A fixed-pitch tidal current energy generating set and its control method

Abstract

The present invention discloses a variable-pitch tidal current power generation unit, which includes a generator, a gearbox, a main blade and a main shaft seal. Behind the generator, there are a clutch, a torque sensor and a damping device in sequence. The damping device is connected to and disconnected from the main shaft through the clutch, and includes a damping housing, a reluctance rotor arranged in the damping housing, and support frames symmetrically arranged on the upper and lower sides of the reluctance rotor. On the two support frames, there are a total of four iron cores in two groups on the left and right and windings wound on the surfaces of the iron cores. The winding directions of the four windings are the same. The present invention ensures that the variable-pitch tidal current power generation unit can be safely and stably connected to the grid, generate electricity and stop under various flow velocities. At the same time, when the unit needs to be forced to stop or the control is unstable during low-speed operation, the motor speed can be appropriately increased to achieve grid connection control and stable output of electric energy. When the unit is under maintenance, the blade can be finely adjusted and fixed.

Description

Technical Field

[0001] The present invention relates to the field of ocean energy power generation, and particularly relates to a fixed pitch current energy generating set and a control method thereof. Background Art

[0002] Tidal current energy is a renewable energy that utilizes the energy generated by the flow of ocean tides. It generates electricity by using the water flow energy formed by the ebb and flow of the tides. The development and utilization of tidal current energy do not emit any pollutants and is an environmentally friendly green energy. The flow velocity and direction of the tide change periodically with time during the tidal period.

[0003] The operation of a tidal current energy generating set is the same as the principle of wind power generation. By monitoring the flow velocity and direction of the oncoming flow near the installation point of the generating set, the start-stop operation control of the generating set is carried out. Currently, the capacity of the generating set is generally below the MW level. Considering the cost and reliability of the generating set, most tidal current energy adopts a fixed pitch blade form without a variable pitch structure.

[0004] The fixed pitch blade can only start when the water flow velocity is relatively small. At this time, the rotational speed of the blade can be controlled below the rated flow velocity and operate stably. Only then can the frequency converter be normally connected to the grid. However, this flow velocity window period is often relatively short and is easily missed. When the oncoming flow is too large and the generating set is started, it will cause the rotational speed of the blade to be too fast, which will result in a relatively large terminal voltage of the generating set. Therefore, it cannot be connected to the grid through the frequency converter, and the generating set can only be forced to stop, and then wait for the next tidal period, which greatly shortens the power generation time and reduces the economic benefits.

[0005] When the oncoming flow is too large during the operation of the generating set, the generating set must also perform peak shaving and grid connection, otherwise it will cause the generating set to be overloaded and may damage the frequency converter. However, peak shaving and grid connection require increasing the capacity of the generating set and increasing the cost. For example, using the commonly used speed reduction and stall peak shaving will bring vibration problems to the generating set; during the shutdown process of the generating set, during the connection process between the electrical brake and the mechanical brake of the frequency converter, the rotational speed of the generating set will have a certain fluctuation, which will cause a certain impact on the gearbox. When the generating set is repaired, the process of fine-tuning the blade direction and fixing at the same time is relatively complicated. Summary of the Invention

[0006] In order to solve the above problems in the prior art, one of the objectives of the present invention is to propose a fixed pitch current energy generating set.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows: A tidal current fixed pitch generator set, including a generator and blades connected to the output end of the main shaft of the generator through a gearbox. The main shaft transmits torque by means of the blades, and the main shaft is connected to the generator through the gearbox for power generation. It also includes a main shaft seal arranged on the main shaft between the blades and the gearbox. The sealing between the blades and the gearbox is realized by the main shaft seal. A clutch and a damping device are sequentially arranged on the main shaft behind the generator. The damping device arranged behind the generator is connected to and disconnected from the main shaft through the clutch. The damping device includes a damping housing, a reluctance rotor arranged in the damping housing, and support frames symmetrically arranged on the upper and lower sides of the reluctance rotor. A total of four iron cores in two groups, left and right, are respectively arranged on the two support frames, and windings are wound on the surfaces of the iron cores. The winding directions of the four windings are the same.

[0008] Furthermore, it also includes a unit housing. The clutch and the generator are located inside the unit housing, and the damping device is located outside the unit housing.

[0009] The second object of the present invention is to propose a control method for a tidal current fixed pitch generator set. The steps are as follows:

[0010] When the generator set operates in high-speed start-up, high water flow rate, or overload during operation, or in the stop braking condition, direct current is passed through the windings; the currents flowing into the left and right windings in the lower layer are opposite, the current direction of the left-side winding in the upper layer is the same as that of the left-side winding in the lower layer, and the current direction of the right-side winding in the upper layer is the same as that of the right-side winding in the lower layer.

[0011] When the generator set operates in low water flow, unstable control, or the stop condition, when the damping device operates at a low speed, three-phase alternating current is passed through the windings, the potentials of the upper and lower layers of windings are opposite, and the potentials of the left and right sides of the windings are the same.

[0012] When the generator set needs to be repaired, alternating current is first passed through the windings to finely adjust the blade direction, and then direct current is passed through to fix the blades.

[0013] The beneficial effects of the present invention are as follows:

[0014] In the present invention, a damping device is added at the end of the main shaft. When the damping device operates in high-speed start-up, high water flow rate, and stop conditions, direct current is passed through the windings. The currents flowing into the left and right windings in the lower layer are opposite, the current direction of the left-side winding in the upper layer is the same as that of the left-side winding in the lower layer, and the current direction of the right-side winding in the upper layer is the same as that of the right-side winding in the lower layer. When the water flow is low and forced stop is required, or when grid connection control and power output are unstable, that is, when the damping device operates at a lower speed, alternating current is passed through the windings, the potentials of the upper and lower layers of windings are opposite, and the potentials of the left and right sides of the windings are the same. When the unit needs to be repaired, alternating current is first passed through the windings to finely adjust the blade direction, and then direct current is passed through to fix the blades.

[0015] The present invention solves or improves the problems that a fixed-pitch unit cannot start under a large flow rate of oncoming flow, is overloaded during operation, and has a large impact during shutdown braking. It can ensure that the generator set operates smoothly during grid connection, power generation, and shutdown processes. Moreover, when the water flow is low and forced shutdown is required or grid connection control and power output are unstable, the unit can still operate stably. It can also play a role in adjusting and fixing the blade during the maintenance process of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the overall structure diagram of the present invention;

[0017] Figure 2 is the structural schematic diagram of the damping device of the present invention.

[0018] Each reference numeral is: 1 - damping device, 2 - clutch, 3 - generator, 4 - gearbox, 5 - main shaft, 6 - main shaft seal, 7 - blade, 8 - damping housing, 9 - unit housing, 11 - support frame, 12 - winding, 13 - iron core, 14 - reluctance rotor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present invention and are not intended to limit the protection scope of the present invention. For example, although each component in the drawings is drawn at a specific ratio, these ratio relationships are only exemplary, and those skilled in the art can adjust them as needed to adapt to specific application scenarios.

[0020] It should be noted that in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "inner", "outer", etc. indicating directions or position relationships are based on the azimuth or position relationships shown in the drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific azimuth, be constructed or operated in a specific azimuth, and thus should not be construed as a limitation of the invention.

[0021] In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" 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 directly connected or indirectly connected through an intermediate medium, and it can be the connection inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0022] When the unit starts at high flow velocity, overloads during operation, or has impact during shutdown braking, by passing a direct current through the winding, fixed opposite magnetic fields will be generated on the left and right sides of the reluctance rotor. According to the right-hand rule and the left-hand rule, it can be found that a large reaction force will be generated at this time to inhibit the rotation of the main shaft. The magnitude of the damping can be adjusted by the current. When the rotational speed of the generator set is low and shutdown is required or the control is unstable, an alternating three-phase current can be passed through the winding. The phases of the upper and lower layers of the winding are opposite, so a rotating magnetic field will flow into the reluctance rotor. The reluctance rotor will generate a force to drive the rotation of the main shaft under the rotating magnetic field, which will increase the rotational speed of the generator set under appropriate circumstances, thereby reducing the shutdown time during the grid connection process, avoiding frequent start-stop of the unit and accelerating the aging of the frequency converter, and at the same time being used for stable state control and power output during grid connection. During the maintenance of the unit, the blade direction can also be fixed through the damping device.

[0023] According to an example of the present invention, as Figure 1 shown, a variable-pitch tidal current energy generator set with a damping device disclosed by the present invention includes a generator 3 and a blade 7 connected to the output end of the main shaft 5 of the generator 3 through a gearbox 4. The main shaft 5 transmits torque by means of the blade 7. The main shaft 5 is connected to the generator 3 through the gearbox 4 for power generation. It also includes a main shaft seal 6 arranged on the main shaft 5 between the blade 7 and the gearbox 4. The seal between the blade 7 and the gearbox 4 is realized by the main shaft seal 6. A clutch 2 and a damping device 1 are sequentially arranged behind the generator 3 on the main shaft 5. The stable operation of the generator set is realized by using the damping device 1 placed at the end of the main shaft 5.

[0024] Referring to Figure 2 shown, the damping device 1 includes a damping housing 8, a reluctance rotor 14 arranged in the damping housing 8, and support frames 11 symmetrically arranged on the upper and lower sides of the reluctance rotor 14. A total of four iron cores 13 in two groups, left and right, are respectively arranged on the two support frames 11, and windings 12 are wound on the surfaces of the iron cores 13. The winding directions of the four windings 12 are the same. The support frames 11 support 2 iron cores 13 and 4 sets of windings 12, and the strength of the magnetic field in the iron cores 13 is adjusted by adjusting the magnitude of the current.

[0025] The present invention realizes the stable operation of the unit when it cannot start at high flow velocity of the oncoming flow, overloads during operation, or has impact during shutdown braking through the auxiliary operation device. At the same time, it can increase the rotational speed of the generator set under appropriate circumstances, thereby reducing the shutdown time during the grid connection process, avoiding frequent start-stop of the unit and accelerating the aging of the frequency converter, and at the same time being used for stable state control and power output during grid connection.

[0026] The present invention further includes a unit housing 9. The clutch 2 and the generator 3 are located inside the unit housing 9, and the damping device 1 is located outside the unit housing 9.

[0027] The damping device of the present invention includes four groups of stator armatures. When the generator 3 starts at a high flow rate, operates overloaded, or has an impact during shutdown braking, the surface of the upper left iron core 13 that generates a magnetic field facing the damping disc is the N pole, the surface of the upper right iron core 13 that generates a magnetic field facing the damping disc is the S pole, the surface of the lower left iron core 13 that generates a magnetic field facing the damping disc is the N pole, and the surface of the lower right iron core 13 that generates a magnetic field facing the damping disc is the S pole. The current of the stator armature winding is adjusted according to the required resistance, thereby forming a damping force opposite to the shaft rotation direction. When the above working conditions are completed, cutting off the power supply will not affect the normal operation of the generator 3.

[0028] When the generator 3 needs to be forced to stop at a low speed or for stable state control and power output when increasing the speed of the generator 3 for grid connection, alternating three-phase electricity can be passed through the winding 12. The windings 12 of the upper and lower layers have opposite phases. The surface of the upper left iron core 13 that generates a magnetic field facing the damping disc is the N pole, the surface of the upper right iron core 13 that generates a magnetic field facing the damping disc is the N pole, the surface of the lower left iron core 13 that generates a magnetic field facing the damping disc is the S pole, and the surface of the lower right iron core 13 that generates a magnetic field facing the damping disc is the S pole. Therefore, a rotating magnetic field will flow into the reluctance rotor 14. The reluctance rotor 14 will generate a force to drive the main shaft 5 to rotate under the rotating magnetic field, which will increase the speed of the generator 3 under appropriate circumstances, thereby increasing the speed of the generator set, reducing the shutdown time during grid connection, avoiding frequent start and stop of the unit and accelerating the aging of the frequency converter, and at the same time being used for stable state control and power output during grid connection.

[0029] When the generator set needs to be stopped for maintenance, alternating current is passed through the winding 12, and the direction of the alternating current is the same as the direction of the power supply added when the unit is at a low speed, so that the main shaft 5 is finely adjusted to expose the maintenance point at a convenient position for operation. Subsequently, direct current is passed through the winding 12, and the input direction of the direct current is the same as the power supply during shutdown braking of the unit, so as to achieve the purpose of fixing the unit. When the unit needs to be maintained, the blade 7 needs to be finely adjusted and then fixed. First, alternating current is passed through the winding 12 to finely adjust the direction of the blade 7, and then direct current is passed through to fix the blade 7.

[0030] The above embodiments only illustrate the principle and its effects of the present invention, as well as some applied embodiments. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A control method for a tidal current energy fixed pitch generator set. The tidal current energy fixed pitch generator set includes a generator (3) and a blade (7) connected to the output end of the main shaft (5) of the generator (3) through a gearbox (4), and also includes a main shaft seal (6) arranged between the blade (7) and the gearbox (4), characterized in that: Behind the generator (3) described above, a clutch (2) and a damping device (1) are successively arranged on the main shaft (5). The damping device (1) includes a damping housing (8), a reluctance rotor (14) arranged in the damping housing (8), and support frames (11) symmetrically arranged on the upper and lower sides of the reluctance rotor (14). On the support frames (11), two sets of iron cores (13) are respectively arranged on the left and right, and windings (12) are wound on the surfaces of the iron cores (13). The winding directions of the four windings (12) are the same; When the generator set operates under high-speed starting, large flow rate, overload during operation, or stop braking conditions, direct current is passed through the windings (12); when the generator set operates under low water flow, unstable control, or stop conditions, and the damping device (1) operates at a low speed, three-phase alternating current is passed through the windings (12); when the generator set needs to be repaired, alternating current is first passed through the windings (12) to finely adjust the direction of the blade (7), and then direct current is passed through to fix the blade (7).

2. The control method of a variable-pitch generating set for tidal current energy according to claim 1, characterized in that It further includes a unit housing (9). The clutch (2) and the generator (3) are located inside the unit housing (9), and the damping device (1) is located outside the unit housing (9).

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