Surface-mounted permanent magnet doubly-fed wind power generator for frequency division power transmission system

Abstract

The application discloses a surface-mounted permanent-magnetic double-fed wind power generator for a 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 and a plurality of rotor permanent magnets, each rotor permanent magnet is fixed on the outer wall of the rotor iron core, and the rotor permanent magnets are opposite to the stator; the rotor permanent magnets generate a radial component of air gap magnetomotive force, which comprises a fundamental wave with p pole pairs and a harmonic wave with 3p pole pairs; the stator comprises a stator iron core and a stator armature winding, a plurality of stator teeth are arranged on the inner wall of the stator iron core, stator slots are formed between adjacent stator teeth, and the stator armature winding comprises two sets of windings; wherein, the first set of windings and the second set of windings are sequentially located in the stator slots from inside to outside; the generator can respectively emit 50 / 3 Hz and 50 Hz electric energy, and simultaneously 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 surface-mounted permanent magnet doubly fed wind turbine generator for frequency division transmission systems. 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 surface-mounted 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 surface-mount permanent magnet doubly-fed wind turbine generator for a frequency division 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 several rotor permanent magnets. Each rotor permanent magnet is fixed on the outer wall of the rotor core and faces the stator. The radial component of the air gap magnetomotive force generated by the rotor permanent magnet includes a fundamental wave with p pole pairs and a harmonic wave with 3p pole pairs.

[0007] The stator includes a stator core and a stator armature winding. The inner wall of the stator core is provided with a number of stator teeth, and stator slots are formed between adjacent stator teeth. The stator armature winding includes two sets of windings, wherein the first set of windings and the second set of windings are located in the stator slots from the inside to the outside.

[0008] The permanent magnets of each rotor are evenly distributed along the circumference.

[0009] The radial thickness h of the rotor permanent magnet gradually changes along the circumference of the rotor core.

[0010] The radial thickness h of the rotor permanent magnet is:

[0011]

[0012] Where h1 and h2 are thickness adjustment factors, and α is the angle in the circumferential direction.

[0013] The first set of windings is a 50 / 3 Hz winding, and the first set of windings is arranged in the stator slots according to a three-phase symmetrical winding structure.

[0014] The second set of windings is a 50 Hz winding, and the second set of windings is arranged in the remaining space of the stator slots according to a three-phase symmetrical winding structure.

[0015] During operation, the first winding generates a fundamental magnetic field with p pole pairs, which interacts with the fundamental magnetic field generated by the rotor permanent magnet to produce alternating current with a frequency of 50 / 3 Hz.

[0016] During operation, the second winding generates a fundamental magnetic field with 3p pole pairs, which interacts with the 3p harmonic magnetic field generated by the rotor permanent magnet to produce alternating current with a frequency of 50 Hz.

[0017] The rotor core has a circular ring structure.

[0018] The present invention has the following beneficial effects:

[0019] In the specific operation of the surface-mounted permanent magnet doubly-fed wind turbine generator used in the frequency division transmission system of this invention, the stator armature winding includes two sets of windings. During operation, the two sets of windings respectively generate 50 / 3 Hz and 50 Hz electrical energy. The 50 / 3 Hz energy can be directly transmitted to the frequency division transmission grid, thus eliminating the need for an intermediate frequency converter, improving the economy and reliability of the frequency division transmission system, and reducing costs. The 50 Hz energy can be connected to the frequency division transmission grid via a frequency converter, and simultaneously directly connected to the power plant's auxiliary power system, thus eliminating the need for a frequency converter between the wind turbine generator and the power plant, further improving the economy and operational reliability of the entire system. Furthermore, this invention only requires control of the 50 Hz winding to adjust and control the wind turbine generator's operating state, thus simplifying the control system and further improving the economy and reliability of the entire system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the rotor structure of the present invention;

[0022] Figure 3 This is a schematic diagram of the winding connection of the present invention;

[0023] Figure 4 This is a radial component distribution diagram of the unloaded air gap magnetic flux density of the present invention;

[0024] Figure 5 This is the radial component harmonic diagram of the unloaded air gap magnetic flux density of the present invention;

[0025] Figure 6 This is the back EMF diagram of the 50 / 3 Hz winding of the present invention;

[0026] Figure 7 This is the back EMF diagram of the 50 Hz winding of the present invention.

[0027] Among them, 1 is the stator, 2 is the rotor, 3 is the rotor permanent magnet, 4 is the rotor core, 5 is the stator core, and 6 is the stator armature winding. Detailed Implementation

[0028] 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.

[0029] 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.

[0030] refer to Figure 1 The surface-mounted permanent magnet doubly fed wind turbine generator for frequency division transmission system of the present invention 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.

[0031] The rotor 2 includes a rotor core 4 and several rotor permanent magnets 3. The rotor core 4 has a circular structure, and each rotor permanent magnet 3 is fixed on the outer wall of the rotor core 4, with the rotor permanent magnet 3 facing the stator 1.

[0032] The stator 1 includes a stator core 5 and a stator armature winding 6. The inner wall of the stator core 5 is provided with a plurality of stator teeth, and stator slots are formed between adjacent stator teeth. The stator armature winding 6 is wound in each stator slot.

[0033] refer to Figure 1 and Figure 2 Each rotor permanent magnet 3 is uniformly distributed circumferentially, and the radial thickness h of the rotor permanent magnet 3 gradually changes along the circumferential direction of the rotor core 4. The radial component of the air gap magnetomotive force generated by the rotor permanent magnet 3 includes a fundamental wave with p pole pairs and a 3p pole pair harmonic, where p is a positive integer. The radial thickness h of the rotor permanent magnet 3 is:

[0034]

[0035] Where h1 and h2 are thickness adjustment factors, α is the angle in the circumferential direction, and the value of α ranges from 0° to 360°. By changing the size of h1 and h2, the magnitude of the p-pole fundamental wave and the 3p-pole harmonic in the air gap magnetomotive force is adjusted.

[0036] refer to Figure 1 and Figure 3 The stator armature winding 6 comprises two sets of three-phase symmetrically distributed windings. The first set of windings is a 50 / 3 Hz winding, which is arranged in the lower layer of the stator slot according to the three-phase symmetrical winding structure. During operation, the first set of windings generates a fundamental magnetic field with p pole pairs, which interacts with the p pole fundamental magnetic field generated by the rotor permanent magnet 3 to generate alternating current with a frequency of 50 / 3 Hz. The second set of windings is a 50 Hz winding, which is arranged in the upper layer of the stator slot according to the three-phase symmetrical winding structure. During operation, the second set of windings generates a fundamental magnetic field with 3p pole pairs, which interacts with the 3p pole harmonic magnetic field generated by the rotor permanent magnet 3 to generate alternating current with a frequency of 50 Hz.

[0037] Example 1

[0038] refer to Figure 1 In this embodiment, a generator with a fundamental magnetic pole pair of the air gap radial magnetic field is used as an example, i.e., p = 1. In this embodiment, h1 is 1.8 times h2.

[0039] refer to Figure 4 and Figure 5 , Figure 4 This describes the radial component distribution of the unloaded air gap magnetic flux density in this embodiment. Figure 5 The radial component harmonic content of the unloaded air gap magnetic flux density in this embodiment is determined by... Figure 5 It can be seen that the radial component of the air gap magnetic field generated by the rotor permanent magnet 3 mainly includes a fundamental magnetic field with one pair of poles and a harmonic magnetic field with three pairs of poles.

[0040] In this embodiment, the rated speed of rotor 2 is 1000 rpm during operation.

[0041] Figure 6 and Figure 7 The back potential waveform diagram of the present invention is shown below. Figure 6 It can be seen that the 50 / 3 Hz winding in this invention outputs a voltage with a frequency of 50 / 3 Hz, which is determined by... Figure 7 It can be seen that the 50 Hz winding outputs a voltage with a frequency of 50 Hz, which can enable the two sets of windings to output electrical energy at different frequencies.

[0042] 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 50 Hz winding 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.

[0043] 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.

[0044] 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 surface-mounted 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), the stator (1) is sleeved on the rotor (2), and there is an air gap between the stator (1) and the rotor (2); The rotor (2) includes a rotor core (4) and several rotor permanent magnets (3). Each rotor permanent magnet (3) is fixed to the outer wall of the rotor core (4), and the rotor permanent magnet (3) faces the stator (1). The radial component of the air gap magnetomotive force generated by the rotor permanent magnet (3) includes a number of magnetic pole pairs. p The fundamental wave of the opposite pole and 3 p Harmonics of opposite poles; The stator (1) includes a stator core (5) and a stator armature winding (6). The inner wall of the stator core (5) is provided with a number of stator teeth, and stator slots are formed between adjacent stator teeth. The stator armature winding (6) includes two sets of windings, wherein the first set of windings and the second set of windings are located in the stator slots from the inside to the outside. The first set of windings is a 50 / 3 Hz winding, and the first set of windings is arranged in the stator slots according to a three-phase symmetrical winding structure. The second set of windings is a 50 Hz winding, and the second set of windings is arranged in the remaining space of the stator slots according to a three-phase symmetrical winding structure.

2. The surface-mounted permanent magnet doubly-fed wind turbine generator for a frequency division transmission system according to claim 1, characterized in that, Each rotor permanent magnet (3) is evenly distributed along the circumference.

3. The surface-mounted permanent magnet doubly-fed wind turbine generator for a frequency division transmission system according to claim 1, characterized in that, Radial thickness of rotor permanent magnet (3) h The change gradually occurs along the circumference of the rotor core (4).

4. The surface-mounted permanent magnet doubly-fed wind turbine generator for a frequency division transmission system according to claim 1, characterized in that, Radial thickness of rotor permanent magnet (3) h for: in, h 1 and h 2 is the thickness adjustment factor. α It represents the angle along the circumference.

5. The surface-mounted permanent magnet doubly-fed wind turbine generator for a frequency division transmission system according to claim 1, characterized in that, During operation, the first winding generates a number of magnetic pole pairs. p The fundamental magnetic field of the opposite pole, and the magnetic field generated by the rotor permanent magnet (3) p The polar fundamental wave magnetic field interacts with each other to generate alternating current with a frequency of 50 / 3 Hz.

6. The surface-mounted permanent magnet doubly-fed wind turbine generator for a frequency division transmission system according to claim 1, characterized in that, During operation, the second winding generates 3 magnetic pole pairs. p The fundamental magnetic field of the opposite pole, and the 3 generated by the rotor permanent magnet (3) p The polar harmonic magnetic fields interact to generate alternating current with a frequency of 50 Hz.

7. The surface-mounted permanent magnet doubly-fed wind turbine generator for a frequency division transmission system according to claim 1, characterized in that, The rotor core (4) has a circular ring structure.

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