Summary
Facing the increasingly serious energy crisis in the world, the development and utilization of renewable energy have received great attention. Among them, the solar energy radiated to the earth is very rich, and the green and clean solar energy will not harm our living environment, so it has been widely used by people. Photovoltaic power generation is widely used as a renewable energy source, and the technology is constantly innovating.
In recent years, with a large number of photovoltaics connected to the distribution network, on the one hand, the ability of the grid to cope with the load has been improved, and on the other hand, intermittent photovoltaic power supply has also brought a certain impact on the stable operation of the grid. At the same time, in the daily operation of the distribution network, in order to cope with certain situations, the network is usually reconfigured through switching actions to ensure the economy and stability of the power grid. The access of photovoltaics will also make the distribution network reconfiguration more efficient. Complexity makes it difficult for traditional network reconfiguration schemes to meet the operation control requirements of power grids under complex network structures. In this regard, this paper launches a research on the distribution network reconfiguration strategy including photovoltaic power generation.
In the MATLAB/Simulink simulation environment, a distribution network system simulation model of photovoltaic power generation grid connection was built, the network reconstruction strategy including photovoltaic distribution network was studied, and a time-period reconstruction model considering economy, reliability and security was constructed , using a multi-agent system to establish a dynamic optimization and reconstruction strategy for the active distribution network with random photovoltaics and fluctuating flexible loads, realize the collaborative reconstruction of the active distribution network, and improve the self-healing ability of the active distribution network and the reliability of load power supply sex. At the same time, a series of simulation experiments are carried out on the proposed control scheme, which verifies the flexibility and reliability of the proposed control method from multiple perspectives.
Keywords: photovoltaic power generation, grid connection, MATLAB simulation, distribution network, dynamic reconfiguration
Abstract
In the face of the increasingly serious global energy crisis, the development and utilization of renewable energy has attracted great attention.Among them, radiation to the earth's solar energy resources is very rich, green and clean solar energy will not harm our living environment, so it has been widely used by people.Photovoltaic power generation as a renewable energy is widely used, technology innovation.In order to improve the photoelectric conversion efficiency of photovoltaic power generation system, the system needs to track the maximum power point in real time.
Due to the improvement of people's living standard, the continuous progress of science and technology, and the continuous improvement of control, the consumption of non-renewable energy is serious or even exhausted, thus promoting the renewable energy to become the leading industry.Photovoltaic power generation has become a beautiful landscape at the present stage. Due to its advantages of mature development technology, relatively small cost and almost no pollution, it has a high prospect in the new energy power generation industry and has become the focus of attention of all countries in the world.At the same time, due to the variability, randomness and uncontrollability of light intensity, the stability of photovoltaic power generation system is greatly affected.The photovoltaic power generation industry continues to innovate, generating more and more electricity.Therefore, the new generation of us should seriously study the impact of photovoltaic power generation.
In the MATLAB/Simulink simulation environment, a simulation model of the single-phase transformer-free grid-connected photovoltaic power supply system was built, and a series of simulation experiments were carried out to verify the flexibility and reliability of the proposed control method from multiple perspectives.
Keywords: Photovoltaic power generation, grid-connected, MATLAB simulation, Distribution network, dynamic reconstruction
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Table of contents
3.2.1 LCL type filter model................................... ................... 11
4.4.2 Comparison of MP and different heuristics................................... .......... 31
4.4.3 Effects of different steps in SOE................................... ................... 34
4.4.5 Comparison of single-hour and multi-hour DNR................................... .......... 37
4.4.6 Comparison of hourly, 24-hour and block DNR................................... .39
4.4.7 Comparison between DDNR and SDNR................................... .......... 40
4.4.8 Number of scenes in 24-hour SDNR................................... .......... 41
Chapter 1 Introduction
1.1 Research topic background
At present, with the rapid development of the national economy, the development of my country's power grid is also getting faster and faster, especially the distribution network involving residents' lives has undergone rapid changes, and the access of a large number of distributed photovoltaics and flexible loads to power distribution The operation of the network brings certain challenges. At present, due to the needs of economic development, the current traditional fossil energy has been difficult to meet the energy demand of the country's economic development, especially in China with a large population, and the per capita possession of traditional fossil energy is relatively low in the world. As of the end of 2018, China's per capita fossil energy Energy holdings are only 40% of the world average, which requires China to actively explore the development and utilization of new energy sources to alleviate the increasingly serious energy crisis in the country. At the same time, considering the environmental pollution and greenhouse effect caused by fossil energy, it is also China is required to actively develop new energy sources. The grid power generation supported by the people mainly relies on thermal power plants for power generation. In view of this situation, the State Grid actively explores new energy power generation strategies, and new energy power generation such as wind farms, photovoltaic power stations, and hydropower stations are heavily invested. , which not only relieves the power supply pressure of the power grid, but also alleviates the environmental problems of our country. As the most widely distributed clean energy at present, solar energy has become the focus of the development of the national grid. With the great investment of the grid, the power generation technology has gradually matured in recent years. The user's photovoltaic power generation growth rate is increasing by about 20% per year. Photovoltaic power generation is providing a huge impetus for the construction of an efficient and clean power system power supply system, and has become a key power generation technology and an important supporting force for the current power grid development.
1.2 Development status at home and abroad
1.2.1 Development Status of Photovoltaic Power Generation
my country's photovoltaic industry started in the 1970s, but it did not start to develop really until around 2005. In 2011, the production capacity of photovoltaic cells in my country reached 35GW, and the output reached 13GW, ranking first in the world, accounting for about 68% of the world. Therefore, the domestic photovoltaic industry is limited to the production of photovoltaic cells to a certain extent. However, the total installed capacity of photovoltaic power generation in my country lags far behind developed countries in Europe and the United States. In this situation, my country has introduced a number of incentive policies for the photovoltaic industry. The Ministry of Finance of the People's Republic of China, together with relevant departments, supports photovoltaic power generation demonstration projects of more than 500MW through financial subsidies. On January 17, 2017, the National Development and Reform Commission and the Energy Administration issued the "Thirteenth Five-Year Plan for Energy Development", requiring the promotion of sustainable development of new energy sources, such as hydropower, nuclear power, wind power, and solar energy. It is specified that in 2020, the planned installed capacity of photovoltaics will exceed 100GW, and the scale of solar power generation will reach more than 110 million kilowatts, including 60 million kilowatts of distributed photovoltaics, 45 million kilowatts of photovoltaic power stations, and 5 million kilowatts of solar thermal power generation.
Our photovoltaic power generation technology also made unprecedented progress in the mid-1970s because of the innovation of intelligent control technology. Different photovoltaic power generation systems, such as green bamboo shoots after rain in spring, are gradually applied in many parts of the country. Developed countries such as Europe and the United States have advanced levels in photovoltaic power generation technology. They began to conduct in-depth research on photovoltaic power generation technology control systems in the 1960s. After 1980, researchers basically realized the control system of photovoltaic power generation systems. Control. At the end of the 20th century, mass production of control modules for photovoltaic power generation technology began, but because of the high production costs, this latest research and development project was only used in a few places. However, nowadays, the photovoltaic power generation control system has been successfully combined with electronic technology, and has gradually matured. Due to the reduction in purchase costs, more and more people have begun to install photovoltaic power generation systems.
Driven by the European photovoltaic market, the Chinese government has vigorously supported and invested in domestic industries, which has promoted the development of China's photovoltaic industry to a certain extent. However, compared with developed countries, the development of my country's photovoltaic industry is still quite slow, because our country There is still a big gap between my country's photovoltaic technology and industry, mainly in high production costs, relatively backward technology, imperfect industrial chain, and low conversion efficiency. Therefore, my country's photovoltaic industry is still facing a very severe situation, and overall needs to be further improved.
1.2.2 Development Status of Distribution Network
The active distribution network refers to the power distribution system that realizes the power flow management of the distribution network through active control and management of the grid structure and intelligent equipment of the distribution network, thereby improving the economy and reliability of the power grid. At present, with more and more distributed photovoltaics connected to the grid, the research on active distribution network has become a hot spot, and domestic scholars have carried out a lot of research on it.
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