Tidal current energy fixed-pitch generator set and control method thereof

Abstract

The invention discloses a tidal current energy fixed-pitch generator set which comprises a generator, a gear box, a main blade and a main shaft seal, a clutch, a torque sensor and a damping device are sequentially arranged behind the generator, and the damping device is connected and disconnected with a main shaft through the clutch. Comprising a damping shell, a reluctance rotor arranged in the damping shell and supporting frames symmetrically arranged on the upper side and the lower side of the reluctance rotor, the two supporting frames are each provided with a left iron core, a right iron core and windings wound around the surfaces of the iron cores, and the winding directions of the four windings are consistent; according to the invention, safe and stable grid connection, power generation and shutdown of the tidal current energy fixed-pitch generator set at various flow speeds can be ensured, meanwhile, when the set needs to be forced to be shut down or is unstably controlled during low-speed operation, the rotating speed of the motor can be properly increased so as to realize grid connection control and stable output of electric energy, and the blades can be finely adjusted and fixed when the set is maintained.

Description

Technical Field

[0001] The present invention relates to the field of ocean energy power generation, and in particular to a tidal energy fixed-pitch generator set and a control method thereof. Background Art

[0002] Tidal energy is a renewable energy source that uses the energy generated by the flow of ocean currents. It uses the water flow energy formed by the ebb and flow of the tide to generate electricity. The development and utilization of tidal energy does not emit any pollutants and is an environmentally friendly green energy. The flow rate and direction of the tide change over time during the tidal period.

[0003] Tidal energy generators operate on the same principles as wind power generation. They monitor the velocity and direction of incoming flow near the generator installation point to control the generator's start and stop. Currently, generator capacities are generally below the MW level. For cost and reliability reasons, most tidal energy generators use fixed-pitch blades without variable-pitch structures.

[0004] The fixed-pitch blades can only be started when the water flow rate is relatively low. At this time, the blade speed can be controlled below the rated flow rate and run stably. Only then can the inverter be connected to the grid normally, but this flow rate window period is often relatively short and easy to miss. When the incoming flow is too large and the generator set is started, the blade rotation speed will be too fast, which will cause the terminal voltage of the generator set to be large. Therefore, it is impossible to connect to the grid through the inverter. The unit can only be forced to shut down and wait for the next tide period, which greatly shortens the power generation time and reduces economic benefits.

[0005] When the incoming current is too large during the operation of the unit, the unit must also be peak-shaving and grid-connected, otherwise it will cause the unit to be overloaded and may damage the inverter. However, peak-shaving and grid-connection require increasing the capacity of the unit and increase costs. For example, the use of the commonly used speed reduction stall peak regulation will cause vibration problems in the unit; during the shutdown process of the unit, the speed of the unit will fluctuate during the connection process of the inverter's electrical brake and mechanical brake, which will cause a certain impact on the gearbox. When the unit is repaired, the process of fine-tuning the blade direction and fixing it 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 provide a tidal current energy fixed pitch generator set.

[0007] The technical solution adopted by the present invention to solve its technical problems is: a tidal energy fixed-pitch generator set, including a generator and blades connected to the main shaft output end of the generator through a gearbox, the main shaft uses the blades to transmit torque, the main shaft is connected to the generator through a gearbox to generate electricity, and also includes a main shaft seal arranged on the main shaft between the blades and the gearbox, and the sealing of the blades and the gearbox is realized by the main shaft seal. A clutch and a damping device located on the main shaft are sequentially arranged behind the generator, and the damping device arranged behind the generator is connected and disconnected with the main shaft through a 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. The two support frames are respectively provided with two groups of four iron cores in total and windings wound on the surface of the iron cores, and the winding directions of the four windings are consistent.

[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 provide a control method for a tidal current constant pitch generator set, the steps of which are: When the generator set is running at high speed starting, high flow rate, overload or shutdown brake conditions, DC is passed into the winding; the currents flowing into the left and right windings of the lower layer are opposite, the current direction of the upper left winding is consistent with the current direction of the lower left winding, and the current direction of the upper right winding is consistent with the current direction of the lower right winding. When the generator set is running at low water flow, unstable control or shutdown conditions, and the damping device is running at low speed, three-phase AC is applied to the winding, the upper and lower windings have opposite potentials, while the left and right windings have the same potential; When the generator set needs maintenance, AC power is first passed through the winding to fine-tune the direction of the blades, and then DC power is passed through to fix the blades.

[0010] The beneficial effects of the present invention are: The present invention adds a damping device to the end of the main shaft. When the damping device operates at high-speed start-up, high flow rate, and shutdown, direct current is passed through the winding. The currents flowing into the left and right windings of the lower layer are opposite. The current direction of the left winding of the upper layer is consistent with the current direction of the left winding of the lower layer, and the current direction of the right winding of the upper layer is consistent with the current direction of the right winding of the lower layer. When the water flow is low and forced shutdown is required or grid-connected control and power output are unstable, that is, when the damping device operates at a low speed, alternating current is passed through the winding. The potentials of the upper and lower windings are opposite, and the potentials of the windings on the left and right sides are the same. When the unit needs maintenance, alternating current is first passed through the winding to fine-tune the direction of the blades, and then direct current is passed through to fix the blades.

[0011] The present invention solves or improves the problems of fixed-pitch generator sets unable to start due to high flow rates, overload during operation, and large braking impact during shutdown through a damping device. It can ensure that the generator set operates smoothly during grid connection, power generation and shutdown processes, and when the water flow is low and forced to shut down or causes unstable grid control and power output, the unit can still operate stably, and can also play the function of adjusting and fixing the blades during the unit maintenance process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the overall structural diagram of the present invention; Figure 2 Schematic diagram of the structure of the damping device of the present invention.

[0013] The figures are marked as follows: 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

[0014] The following describes embodiments of the present invention in detail with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely intended to illustrate the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. For example, although the various components in the drawings are drawn at specific proportions, these proportions are merely illustrative and those skilled in the art may adjust them as needed to suit specific applications.

[0015] It should be noted that, in the description of the present invention, terms such as "center", "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operate in a specific orientation. Therefore, they cannot be understood as limiting the invention.

[0016] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and connections within two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0017] When the unit starts at a high flow rate, is overloaded during operation, or has an impact on the shutdown brake, by passing DC 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 suppress the rotation of the main shaft. The current can be used to adjust the damping size. When the speed of the generator set is low and needs to be shut down or the control is unstable, alternating three-phase power can be passed through the winding. The phases of the upper and lower layers of windings are opposite, so a rotating magnetic field will flow into the reluctance rotor. The reluctance rotor will generate a force to drive the main shaft to rotate under the rotating magnetic field. This will increase the speed of the generator set under appropriate circumstances, thereby reducing the downtime during the grid connection process, avoiding frequent starting and stopping of the unit and accelerating the aging of the inverter, and is used for stable state control and power output during grid connection. The damping device can also be used to fix the blade direction during the unit maintenance process.

[0018] According to an example of the present invention, Figure 1 As shown, the present invention discloses a tidal energy fixed-pitch generator set with a damping device, including 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 uses the blade 7 to transmit torque. The main shaft 5 is connected to the generator 3 through the gearbox 4 to generate electricity. It also includes a main shaft seal 6 arranged on the main shaft 5 between the blade 7 and the gearbox 4. The sealing between the blade 7 and the gearbox 4 is achieved by the main shaft seal 6. The clutch 2 and the damping device 1 located on the main shaft 5 are sequentially arranged behind the generator 3. The damping device 1 placed at the end of the main shaft 5 is used to achieve stable operation of the generator set.

[0019] Reference Figure 2 As shown, the damping device 1 includes a damping housing 8, a reluctance rotor 14 disposed within the damping housing 8, and support frames 11 symmetrically arranged above and below the reluctance rotor 14. The two support frames 11 are each provided with two left and right groups of four cores 13 and windings 12 wound around the surfaces of the cores 13. The four windings 12 are wound in the same direction. The support frames 11 support the two cores 13 and the four sets of windings 12. The strength of the magnetic field within the cores 13 is adjusted by adjusting the current.

[0020] The present invention uses an auxiliary operation device to achieve stable operation of the unit when it cannot start due to high flow rate, is overloaded during operation, or has impact when the shutdown brake is applied. At the same time, the rotation speed of the generator set can be increased under appropriate circumstances, thereby reducing the downtime during the grid connection process, avoiding frequent starting and stopping of the unit that accelerates the aging of the inverter, and is used for stable state control and power output during grid connection.

[0021] The present invention further comprises a machine housing 9 , wherein the clutch 2 and the generator 3 are located inside the machine housing 9 , and the damping device 1 is located outside the machine housing 9 .

[0022] The damping device of the present invention includes four groups of stator armatures. When the generator 3 is started at a high flow rate, overloaded during operation, or has an impact when stopped and braked, the magnetic field generated in the upper left iron core 13 faces the damping disk with an N pole, and the magnetic field generated in the upper right iron core 13 faces the damping disk with an S pole. The magnetic field generated in the lower left iron core 13 faces the damping disk with an N pole, and the magnetic field generated in the lower right iron core 13 faces the damping disk with an S pole. The current of the stator armature winding is adjusted according to the required resistance size to form a damping force opposite to the direction of shaft rotation. When the above working conditions are completed, cutting off the power supply will not affect the normal operation of the generator 3.

[0023] When the generator 3's speed is too low and needs to be shut down, or to increase the speed for grid-connected stable state control and power output, alternating three-phase power can be fed into the winding 12. The upper and lower windings 12 have opposite phases. The magnetic field generated in the upper left core 13 faces the damping disk with an N pole, while the magnetic field generated in the upper right core 13 faces the damping disk with an N pole. The magnetic field generated in the lower left core 13 faces the damping disk with an S pole, while the magnetic field generated in the lower right core 13 faces the damping disk with an S pole. This causes a rotating magnetic field to flow into the reluctance rotor 14. Under the rotating magnetic field, the reluctance rotor 14 generates a force that drives the main shaft 5 to rotate. This can increase the speed of the generator 3 and the speed of the generator set under appropriate circumstances, thereby reducing downtime during grid connection and preventing frequent starting and stopping of the set that accelerates inverter aging. It also provides stable state control and power output during grid connection.

[0024] When the generator set needs to be stopped for maintenance, AC power flows through winding 12. The direction of the AC power is consistent with the power supply direction when the generator set is running at low speed. This allows for fine adjustment of main shaft 5, exposing the maintenance point to a convenient location. Then, DC power is supplied to winding 12. The DC power input direction is the same as the power supply direction when the generator set is stopped and braked, thereby achieving the purpose of fixing the generator set. When the generator set needs maintenance and blades 7 need to be fine-tuned before being fixed, AC power is first supplied to winding 12 to fine-tune the direction of blades 7, and then DC power is supplied to fix the blades 7.

[0025] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some embodiments of its application. A person skilled in the art may make several modifications and improvements without departing from the inventive concept of the present invention, and all of these modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A tidal current energy fixed pitch generator set, comprising a generator (3) and a blade (7) connected to an output end of a main shaft (5) of the generator (3) via a gear box (4), and further comprising a main shaft seal (6) arranged between the blade (7) and the gear box (4), characterized in that: A clutch (2) and a damping device (1) located on a main shaft (5) are sequentially arranged at the rear of the generator (3); the damping device (1) comprises a damping housing (8), a reluctance rotor (14) arranged in the damping housing (8), and a support frame (11) symmetrically arranged on the upper and lower sides of the reluctance rotor (14); the support frame (11) is respectively provided with two groups of left and right iron cores (13) and windings (12) wound on the surfaces of the iron cores (13); and the winding directions of the four windings (12) are consistent.

2. A tidal current energy fixed pitch generator set according to claim 1, characterized in that: It also includes a machine housing (9), wherein the clutch (2) and the generator (3) are located inside the machine housing (9), and the damping device (1) is located outside the machine housing (9).

3. A control method for a tidal current energy fixed pitch generator set as claimed in claim 1, characterized in that: Here are the steps: When the generator set is running at high speed starting, high flow rate, overload during operation, or shutdown brake conditions, direct current is passed through the winding (12); When the generator set is operating under low water flow, unstable control or needs to be shut down, the damping device (1) operates at a low speed and three-phase alternating current is supplied to the winding (12); When the generator set needs to be repaired, the winding (12) is first supplied with alternating current to fine-tune the direction of the blade (7), and then direct current is supplied to fix the blade (7).

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