1. Introduction to solar photovoltaic power generation
With the shortage of fossil energy and people’s increasing attention to the environment, the development of new energy is an important link in the future development. Solar energy is widely distributed, inexhaustible and cheap, and has always been the ideal clean energy for people. Photovoltaic power generation is an important way to utilize solar energy. The principle of photovoltaic power generation is mainly a technology that uses the photovoltaic effect of semiconductors to directly convert light energy into electrical energy. Photovoltaic power station is a kind of power generation system that uses solar energy to convert solar energy into electric energy through solar panels, inverters, box transformers and other electronic components, and transmit electricity to the grid. China’s solar photovoltaic industry started relatively late. By the end of 2017, China’s cumulative grid-connected installed capacity of solar photovoltaic power generation has reached 130GW. The “agricultural scenery” complementary power generation project is to plant appropriate crops under the solar photovoltaic panels, and install wind turbines in places with high wind power density for wind power generation, which can not only prevent soil erosion, improve land utilization, but also maximize the use of natural resources. This paper takes the “agricultural scenery” complementary photovoltaic power station in Yan bi an County, Sichuan Province as an example to provide reference for the future development of photovoltaic industry in Sichuan.
2. Introduction to the “agricultural scenery” complementary power generation project
The “agricultural scenery” complementary power generation project in Yanbian County, Panzhihua City, Sichuan Province is located in Damianshan, Yanbian County, Panzhihua City, Sichuan Province. The design operation period of the photovoltaic power station is 25 years. After being put into operation, it can save about 9000 tons of standard coal, 21900 tons of carbon dioxide (CO2), 9.35 tons of sulfur dioxide (SO2), 9.35 tons of nitrogen oxide (NOx), 2.81 tons of soot and 80000 m3 of water. The project was commenced on December 10, 2016. It only took more than six months from completion to production. The project, together with the 100MW wind power project and the 450-mu ecological agricultural park, constitutes the first “agricultural scenery” power generation complementary project in Sichuan Province, marking the initial results of the “new energy+” development strategy.
3. Advantages of “agricultural scenery” complementary power generation project
The combination of photovoltaic and agriculture can improve the land utilization rate without occupying additional resources. The electricity generated by photovoltaic can be used for agricultural power demand. Photovoltaic agricultural greenhouses in some regions have become local science and technology demonstration projects, integrating tourism projects such as sightseeing, leisure and experience with photovoltaic agriculture to form a highly characteristic and large-scale demonstration project. However, the cost of photovoltaic greenhouse is relatively high at present. With the advent of photovoltaic power generation at parity, the combination of modern agriculture and clean energy will become a development trend. Therefore, agricultural and photovoltaic projects have great development potential. Damian Mountain in Yanbian County has vast land, relatively undeveloped unfavorable geology, obvious monsoon in winter and spring, and high annual solar radiation. It belongs to the area where wind energy and solar energy resources can be utilized. Yanbian County has built a 146MW wind power project with 73 wind turbines in the first and second phases of Damianshan, a 20MW photovoltaic power generation project and a 450-mu ecological agricultural park, and has become the first “agricultural scenery” complementary industry pilot project base in Sichuan Province. Mango, blueberry, pitaya and other fruits are planted around the wind farm and photovoltaic field. Because the photovoltaic project occupies a large area of land, planting fruits and vegetables around it can improve the land utilization rate, will not change the nature of the land, and prevent water and soil loss. The photovoltaic project power generation can be used for agricultural needs without additional resources. The fan covers a small area, and vegetables and fruits can also be planted around it. After the completion of the construction, wind power generation, photovoltaic power generation and agricultural planting can become a major feature to attract tourists to travel and sightseeing, and promote the income and economic development of local farmers. At present, the national policy strongly supports the common development of industries, and the application market of photovoltaic products in agriculture has great potential. The combination of photovoltaic and agriculture is not only conducive to the photovoltaic industry itself, but also has important significance for the transformation of agriculture, and has become a new model for the development of modern agriculture. In terms of environmental protection, wind power generation and photovoltaic power generation belong to the new energy industry, with less environmental pollution. Agricultural planting on the same land will greatly improve the land utilization rate. Therefore, from the perspective of economic benefits and environmental protection, the “agricultural scenery” complementary pilot project has great development prospects.
4. Existing problems and suggestions
Although new energy is developing rapidly at present, there are still many problems in technology. For example, the efficiency conversion of photovoltaic power generation and the power storage of wind power generation. On the other hand, in the Sichuan Basin, most of the regions with abundant wind and solar energy resources are located in mountainous areas and lack of water resources. Therefore, if we develop agriculture while developing new energy, irrigation will become the first problem to be solved. Although wind power generation and photovoltaic power generation are clean and renewable energy, their sources are highly uncertain and will be affected by natural factors such as season, climate and altitude, so the output power will have great volatility. Therefore, both of these power generation methods need to use energy storage devices to provide stable power output. In addition, in many areas, the wind is generally stronger at night, while photovoltaic power generation can only be carried out in the daytime. In a certain season, the solar radiation intensity is the highest, while the wind is generally smaller at this time. In order to improve the efficiency of power generation and equipment utilization, wind power and photovoltaic can share some energy storage equipment and use intelligent control devices to improve the overall conversion and utilization efficiency. The wind turbine in the wind farm adopts the doubly-fed induction generator. In order to improve the efficiency of wind power generation, many experts at home and abroad have studied the control strategy of the doubly-fed wind power generation system, and proposed algorithms and control systems based on MPPT, grid voltage, vector control and other aspects. Some scholars also proposed a reactive power limit calculation method for doubly fed machine wind power generation system, and gave the corresponding reactive power allocation strategy. For the control system of wind turbines, we should pay attention to the latest development trend of the wind power industry, keep abreast of the latest research results, update the system control, and improve the power generation and efficiency. For the photovoltaic power generation system, the current research focuses on the research and development of solar panel materials to absorb more solar radiation and improve the conversion efficiency. For example, EVA adhesive film is used to bond the composite film to the light-receiving surface of the photovoltaic panel. According to the statistics of relevant documents, the maximum power control point tracking (MPPT) of photovoltaic power generation has been realized through modern power electronic technology and control system. After research, some experts have proposed an improved adaptive mountain-climbing algorithm, which is simulated by Matlab/Simulink. Under the control of this algorithm, the system can track the maximum power point stably and quickly, with high tracking accuracy results, It can track the maximum power of photovoltaic cells under adverse conditions such as sudden changes in light, and has strong adaptability. The photovoltaic power station shall adopt a special monitoring system for data collection, which can compare the power generation at different times and understand the power generation of different parties. If the scale of the power station is expanded in the future, it can provide reference for the installation location and angle of the photovoltaic array. For the agricultural development of photovoltaic power stations, because the power stations are located in mountainous areas with weeds, there may be fire hazards. On the other hand, too high weeds will block the photovoltaic panels and affect the power generation efficiency. Therefore, special personnel are required to clean weeds regularly. Therefore, when planting in agriculture, it is necessary to consider the plant growth, which cannot affect the photovoltaic power generation. On the other hand, photovoltaic panels may block the sun, so when choosing plants to grow, you should prefer to choose plants that prefer shade.
5. Conclusion
To sum up, the “agricultural scenery” complementary power generation project can make up for the respective shortcomings of wind power generation and solar power generation, improve the comprehensive utilization rate of land, reduce management costs, and basically have no pollution to the environment. However, in the process of real implementation, there are still many difficulties. On the one hand, the lack of water resources in mountainous areas leads to difficulties in agricultural irrigation, on the other hand, there are many problems in the technology of new energy, which requires a large number of professional talents to maintain and manage. In addition, because the development time of the “agricultural scenery” project is still short, and the comprehensive impact on the environment is difficult to analyze in a short time, therefore, in the process of development, it is also necessary to pay close attention to environmental changes and make reasonable measures in time. In the future development process, new energy is still one of the important development goals. The technology of new energy still needs to be vigorously developed. The conversion efficiency of solar power generation and the storage and storage of wind power generation need to be solved. Although the new energy technology still has defects at present, with the increasingly serious environmental problems and the rapid development of technology, the new energy industry has great development potential in the future. There are many mountains in Sichuan Basin, and the mountains are sparsely populated. Noise and dust will not cause much impact, so it is suitable for the development of new energy industry and agriculture. The “agricultural scenery” power generation project can not only provide clean power, but also promote the common development of the industry. Therefore, the “agricultural scenery” complementary power generation project is a project worthy of vigorous development in the future.
