Introduction to Wind Energy
Wind has been one of the most amazing phenomena in nature since time immemorial. Wind has no specific form, no specific color, and no specific flavor, but humans can still feel the power and presence of wind. The relationship between wind and gods can often be heard in various legends. For example, Aristotle believed that wind is one of the most basic elements in the world. “represents courage, and the Navajo people of North America believe that wind means life. From a scientific point of view, wind energy is a derivative of solar energy and is the kinetic energy generated by the mass flow of air on the earth’s surface. Wind energy depends on the density of the wind and the accumulated hours of available wind energy per year. Wind energy density is the available wind power per unit windward area and is proportional to the cube of the wind speed and air density. Simply put, the faster the wind, the denser and stronger the wind. The wind covers the whole world, and it has its own “walking course” called the oncoming airflow.
Introduction to Wind Energy Systems
The wind turbine not only refers to the generator itself, but also refers to the system of the generator. Energy devices and other components. Regarding the classification of wind turbines, most people divide wind turbines into large, medium and small according to their power. Generally speaking, the large-scale wind turbine refers to the generator power of more than 100 kW, the medium-sized wind turbine refers to the generator power of 20 kW to 100 kW, and the small-scale refers to the generator power of less than 20 kW.
In addition to being classified by power, wind turbines can also be of two types: “horizontal axis” and “vertical axis”. The horizontal axis wind turbine has the same form and function as the traditional wind wheel, and both use the horizontal bearing to provide mechanical energy. Most horizontal axis wind turbines have three blades, although some small wind turbines have four or five blades. The cycle of some wind turbines rotates in a clockwise direction, while others rotate in a counterclockwise direction. Horizontal axis wind turbines are also available in upwind or downwind designs. The most common design of vertical-axis wind turbines is the same as the anemometer form, which rotates in circles in the horizontal plane. The most famous form of vertical axis wind turbine is called the “Darieu form”, because the Darieu form is the original form of the vertical axis wind turbine. Within the design range of the Darrieux form, vertical axis generators come in a variety of forms, such as: S-type, H-type, C-type and even O-type. Whether wind power is horizontal or vertical, it uses mechanical energy to generate electricity. Previously, gears and mechanical power were used to drive generators, which then converted mechanical energy into electrical energy. At present, more and more wind turbines use direct power generation. This generator does not need gears, so the wind energy utilization factor is higher and the maintenance is more convenient. However, such high technology is still expensive, especially large wind turbines, which few people can afford. Finally, the wind turbine system can be divided into two categories, one is the grid-connected wind power system; the other is the independent wind power system. The grid-connected wind power system refers to the fact that when the wind turbine The grid; whereas an independent wind power system is off-grid and all electricity is used locally.
The development of wind energy in China
In modern society, clean energy is more and more important, and the whole world pays attention to non-polluting energy. At present, wind energy is one of the fastest growing new energy sources, especially in China, which doubled every year from 2005 to 2008. Since the first energy policy symposium held by the State Science and Technology Commission in Hangzhou in 1979, China has begun to pay attention to the development of new energy sources and their use value. So far, wind energy has been converted into electrical energy through wind turbines. There are two main ways of using wind power. One is the independent operation of the power supply system. Convert it into alternating current to supply power to terminal appliances, and solve the problem of electricity consumption in small communities. The other type is that as a conventional grid power supply, networked wind power generation is the most economical way to utilize wind energy on a large scale. With the continuous growth of wind turbines, their power generation methods have also developed. Initially, the electricity of wind turbines could only be used locally at that time, because the alternating current of the grid and the direct current of wind energy were incompatible with water and fire. With the improvement of the power grid and the development of science and technology, the possibility of grid connection begins to increase. All developed countries attach importance to the usage of grid connection, especially the United States. China has been supporting and expanding the development of renewable energy from the 8th Five-Year Plan to the 10th Five-Year Plan. Since the “Twelfth Five-Year Plan”, the grid-connected power generated by renewable energy has been supported. In the “Twelfth Five-Year Plan”, the ability to connect wind energy to the grid has reached a very important position.
To effectively manage large-scale variable renewable energy, energy must be used flexibly in all sectors of the energy system, from generation to transmission and distribution systems, energy storage (electricity and heat), and increasingly flexible demand areas (demand-side management and department connection). Globally, to integrate 60% of variable renewable energy generation (35% from wind) by 2050, compared to 2018 investment in grid and battery storage ($297 billion/year) , average annual investment in the grid, generation adequacy and some flexibility measures (i.e. energy storage) will need to increase by more than a quarter to $374 billion per year between now and around 2050.
Unlocking the enormous potential of wind power is critical to meeting climate goals. It is only by mitigating the current barriers (on different scales – technological, economic, socio-political and environmental) hindering the growth of the market, and by developing the right policies, strategies, business models and financial instruments, to ensure the rapid growth of wind energy in the next three decades, transition to a low-carbon sustainable energy future.