Built-in permanent magnet type doubly-fed wind power generator for power distribution system

Abstract

The application discloses a built-in permanent-magnetic double-fed wind driven generator for frequency division power transmission system, which comprises a stator and a rotor, the stator is sleeved on the rotor, and an air gap is formed between the stator and the rotor; the rotor comprises a rotor iron core, the rotor iron core is provided with a plurality of accommodation cavities, each of the accommodation cavities is provided with a rotor permanent magnet, and a plurality of rotor slots are formed in the outer wall of the rotor iron core; the stator comprises a stator iron core and a stator armature winding, and a plurality of stator teeth are formed in the inner side of the stator iron core; the stator armature winding comprises a 50 / 3 Hz winding and a 50 Hz winding, wherein the 50 / 3 Hz winding is wound on the stator teeth according to a three-phase symmetrical winding structure, and the 50 Hz winding is wound on the stator teeth according to a three-phase symmetrical winding structure; the generator can respectively emit 50 / 3 Hz and 50 Hz electric energy, and has the characteristics of high economy, high operation reliability and superior performance.

Description

Technical Field

[0001] This invention belongs to the field of new energy and power engineering technology, and relates to a built-in permanent magnet doubly fed wind turbine generator for frequency division transmission system. Background Technology

[0002] With the global energy crisis intensifying and environmental pollution becoming increasingly prominent, many countries have prioritized new energy sources in their national energy development goals. Offshore wind energy, characterized by abundant resources, minimal land occupation, and low environmental impact, possesses promising development prospects. In recent years, with the continuous development of offshore wind power technology, the distances of offshore wind turbines from shore have been increasing, rendering traditional power transmission technologies obsolete. The frequency-division transmission system proposed by Academician Wang Xifan of Xi'an Jiaotong University reduces transmission reactance by lowering the transmission frequency, thereby significantly increasing system transmission capacity and greatly extending the transmission distance of high-voltage AC power. This is of great significance for offshore wind power generation requiring long-distance power transmission.

[0003] Wind turbines, as the conversion unit between wind energy and electrical energy, are one of the core components of frequency-division transmission systems. Currently, scholars have studied the types of generators suitable for frequency-division transmission systems, and the results show that traditional low-speed direct-drive permanent magnet generators can be used in these systems. However, when traditional direct-drive permanent magnet generators are connected to the grid, a full-power inverter is required for rectification and inversion to output stable 50 / 3 Hz AC power. For high-power offshore wind turbines, the required inverter capacity and cost are enormous. Furthermore, when traditional direct-drive permanent magnet wind turbines are used in frequency-division transmission systems, they can only generate 50 / 3 Hz power, while the power plant's power system requires 50 Hz power. To meet the needs of the plant's power system, additional frequency converters are usually required, further increasing the cost of the frequency-division transmission system. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a built-in permanent magnet doubly fed wind turbine generator for frequency division transmission systems. This generator can generate 50 / 3 Hz and 50 Hz power respectively, and has the characteristics of high economy, high operational reliability and superior performance.

[0005] To achieve the above objectives, the present invention discloses a built-in permanent magnet doubly fed wind turbine generator for a frequency division power transmission system, comprising a stator and a rotor, wherein the stator is sleeved on the rotor and there is an air gap between the stator and the rotor;

[0006] The rotor includes a rotor core, and a mounting cavity is provided inside the rotor core. A rotor permanent magnet is provided in each mounting cavity, and a plurality of rotor slots are provided on the outer wall of the rotor core.

[0007] The stator includes a stator core and a stator armature winding, and a plurality of stator teeth are provided on the inner side of the stator core;

[0008] The stator armature winding includes a 50 / 3 Hz winding and a 50 Hz winding. The 50 / 3 Hz winding is wound on the stator teeth in a three-phase symmetrical winding structure, and the 50 Hz winding is wound on the stator teeth in a three-phase symmetrical winding structure.

[0009] The number of pole pairs of the rotor permanent magnet is the same as the number of pole pairs of the 50 / 3 Hz winding.

[0010] Stator slots are formed between adjacent stator teeth, and both the 50 / 3 Hz winding and the 50 Hz winding are located within the stator slots.

[0011] The distribution of air gap magnetic reluctance is adjusted by the rotor slots to generate 3p pole pair magnetic field harmonic components. The content of 3p pole pair magnetic field harmonics in the air gap is adjusted by adjusting the size and shape of the rotor slots, where p is an integer.

[0012] When in operation, the 50 / 3 Hz winding generates a fundamental magnetic field with p pole pairs.

[0013] The 50 / 3 Hz winding interacts with the magnetic field of the p-pole in the air gap to generate alternating current with a frequency of 50 / 3 Hz.

[0014] When in operation, the 50Hz winding generates a fundamental magnetic field with 3p pole pairs.

[0015] The 50Hz winding interacts with the magnetic fields of the p-pair and 3p-pair in the air gap to generate alternating current with a frequency of 50 Hz.

[0016] The present invention has the following beneficial effects:

[0017] In the frequency division power transmission system of this invention, the built-in permanent magnet doubly-fed wind turbine generator has an air gap between the stator and rotor during operation. The rotor core has mounting cavities, each containing a rotor permanent magnet. The outer wall of the rotor core has several rotor slots. Simultaneously, a 50 / 3 Hz winding and a 50 Hz winding are wound on the stator teeth in a three-phase symmetrical structure. The 50 / 3 Hz winding can generate 50 / 3 Hz electrical energy, and the 50 Hz winding can generate 50 Hz electrical energy. The 50 / 3 Hz electrical energy can be directly transmitted... The power is sent to the frequency-divided power grid, thus eliminating the need for an intermediate frequency converter and improving the economy and reliability of the frequency-divided power transmission system. The 50Hz power can be connected to the frequency-divided power grid via a frequency converter and directly connected to the power plant's auxiliary power system, thus eliminating the need for a frequency converter between the wind turbine and the power plant, further improving the economy and operational reliability of the entire system. At the same time, this invention only requires control of the 50Hz winding to adjust and control the operating status of the wind turbine, thus simplifying the control system and further improving the economy and reliability of the entire system. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the rotor 2 in this invention;

[0020] Figure 3 This is a schematic diagram of the structure of stator 1 in this invention;

[0021] Figure 4 This is a diagram showing the harmonic content of the radial component of the unloaded air gap magnetic flux density in this invention.

[0022] Figure 5 This is the back EMF diagram of the 50 / 3 Hz winding 6-1 in this invention;

[0023] Figure 6 This is the back electromotive force diagram of the 50Hz winding 6-2 in this invention.

[0024] In this diagram, 1 represents the stator, 2 represents the rotor, 3 represents the rotor permanent magnet, 4 represents the rotor core, 5 represents the stator core, 6 represents the stator armature winding, 6-1 represents the 50 / 3 Hz winding, 6-2 represents the 50 Hz winding, and 7 represents the rotor slot. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0026] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0027] refer to Figure 1 The frequency division power transmission system of the present invention uses a built-in permanent magnet doubly fed wind turbine generator, which includes a stator 1 and a rotor 2. The stator 1 is sleeved on the rotor 2, and there is an air gap between the stator 1 and the rotor 2.

[0028] The rotor 2 includes a rotor core 4, and the rotor core 4 is provided with a plurality of mounting cavities, each of which is provided with a plurality of rotor permanent magnets 3.

[0029] The stator 1 includes a stator core 5 and a stator armature winding 6. The inner side of the stator core 5 is provided with a plurality of stator teeth, and stator slots are formed between adjacent stator teeth.

[0030] refer to Figure 1 and Figure 3 The stator armature winding 6 includes a 50 / 3 Hz winding 6-1 and a 50 Hz winding 6-2. The 50 / 3 Hz winding 6-1 is wound on the stator teeth in a three-phase symmetrical winding structure. During operation, the 50 / 3 Hz winding 6-1 generates a fundamental magnetic field with p pole pairs. The 50 Hz winding 6-2 is wound on the stator teeth in a three-phase symmetrical winding structure. During operation, the 50 Hz winding 6-2 generates a fundamental magnetic field with 3p pole pairs, where p is a positive integer. It should be noted that both the 50 / 3 Hz winding 6-1 and the 50 Hz winding 6-2 are located in the stator slots and are distributed sequentially from the inside to the outside.

[0031] The number of pole pairs of rotor permanent magnet 3 is the same as the number of pole pairs of 50 / 3 Hz winding 6-1, that is, the number of pole pairs of rotor permanent magnet 3 is p pairs.

[0032] refer to Figure 1 and Figure 2 The outer wall of the rotor core 4 is provided with a plurality of rotor slots 7, wherein the distribution of air gap magnetic resistance is adjusted by the rotor slots 7, thereby generating 3p pole magnetic field harmonic components. The content of 3p pole magnetic field harmonics in the air gap is adjusted by adjusting the size and shape of the rotor slots 7.

[0033] When the present invention is in operation, the 50 / 3 Hz winding 6-1 interacts with the magnetic field of the p-p pair in the air gap to generate alternating current with a frequency of 50 / 3 Hz; the 50 Hz winding 6-2 interacts with the magnetic fields of the p-p and 3p pairs in the air gap to generate alternating current with a frequency of 50 Hz.

[0034] Example 1

[0035] refer to Figure 1 In this embodiment, a generator with two pole pairs of the fundamental wave of the air gap radial magnetic field is used as an example, i.e., p = 2.

[0036] The 50 / 3 Hz winding 6-1 is wound on the stator teeth in a three-phase symmetrical winding structure. During operation, the 50 / 3 Hz winding 6-1 generates a fundamental magnetic field with two pole pairs. The 50 Hz winding 6-2 is wound in the remaining space of the stator teeth in a three-phase symmetrical winding structure. During operation, the 50 Hz winding 6-2 generates a fundamental magnetic field with six pole pairs.

[0037] See Figure 1 and Figure 2 By adjusting the distribution of air gap magnetic resistance through rotor slot 7, six pairs of magnetic field harmonic components are generated. By adjusting the size and shape of rotor slot 7, the content of six pairs of magnetic field harmonics in the air gap can be adjusted.

[0038] refer to Figure 4 , Figure 4 This describes the harmonic content of the radial component of the unloaded air gap magnetic flux density in this embodiment. Figure 4 It can be seen that the radial component of the air gap magnetic field generated by the rotor permanent magnet 3 mainly includes the fundamental magnetic field of two pairs of poles and the harmonic magnetic field of six pairs of poles.

[0039] In this embodiment, the rated speed of rotor 2 is 500 rpm. At the rated speed, the 50 / 3 Hz winding 6-1 interacts with the magnetic field of the two pairs of poles in the air gap to generate alternating current with a frequency of 50 / 3 Hz; the 50 Hz winding 6-2 interacts with the magnetic fields of the two pairs of poles and the six pairs of poles in the air gap to generate alternating current with a frequency of 50 Hz.

[0040] Figure 5 and Figure 6 The back potential waveform diagram of the present invention is shown below. Figure 5 It can be seen that in this invention, the 50 / 3 Hz winding 6-1 outputs a voltage with a frequency of 50 / 3 Hz, which is determined by... Figure 6 It can be seen that the 50Hz winding 6-2 outputs a voltage with a frequency of 50 Hz, enabling the two sets of windings to output electrical energy at different frequencies.

[0041] In summary, this invention can generate 50 / 3 Hz and 50 Hz electrical energy respectively during operation. The 50 / 3 Hz energy can be directly transmitted to the frequency-division power grid, eliminating the need for an intermediate frequency converter and improving the economy and reliability of the frequency-division power transmission system. The 50 Hz energy can be connected to the frequency-division power grid via a frequency converter and simultaneously connected directly to the power plant's auxiliary power system, eliminating the need for a frequency converter between the wind turbine and the power plant, further improving the economy and operational reliability of the entire system. Furthermore, this invention only requires control of the 50Hz winding 6-2 to adjust and control the wind turbine's operating status, thus simplifying the control system and further improving the overall system's economy and reliability.

[0042] This invention patent uses an internal rotor motor model as an example, but other external rotor motors that conform to the principles described in this patent are also within the scope of protection of this patent.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A built-in permanent magnet doubly-fed wind turbine generator for a frequency division transmission system, characterized in that, It includes a stator (1) and a rotor (2), with the stator (1) sleeved on the rotor (2) and an air gap between the stator (1) and the rotor (2); The rotor (2) includes a rotor core (4), and a mounting cavity is provided inside the rotor core (4). A rotor permanent magnet (3) is provided in each mounting cavity. Several rotor slots (7) are provided on the outer wall of the rotor core (4). The stator (1) includes a stator core (5) and a stator armature winding (6), and a plurality of stator teeth are provided on the inner side of the stator core (5); The stator armature winding (6) includes a 50 / 3 Hz winding (6-1) and a 50 Hz winding (6-2), wherein the 50 / 3 Hz winding (6-1) is wound on the stator teeth in a three-phase symmetrical winding structure, and the 50 Hz winding (6-2) is wound on the stator teeth in a three-phase symmetrical winding structure. The number of pole pairs of the rotor permanent magnet (3) is the same as the number of pole pairs of the 50 / 3 Hz winding (6-1); The distribution of air gap magnetic resistance is adjusted by the rotor slots (7) to generate 3 p The harmonic components of the magnetic field of the opposite pole are adjusted by adjusting the size and shape of the rotor slot (7) to regulate the 3 in the air gap. p The content of magnetic field harmonics of the opposite pole, among which, p It is an integer.

2. The built-in permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 1, characterized in that, Stator slots are formed between adjacent stator teeth, and the 50 / 3 Hz winding (6-1) and the 50 Hz winding (6-2) are both located in the stator slots.

3. The built-in permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 2, characterized in that, During operation, the 50 / 3 Hz winding (6-1) generates a number of magnetic pole pairs. p The fundamental magnetic field of the opposite pole.

4. The built-in permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 3, characterized in that, 50 / 3 Hz winding (6-1) and air gap p The magnetic fields of opposite poles interact to generate alternating current with a frequency of 50 / 3 Hz.

5. The built-in permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 2, characterized in that, During operation, the 50 Hz winding (6-2) generates 3 pole pairs. p The fundamental magnetic field of the opposite pole.

6. The built-in permanent magnet doubly-fed wind turbine generator for the frequency division transmission system according to claim 5, characterized in that, 50 Hz winding (6-2) and 3 in the air gap p The magnetic fields of opposite poles interact to generate alternating current with a frequency of 50 Hz.

Images