Principle and application of permanent magnet synchronous wind turbine

China's wind energy resources are abundant, and the wind energy potential that can be developed is huge. According to relevant information, China's terrestrial wind energy resources can be developed at 2.38 billion kilowatts, and offshore wind energy resources can be developed at about 200 million kilowatts. China's wind energy resources are relatively concentrated. The development of potential wind energy resources in the “Three North” regions (North China, Northeast China and Northwest China) and the southeast coastal areas and coastal islands accounts for about 80% of the national total. The geographical distribution of wind energy resources and coal resources has a high coincidence. Degree, and the power load is reversed.

Recently, a high-speed permanent magnet synchronous wind turbine with independent intellectual property rights and a maximum power of 2.5MW was successfully launched at CSR Zhuzhou Motor Co., Ltd. The generator has many advantages such as high efficiency, small size, compact structure, low cost, high reliability, small maintenance, etc. The whole power variable flow control is adopted to make the unit have good low voltage ride through performance; the generator and direct drive Compared with the permanent magnet synchronous wind turbine, the volume is greatly reduced and the weight is greatly reduced. In particular, the amount of magnetic steel is greatly reduced. Today, the price of rare earth is high, and the cost-effective advantage of the product is More prominent and has a good market. prospect. The successful development of the generator indicates that Chinese enterprises have the ability to independently develop high-speed permanent magnet synchronous wind turbines with international advanced level.

During the "Twelfth Five-Year Plan" period, China's wind power installed capacity will account for a larger proportion of total power generation capacity. For power grid safety considerations, wind turbines must be "prevented by the wind" under the "low voltage ride through" guarantee. According to relevant sources from the Energy Research Institute of the National Development and Reform Commission of China, the cost of land-based wind power will be equal to that of coal-fired power in 2020. After that, wind power will gradually be separated from state subsidies, and “cost reduction” has become a new “bottleneck” for the future development of the wind power industry. CSR Zhuzhou Motor Co., Ltd. successfully launched a 2.5MW high-speed permanent magnet synchronous wind turbine, which realized the low-cost manufacturing of the generator, making the unit extremely easy to achieve low voltage traversing, and is at the leading level in China.

Due to the small mechanical loss, high operating efficiency and low maintenance cost, permanent magnet synchronous wind turbines have become a major wind turbine type after the doubly-fed induction wind turbines, and have been widely used. The basic structure of the permanent magnet synchronous wind power generation system is shown in Figure 1. It is mainly composed of a wind turbine, a permanent magnet synchronous engine, a frequency converter and a transformer.

(1) Basic principle The basic principle of permanent magnet synchronous wind power generation is to use the wind to drive the wind turbine blade to rotate and drag the rotor of the permanent magnet synchronous generator to realize power generation. The permanent magnet synchronous wind power generation system is similar to the cage type variable speed constant frequency wind power generation system, except that the generator used is a permanent magnet type generator, and the rotor is a permanent magnet type structure, and the external excitation power supply is not required, thereby improving the efficiency. Its variable frequency constant speed control is realized in the stator circuit, and the variable frequency alternating current of the permanent magnet synchronous generator is converted into the alternating current of the same frequency of the power grid through the frequency converter to realize the grid connection of the wind power generation, so the capacity of the frequency converter and the system The rated capacity is the same.

(2) Technical characteristics In the past few decades, permanent magnet synchronous generators have become more and more attractive due to the improvement of permanent magnet material properties and power electronic devices. The wind power generation system using the permanent magnet synchronous generator has the following characteristics: 1) The permanent magnet synchronous generator system does not require an excitation device, and has the advantages of light weight, high efficiency, high power factor, good reliability, etc.; 2) wide variable speed operation range , can be super-synchronous operation or sub-synchronous operation; 3) rotor non-excited winding, simple magnetic pole structure, small inverter capacity, can be made into multi-pole motor; 4) synchronous speed reduction, wind turbine and permanent magnet generator can be Direct coupling eliminates the gear speed increase box in the wind power generation system, reduces the maintenance work of the generator and reduces noise, and makes the direct drive permanent magnet wind power generator system.

(3) Applicable occasions 1) In areas where power facilities are scarce, transportation is inconvenient, and conventional fuel is scarce, but wind resources are abundant, some power problems can be solved, such as providing power for highway lighting equipment; 2) the capacity of the single unit is relatively small. The wind farm, permanent magnet synchronous power generation system can efficiently connect to the grid to generate electricity; 3) provide AC or DC power for remote, lightly loaded users such as rural areas, pastoral areas, border guard posts, and meteorological stations.