In view of the current development trend of 1500V photovoltaic power generation technology and the market demand of related accessories, Guangzhou jinshengyang Technology Co., Ltd. has developed and launched pvxx-29bxx Series power supply can directly take power from 1500V high-voltage terminal to supply power for the monitoring circuit of photovoltaic system, simplify the design of photovoltaic system circuit, avoid the problem of high construction and maintenance cost caused by using municipal power or battery power supply, and improve the comprehensive benefits of photovoltaic power generation system. The product has multiple protection functions to further improve the safety performance of the power supply and its load when the power supply module or external circuit works abnormally.

1、 Introduction

The 2015 Paris climate conference issued a new global low-carbon emission reduction agreement “legally binding and applicable to all parties” in the United Nations Framework Convention on climate change, further promoting the development and popularization of green and environmental protection new energy such as photovoltaic and wind power. In 2015, China passed the 13th five year plan for economic and social development, in which the photovoltaic power generation market will continue to grow and the initial planned installed capacity will reach 150 million kilowatts. With the guidance and support of internal and external policies and demands, as well as the development of energy Internet of things, photovoltaic power generation is further scaled and intelligent, which is conducive to reducing the cost of photovoltaic power generation, promoting technological innovation and industrial upgrading.

The development goal of global photovoltaic industry is to compete with traditional power to provide clean energy with lower cost and higher income. The current mainstream photovoltaic power generation system is designed and built based on 1000V DC voltage. However, from the system point of view, with higher input and output voltage level, the line loss of AC / DC side and winding loss of transformer low-voltage side can be reduced, and the system efficiency of power station is expected to be increased by 1.5-2%. GTM’s analysis report “1500 V photovoltaic systems and components: costs, suppliers and expectations 2016-2022” predicts that the global demand for 1500 V photovoltaic systems will account for about 9% in 2016, equivalent to about 4.6 GW. Therefore, 1500V photovoltaic power generation system will be the future development trend.

2、 Basic structure and module requirements of photovoltaic power generation system

In the solar photovoltaic power generation system, in order to reduce the connection between the photovoltaic cell array and the inverter, the photovoltaic array is constructed in the form of string, and then the corresponding number of photovoltaic arrays are connected in parallel to the photovoltaic combiner box for electric energy convergence, which is output to the photovoltaic inverter through the DC cabinet, and connected to the grid after the inverter is boosted. Therefore, the complete photovoltaic power generation system includes photovoltaic array group and photovoltaic convergence Box, DC cabinet, photovoltaic inverter, step-up transformer and other parts. As shown in Figure 1:

Circuit design of 1500V photovoltaic power generation system based on pvxx-29bxx series power supply

The output voltage of photovoltaic array is the highest voltage range of the system, and there is a large fluctuation. Photovoltaic combiner box needs to monitor the voltage, current, power, lightning protection and other states of each group of photovoltaic array, and realize the functions of fault alarm, positioning and communication of photovoltaic array. In the process of AC / DC power conversion, photovoltaic inverter needs to monitor the voltage and current in the conversion process, and drive the control power devices to work. Due to the output voltage of photovoltaic array is more than 1kV, ordinary module power supply can not work directly from the high-voltage line. If the external independent power supply is used to supply power to multiple PV combiner boxes and inverters and other monitoring units, there are problems such as unstable working voltage, system wiring problems, short-circuit fault of single combiner box, which will lead to the termination of power supply of the whole monitoring system.

Therefore, the photovoltaic power generation system has the following requirements for module power supply:

200-1500vdc voltage input, output 12V / 15V / 24V and other conventional voltage

High isolation voltage characteristic between input and output

It has input undervoltage protection, anti reverse connection protection, output over-current, short circuit, over-voltage and other protection functions

It should meet the requirements of extreme working temperature difference in different regions

In view of the high voltage characteristics and application requirements of photovoltaic power generation system, Guangzhou jinshengyang Technology Co., Ltd. specially developed a 200-1500vdc voltage input, 4000vac isolated module power supply, and combined with the safety isolation characteristics of each unit circuit of the photovoltaic system, it provides a complete set of power supply scheme for the control unit.

3、 Power supply scheme of PV combiner box monitoring unit

In order to further improve the reliability and practicability of the system, the photovoltaic special DC lightning protection module, DC fuse and circuit breaker are configured in the PV combiner box, and the functional circuits such as working state monitoring, control processing and communication are set up.

Circuit design of 1500V photovoltaic power generation system based on pvxx-29bxx series power supply

As shown in Figure 2, in the PV combiner box system, the pvxx-29b24 series has the characteristics of 200-1500vdc voltage input, 4000vac isolation and withstand voltage, and high reliability. It can directly take power from the high-voltage terminal, and output the voltage of 24 VDC to the monitoring circuit through conversion. F0505s-1wr2 is used to isolate power supply for Hall sensor to fully ensure the safety isolation between high and low voltage; b0503xt-2wr2 module is used for isolation conversion, and 3.3V is output to supply power to MCU; td501d485h communication module with integrated isolated power supply is used for communication, which can suppress electromagnetic interference and eliminate the influence of grounding loop. The overall power supply scheme not only meets the functional requirements and safety isolation, but also facilitates the simplification of the overall system design, stability and reliability.

4、 Power supply scheme of photovoltaic inverter monitoring unit

The front-end combiner box is used for power confluence, which is detected by DC cabinet, and then converted to AC by inverter. In the working process of the inverter, the monitoring, control and communication of the conversion process are also needed to ensure that the inverter voltage meets the index requirements. This part of the monitoring unit can work directly from the high voltage (200-1500vdc) bus.

Circuit design of 1500V photovoltaic power generation system based on pvxx-29bxx series power supply

As shown in Figure 3, the PV series module power supply directly takes power from the high-voltage bus, and then outputs 5VDC voltage through the non isolated conversion module k7805-500r3; b0503xt-2wr2 provides MCU with 3.3V working voltage meeting functional isolation and withstand voltage; the isolated and high-speed td501d485h communication module can suppress electromagnetic interference and eliminate grounding loop, and protect the system circuit from external network In addition, Jin Shengyang developed an isolation driver qp12w08s-37 integrated with DC-DC power supply for IGBT inverter full bridge, which simplifies the design of customer drive control circuit and improves the reliability.

5、 Introduction of pvxx-29bxx series module power supply

Pvxx-29bxx series are 200-1500vdc voltage input, 4000vac isolated voltage withstand, high reliability DC-DC switching power supply module, which can be widely used in photovoltaic power generation and high-voltage frequency conversion and other occasions, to provide stable working voltage for load equipment, and its self-contained multiple protection functions can improve the safety performance of power supply and load under abnormal working conditions of module power supply.

Product features:

Ultra wide voltage range input: 200 ~ 1500vdc

Industrial grade working temperature: – 40 ℃ ~ + 70 ℃

4000vac high isolation voltage

High efficiency and low ripple noise

Input under voltage protection, anti reverse connection protection, output short circuit, over-current and over-voltage protection

Work at 5000m high altitude

· comply with en62109 certification

Various installation methods such as PCB, wiring and guide rail

Circuit design of 1500V photovoltaic power generation system based on pvxx-29bxx series power supply

The principle block diagram of pvxx-29bxx series power supply is shown in Figure 5. The flyback topology is adopted, the mature and reliable PWM control IC is selected, and the power conversion circuit is designed for high-voltage double tube series connection and isolated drive. The high-voltage starting part adopts the patented technology of jinshengyang high-voltage start-up. At the same time, the product has multiple protection circuits such as input undervoltage, output over-current, short-circuit overvoltage, etc The high reliability of the products.

Circuit design of 1500V photovoltaic power generation system based on pvxx-29bxx series power supply

6、 Summary

The gradual scale and popularization of photovoltaic energy is a healthy and reasonable development trend of global energy demand in the future. Jin Shengyang actively participates in the green development of energy technology. Combining with the advantages of its own technology platform and independent innovation ability, Jin Shengyang has carefully researched and developed a new generation of 1500V high-voltage photovoltaic special power module pvxx according to the characteristics of the test and monitoring unit of photovoltaic power generation system_ 29bxx series products, and provide a complete set of monitoring unit power application scheme, simplify the circuit scheme of photovoltaic power generation system, reduce the construction and maintenance cost of photovoltaic system, and comprehensively improve the stability, safety and reliability of the system.

Editor in charge: GT

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