Wind power: Technology, industry and industrial chain

1, wind power technology principle

The principle of wind power generation is to use the wind to drive the fan blade rotation, when the wind blows to the blade to drive the wind wheel rotation, wind energy into kinetic energy, and then to promote the generator to generate electricity.

The process of wind power generation is similar to that of thermal power and hydropower, which are driven by other energies to generate electricity from generators. The physical principle of the generator is the law of electromagnetic induction we learned in junior high school, that is, when the conductor cuts the motion of the magnetic inductance line in the magnetic field, current will be generated in the conductor. In wind power generation, the kinetic energy generated by the wind blowing the blade drives the conductor to move. In thermal power generation, coal burning turns water into steam and drives the motor to generate electricity. In hydropower, it is the kinetic energy of the flow of water that makes the electric motor produce electricity.

Photovoltaic power generation is not the same, photovoltaic power generation is based on the photoelectric effect, in 1954 Bell Laboratories successfully developed the first practical value of silicon solar cells, and as early as the 19th century generators have been put into use, human from the steam era into the electrical age. Compared with photovoltaic, wind power is the core technology is relatively mature traditional industry, in the investment market, photovoltaic attention is also higher than wind power, the valuation is of course higher.

New energy power generation is facing the test of cost reduction and efficiency increase, photovoltaic in recent years with the rapid development of conversion efficiency and cost reduction, and wind power generation has a Betz limit law, that is, no matter how to design the turbine, the fan can only extract 59% of the energy in the wind, and the conversion efficiency limit can be achieved by the wind turbine in operation today is about 40%. Therefore, there is not much room for improvement in the core technology of wind power generation, and basically there is only one way to reduce the cost.

Relative to the photovoltaic PERC, TOPCon, HJT, the technical path of wind power is very simple, but in the rapid development of sustainable energy today, wind power and photovoltaic are an indispensable part, as long as the demand is large enough, even if the technology is mature, it is also an industry worth our research and learning.

Before we briefly introduced the principle of wind power generation, now let's look at how an actual wind turbine is composed.

The wind turbine has many parts, and the core can be simplified into three parts: wind turbine, generator and tower barrel.

A wind wheel is generally composed of three blades. When the wind blows towards the blades, it drives the wind wheel, and the wind energy is converted into mechanical energy. The material of the blade requires high strength and light weight, and is made of glass fiber or other composite materials (such as carbon fiber). Due to the variable wind speed, the wind wheel speed is unstable, and before driving the generator, it is necessary to attach the gear gearbox that increases the speed to the rated speed of the generator, and then add a speed regulating structure to keep the speed stable, and then connect to the generator. In order to ensure that the wind wheel is always aligned with the wind direction to obtain maximum power, a tail rudder (yaw system) similar to a wind vane is installed behind the wind wheel.

The function of a generator is a machine that converts kinetic energy into electrical energy.

The tower barrel is the frame that supports the wind wheel, the tail rudder and the generator, and it is generally built relatively high in order to obtain a larger and more uniform wind force, but also to have enough strength. The height of the tower depends on the influence of the ground obstacles on the wind speed, as well as the diameter of the wind wheel, and can now do more than 100 meters.

We said earlier that there is not much room for efficiency gains in wind power, so the focus is on cost reduction. A typical trend is that the fan capacity is getting larger and larger. The average single-unit capacity of onshore wind turbines in China increased from 1.5MW in 2011 to 3.1MW in 2021, and the average single-unit capacity of offshore wind turbines increased from 1.9MW in 2013 to 5.6MW in 2021.

If the total installed capacity of a wind farm is fixed, the number of fans required now is half of that of 10 years ago, and the corresponding land, construction, operation and maintenance costs are reduced. At the same time, the blades are getting longer and longer, increasing the sweep area, the tower barrel is getting higher and higher, and the higher the wind speed is, so that even if the conversion efficiency does not increase, the captured wind energy increases, the power generation will increase, and the cost of KWH will also decrease.

The impact of large-scale fan application on cost reduction is also very significant, according to Goldwind Technology statistics, the average bidding price of 4S fan from 2020Q3 more than 3,000 yuan /kw to 2021Q4 about 2,300 yuan /kw.