Hoisting method for wind driven generator blade assembly

Abstract

The invention relates to the technical field of wind power generation, in particular to a hoisting method for a wind driven generator blade assembly. S1, the fixing device is detached, and the hoisting position is determined. And S2, the protection assembly and the adjusting assembly are installed. And S3, trying to hoist and adjusting the balance state. And S4, the front tool is disassembled, and lubricating treatment is conducted. And S5, the blades are adjusted to be aligned with the hub. And S6, the fastening assembly is installed and pre-tightened. And S7, the connecting pieces are symmetrically fastened step by step. And S8, the remaining blades are repeatedly installed. By marking on the basis of the gravity center point of the blade, combining with fixing of a balance beam lifting appliance and then finely adjusting the lifting point through trial lifting, the problem of lifting belt deviation caused by gravity center estimation through traditional experience is solved, the lifting torque offset is reduced, the stability of the blade hovering posture is improved, and the double cable wind ropes and the root control rope of the blade tip are adopted for cooperative adjustment. The swing amplitude of the blade tip under the high-altitude wind load is reduced, and the time consumed for aligning the blade root bolt is shortened to be within 30 minutes from 1-2 hours.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and specifically to a hoisting method for blade assembly of a wind turbine. Background Art

[0002] With the development of wind turbine generators towards large-scale and high-power directions, the length and weight of blades have increased significantly (for some models, the blade length has exceeded 80 meters and the weight has reached more than 20 tons), which poses higher requirements for blade hoisting technology. The traditional hoisting method generally uses the way of tying two lifting ropes at both ends of the blade and completes the assembly through the coordinated operation of the main crane and the auxiliary crane. However, there are the following technical defects: The traditional method relies on empirical estimation of the blade center of gravity position, resulting in the deviation of the sling fixing point from the actual center of gravity, which is likely to cause the blade attitude to be unbalanced (such as trailing edge distortion or local stress exceeding the limit) during hoisting, causing blade structural damage or even fracture. In addition, the fixing method without using a balance beam sling is difficult to eliminate the torque offset during hoisting, further increasing the risk of blade swing; In the prior art, only a single guy wire is used to tie the blade tip, resulting in the swing amplitude of the blade tip exceeding ±2° under the action of high-altitude wind load, and it is necessary to frequently adjust the position of the crane to stabilize the attitude, extending the hoisting cycle. At the same time, the coordination between the blade root control rope and the guy wire is poor, and it is difficult to achieve three-dimensional fine adjustment, resulting in a time-consuming alignment of the blade root bolts and the hub flange holes of up to 1 - 2 hours; The existing process does not establish a standardized step-by-step operation process. After each blade is hoisted, it is necessary to re-adjust the crane parameters (such as boom angle, counterweight ratio), resulting in a total hoisting time of more than 8 hours for the three-blade assembly, too high a crane occupancy rate, and an increase in comprehensive cost of more than 30%. Summary of the Invention

[0003] The present invention aims to solve the above problems, and thus provides a hoisting method for blade assembly of a wind turbine that ensures stable installation.

[0004] The technical solution adopted by the present invention to solve the above problems is as follows: A hoisting method for blade assembly of a wind turbine, characterized by comprising the following steps: S1: Remove the blade fixing straps, determine the hoisting position based on the blade center of gravity point, mark this position on the blade surface, and fix the blade with the sling of the balance beam sling according to the marked position to match the balance beam sling with the blade center of gravity.

[0005] S2: Install a protective sleeve at the blade tip, tie two guy wires at the blade tip, and tie a control rope at the blade root to adjust the blade spatial attitude, and remove the obstacles in the hub in advance to avoid installation interference.

[0006] S3: Use a crane to conduct a trial hoisting of the blade, observe the blade attitude and the integrity of the trailing edge, and repeat the trial hoisting by slightly adjusting the hoisting point position until the blade hovers stably without damage.

[0007] ‌S4: After the trial lifting is successful, disassemble the front fixture nut and remove the front fixture, apply lubricant to the contact surface and lift again, and adjust the blade spatial position through the crane and control rope.

[0008] S5: Combine manual pitch operation to align the blade root bolt with the hub pitch bearing flange hole. When the zero mark on the pitch bearing coincides with the mark on the blade bolt hole side, fine-tune the blade until all bolt holes are fully aligned with the flange surface and initially embedded.

[0009] ‌S6: Apply lubricant to washers and nuts and install them on bolts. Manually pre-tighten until there is no gap between the blade and the pitch bearing mounting surface. Remove the wind rope and keep the crane under continuous force to stabilize the blade position.

[0010] ‌S7: Use the tool to symmetrically pre-tighten the nuts to the first torque value; perform final tightening using the tensioner in two steps, stretching to the first tensile force value for the first time, and stretching to the second tensile force value for the second time after a certain period of time; only some bolts are allowed to be stretched at the same time in each circle, and the full circle stretching is completed by manual pitch change.

[0011] S8: Complete the hoisting and fixing of the second and third blades in sequence according to S1-S7 to ensure that the installation parameters of each blade are consistent and the flange surface fit meets the standards.

[0012] Compared with the prior art, the present invention adopting the above technical solution has the following outstanding features: By marking the center of gravity of the blade and fixing it with a balance beam hoist, and then fine-tuning the hoisting point through trial hoisting, the problem of sling offset caused by traditional empirical estimation of the center of gravity is solved, the hoisting torque offset is reduced, and the stability of the blade hovering posture is improved. The double-cable wind rope at the blade tip and the root control rope are used for coordinated adjustment to reduce the swing amplitude of the blade tip under high-altitude wind loads, and the time for aligning the blade root bolts is shortened from 1-2 hours to within 30 minutes. By repeating standardized steps, the total time for the three-blade assembly is shortened from 8 hours to 5 hours, the crane occupancy rate is reduced by 35%, and the comprehensive cost is reduced by 28%.

[0013] Preferably, a further technical solution of the present invention is: Furthermore, the length of the wind rope in S2 is between 50 and 55 meters. Compared with the traditional wind rope length of 30 to 40 meters, the 50-55 meter wind rope length can increase the high-altitude attitude adjustment range. Combined with the blade tip protection cover design, the swing amplitude of the blade tip under high-altitude wind load is reduced from ±2° to ±0.5°‌.

[0014] Further, in S6, the lubricant is molybdenum disulfide lubricant; the friction coefficient of molybdenum disulfide lubricant is stable at 0.08 - 0.12, while that of ordinary grease is 0.12 - 0.18. The molybdenum disulfide lubricant can reduce the dispersion degree of the friction coefficient. The molybdenum disulfide lubricant can reduce the dispersion degree of the bolt pre-tightening force from ±15% to ±5%, improving the ability of the flange surface to bear force evenly.

[0015] Further, in S7, the first torque value is 700 ± 70 Nm, the first tensile force value is 300 - 350 kN, the second tensile force value is 400 - 450 kN, and the interval time between the two tensile operations is 25 - 35 minutes; the two tensile operations combined with the 25 - 35 - minute interval time release the residual stress in stages, making the stress distribution on the flange surface more uniform and reducing the risk of local stress concentration by 50%; the symmetric pre-tightening process with the first torque value of 700 ± 70 Nm can optimize the bolt fastening accuracy. Combining with the manual pitch-by-turn stretching, it ensures the synchronism of the stretching of each bolt circle, and the overall pre-tightening force error ≤ ±5%. Description of the Drawings

[0016] Figure 1 It is a schematic diagram of the usage process of the embodiment of the present invention; Figure 2 It is a schematic structural diagram of the embodiment of the present invention; The marks in the figure are: crane 1, blade 2, balance beam sling 3, guy wire 4. Detailed Embodiments

[0017] The present invention will be further described below in conjunction with embodiments. The purpose is only to better understand the content of the present invention. Therefore, the examples given do not limit the protection scope of the present invention.

[0018] A hoisting method for the alignment of a wind turbine blade group, characterized in that it includes the following steps: S1: Dismantle the fixing device and determine the hoisting position: Dismantle the fixing straps of the blade 2, determine the hoisting position based on the center of gravity of the blade 2, mark this position on the surface of the blade 2, and fix the blade 2 with the sling of the balance beam sling 3 according to the marked position, so that the balance beam sling 3 matches the center of gravity of the blade 2.

[0019] S2: Install the protection components and adjustment components: Install a protective sleeve at the tip of the blade 2, tie two guy wires 4 at the tip, tie a control rope at the root of the blade 2 to adjust the spatial attitude of the blade 2, and remove the obstacles in the hub in advance to avoid installation interference, such as induction blocks, limit switches, etc.

[0020] S3: Conduct a trial hoist and adjust the balance state: Use the crane 1 to conduct a trial hoist on the blade 2, observe the attitude of the blade 2 and the integrity of the trailing edge, and repeat the trial hoist by slightly adjusting the hoisting point position until the blade 2 hovers stably without damage.

[0021] S4: Dismantle the front tooling and perform lubrication treatment: After the trial lift is successful, remove the nuts of the front tooling and remove the front tooling. Apply lubricant to the contact surface and then lift again. Coordinate the crane 1 and the control rope to adjust the spatial position of the blade 2.

[0022] S5: Align the blade 2 with the hub: Combine manual pitch operation to align the root bolts of the blade with the flange holes of the pitch bearing of the hub. When the zeroing mark on the pitch bearing coincides with the mark on the bolt hole side of the blade 2, finely adjust the blade 2 until all bolt holes are completely aligned with the flange surface and are initially inserted.

[0023] S6: Install the fastening components and perform pre-tightening: Apply lubricant to the washer and nut and install them on the bolt. The lubricant can enhance the sealing reliability, reduce the wear of the engaging surface between the bolt and the nut, reduce the deformation of the flange surface by 60% (0.2 - 0.3 mm), and reduce the sealing failure rate from 15% to less than 2%. Manually pre-tighten until there is no gap between the blade 2 and the installation surface of the pitch bearing, remove the guy wire 4 and keep the crane 1 continuously stressed to stabilize the position of the blade 2.

[0024] S7: Symmetrically tighten the connecting parts step by step: Use tools to symmetrically pre-tighten the nuts to the first torque value; perform final tightening twice through the stretcher, stretch to the first stretching force value for the first time, and stretch to the second stretching force value after a certain interval for the second time; only allow some bolts to be stretched simultaneously in each circle, and complete the whole circle of stretching through manual pitching.

[0025] S8: Repeat the installation of the remaining blades 2: Complete the hoisting and fixing of the second and third blades 2 in sequence according to S1 - S7, ensuring that the installation parameters of each blade 2 are consistent and the fitting degree of the flange surface meets the standard.

[0026] Furthermore, the length of the guy wire 4 in S2 is between 50 - 55 meters. The length of the guy wire 4 of 50 - 55 meters is superior to the traditional guy wire 4 with a length of 30 - 40 meters, which can increase the adjustment range of the high-altitude attitude. Combined with the design of the blade tip protective cover, the swing amplitude of the blade tip under high-altitude wind load is reduced from ±2° to ±0.5°.

[0027] Furthermore, the lubricant in S6 is molybdenum disulfide lubricant; the friction coefficient of molybdenum disulfide lubricant is stable at 0.08 - 0.12, while that of ordinary grease is 0.12 - 0.18. Molybdenum disulfide lubricant can reduce the dispersion of the friction coefficient. Molybdenum disulfide lubricant can reduce the dispersion of the bolt pre-tightening force from ±15% to ±5%, improving the uniform stress-bearing capacity of the flange surface.

[0028] Furthermore, in S7, the first torque value is 700 ± 70 Nm, the first tensile force value is 300 - 350 kN, the second tensile force value is 400 - 450 kN, and the time interval between the two tensile forces is 25 - 35 minutes. With the two tensile forces combined with a 25 - 35 - minute interval, the residual stress is released in stages to make the stress distribution on the flange surface more uniform, and the risk of local stress concentration is reduced by 50%. The symmetric pre - tightening process with the first torque value of 700 ± 70 Nm can optimize the bolt tightening accuracy. Combined with the manual pitch - by - pitch stretching, it ensures the synchronism of bolt stretching in each circle, and the overall pre - tightening force error ≤ ±5%.

[0029] By marking based on the center - of - gravity point of the blade 2 and fixing it with the balance beam spreader 3, and then fine - tuning the lifting point through trial lifting, the problem of sling offset caused by estimating the center of gravity based on traditional experience is solved. The offset of the lifting torque is reduced by more than 60%, and the stability of the hovering attitude of the blade 2 is improved by 40%. By using the double - cable guy ropes 4 (S2) at the blade tip and the root control rope for coordinated adjustment (length 50 - 55 meters), the swing amplitude of the blade tip under high - altitude wind load is reduced from ±2° to ±0.5°, and the time taken for aligning the root bolts of the blade is shortened from 1 - 2 hours to within 30 minutes. By repeating the standardized steps (S8), the total time taken for the three - blade 2 - group alignment is shortened from 8 hours to 5 hours, the occupancy rate of the crane 1 is reduced by 35%, and the comprehensive cost is reduced by 28%.

[0030] The above - mentioned are only the preferred and feasible embodiments of the present invention, and do not limit the scope of the rights of the present invention. Any equivalent changes made by using the content of the specification and drawings of the present invention are included within the scope of the rights of the present invention.

Claims

1. A method for hoisting a pair of wind turbine blades, characterized in that: The steps include: S1: Remove the blade fixing straps, determine the lifting position based on the blade's center of gravity, mark the position on the blade surface, and use the balance beam sling's straps to fix the blade at the marked position, so that the balance beam sling matches the blade's center of gravity; ‌S2: Install a protective cover at the tip of the blade, tie two wind ropes at the tip of the blade, and tie a control rope at the root of the blade to adjust the spatial posture of the blade, and remove obstacles in the hub in advance to avoid interference during installation; ‌S3: Use a crane to test-lift the blade, observe the blade posture and trailing edge integrity, and adjust the lifting point position slightly, repeat the test lifting until the blade hovers stably and without damage; S4: After the trial lifting is successful, disassemble the front fixture nut and remove the front fixture, apply lubricant to the contact surface and lift again, and adjust the blade spatial position through the crane and control rope; S5: Combine manual pitch operation to align the blade root bolt with the hub pitch bearing flange hole. When the zero mark on the pitch bearing coincides with the mark on the blade bolt hole side, fine-tune the blade until all bolt holes are fully aligned with the flange surface and preliminarily embedded. S6: Apply lubricant to washers and nuts and install them on bolts. Manually pre-tighten until there is no gap between the blade and the pitch bearing mounting surface. Remove the wind rope and keep the crane under continuous force to stabilize the blade position. ‌S7: Use the tool to symmetrically pre-tighten the nuts to the first torque value; perform final tightening through the tensioner twice, the first stretching to the first tensile force value, and the second stretching to the second tensile force value after a certain interval; only part of the bolts are allowed to be stretched at the same time in each circle, and the full circle stretching is completed by manual pitch change‌; S8: Complete the hoisting and fixing of the second and third blades in sequence according to S1-S7 to ensure that the installation parameters of each blade are consistent and the flange surface fit meets the standards.

2. The method for hoisting a pair of wind turbine blades according to claim 1, characterized in that: The length of the guy rope in S2 is between 50-55 meters.

3. The method for hoisting a pair of wind turbine blades according to claim 1, characterized in that: The lubricant in S6 is molybdenum disulfide lubricant.

4. The method for hoisting a pair of wind turbine blades according to claim 1, characterized in that: In S7, the first torque value is 700±70 Nm ‌, the first tensile force value is 300-350 kN, the second tensile force value is 400-450 kN, and the interval between the two stretches is 25-35 minutes ‌.

Images