Wind driven generator variable-speed magnetic coupling transmission system and method capable of participating in primary frequency modulation of power grid

Abstract

The invention discloses a wind driven generator variable-speed magnetic coupling transmission system and method capable of participating in primary frequency modulation of a power grid. The system comprises fan blades, a driving shaft, a driving shaft bearing seat 3, a magnetic coupler, a steel wire shaft, a driven shaft I, a transverse transmission bearing, a base, a transverse displacement speed regulating mechanism, a driven shaft II, a driven shaft bearing seat, a generator, a chassis and a tower. A plurality of layers of copper ring conductors and permanent magnet ring concentric cylinders which are alternately arranged are arranged on a driving disc and a driven disc, efficient transmission of torque is achieved, meanwhile, friction and vibration are reduced, normal operation of a system is guaranteed, and the service life is prolonged; the speed regulating mechanism is used for maintaining the synchronous rotating speed of the generator, thereby improving the generating efficiency. The speed regulation device is applied to the rotating shaft of the power driving system of the wind driven generator, and the driven disc is controlled to displace through the speed regulation device, so that the effect of controlling the magnetic force is achieved, the synchronous rotating speed of the generator is maintained, and electric energy with constant frequency is output to facilitate direct grid connection of the wind driven generator.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and relates to wind generator equipment, in particular to a variable speed magnetic coupling transmission system and method for a wind generator capable of participating in primary frequency modulation of a power grid. Background Art

[0002] Traditional wind turbines use a gearbox structure with a fixed ratio transmission. This structure uses rigid materials to connect the wind wheel and the generator rotor. In actual use, due to the instability of wind speed, the wind turbine cannot maintain a constant speed and it is difficult to generate AC power with a constant frequency, resulting in low power generation efficiency. At the same time, rigid transmission will cause vibration, reduce the life of the gear, and in severe cases, cause stalling and damage to the equipment, resulting in high maintenance costs.

[0003] As a contactless power transmission device, the magnetic coupling has the characteristics of no friction and overload protection compared with the traditional contact power transmission device. Due to the design without mechanical connection, even the vibration generated by the power source itself will not be transmitted to the load end. It does not generate electromagnetic interference to the entire system, has a simple structure, and effectively improves the stability of operation.

[0004] With the large-scale access of wind turbines to the power system, wind turbines have a great impact on the stability of the power system, especially their active power regulation capability cannot meet the frequency control requirements of the power system. For this reason, the state has issued relevant documents requiring that wind turbines connected to the grid must have a primary frequency regulation function to cope with the potential challenges brought by the intermittent and instability of wind power generation to the power grid, thereby maintaining the safe operation of the entire power system. Summary of the invention

[0005] The purpose of the present invention is to provide a wind turbine variable speed magnetic coupling transmission system and method which has a simple structure and can participate in the primary frequency modulation of the power grid. By configuring multiple layers of alternately arranged copper ring conductors and permanent magnet ring concentric cylinders on the driving disk and the driven disk, efficient torque transmission is achieved, while friction and vibration are reduced, the normal operation of the system is ensured, and the service life is extended; the speed regulating mechanism is used to maintain the synchronous speed of the generator, thereby improving the power generation efficiency.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A variable speed magnetic coupling transmission system for a wind turbine generator capable of participating in primary frequency modulation of a power grid comprises a wind turbine blade, a driving shaft, a driving shaft bearing seat, a magnetic coupler, a steel wire shaft, a driven shaft I, a transverse transmission bearing, a base, a transverse displacement speed regulating mechanism, a driven shaft II, a driven shaft bearing seat, a generator, a chassis and a tower.

[0008] The chassis is fixed on the top of the tower; the driving shaft is installed on the chassis through the driving shaft bearing seat, and one end of the driving shaft is coaxially connected to the fan blade; the other end of the driving shaft is coaxially connected to the driving disk of the magnetic coupler, one end of the steel wire shaft is coaxially connected to the driven disk of the magnetic coupler, and the other end of the steel wire shaft is coaxially connected to one end of the driven shaft I; a transverse transmission bearing is assembled on the driven shaft I, and the transverse transmission bearing is installed on the base, and the base is fixed to the chassis, the other end of the driven shaft I is connected to one end of the transverse displacement speed regulating mechanism, the other end of the transverse displacement speed regulating mechanism is connected to one end of the driven shaft II, and the other end of the driven shaft II is coaxially connected to the rotating shaft of the generator; the chassis installs the driven shaft II through the driven shaft bearing seat.

[0009] Further preferably, the magnetic coupler comprises an active disk, a driven disk, a copper ring conductor, and a permanent magnet ring; the active disk is provided with a plurality of concentric ring cylinders I, each of which is fixed with a copper ring conductor on the central side; the driven disk is provided with a plurality of concentric ring cylinders II, each of which is fixed with a permanent magnet ring on the outer circumference, and the permanent magnet ring is composed of a permanent magnet with an N pole on the outside and an S pole on the inside and a permanent magnet with an S pole on the outside and an N pole on the inside, which are evenly arranged; after the ring cylinder I of the active disk and the ring cylinder II of the driven disk are interlaced, the corresponding copper ring conductor and the permanent magnet ring are directly opposite. The first ring of the driven disk is embedded in the gap between the first ring and the second ring of the active disk, and so on. When the driving shaft rotates and drives the driving disk to rotate, the copper ring conductor on the driving disk cuts the magnetic lines in the permanent magnet ring on the driven disk. The magnetic field formed by the generated eddy current couples with the magnetic field generated by the permanent magnet ring to generate torque, which drives the driven disk to rotate and completes the magnetic drive process. The path of magnetic drive is: driving shaft-driving disk-driven disk-wire shaft-driven shaft I.

[0010] Further preferably, the lateral displacement speed regulating mechanism adopts a scissor-type speed regulating device. The scissor-type speed regulating device includes a load-bearing plate I, a load-bearing plate II, an upper connecting shaft of a scissor-type rod, a lower connecting shaft of a scissor-type rod, a bidirectional electric drive, and an outer tube of a telescopic rod; the load-bearing plate I and the load-bearing plate II are arranged opposite each other, the load-bearing plate I is connected to the other end of the driven shaft I, and the load-bearing plate II is connected to one end of the driven shaft II; the middle part of the load-bearing plate I is equipped with an articulated rod I through an articulated seat I, and four scissor-type rods I are symmetrically arranged on both sides of the articulated rod I in pairs, and one end of the two scissor-type rods I on the same side is hinged to the articulated rod I; similarly, the middle part of the load-bearing plate II is equipped with an articulated rod II through an articulated seat II, and the four scissor-type rods Ⅱ Two scissor rods Ⅱ are symmetrically arranged on both sides of the articulated rod Ⅱ and are located on the same side. One end of the two scissor rods Ⅱ is hinged to the articulated rod Ⅱ; the two ends of the upper connecting shaft of the scissor rod are respectively hinged to the other ends of the scissor rod Ⅰ and scissor rod Ⅱ located at the upper part. Similarly, the two ends of the lower connecting shaft of the scissor rod are respectively hinged to the other ends of the scissor rod Ⅰ and scissor rod Ⅱ located at the lower part; the telescopic rods at both ends of the bidirectional electric drive are respectively connected to the upper connecting shaft of the scissor rod and the lower connecting shaft of the scissor rod through the outer tube of the telescopic rod; an angle sensor is installed at the end of the upper connecting shaft of the scissor rod to detect the angle information between the scissor rod Ⅰ and the scissor rod Ⅱ in real time. The upper and lower telescopic rod outer tubes are driven to extend and contract (change the distance between the upper and lower connecting shafts of the scissor rod) through the action of the bidirectional electric drive, driving the scissor rods Ⅰ and scissor rods Ⅱ of the same size to move, thereby adjusting the distance between the load-bearing plate Ⅰ and the load-bearing plate Ⅱ.

[0011] Further preferably, a row of rolling wheels is installed on the base, the transverse transmission bearing is located on the rolling wheels, and limit baffles are respectively provided on the front and rear sides of the base to ensure that the driven shaft will not fall off when it moves laterally within a small range.

[0012] The working principle of the system of the present invention is that the driven disc can realize axial movement under the force of the scissor-type speed regulating device, and the driven disc can be displaced laterally by changing the telescopic length of the outer tube of the telescopic rod of the bidirectional electric driver, which can change the strength of the induced magnetic field, further change the magnitude of the magnetic torque, and realize the adjustment of the generator speed. There is a certain air gap between the active disc and the driven disc, which ensures that the driven disc is displaced within a certain range and does not contact the active disc.

[0013] The basic principle of the variable speed magnetic coupling transmission system of the wind turbine generator of the present invention being able to participate in the primary frequency modulation of the power grid is as follows:

[0014] The cutting speed of the copper ring conductor in the magnetic field in the air gap is:

[0015] v=πd(n 1 -n 2 ) / 60=2τsf (1)

[0016] Where, τ is the pole pitch of the induced magnetic field of the copper ring conductor, s is the slip rate between the active disk and the driven disk, and f is the current alternating frequency.

[0017] The instantaneous induced electromotive force of a single copper ring conductor is:

[0018] E i =B r Lv=B c Lvcos(ω 1 t+θ i ) (2)

[0019] In the formula, B r is the air gap flux density, L is the coupling length of the copper ring conductor in the permanent magnet ring of the driven disk, ω 1 is the relative angular velocity of the active disk and the driven disk, t is the time, θ i is the initial angle of the i-th copper ring conductor, i=1,2,3…M (M is the number of copper ring conductors).

[0020] The instantaneous induced current and instantaneous electromagnetic power of the i-th copper ring conductor are:

[0021]

[0022]

[0023] In the formula, r 1 is the resistance of the copper conductor, Z i is the effective value of impedance.

[0024] By integrating equation (4), we can obtain the total electromagnetic power and magnetic torque transmitted by the active disk to the driven disk:

[0025]

[0026]

[0027] In formula (6), ω is the angular velocity of the driven disk, and k is the adjustment coefficient.

[0028] It can be seen from formula (6) that the magnetic torque T is proportional to the square of the coupling length L of the copper ring conductor in the permanent magnet ring. Therefore, the torque and speed can be adjusted by changing L. When L increases, the magnetic torque T increases accordingly, the slip rate s between the master and driven disks will decrease, and the corresponding output speed will increase; vice versa.

[0029] After the bidirectional electric drive starts to move, the angle β between the scissor rod and the outer tube of the telescopic rod changes: when the bidirectional electric drive performs the action of shortening the outer tube of the telescopic rod, the angle β changes from β 0 Increase to β 1, the coupling length variation ΔL between the copper ring conductor and the permanent magnet ring increases. At this time, the air gap inside the magnetic coupler decreases, the magnetic torque increases, the generator speed increases, and the angle β and the coupling length variation ΔL have the following relationship:

[0030] ΔL=AE=m(sinβ 0 -sinβ 1 ) (10)

[0031] When the bidirectional electric drive performs the action of extending the outer tube of the telescopic rod, the angle β changes from β 0 Reduce to β 2 , the coupling length variation ΔL between the copper ring conductor and the permanent magnet ring decreases. At this time, the air gap inside the magnetic coupler increases, the magnetic torque decreases, the generator speed decreases, and the angle β and the coupling length variation ΔL have the following relationship:

[0032] ΔL=AE′=m(sinβ 2 -sinβ 0 ) (11)

[0033] The above-mentioned variable speed magnetic coupling transmission system of the wind turbine generator capable of participating in the primary frequency modulation of the power grid realizes the rapid response of the rotational kinetic energy by controlling the magnetic torque of the wind turbine generator and participates in the frequency modulation of the power grid. The specific method includes the following steps:

[0034] Step S1, setting range and sampling: setting the real-time frequency f of the grid connection point t With rated frequency f n The frequency deviation value is limited to ±0.05Hz; Get the initial value of the generator output power P 0 and the real-time frequency of the grid connection point f t , detect the frequency fluctuation of the grid points;

[0035] Specifically, this measure can quickly obtain the real-time status information of the power grid. Once the frequency of the grid connection point is monitored to fluctuate, corresponding measures can be taken immediately to adjust the grid connection power, thereby ensuring that the power grid maintains stability and reliability.

[0036] Step S2, determine whether the frequency deviation value of the grid connection point exceeds the specified range; if so, execute step S3, otherwise execute step S1.

[0037] Step S3: The generator enters the primary frequency regulation state, and the generator output power regulation target P is calculated according to the following formula:

[0038] P=P 0 -KP n (f t -f n ) (9)

[0039] In formula (9), P is the power regulation target of the generator primary frequency regulation, P 0 is the initial value of the generator active power, K is the generator primary frequency regulation droop coefficient (generally K = 0.5), the generator rated power P n , f t is the frequency value of the current power grid, f n is the rated frequency of the current power grid.

[0040] Step S4: Determine the real-time frequency f of the interconnection point t With rated frequency f n Is the deviation value of positive?

[0041] At this time, the frequency deviation of the grid connection point is f t -f n It may be positive or negative; if the frequency deviation is positive, then f t -f n >0.05Hz, execute step S5, otherwise the frequency deviation value is negative, and f t -f n <-0.05Hz, go to step S6.

[0042] Step S5, the scissor-type speed regulating device extends the outer tube of the telescopic rod through the bidirectional electric drive, thereby reducing the coupling length of the magnetic coupler and reducing the active output of the generator;

[0043] Specifically, the scissor-type speed regulating device performs the action of extending the outer tube of the telescopic rod through the bidirectional electric drive, and calculates the coupling length change ΔL in the magnetic coupler according to formula (8):

[0044] ΔL=AE′=m(sinβ 2 -sinβ 0 ) (8)

[0045] According to formula (6), the change of electromagnetic torque T can be calculated:

[0046]

[0047] It can be seen from the above formula that the coupling length of the magnetic coupler is reduced and the electromagnetic torque is reduced. According to the formula P=T×ω, the generator output power is controlled to reach the regulation target and the active power is reduced; where ω is the generator speed.

[0048] Step S6, the scissor-type speed regulating device shortens the outer tube of the telescopic rod through the bidirectional electric drive, thereby increasing the coupling length of the magnetic coupler and improving the active output of the generator;

[0049] Specifically, the scissor-type speed regulating device shortens the outer tube of the telescopic rod through a bidirectional electric drive, and calculates the coupling length change ΔL in the magnetic coupler according to formula (7):

[0050] ΔL=AE=m(sinβ 0 -sinβ 1 ) (7)

[0051] According to formula (6), the change of electromagnetic torque ΔT can be calculated:

[0052]

[0053] It can be seen from the above formula that as the coupling length of the magnetic coupler increases, the electromagnetic torque increases. According to the formula P=T×ω, the generator output power is controlled to reach the regulation target and the active power is increased; where ω is the generator speed.

[0054] Step S7, determine whether the frequency of the grid connection point is restored to the specified range; if so, execute step S8, otherwise execute step S9.

[0055] Step S8: The wind turbine generator exits the primary frequency modulation state, and the bidirectional electric drive performs a reset action to restore the magnetic coupler to the initial coupling length, thereby preventing the primary frequency modulation from affecting the stability of the power grid.

[0056] Step S9, determine whether the magnetic coupling has reached the maximum action limit; if so, execute step S10, otherwise execute step S4.

[0057] Step S10: The magnetic coupler keeps running at the maximum action position.

[0058] Since there is no traditional mechanical connection method, even if the power source itself generates vibration, it cannot be transmitted to the load and affect the load, thereby significantly reducing the vibration problem of the entire system. Compared with the prior art, the present invention has the following advantages:

[0059] First, the present invention does not generate electromagnetic interference to the overall environment, has a simple structural design, and can easily adapt to various harsh environments.

[0060] Second, the present invention does not generate electromagnetic harmonics, thus achieving pollution-free emissions.

[0061] Third, the compact size of the present invention makes the installation process extremely convenient, and it is particularly convenient and flexible whether it is used for the transformation of an existing system or the integration of a new system.

[0062] The invention has reasonable design, simple structure and strong controllability, and creatively applies a speed regulating device to the rotating shaft of a wind turbine power drive system. The speed regulating device is used to control the displacement of a driven disk, thereby achieving the effect of controlling the magnitude of the magnetic force, maintaining the synchronous speed of the generator, and outputting electric energy with a constant frequency so that the wind turbine can be directly connected to the grid. The invention has good practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0064] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0065] Figure 1 A schematic structural diagram of a variable speed magnetic machine drive system for a wind turbine generator according to the present invention is shown.

[0066] Figure 2 A schematic diagram showing the structure of the magnetic coupler in the present invention.

[0067] Figure 3 A schematic structural diagram of a scissor-type speed regulating device in the present invention is shown.

[0068] Figure 4 A simplified diagram showing the motion analysis of the scissor-type speed regulating device in the present invention.

[0069] Figure 5 A schematic diagram showing a primary frequency modulation process of the present invention. Figure 6 A schematic flow chart of the method of the present invention is shown.

[0070] In the figure: 1-fan blade, 2-driving shaft, 3-driving shaft bearing seat, 4-magnetic coupler, 5-wire shaft, 6-driven shaft I, 7-transverse transmission bearing, 8-limit baffle, 9-base, 10-rolling wheel, 11-scissor-type speed regulating mechanism, 12-driven shaft II, 13-driven shaft bearing seat, 14-generator, 15-chassis, 16-tower; 40-driving disc, 401-ring cylinder I, 41-driven disc, 411-ring cylinder II, 42- Copper ring conductor, 43-permanent magnet ring, 431-permanent magnet; 111-load-bearing plate Ⅰ, 1111-articulated seat Ⅰ, 1112-articulated rod Ⅰ, 1113-scissor rod Ⅰ; 112-load-bearing plate Ⅱ, 1121-articulated seat Ⅱ, 1122-articulated rod Ⅱ, 1123-scissor rod Ⅱ; 113-scissor rod upper connecting shaft, 114-scissor rod lower connecting shaft, 115-bidirectional electric drive, 116-telescopic rod outer tube, 117-angle sensor. DETAILED DESCRIPTION

[0071] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0072] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0073] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0074] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0075] A variable speed magnetic coupling transmission system of a wind turbine generator capable of participating in primary frequency modulation of a power grid comprises a wind turbine blade 1, a driving shaft 2, a driving shaft bearing seat 3, a magnetic coupler 4, a steel wire shaft 5, a driven shaft I 6, a transverse transmission bearing 7, a base 9, a transverse displacement speed regulating mechanism 11, a driven shaft II 12, a driven shaft bearing seat 13, a generator 14, a chassis 15 and a tower 16.

[0076] like Figure 1 As shown, the chassis 15 is fixed to the top of the tower 16; the driving shaft 2 is installed on the chassis 15 through the driving shaft bearing seat 3. One end of the driving shaft 2 as the input power is coaxially connected to the fan blade 1, and the other end of the driving shaft 2 is connected to the wire shaft 5, the driven shaft I6, the scissor-type speed regulating device 11, the driven shaft II12 and the generator 13 in sequence through the magnetic coupler 4. Among them, the driven shaft II12 is installed in the driven shaft bearing seat 13, and the driven shaft bearing seat 13 is fixed on the chassis 15. The generator 14 is fixed on the chassis 15. Specifically: the other end of the driving shaft 2 is coaxially connected to the driving disk 40 of the magnetic coupler 4, one end of the wire shaft 5 is coaxially connected to the driven disk 41 of the magnetic coupler 4, and the other end of the wire shaft 5 is coaxially connected to one end of the driven shaft I6. The driven shaft I6 is equipped with a transverse transmission bearing 7, which is installed on the base 9, that is, a row of rolling wheels 10 are installed on the base 9, and the transverse transmission bearing 7 is located on the rolling wheels 10. The front and rear sides of the base 9 are respectively provided with limit baffles 88, which can ensure that the driven shaft I6 will not fall off when it moves horizontally within a small range. The base 9 is fixed to the chassis 15, and the other end of the driven shaft I6 is connected to one end of the transverse displacement speed regulating mechanism 11, and the other end of the transverse displacement speed regulating mechanism 11 is connected to one end of the driven shaft II 12, and the other end of the driven shaft II 12 is coaxially connected to the rotating shaft of the generator 14.

[0077] The steel wire shaft 5 is composed of a plurality of bent steel wires, and its principle is to realize rotation transmission by utilizing the flexibility of the steel wires. When the driven disk 41 rotates, the steel wires are twisted, and power is transmitted in the axial direction, and the torque generated by the driven disk 41 can be transmitted to the generator 14. During the transmission process, when the force exceeds a certain limit, the steel wire shaft 5 can bear a certain degree of elastic load, and play a role in buffering and protecting the equipment.

[0078] like Figure 2 , 3As shown, the magnetic coupler 4 includes an active disk 40, a driven disk 41, a copper ring conductor 42, and a permanent magnet ring 43. The active disk 40 is provided with a plurality of concentric ring cylinders I 401, that is, a cylindrical structure composed of a plurality of concentric cylinders I and equipped with a copper ring conductor, and a copper ring conductor 42 is fixed to the center side of each ring cylinder I 401. The driven disk 41 has a similar structure to the active disk 40, and is provided with a plurality of concentric ring cylinders II 411, and a permanent magnet ring 43 is fixed to the outer peripheral side of each ring cylinder II 411. The permanent magnet ring 43 is composed of a permanent magnet 431 with an N pole on the outside and an S pole on the inside and a permanent magnet 431 with an S pole on the outside and an N pole on the inside, which are evenly arranged to form a complete ring. After the ring cylinder I 401 of the active disk 40 and the ring cylinder II 411 of the driven disk 41 are interlaced (i.e., the first ring of the driven disk 41 is embedded in the gap between the first ring and the second ring of the active disk 40, and so on), the corresponding copper ring conductor 42 and the permanent magnet ring 43 are facing each other. When the active shaft 2 rotates to drive the active disk 40 to rotate, the copper ring conductor 42 on the active disk 40 cuts the magnetic lines of force in the permanent magnet ring 43 on the driven disk 41, and the magnetic field formed by the generated eddy current is coupled with the magnetic field generated by the permanent magnet ring 43, generating torque, driving the driven disk 41 to rotate, and completing the process of magnetic drive. The path of magnetic drive is: active shaft 2-active disk 40-driven disk 41-wire shaft 5-driven shaft I 6.

[0079] In this embodiment, the lateral displacement speed regulating mechanism 11 adopts a scissor-type speed regulating device. Figure 4As shown, the scissor-type speed regulating device includes a load-bearing plate Ⅰ111, a load-bearing plate Ⅱ112, an upper connecting shaft 113 of the scissor-fork rod, a lower connecting shaft 114 of the scissor-fork rod, a bidirectional electric driver 115, and an outer tube of a telescopic rod 116. The load-bearing plate Ⅰ111 and the load-bearing plate Ⅱ112 are coaxially arranged opposite to each other, the load-bearing plate Ⅰ111 is connected to the other end of the driven shaft Ⅰ6, and the load-bearing plate Ⅱ112 is connected to one end of the driven shaft Ⅱ12. An articulated rod Ⅰ1112 is installed in the middle of the load-bearing plate Ⅰ111 through two articulated seats Ⅰ1111, and four scissor rods Ⅰ1113 with the same size are symmetrically arranged on both sides of the articulated rod Ⅰ1112, and one end of the two scissor rods Ⅰ1113 on the same side is hinged to the end of the articulated rod Ⅰ1112; similarly, an articulated rod Ⅱ1122 is installed in the middle of the load-bearing plate Ⅱ112 through two articulated seats Ⅱ1121, and four scissor rods Ⅱ1123 with the same size are symmetrically arranged on both sides of the articulated rod Ⅱ1122, and one end of the two scissor rods Ⅱ1123 on the same side is hinged to the end of the articulated rod Ⅱ1122. The two ends of the upper connecting shaft 113 of the scissor rod are respectively hinged to the other ends of the scissor rod Ⅰ1113 and the scissor rod Ⅱ1121 located at the upper part; similarly, the two ends of the lower connecting shaft 114 of the scissor rod are respectively hinged to the other ends of the scissor rod Ⅰ1113 and the scissor rod Ⅱ1123 located at the lower part; thus, the scissor rod Ⅰ1113 and the scissor rod Ⅱ1123 located on the same side form a parallelogram structure. The telescopic rods at both ends of the bidirectional electric drive 115 are respectively connected to the upper connecting shaft 113 of the scissor rod and the lower connecting shaft 114 of the scissor rod through the telescopic rod outer tube 116, that is, the telescopic rod outer tube 116 is embedded between the upper and lower connecting shafts of the scissor rod. An angle sensor 117 is installed at the end of the upper connecting shaft 113 of the scissor rod. After the bidirectional electric driver 115 drives the telescopic rod outer tube 116 to extend and retract, the distance between the upper connecting shaft 113 of the scissor rod and the lower connecting shaft 114 of the scissor rod is changed, thereby adjusting the distance between the bearing plate I 111 and the bearing plate II 112. Since the position of the driven shaft II 12 is fixed, that is, the position of the bearing plate II 112 remains unchanged, the bearing plate I 111 moves axially, thereby realizing the axial displacement of the driven plate 41 through the driven shaft I 6 and the wire shaft 5.

[0080] The working principle of the system of the present invention is that the driven disc 41 can realize axial movement under the force of the scissor-type speed regulating device, and the driven disc 41 can be displaced laterally by changing the length of the telescopic rod outer tube 116 of the bidirectional electric driver 115, which can change the strength of the induced magnetic field, further change the magnitude of the magnetic torque, and realize the adjustment of the generator speed. There is an air gap between the active disc 40 and the driven disc 41, which ensures that the driven disc 41 is displaced within a certain range and does not contact the active disc 40.

[0081] The core goal of the primary frequency regulation of wind turbines is that when the grid frequency fluctuates beyond a preset limit, the wind turbines can respond quickly and adjust the load according to the set regulation target. Specifically, when the grid frequency rises for some reason, the primary frequency regulation function will prompt the wind turbine to quickly reduce the load to curb the further increase in frequency; on the contrary, if the grid frequency drops, the wind turbine is required to quickly increase the load to stabilize the frequency within a reasonable range. The specific embodiments of the method of the present invention are as follows:

[0082] The cutting speed of the copper ring conductor 42 in the magnetic field in the air gap is:

[0083] v=πd(n 1 -n 2 ) / 60=2τsf (1)

[0084] Wherein, τ is the pole moment of the induced magnetic field of the copper conductor, s is the slip rate between the active disk 40 and the driven disk 41, and f is the current alternating frequency.

[0085] The instantaneous induced electromotive force of a single copper ring conductor is:

[0086] E i =B r Lv=B c Lvcos(ω 1 t+θ i ) (2)

[0087] In the formula, B r is the air gap flux density, L is the coupling length of the copper ring conductor in the permanent magnet ring of the driven disk, ω 1 is the relative angular velocity of the active disk 40 and the driven disk 41, t is time, θ i is the initial angle of the i-th copper ring conductor, i=1,2,3…M (M is the number of copper ring conductors).

[0088] The instantaneous induced current and instantaneous electromagnetic power of the i-th copper ring conductor are:

[0089]

[0090]

[0091] In the formula, r 1 is the copper ring conductor resistance, Z i is the effective value of impedance.

[0092] By integrating equation (4), we can obtain the total electromagnetic power and magnetic torque transmitted by the active disk 40 to the driven disk 41:

[0093]

[0094]

[0095] In formula (6), ω is the angular velocity of the driven disk 41, and k is the adjustment coefficient.

[0096] It can be seen from formula (6) that the magnetic torque T is proportional to the square of the coupling length L of the copper ring conductor 42 in the permanent magnet ring 43. Therefore, the torque and speed can be adjusted by changing L. When L increases, the magnetic torque T increases accordingly, the slip rate s between the master and slave disks will decrease, and the corresponding output speed will increase; vice versa.

[0097] The motion analysis of the scissor-type speed regulating device is as follows: Figure 5 As shown, a coordinate system is established with a fixed hinge point A according to the geometric relationship. The upper and lower hinge points B and C of the telescopic rod outer tube of the bidirectional electric actuator have freedom in the Y direction, and the midpoint is E. The length of a single scissor rod is set to be m, the initial length of the telescopic rod outer tube of the bidirectional electric actuator is n, the angle between the scissor rod I and the fixed hinge point A is α, and the angle between the telescopic rod outer tube of the scissor rod I and the bidirectional electric actuator is β; the scissor rod II is the same.

[0098] From the geometric relationship, the initial coordinates of the hinge point B are:

[0099]

[0100] The initial coordinates of point C are:

[0101]

[0102] The initial coordinates of the fixed hinge point D are:

[0103]

[0104] After the bidirectional electric drive starts to move, the angle β between the scissor rod and the outer tube of the telescopic rod of the bidirectional electric drive changes: when the bidirectional electric drive performs the action of shortening the outer tube of the telescopic rod, the angle β changes from the initial angle β 0 Increase to β 1 , the coupling length variation of the copper ring conductor 42 and the permanent magnet ring 43 is ΔL, at this time, the air gap inside the magnetic coupler 4 is reduced, the magnetic torque is increased, the speed of the generator 14 is increased, and the angle β and the coupling length variation ΔL have the following relationship:

[0105] ΔL=AE=m(sinβ 0 -sinβ 1 ) (10)

[0106] When the bidirectional electric drive performs the action of extending the outer tube of the telescopic rod, the angle β changes from the initial angle β 0 Reduce to β 2, the coupling length variation of the copper ring conductor 42 and the permanent magnet ring 43 is ΔL, at this time, the air gap inside the magnetic coupler 4 increases, the magnetic torque decreases, the speed of the generator 14 decreases, and the angle β and the coupling length variation ΔL have the following relationship:

[0107] ΔL=AE′=m(sinβ 2 -sinβ 0 ) (11)

[0108] The variable speed magnetic coupling transmission system of a wind turbine generator capable of participating in primary frequency modulation of a power grid according to an embodiment of the present invention realizes a rapid response of rotational kinetic energy by controlling the magnetic torque of the wind turbine generator, and participates in the frequency modulation of the power grid, such as Figure 6 As shown, including:

[0109] Step S1, setting range and sampling: setting the real-time frequency f of the grid connection point t With rated frequency f n The frequency deviation value is limited to ±0.05Hz; Get the initial value P of the output power of the generator 14 0 =0.95pu, rated output power P n =1p.u., the real-time frequency of the detection and connection point is f t =49.92Hz, rated frequency f n =50Hz.

[0110] Step S2, determining whether the frequency deviation value of the grid connection point exceeds a limited range;

[0111] At this time, the frequency deviation value is -0.08Hz<-0.05Hz, which exceeds the limit range, and step S3 is executed.

[0112] Step S3: The generator 14 enters a primary frequency regulation state, and the generator output power regulation target P is calculated as:

[0113] P=P 0 -KP n (f t -f n )=1.006pu.

[0114] Step S4: The frequency deviation value is negative, and f t -f n <-0.05Hz, go to step S6.

[0115] Step S6: The scissor-type speed regulating device shortens the outer tube of the telescopic rod through the bidirectional electric drive, and the angle between the scissor-type rod and the bidirectional electric telescopic rod is changed from β 0 =59° increases to β 1=60°, the length of a single scissor rod m = 300 mm, the initial coupling length L = 20 mm, the coupling length action range is 0-50 mm, the adjustment coefficient k is 0.6, and the coupling length increase ΔL in the magnetic coupler 4 is calculated according to formula (10):

[0116] ΔL=AE=m(sinβ 0 -sinβ 1 )=27mm

[0117] According to formula (6), the increase of electromagnetic torque ΔT can be calculated:

[0118] ΔT=kΔL 2 =0.044pu

[0119] At this time, the electromagnetic torque T increases, and according to the formula P=T×ω, the output power of the generator 14 is controlled to reach the adjustment target, and the active power is increased; where ω is the rotation speed of the generator 14.

[0120] Step S7: At this time, the frequency of the grid connection point is restored to within the specified range, and step S8 is executed.

[0121] Step S8, the wind turbine generator exits the primary frequency modulation state, and the bidirectional electric telescopic rod 22 performs a reset action to restore the magnetic coupler 4 to the initial coupling length, thereby preventing the primary frequency modulation from affecting the stability of the power grid.

[0122] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A variable speed magnetic coupling transmission system for a wind turbine generator capable of participating in primary frequency modulation of a power grid, comprising a wind turbine blade (1), a driving shaft (2), a driving shaft bearing seat (3), a magnetic coupling (4), a steel wire shaft (5), a driven shaft I (6), a transverse transmission bearing (7), a base (9), a transverse displacement speed regulating mechanism (11), a driven shaft II (12), a driven shaft bearing seat (13), a generator (14), a chassis (15) and a tower (16); The chassis (15) is fixed to the top of the tower (16); a driving shaft (2) is mounted on the chassis (15) via a driving shaft bearing seat (3), and one end of the driving shaft (2) is coaxially connected to the fan blade (1); the characteristics are: The other end of the driving shaft (2) is coaxially connected to the driving disk (40) of the magnetic coupler (4), one end of the steel wire shaft (5) is coaxially connected to the driven disk (41) of the magnetic coupler (4), and the other end of the steel wire shaft (5) is coaxially connected to one end of the driven shaft I (6); the driven shaft I (6) is equipped with a transverse transmission bearing (7), the transverse transmission bearing (7) is installed on a base (9), the base (9) is fixed to a chassis (15), the other end of the driven shaft I (6) is connected to one end of a transverse displacement speed regulating mechanism (11), the other end of the transverse displacement speed regulating mechanism (11) is connected to one end of a driven shaft II (12), and the other end of the driven shaft II (12) is coaxially connected to the rotating shaft of a generator (14); the chassis (15) is equipped with the driven shaft II (12) through a driven shaft bearing seat (13).

2. A variable speed magnetic coupling transmission system for a wind turbine generator capable of participating in primary frequency modulation of a power grid according to claim 1, characterized in that: The magnetic coupler (4) comprises an active disk (40), a driven disk (41), a copper ring conductor (42), and a permanent magnet ring (43); the active disk (40) is provided with a plurality of concentric ring cylinders I (401), and a copper ring conductor (42) is fixed on the central side of each ring cylinder I (401); the driven disk (41) is provided with a plurality of concentric ring cylinders II (411), and a permanent magnet ring (43) is fixed on the outer peripheral side of each ring cylinder II (411), and the permanent magnet ring (43) is composed of permanent magnets (431) with N poles on the outside and S poles on the inside and permanent magnets (431) with S poles on the outside and N poles on the inside, which are evenly arranged; after the ring cylinders I (401) of the active disk (40) and the ring cylinders II (411) of the driven disk (41) are interlaced, the corresponding copper ring conductors (42) and permanent magnet rings (43) are directly opposite.

3. A variable speed magnetic coupling transmission system for a wind turbine generator capable of participating in primary frequency modulation of a power grid according to claim 1 or 2, characterized in that: The lateral displacement speed regulating mechanism (11) adopts a scissor-type speed regulating device.

4. A variable speed magnetic coupling transmission system for a wind turbine generator capable of participating in primary frequency modulation of a power grid according to claim 3, characterized in that: The scissor-type speed regulating device comprises a load-bearing plate I (111), a load-bearing plate II (112), an upper connecting shaft (113) of a scissor-type rod, a lower connecting shaft (114) of a scissor-type rod, a bidirectional electric drive (115), and an outer tube (116) of a telescopic rod; The load-bearing plate I (111) and the load-bearing plate II (112) are arranged opposite to each other, the load-bearing plate I (111) is connected to the other end of the driven shaft I (6), and the load-bearing plate II (112) is connected to one end of the driven shaft II (12); the middle part of the load-bearing plate I (111) is equipped with an articulated rod I (1112) through an articulated seat I (1111), and four scissor rods I (1113) are symmetrically arranged on both sides of the articulated rod I (1112), and one end of the two scissor rods I (1113) on the same side is articulated to the articulated rod I (1112); similarly, the middle part of the load-bearing plate II (112) is equipped with an articulated rod II (1122) through an articulated seat II (1121), and the four scissor rods II (1123) are symmetrically arranged on the articulated seat II (1121). One end of two scissor rods II (1123) on both sides of rod II (1122) and located on the same side is hinged to the hinged rod II (1122); the two ends of the upper connecting shaft (113) of the scissor rod are respectively hinged to the other end of the scissor rod I (1113) and the scissor rod II (1121) located at the upper part; similarly, the two ends of the lower connecting shaft (114) of the scissor rod are respectively hinged to the other end of the scissor rod I (1113) and the scissor rod II (1123) located at the lower part; the telescopic rods at both ends of the bidirectional electric drive (115) are respectively connected to the upper connecting shaft (113) of the scissor rod and the lower connecting shaft (114) of the scissor rod through the outer tube (116) of the telescopic rod; and the end of the upper connecting shaft (113) of the scissor rod is installed with an angle sensor (117).

5. A variable speed magnetic coupling transmission system for a wind turbine generator capable of participating in primary frequency modulation of a power grid according to claim 1, characterized in that: A row of rolling wheels (10) is installed on the base (9), and the transverse transmission bearing (7) is located on the rolling wheels (10).

6. A variable speed magnetic coupling transmission system for a wind turbine generator capable of participating in primary frequency modulation of a power grid according to claim 5, characterized in that: The base (9) is provided with limit baffles (8) on the front and rear sides respectively.

7. A method for a wind turbine variable speed magnetic coupling transmission system to participate in primary frequency modulation of a power grid, characterized in that: The steps include: Step S1, setting range and sampling: setting the real-time frequency f of the grid connection point t With rated frequency f n The frequency deviation value is limited to ±0.05Hz; obtain the initial value of the generator output power P0 and the real-time frequency f of the grid connection point t , detect the frequency fluctuation of the grid points; Step S2, determine whether the frequency deviation value of the grid connection point exceeds the specified range, if so, execute step S3, otherwise execute step S1; Step S3: The generator enters the primary frequency regulation state, and the generator output power regulation target P is calculated according to the following formula: P=P0-KP n (f t -f n ) (9) In formula (9), P is the power regulation target of the generator primary frequency regulation, P0 is the initial value of the generator active power, K is the generator primary frequency regulation droop coefficient, P n is the rated power of the generator, f t is the frequency value of the current power grid, f n is the rated frequency of the current power grid; Step S4: Determine the real-time frequency f of the interconnection point t With rated frequency f n Is the deviation value of positive? If the frequency deviation is positive, then f t -f n >0.05Hz, execute step S5; otherwise, the frequency deviation value is negative, and f t -f n <-0.05Hz, go to step S6; Step S5, the lateral displacement speed regulating mechanism executes the action of extending the outer tube of the telescopic rod through the bidirectional electric drive, thereby reducing the coupling length of the magnetic coupler and reducing the active output of the generator; Step S6, the lateral displacement speed regulating mechanism shortens the outer tube of the telescopic rod through the bidirectional electric drive, thereby increasing the coupling length of the magnetic coupler and improving the active output of the generator; Step S7, determine whether the frequency of the grid connection point is restored to the limited range; if so, execute step S8, otherwise execute step S9; Step S8, the wind turbine generator exits the primary frequency modulation state, and the bidirectional electric drive performs a reset action to restore the magnetic coupler to the initial coupling length, thereby preventing the primary frequency modulation from affecting the stability of the power grid; Step S9, determining whether the magnetic coupling has reached the maximum action limit; if so, executing step S10, otherwise executing step S4; Step S10: The magnetic coupler keeps running at the maximum action position.

8. The method for a wind turbine variable speed magnetic coupling transmission system to participate in primary frequency modulation of a power grid according to claim 7, characterized in that: In step S3, the generator primary frequency modulation droop coefficient K=0.

5.

9. A method for a wind turbine variable speed magnetic coupling transmission system to participate in primary frequency modulation of a power grid according to claim 7, characterized in that: Step S5 is specifically as follows: The lateral displacement speed regulating mechanism performs the action of extending the outer tube of the telescopic rod through the bidirectional electric drive, and the coupling length change ΔL in the magnetic coupler is calculated according to formula (8): ΔL=AE′=m(sinβ2-sinβ0) (11) According to formula (6), the change of electromagnetic torque T is calculated as: It can be seen from the above formula that the coupling length of the magnetic coupler is reduced and the electromagnetic torque is reduced. According to the formula P=T×ω, the generator output power is controlled to reach the regulation target and the active power is reduced, where ω is the generator speed.

10. The method for a wind turbine variable speed magnetic coupling transmission system to participate in primary frequency modulation of a power grid according to claim 7, characterized in that: Step S6 is specifically as follows: The lateral displacement speed regulating mechanism shortens the outer tube of the telescopic rod through a bidirectional electric drive, and the coupling length change ΔL in the magnetic coupler is calculated according to formula (7): ΔL=AE=m(sinβ0-sinβ1) (10) According to formula (6), the change of electromagnetic torque ΔT is calculated as: It can be seen from the above formula that as the coupling length of the magnetic coupler increases, the electromagnetic torque increases. According to the formula P=T×ω, the generator output power is controlled to reach the regulation target and the active power is increased, where ω is the generator speed.

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