Regulation and control method for enabling electro-magnetic synchronous wind driven generator to rotate at constant rotating speed

Abstract

The invention discloses a regulation and control method for enabling an electro-magnetic synchronous wind driven generator to rotate at a constant rotating speed, and solves the problem of how to improve the power supply quality and the power grid friendliness of wind power generation. Comprising an impeller (1), an electro-magnetic synchronous generator (4), a variable-frequency and variable-speed motor (3), a frequency converter, an electric controller and a three-phase alternating-current power grid, the electro-magnetic synchronous generator is electrically connected with the three-phase alternating-current power grid, the variable-frequency and variable-speed motor is electrically connected with the three-phase alternating-current power grid through the frequency converter, and the variable-frequency and variable-speed motor is arranged between the impeller (1) and a rotating shaft of the electro-magnetic synchronous generator (4). A gear box speed regulating mechanism (2) is mechanically connected to the main shaft (1) and consists of an outer gear ring (5), an annular sheet-shaped planet carrier (6), a sun gear (7) and a pinion (8); the difference between the rotating speed of the impeller (1) and the rotating speed of the planet carrier outer gear ring (13) is equal to the rotating speed of the sun gear output shaft (14); the manufacturing cost of the motor is reduced, and the later operation and maintenance cost is also reduced.

Description

Technical Field

[0001] The invention relates to the technical field of wind power generation, and in particular to a control method for making an electrically excited synchronous wind power generator rotate at a constant speed. Background Art

[0002] At present, in the field of wind power generation technology, there are two main commonly used technical routes. The first is to use a gearbox and a doubly fed asynchronous motor, plus a slip power conversion method; the second is to use a gearbox and a permanent magnet synchronous motor, plus a full power conversion method; the wind turbine main engine in the first method adopts a doubly fed asynchronous motor, and the power supply of the motor rotor is carried out in the following way: the three-phase power grid supplies power to the inverter, and the inverter is connected to the three-phase winding of the doubly fed motor rotor after frequency conversion, and the rotation speed of the magnetic field generated by the three-phase winding of the rotor is changed by the inverter, so as to achieve the stability of the stator winding power generation frequency. This structure is provided with a three-phase slip ring and carbon brush structure on the rotor, and there are problems that the slip ring and carbon brush are easy to be damaged and the maintenance cost is high; when the wind turbine of the second method adopts a permanent magnet synchronous generator, A full-power frequency converter must be installed between the wind turbine and the power grid to achieve stable output power supply frequency. The full-power frequency converter has the problem of high cost. In addition, permanent magnet motors also have the problem of permanent magnet overheating and easy demagnetization. The strong excitation ability and reactive power support ability of permanent magnet synchronous motors and doubly fed asynchronous motors are poor. The voltage ride-through ability of permanent magnet synchronous motors will be limited by the capacity of the converter, and the voltage mutation of doubly fed asynchronous motors will cause the transient voltage of the rotor to increase significantly, causing serious damage to the frequency converter connected to the rotor. Both permanent magnet synchronous generators and doubly fed asynchronous wind turbines have the disadvantages of low power supply quality and poor grid friendliness. How to reduce the manufacturing and operation and maintenance costs of wind power generation systems and improve power supply quality and grid friendliness has become a major problem that needs to be solved urgently in the field of wind power technology. Summary of the invention

[0003] The present invention provides a control method for making an electrically excited synchronous wind turbine generator rotate at a constant speed, solving the technical problem of how to improve the power supply quality and grid friendliness of wind power generation.

[0004] The present invention solves the above technical problems through the following technical solutions: The overall concept of the present invention is as follows: In a wind power generation system, a wind generator adopts a brushless electrically excited synchronous generator, and a planetary gear speed regulating gearbox is arranged between the impeller and the wind generator rotor. In response to the change of the impeller speed, a compensating speed regulating system is arranged in the gearbox through a mechanical structure. When the impeller speed is high, the compensating speed regulating system reduces its speed, and when the impeller speed is low, the compensating speed regulating system increases its speed, so that the speed of the output shaft of the planetary gear speed regulating gearbox is constant, thereby making the speed of the wind generator rotor constant, and realizing that the voltage frequency emitted by the wind generator is kept at the fixed frequency required by the power grid.

[0005] A wind power generation system that makes an electrically excited synchronous generator rotate at a constant speed, comprising an impeller, an electrically excited synchronous generator, a variable frequency speed regulating motor, a frequency converter, an electronic controller and a three-phase AC power grid, wherein the electrically excited synchronous generator is electrically connected to the three-phase AC power grid, and the variable frequency speed regulating motor is electrically connected to the three-phase AC power grid through the frequency converter, and a gearbox speed regulating mechanism is mechanically connected between the impeller and the rotating shaft of the electrically excited synchronous generator, and the gearbox speed regulating mechanism is composed of an outer gear ring, an annular planet carrier, a sun gear and a pinion; annular inner teeth are arranged on the inner side surface of the annular ring of the outer gear ring, and a speed regulating gearbox input shaft is connected to the left end side surface of the outer gear ring; the base of the annular planet carrier is an annular plate, and planetary gear shafts are arranged at equal intervals of 120 arcs on the left annular vertical surface of the annular planet carrier, and three The planetary gear shafts are arranged on the circumference of a concentric circle. On each planetary gear shaft, a planetary gear is movably arranged. On the right annular vertical surface of the annular planetary carrier, an outer gear ring of the planetary carrier is fixedly arranged. On the right vertical surface of the sun gear, a sun gear output shaft is fixedly connected. A sun gear is movably arranged in the outer gear ring. An annular planetary carrier is movably sleeved on the sun gear output shaft on the right side of the sun gear. Each planetary gear on the left annular vertical surface of the annular planetary carrier is respectively meshed with the annular inner teeth and the sun gear set on the outer gear ring. The sun gear output shaft is mechanically connected to the rotating shaft of the electrically excited synchronous generator. A pinion is meshed on the outer gear ring of the planetary carrier, and the pinion shaft on the pinion is mechanically connected to the output shaft of the variable frequency speed regulation motor.

[0006] An impeller speed sensor is arranged on the impeller, a sun gear gear output shaft speed sensor is arranged on the sun gear gear output shaft, and a variable frequency speed regulation motor output shaft speed sensor is arranged on the output shaft of the variable frequency speed regulation motor. The impeller speed sensor, the sun gear gear output shaft speed sensor and the variable frequency speed regulation motor output shaft speed sensor are electrically connected to the electronic controller respectively, and the electronic controller is electrically connected to the frequency converter.

[0007] A control method for making an electrically excited synchronous generator rotate at a constant speed is achieved by a wind power generation system that makes the electrically excited synchronous generator rotate at a constant speed. The impeller rotates under the action of wind power, and the impeller drives the outer gear ring to rotate synchronously through the input shaft of the speed regulating gear box. The outer gear ring drives three planetary gears to rotate synchronously through the annular internal teeth. The three planetary gears drive the sun gear output shaft to rotate synchronously by meshing with the sun gear. The sun gear output shaft is mechanically connected to the rotating shaft of the electrically excited synchronous generator, and synchronously drives the electrically excited synchronous generator to rotate and generate electricity. The electricity generated by the electrically excited synchronous generator is sent to a three-phase AC power grid. If, when the speed of the impeller increases, the electronic controller controls the frequency conversion speed regulating motor to rotate through the frequency converter, and the frequency conversion speed regulating motor drives the pinion to rotate through the frequency conversion speed regulating motor output shaft, and the pinion meshes with the outer gear ring of the planet carrier, so that the annular planet carrier rotates in the opposite direction to the speed of the impeller, thereby reducing the speed of the sun gear output shaft, thereby offsetting the increase in the speed of the impeller; If the speed of the impeller decreases, the electronic controller controls the variable frequency speed regulating motor to rotate in the opposite direction through the inverter, and the variable frequency speed regulating motor drives the pinion to rotate in the opposite direction through the variable frequency speed regulating motor output shaft. The pinion engages with the outer gear ring of the planetary carrier to make the annular planetary carrier rotate in the same direction as the speed of the impeller, thereby increasing the speed of the sun gear output shaft, thereby compensating for the reduced speed of the impeller.

[0008] The speed difference between the impeller and the planet carrier outer gear ring is equal to the speed of the sun gear output shaft; under the condition of keeping the speed of the sun gear output shaft constant, the speed of the planet carrier outer gear ring is dynamically regulated according to the change of the impeller speed; the speed of the planet carrier outer gear ring is regulated by regulating the speed of the variable frequency speed regulating motor, and the speed of the variable frequency speed regulating motor is regulated by the electronic controller through the frequency converter.

[0009] The present invention creatively proposes a new wind power generation technology route, which performs slip speed regulation through an external variable frequency speed regulating motor of a planetary gear speed regulating gearbox, so that the speed output to the motor side remains at a constant synchronous speed, and adopts an electrically excited synchronous motor as a wind turbine generator, which not only reduces the manufacturing cost of the motor, but also reduces the subsequent operation and maintenance cost, thereby achieving a substantial cost reduction in wind power generation; in addition, the use of an electrically excited synchronous motor as a wind turbine generator can also effectively improve the power supply quality and solve the problem of poor excitation capability and reactive power support capability of permanent magnet synchronous generators and double-fed asynchronous generators. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a structural schematic diagram of a wind power generation system of the present invention; Figure 2 It is a structural schematic diagram of the gear box speed regulating mechanism 2 of the present invention; Figure 3 is a schematic structural diagram of the outer gear ring 5 of the present invention; Figure 4 Schematic diagram of the structure of the ring-shaped planet carrier 6 of the present invention; Figure 5 1 is a diagram showing the matching relationship between the ring-shaped planet carrier 6 and the planetary gear 12 of the present invention; Figure 6 is a schematic structural diagram of the sun gear 7 of the present invention; Figure 7 It is a diagram showing the matching relationship between the annular planet carrier 6 and the sun gear 7 of the present invention. DETAILED DESCRIPTION

[0011] The present invention is described in detail below in conjunction with the accompanying drawings: A wind power generation system for rotating an electrically excited synchronous generator at a constant speed, comprising an impeller 1, an electrically excited synchronous generator 4, a variable frequency speed regulating motor 3, a frequency converter, an electronic controller and a three-phase AC power grid, wherein the electrically excited synchronous generator 4 is electrically connected to the three-phase AC power grid, and the variable frequency speed regulating motor 3 is electrically connected to the three-phase AC power grid through the frequency converter, and a gearbox speed regulating mechanism 2 is mechanically connected between the impeller 1 and the rotating shaft of the electrically excited synchronous generator 4, and the gearbox speed regulating mechanism 2 is composed of an outer gear ring 5, an annular planetary carrier 6, a sun gear 7 and a pinion 8; an annular inner tooth 9 is arranged on the inner side surface of the annular ring of the outer gear ring 5, and a speed regulating gearbox input shaft 10 is connected to the left end side surface of the outer gear ring 5; the base of the annular planetary carrier 6 is an annular plate, and planetary gear shafts 11 are arranged at equal intervals of 120 arcs on the left annular vertical surface of the annular planetary carrier 6, and the three planetary gears are connected to the sun gear 7 and the sun gear 8. The shaft 11 is arranged on the circumference of a concentric circle. On each planetary gear shaft 11, a planetary gear 12 is movably arranged. On the right annular vertical surface of the annular planetary carrier 6, a planetary carrier outer gear ring 13 is fixedly arranged; on the right vertical surface of the sun gear 7, a sun gear output shaft 14 is fixedly connected; a sun gear 7 is movably arranged in the outer gear ring 5, and an annular planetary carrier 6 is movably sleeved on the sun gear output shaft 14 on the right side of the sun gear 7. Each planetary gear 12 on the left annular vertical surface of the annular planetary carrier 6 is respectively meshed with the annular inner teeth 9 and the sun gear 7 arranged on the outer gear ring 5, the sun gear output shaft 14 is mechanically connected to the rotating shaft of the electrically excited synchronous generator 4, and a pinion 8 is meshed on the planetary carrier outer gear ring 13, and the pinion shaft on the pinion 8 is mechanically connected to the output shaft of the variable frequency speed regulation motor 3.

[0012] An impeller speed sensor is arranged on the impeller 1, a sun gear gear output shaft speed sensor is arranged on the sun gear gear output shaft 14, and a variable frequency speed regulation motor output shaft speed sensor is arranged on the output shaft of the variable frequency speed regulation motor 3. The impeller speed sensor, the sun gear gear output shaft speed sensor and the variable frequency speed regulation motor output shaft speed sensor are electrically connected to the electronic controller respectively, and the electronic controller is electrically connected to the frequency converter.

[0013] A control method for making an electrically excited synchronous generator rotate at a constant speed is achieved by a wind power generation system that makes the electrically excited synchronous generator rotate at a constant speed. An impeller 1 rotates under the action of wind power. The impeller 1 drives an outer gear ring 5 to rotate synchronously through a speed regulating gear box input shaft 10. The outer gear ring 5 drives three planetary gears 12 to rotate synchronously through annular internal teeth 9. The three planetary gears 12 drive a sun gear output shaft 14 to rotate synchronously through meshing with a sun gear 7. The sun gear output shaft 14 is mechanically connected to a rotating shaft of an electrically excited synchronous generator 4, and synchronously drives the electrically excited synchronous generator 4 to rotate and generate electricity. The electricity generated by the electrically excited synchronous generator 4 is sent to a three-phase AC power grid. If, when the speed of the impeller 1 increases, the electronic controller controls the frequency conversion speed regulating motor 3 to rotate through the frequency converter, and the frequency conversion speed regulating motor 3 drives the pinion 8 to rotate through the frequency conversion speed regulating motor output shaft, and the pinion 8 meshes with the planet carrier outer gear ring 13, so that the ring-shaped planet carrier 6 rotates in the direction opposite to the speed direction of the impeller 1, thereby reducing the speed of the sun gear output shaft 14, thereby offsetting the increase in the speed of the impeller 1; If the speed of the impeller 1 decreases, the electronic controller controls the variable frequency speed regulating motor 3 to rotate in the opposite direction through the inverter, and the variable frequency speed regulating motor 3 drives the pinion 8 to rotate in the opposite direction through the variable frequency speed regulating motor output shaft. The pinion 8 engages with the planetary carrier outer gear ring 13 to make the annular planetary carrier 6 rotate in the same direction as the speed of the impeller 1, thereby increasing the speed of the sun gear output shaft 14, thereby compensating for the reduced speed of the impeller 1.

[0014] The speed difference between the impeller 1 and the planet carrier outer gear ring 13 is equal to the speed of the sun gear output shaft 14; under the condition of keeping the speed of the sun gear output shaft 14 constant, the speed of the planet carrier outer gear ring 13 is dynamically regulated according to the change of the speed of the impeller 1; the speed of the planet carrier outer gear ring 13 is regulated by regulating the speed of the variable frequency speed regulating motor 3, and the speed of the variable frequency speed regulating motor 3 is regulated by the electronic controller through the frequency converter.

[0015] The impeller 1 absorbs wind energy and rotates to generate torque; the gearbox speed regulating mechanism 2 performs slip speed regulation through an external variable frequency speed regulating motor 3, so that the speed output to the electrically excited synchronous motor 4 can be kept constant; the variable frequency speed regulating motor 3 includes an asynchronous motor, a synchronous motor, a permanent magnet motor, a reluctance motor, etc. The variable frequency speed regulating motor 3 is only used for slip speed regulation, so its capacity is much smaller than the rated power of the generator, so the capacity of the frequency converter connected to it is also relatively small, thereby reducing the cost of the frequency converter; the electrically excited synchronous motor 4 can be either a brush structure or a brushless structure. Even if a brush structure is used, since the rotor winding is only used for the excitation of the synchronous generator and does not need to output slip power, the later failure rate of the brush is also much lower than the brush failure rate of the doubly fed wind turbine. Regardless of whether a brushed or brushless structure is adopted, the electrical frequency output by the electrically excited synchronous motor 4 is always consistent with the grid frequency, so direct grid connection can be achieved without connecting a frequency converter; the gearbox speed regulating mechanism 2 of the present invention has three speed interfaces respectively connected to the impeller 1, the variable frequency speed regulating motor 3 and the electrically excited synchronous motor 4; the outer gear ring 5 is connected to the impeller 1 through the speed regulating gearbox input shaft 10 as the mechanical input of the entire power generation system; the mechanical power input by the impeller is transmitted to the planetary gear 12 through the outer gear ring 5 of the gearbox speed regulating mechanism 2; then, it is transmitted to the sun gear 7 by the planetary gear 12, and the mechanical power is transmitted to the electrically excited synchronous motor 4 through the sun gear output shaft 14, so that the speed output to the electrically excited synchronous motor 4 side is a constant synchronous speed.

Claims

1. A control method for causing an electrically excited synchronous wind turbine to rotate at a constant speed, wherein the control is achieved by a wind power generation system that causes the electrically excited synchronous turbine to rotate at a constant speed, the wind power generation system comprising an impeller (1), an electrically excited synchronous generator (4), a variable frequency speed regulating motor (3), a frequency converter, an electric controller and a three-phase AC power grid, the electrically excited synchronous generator (4) being electrically connected to the three-phase AC power grid, the variable frequency speed regulating motor (3) being electrically connected to the three-phase AC power grid via the frequency converter, a gearbox speed regulating mechanism (2) being mechanically connected between the impeller (1) and the rotating shaft of the electrically excited synchronous generator (4), the gearbox speed regulating mechanism (2) The invention is composed of an outer gear ring (5), an annular planet carrier (6), a sun gear (7) and a pinion (8); an annular inner tooth (9) is arranged on the inner side surface of the annular ring of the outer gear ring (5); a speed regulating gear box input shaft (10) is connected to the left end side surface of the outer gear ring (5); the base of the annular planet carrier (6) is an annular plate; planetary gear shafts (11) are arranged at equal intervals of 120 arcs on the left annular vertical surface of the annular planet carrier (6); the three planetary gear shafts (11) are arranged on the circumference of a concentric circle; a planetary gear (12) is movably arranged on each planetary gear shaft (11); and a planetary gear (12) is movably arranged on the annular ring of the outer gear ring (5). A planet carrier outer gear ring (13) is fixedly arranged on the right annular vertical surface of the planet carrier (6); a sun gear output shaft (14) is fixedly connected to the right vertical surface of the sun gear (7); a sun gear (7) is movably arranged in the outer gear ring (5); an annular planet carrier (6) is movably sleeved on the sun gear output shaft (14) on the right side of the sun gear (7); each planet gear (12) on the left annular vertical surface of the annular planet carrier (6) is respectively meshed with annular inner teeth (9) arranged on the outer gear ring (5) and the sun gear (7); the sun gear output shaft (14) is connected to the electric excitation synchronous generator (4). The rotating shafts are mechanically connected together, a pinion (8) is meshed on the planet carrier outer gear ring (13), and the pinion shaft on the pinion (8) is mechanically connected to the output shaft of the variable frequency speed regulating motor (3); an impeller speed sensor is arranged on the impeller (1), a sun gear gear output shaft speed sensor is arranged on the sun gear gear output shaft (14), and a variable frequency speed regulating motor output shaft speed sensor is arranged on the output shaft of the variable frequency speed regulating motor (3); the impeller speed sensor, the sun gear gear output shaft speed sensor and the variable frequency speed regulating motor output shaft speed sensor are respectively electrically connected to the electronic controller, and the electronic controller is electrically connected to the frequency converter; characterized in that Follow these steps: The impeller (1) rotates under the action of wind, and the impeller (1) drives the outer ring gear (5) to rotate synchronously through the input shaft (10) of the speed regulating gear box, and the outer ring gear (5) drives the three planetary gears (12) to rotate synchronously through the annular inner teeth (9), and the three planetary gears (12) drive the sun gear output shaft (14) to rotate synchronously through meshing with the sun gear (7), and the sun gear output shaft (14) is mechanically connected to the rotating shaft of the electrically excited synchronous generator (4), and synchronously drives the electrically excited synchronous generator (4) to rotate and generate electricity, and the electricity generated by the electrically excited synchronous generator (4) is sent to the three-phase AC power grid; If, when the speed of the impeller (1) increases, the electronic controller controls the frequency conversion speed regulating motor (3) to rotate through the frequency converter, the frequency conversion speed regulating motor (3) drives the pinion (8) to rotate through the frequency conversion speed regulating motor output shaft, and the pinion (8) meshes with the outer gear ring (13) of the planet carrier, so that the annular planet carrier (6) rotates in the direction opposite to the speed direction of the impeller (1), thereby reducing the speed of the sun gear output shaft (14), thereby offsetting the increase in the speed of the impeller (1); When the speed of the impeller (1) decreases, the electronic controller controls the variable frequency speed regulating motor (3) to rotate in the opposite direction through the frequency converter, and the variable frequency speed regulating motor (3) drives the pinion (8) to rotate in the opposite direction through the variable frequency speed regulating motor output shaft. The pinion (8) meshes with the outer ring gear (13) of the planet carrier, so that the annular planet carrier (6) rotates in the same direction as the speed of the impeller (1), thereby increasing the speed of the sun gear output shaft (14), thereby compensating for the reduced speed of the impeller (1).

2. A control method for making an electrically excited synchronous wind turbine generator rotate at a constant speed according to claim 1, characterized in that: The speed difference between the impeller (1) and the planet carrier outer gear ring (13) is equal to the speed of the sun gear output shaft (14); under the condition of keeping the speed of the sun gear output shaft (14) constant, the speed of the planet carrier outer gear ring (13) is dynamically regulated according to the change of the speed of the impeller (1); the speed of the planet carrier outer gear ring (13) is regulated by regulating the speed of the variable frequency speed regulating motor (3), and the speed of the variable frequency speed regulating motor (3) is regulated by the electronic controller through the frequency converter.

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