SPDT switch and the oscilloscope are directly powered by 220V AC. the

The negative end of the charging capacitor is grounded, and the positive end of the charging capacitor is connected to the common pin of the SPDT switch. One end of the discharge resistor is grounded, and the other end of the discharge resistor is connected to a select pin of the SPDT switch. The positive pole of the photovoltaic cell to be tested is connected to another selection pin of the SPDT switch, and the negative pole of the photovoltaic cell to be tested is grounded. With a SPDT switch, the charging capacitor switches the circuit between the photovoltaic cell and the discharging resistor. One end of the Hall current sensor is connected to the positive output wire of the photovoltaic cell to measure the output current waveform of the photovoltaic cell. The other end of the Hall current sensor is connected to an oscilloscope probe to send the current waveform to the oscilloscope. The voltage probe that comes with the oscilloscope is connected in parallel between the positive and negative poles of the photovoltaic cell to measure the output voltage waveform of the photovoltaic cell. Multiply the voltage signal and the current signal to get the power curve of the photovoltaic cell, which is also displayed on the oscilloscope. The light intensity sensor is used to measure the light intensity received by the photovoltaic cell to be tested, and is placed outdoors close to the photovoltaic cell to be tested. By adjusting the angle of the light intensity sensor, the light intensity sensor and the photovoltaic cell to be tested are located at the same angle to receive light. The light intensity sensor converts the light intensity into a voltage signal output, and the voltage signal is amplified by the light intensity signal processing module and sent to the oscilloscope for display. . The temperature sensor converts the temperature signal into a voltage signal, and the output terminal of the sensor is connected to the oscilloscope probe through a low-pass filter, and the temperature signal is sent to the oscilloscope for display. the

Description of drawings

Fig. 1 is the electrical characteristic curve of photovoltaic cell;

Fig. 2 is a structural principle diagram of the present invention;

Figure 3 is the test result of the photovoltaic cell under the condition of no cloud cover;

Figure 4 is the test result of the photovoltaic cell under the simulated cloud cover state;

Figure 5 is a drawing of the abstract of Chinese patent CN201010046547.7. the

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. the

As shown in Figure 2, the present invention includes a charging capacitor, a discharging resistor, a timing SPDT switch, a light intensity sensor, a temperature sensor, a Hall current sensor, a light intensity signal processing module, a temperature signal processing module, a power conversion module and an oscilloscope. the

The light intensity sensor is used to measure the amount of radiation received by the photovoltaic cell to be tested. The light intensity sensor and the photovoltaic cell panel to be tested are placed outdoors together, and the light intensity sensor is placed near the photovoltaic cell to be tested. The temperature sensor is attached to the back of the photovoltaic panel and is used to measure the operating temperature of the photovoltaic cell. The light intensity signal processing module is used to amplify and filter the light intensity signal generated by the light intensity sensor, its input end is connected to the light intensity sensor, and the output end of the light intensity signal processing module is connected to an oscilloscope. The input end of the temperature signal processing module is connected to the temperature sensor, and the output end of the temperature signal processing module is connected to an oscilloscope to amplify and filter the temperature signal generated by the temperature sensor. The power conversion module is a rectifier that converts 220V AC voltage into 24V DC voltage to supply power for the above sensors and modules. the

The negative terminal of the charging capacitor is grounded, and the positive terminal of the charging capacitor is connected to the common pin of the SPDT switch. One end of the discharge resistor is grounded, and the other end of the discharge resistor is connected to a select pin of the SPDT switch. The positive pole of the photovoltaic cell to be tested is connected to another selection pin of the SPDT switch, and the negative pole of the photovoltaic cell to be tested is grounded. With a SPDT switch, the charging capacitor switches the circuit between the photovoltaic cell and the discharging resistor. One end of the Hall current sensor is connected to the positive output wire of the photovoltaic cell to measure the output current waveform of the photovoltaic cell. The other end of the Hall current sensor is connected to an oscilloscope probe to send the current waveform to the oscilloscope for display. The voltage probe that comes with the oscilloscope is connected in parallel between the positive and negative poles of the photovoltaic cell to measure the output voltage waveform of the photovoltaic cell and display it on the oscilloscope. Multiply the voltage signal and the current signal to get the power curve of the photovoltaic cell, which is also displayed on the oscilloscope. The light intensity sensor is used to measure the radiation amount of the solar light received by the photovoltaic cell to be tested. By adjusting the angle of the light intensity sensor, the light intensity sensor and the photovoltaic cell to be tested are located at the same angle to receive light. The light intensity sensor converts the light intensity into a voltage signal output, and the signal is amplified by the light intensity signal processing module and sent to the oscilloscope for display. The model of the light intensity signal processing module is CHT-50mV/VO. The temperature sensor converts the temperature signal into a voltage signal and sends it to the oscilloscope for display. the

When the single-pole double-throw switch is connected to the terminal of the photovoltaic cell to be tested, the photovoltaic cell to be tested and the charging capacitor form a charging circuit. According to the formula: V=C×∫I·dt, where V capacitor voltage, I photovoltaic cell output current, C is the capacitance value. When the photovoltaic cell under test charges the capacitor with a constant current, the capacitor voltage rises linearly, and the ratio of voltage to current also increases. At this time, the external characteristics of the capacitor can be regarded as a sliding rheostat with increased resistance. A measurement cycle is completed when the capacitor voltage is charged from 0V to the open-loop voltage of the photovoltaic panel. Because the capacitor charging time is extremely short, it can be regarded as a time point, so the electrical characteristics of the photovoltaic cell to be tested at this time can be obtained. the

In order to monitor the electrical characteristics of the photovoltaic battery panel in real time, it is necessary to repeatedly charge and discharge the capacitor, and the present invention uses a single-pole double-throw switch to realize circuit switching. When the SPDT switch capacitor is switched to the discharge resistor, the capacitor and the discharge resistor form a capacitor-resistance discharge circuit, and the capacitor voltage is restored to 0V, waiting for the next cycle of charging and measurement. The present invention uses the current sensor and the voltage probe attached to the oscilloscope to collect corresponding electrical signals, and sends them to the oscilloscope for visual display, and multiplies the voltage and current to obtain the power curve of the photovoltaic cell to be tested. the

Fig. 3 and Fig. 4 are the results of using the device of the present invention to test the photovoltaic cell panel. As shown in Fig. 3 and Fig. 4, the three curves are current waveform, voltage waveform and power waveform respectively. Figure 3 is the test result under the condition of no cloud cover. It can be seen that the electrical characteristics of a single photovoltaic panel are similar to the theoretical values shown in Figure 1. Within a certain voltage range, the constant current output is close to the voltage inflection point. maximum power point. Figure 4 shows the test results of the simulated cloud cover state, and it can be seen that the current is greatly affected. the

The invention simultaneously measures the temperature and light of the photovoltaic cell to be tested, so the influence of the photovoltaic cell under another condition can be studied under the condition that one condition remains unchanged. As shown in the comparison between Figure 4 and Figure 3, the temperature of the two is controlled to be constant, and only the light conditions are changed. The influence of light on the characteristics of photovoltaic cells can be obtained by observing the changes in the waveforms of the two. In the same way, the influence of temperature on the output of photovoltaic cells can be studied by controlling the light intensity constant and only changing the temperature. the

Claims (3)

1. photovoltaic cell characteristic test device, it is characterized in that described proving installation comprises charging capacitor, discharge resistance, timing single-pole double-throw switch (SPDT), intensity of illumination sensor, temperature sensor, current sensor, light intensity signal processing module, processes temperature signal module, power transfer module and oscillograph; Photovoltaic battery panel to be measured is placed on outdoor; Described intensity of illumination sensor is placed on outdoor distance photovoltaic cell closer locations to be measured; Described temperature sensor is close to the back side of photovoltaic battery panel; The input end of described light intensity signal processing module is connected to the intensity of illumination sensor, and the output terminal access oscillograph of described light intensity signal processing module is in order to the light intensity signal that amplifies and filtering is produced by the intensity of illumination sensor; The input end of described processes temperature signal module connects temperature sensor, and the output terminal access oscillograph of described processes temperature signal module is in order to the temperature signal that amplifies and filtering is produced by temperature sensor; The input end of power transfer module is connected to the 220V AC network, rectification circuit, mu balanced circuit and filtering circuit through power transfer module inside, final output 24V direct current, the power pins that described 24V direct supply is connected to current sensor is its power supply, the 24V direct supply is also connected to the power pins of the signal amplifier in the processes temperature signal module simultaneously, is the processes temperature signal module for power supply; The negativing ending grounding of described charging capacitor, the anode of charging capacitor connects the common pin of single-pole double-throw switch (SPDT); One end ground connection of described discharge resistance, the other end of discharge resistance are connected on the selection pin of single-pole double-throw switch (SPDT); The positive pole of photovoltaic cell to be measured is connected on another selection pin of single-pole double-throw switch (SPDT), photovoltaic cell minus earth to be measured; One end of described Hall current sensor is socketed on the anodal output lead of photovoltaic cell, and the other end of Hall current sensor connects oscilloprobe; The voltage probe that oscillograph carries is connected in parallel between the both positive and negative polarity of photovoltaic cell.

2. according to photovoltaic cell characteristic test device claimed in claim 1, it is characterized in that described intensity of illumination sensor and photovoltaic battery panel to be measured are positioned at same angle and receive illumination.

3. according to claim 1 or 2 described photovoltaic cell characteristic test devices, it is characterized in that described light intensity sensor converts intensity of illumination to voltage signal output, sends into oscilloscope display after the light intensity signal processing module is amplified; Described temperature sensor converts temperature signal to voltage signal and sends into oscilloscope display.

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