The development of the world cannot be separated from the support of energy. Since the first industrial revolution, energy has played an extremely important role in the long history of the world economy with its unique position.However, up to now, the energy used by human beings mainly comes from fossil energy. Taking 2013 as an example, fossil raw materials accounted for 85% of the total energy consumption of 13.4 billion tons of standard coal in the world, while clean energy accounted for only 15%.What is more serious is that due to the needs of its own economic development, the demand for energy is growing at a high speed of nearly 2% per year.According to relevant data, the current world oil reserves can only be consumed for 41 years.Moreover, the combustion of fossil fuels will bring a series of environmental pollution problems.Fossil fuels such as coal, oil and natural gas will produce a large amount of greenhouse gases and toxic substances during the combustion process.
According to the relevant data released by the National Bureau of Statistics, China’s investment in environmental pollution control has shown a significant increase over the years.From 2009 to 2013 alone, the country’s investment in environmental pollution control nearly doubled in four years, surging from 525.84 billion yuan in 2009 to 951.65 billion yuan in 2013.
It can be seen that the consumption of fossil energy is not only unsustainable but also causes serious environmental pollution.In the process of mining, processing and pollution control of fossil energy, a large amount of manpower, material resources and financial resources are needed.Imagine what a virtuous cycle it would be if such a huge amount of funds were used to develop new energy.Because the investment in the development and utilization of new energy is one-time, only a single investment can enjoy the huge returns for decades.Taking solar energy as an example, the life of solar panels is 30 years, and it has the characteristics of convenient maintenance and repair.
In other words, after a single investment in solar photovoltaic arrays, it can ensure their operation for about 30 years, during which time the panels will continue to provide energy to customers.Moreover, for new energy power generation companies, they enjoy a series of preferential development policies and financial support from the state.In other words, new energy companies can not only obtain handsome returns from the power generated, but also receive significant financial support from the state.
Fossil energy represented by oil is not only limited by resource depletion and environmental pollution, but also often affected by political factors due to the overly obvious geographical characteristics of mining.The relationship between the US-led oil-consuming powers in the United States and the Middle East oil giants represented by Saudi Arabia is complex.Since the 21st century, the developed capitalist countries led by the United States have launched large-scale invasion operations against the Middle East countries.In order to protect their oil interests, the capitalist oil-consuming powers led by the United States have recklessly launched the invasion wars against Iraq, Syria, and Libya, regardless of the unanimous opposition of the international community.The turmoil in the international community has exacerbated the tense supply pattern of world energy.As the fastest-growing country in the world, China’s rapid economic development depends heavily on oil imports.In order to curb China’s rise, the US and other capitalist powers have stepped up their military control over the world’s oil production powers on the one hand, and created various crises to try to prevent and suppress China’s rise on the other hand.From the US-Philippine joint military exercise to the US-Vietnam military alliance, there is no exception that the US has planted bombs on China’s oil import lifeline represented by the Malacca Strait.Under the conspiracy of the United States, China’s oil import lifeline represented by the Malacca Strait is being tightened step by step.
Therefore, it is necessary for us to find a new lifeline of energy supply.The discovery of the South China Sea oil field seems to provide a good solution to our country’s energy crisis.However, there are many difficulties in front of us. Firstly, the hostile forces led by the United States are constantly sowing discord among the countries around the South China Sea, creating various friction incidents.Secondly, the oil fields in the South China Sea are mostly deep-sea oil fields, which are extremely difficult to mine. It is difficult to form a scale supply with the current level of technology.
Faced with the severe energy shortage and harsh environmental situation as well as the tense international political situation, how should we respond?
The energy source of solar energy is the huge energy generated by nuclear fusion of deuterium and tritium inside the sun.According to relevant information, the earth can obtain up to 173000TW of energy from the sun every year.If we can collect and utilize this energy well, the energy crisis of human beings will be solved easily.
Electric energy is one of the most widely used, efficient, and convenient energy sources in human history.Today’s world’s energy consumption is mainly in the form of direct or indirect consumption of electric energy.Although humans have made brilliant achievements in the generation, transportation, and use of electric energy in the past 100 years, how to obtain electric energy more efficiently remains a major challenge for humans.After all, thermal power generation is not only inefficient and pollutes the environment, but also a power generation mode based on the consumption of non-renewable resources.Hydropower generation is limited by geographical location and has a significant impact on the ecological environment.As for nuclear power generation, it is too dangerous.
Is there a way to combine solar energy and electric energy, making full use of their advantages to maximize benefits?
The answer is yes.Photovoltaic power generation technology was developed to solve this problem.Photovoltaic power generation technology is a power generation method that uses the photovoltaic effect of semiconductors to convert light energy into electrical energy.Figure 1 shows a typical photovoltaic array.
Compared with traditional energy sources, photovoltaic power generation technology has the following advantages:
(1) Rich in resources: The sun can provide up to 173,000TW of energy for the earth through its internal nuclear fusion reaction.
(2) Clean and environmentally friendly: No greenhouse gases or other exhaust gases are produced, and no sewage or waste residue is discharged.
(3) Easy to construct and disassemble: The modular structure used has the characteristics of easy construction and installation, disassembly and migration, and the ability to expand the power generation capacity at any time.
(4) Long service life: After decades of practical application, it has been proven that the service life of photovoltaic power stations can reach 30 years.
(5) Low relative cost: Raw materials (solar energy) are free, and only the initial investment in solar panels is required for 30 years of use, with low labor costs and maintenance costs.
In summary, solar grid-connected inverters have broad application prospects and are suitable for wide-ranging applications in various regions and environments, especially in regions with relatively scarce resources and harsh environments.Its research, development, application, and promotion will have profound economic and political significance.While bringing huge economic, social, and environmental benefits, it can make significant contributions to solving the energy crisis in China and even the world.
The average growth rate of the world’s photovoltaic industry over the past decade has reached 57.1%, making it one of the fastest-growing industries in the world.As the most important part of the photovoltaic industry, solar inverter control technology mainly combines modulation technology to complete the output from DC signal to AC signal.In 1964, A.Schonung of Germany first proposed the idea of applying pulse width modulation technology to power converters.Dr. S.R.Bowes of the UK has published several important documents on sine wave PWM (SPWM) technology, making detailed and rigorous research on the mathematical essence and principle of SPWM, and reaching a definitive conclusion.This is of epoch-making significance for PWM modulation and even power electronics technology, and it is also the theoretical support for inverters.With the continuous development of new energy technology, the research on photovoltaic grid-connected controllers has also attracted the attention of various research institutions in China. Tsinghua University, Shanghai Jiaotong University, Huazhong University of Science and Technology, Harbin Institute of Technology, and Chongqing University have conducted extensive and in-depth research on related topics.
From a domestic perspective, China currently has 20 photovoltaic power station projects with a capacity of over 200KW.There are also more than 30 large-scale photovoltaic power station projects with a capacity of over 10MW to be built, including 12 large-scale photovoltaic power stations with a capacity of over 100MW.
Internationally, the current large-scale power stations with a capacity of more than 10MW include:
(1) Australia 250MW solar power station;
(2) Portugal 46MW power station;
(3) Osaka 28MW photovoltaic power station in Japan;
China is at the forefront of the world in terms of the scale and key technologies of photovoltaic power generation.
The concept of “Building Integrated Photovoltaics (BIPV)” currently popular in the world, as shown in Figure 2, is to install solar panels on buildings or directly replace building materials with photovoltaic materials.
The development trend of inverter power supply:
(1) High frequency;
(2) Module integration;
(3) Digital and networked control.
The main design content of the household micro-inverter for the solar roof plan is as follows:
Firstly, the basic principles of solar inverters, including high-frequency modulation technology, especially the basic principles of SPWM technology, are introduced, and the circuit topology structures of the DC-DC and DC-AC links of the main circuit are discussed in detail.
Then, the hardware and software structures of the single-phase solar inverter are introduced.The hardware structure mainly includes the design of four modules: power module, interleaved flyback module, full bridge module, and feedback module.The software modules include state machine, device peripheral configuration, maximum power point tracking, compensator design, and other auxiliary function design.
Finally, I conducted relevant programming work using CCS5.5, simulation using MATLAB, and experimental work using a solar inverter prototype.I used CCS5.5 (Code Composer Studio) to complete the programming work for the main chip TMS320F28035, mainly completing the programming work related to maximum power point tracking:
① Main program part: mainly completes the initialization of the application program, configuration of peripherals, management of the application program, background code looping, and task scheduling;
② Peripheral initialization: It mainly completes the initialization of peripherals (such as clocks, phase-locked loops, general-purpose I/O interfaces, etc.) and enables the peripheral clock.
③ Definition of global variables;
④ Call subprograms.
Use MATLAB/SIMULINK to perform experiments on solar cells, BOOST circuits, maximum power point tracking, and pulse width modulation.Use experimental devices such as solar inverter prototype, PC, oscilloscope, etc. to perform experiments on power connection for open-loop detection of inverter, detection of photovoltaic inverter system with maximum power point tracking system, and experimental waveform and analysis of main circuit.