Design Analysis of Horizontal Axis Wind Blade Deformation Device

Foreword: According to the reasonable opinions of senior experts at the 13th World Wind Energy Conference on April 7-9, the device prototype design has been further improved. This article is a revised version of the corresponding statement made at the conference.

Expected economic benefits: The total investment in wind power generation will increase by 3%, and the blades can be deformed in the wind farm. The wind power can be increased by 20%, and the investment will be increased by one year. The profit after tax of the deformed device is double the cost.

1 Project Background

In order to increase the wind energy utilization coefficient, various new types of blades have emerged in recent years, such as folding blades (different patent applications from Guodian United Power Co., Ltd. and Tsinghua University), and vertical stretching, in which the areas with large areas at low and medium wind speeds become larger and the area at high wind speeds becomes smaller. Blades (blade root expansion and contraction, authorized by Huarui Wind Power Co., Ltd.) and transverse telescopic blades (central lateral expansion of blades, patent application from Xi'an Jiaotong University).

2 Technical advancement of the project

The patented horizontal axis wind turbine deformation blade (referred to as a deformation blade) is a large and medium-sized blade, which has a main blade and a secondary blade. The main blade and the secondary blade can relatively move their positions, thereby changing the surface area of ​​the blade. : The secondary blades are connected with the ropes. The ropes are limited by the fixed pulleys. The secondary blades move relative to the main blades in the longitudinal direction under the action of the ropes. The secondary vanes may be thin plate collars surrounding the body section of the main blade, with deicing snow blades on both sides of the front edge of the collar.

Compared with the corresponding folding or telescopic blade described above, the present deformed blade has six main advantages:

1 At low and medium wind speeds, the increase in leaf area at the tip of the tip of the leaf is large. Although the blade rotation resistance slightly increases, the average value of the wind energy utilization coefficient can still be greatly increased.

2 Increased relative costs and risks are very small. Refitted only minimally invasive with minimal impact in unimportant areas (whereas the folding or retractable blades described above affect the greater risk of open cavalling), and Outside the blade can not be completely changed, the conversion process is simple and easy;

3 Large and medium-sized wind farms in the field are the only ones that may rapidly deform the old blades on site;

4 The safety factor of the deformed blade and the original blade is almost the same, which maintains the main advantages of the existing horizontal shaft wind turbine blade;

5 In the winter, most of the snow and ice accumulated on the front of the blade can be effectively removed, which reduces the wind resistance.

6 years of wind power increase, it may increase a total of about 20%. This is an ideal new energy major innovation, has passed the national investigation, has been China's utility model patent rights (patent pending) and is applying for multinational patents.

3 first prototype design

The CAD model, process and installation design of the deforming device prototype (80m diameter 1500 kW rated wind speed of 13m/s horizontal axis wind turbine blade) have been basically completed. The prototype is planned to be completed within three months to complete the prototype test and wind power generation. The scene was refitted and the power generation test was started. The deformation device is divided into five parts: 1 pair of blades; 2 pairs of blade lifting drive systems; 3 pairs of blade positioning and limit systems; 4 removal of ice and snow systems; 5 electrical control systems.

3.1 Secondary blades

This is a thin plate ring sleeve that can surround a section of the main blade, with a length of nearly 8 meters and a maximum width of 3.15 meters after deformation. It can increase the windward area of ​​10.8 square meters at the tip of the main leaf, and its main body has a size of 0.6 mm x 1 meter. Made of stainless steel plate, it can be divided into 8 sections with the main blade bending, and only the adjacent section of the front and rear vanes along the front and rear, respectively, are fixed by riveting joints.

3.2 Secondary blade lifting drive system

Mainly by the winch (special winch), steel rope and related sets of fixed pulley device. The winch frame is fixed by several bolts passing through the wall of the root of the main blade. The steel rope is made by connecting 11 mm diameter steel wire rope and 6 mm steel wire rope. In order to reduce the impact on the aerodynamic efficiency of the main blade, pull the steel wire rope pulley to be located at about 11 meters of the main blade tip, and The steel ropes are all mounted together beside the leading edge of the main blade; in order to reduce the moment experienced by the winch frame, the pull-back steel rope projects between the windlass and the winch frame along the surface of the winch frame. According to calculations, for any section of the main blade, the maximum bending moment when the main blade is equipped with the secondary blade wind speed of 8m/s is 80% of the bending moment when no secondary blade is installed at 13m/s, so the secondary blades of the prototype are The lifting time is set at a wind speed of about 6 m/s or less, and about 8 m/s.

In order to install pull-back steel ropes and fixed pulleys, a longitudinal groove is formed beside the leading edge of the main blade. This is the place where the installation of the deformation device is the most traumatic to the main blade. According to calculations, the safety factor of the section of the blade in the slot is reduced by about 0.5%, so the effect of the slot on the strength of the main blade is negligible.

3.3 Secondary blade limit and positioning system

The system is to solve the problems of unfolding, retracting and shaking of the secondary blades relative to the primary blades during different positions of the primary blade and during lifting and lowering.

The system has:

1 A pair of vane slide rails and their limiting plate device (see Appendix 3.1, 3.2 for the assembly sketch) The auxiliary vane slide rails are fixed beside the front edge of the auxiliary vane; there are spaced rails along the leading edge of the main vane: every few hundred millimeters A slide rail limit plate is fixed, and the limit plate is made of about 1 mm stainless steel thin steel plate. The steel rope can pull the slide rail and the auxiliary vane to move up and down along the limit plate, and when the auxiliary vane is lifted into place, the two directions are two-way. The tensioned steel rope makes the front edge of the secondary vane unable to wobble in the radial direction of the wind wheel, and the limit strip of the slide rail prevents the front edge of the secondary vane from shaking in the axial direction of the wind turbine;

2 front and rear positioning plate (see Annex 1) In order to make the secondary blades easy to nest and wind resistance is small, made of about 0.7 mm stainless steel sheet, the bottom fixed hoop mounted on the surface of the main blade, so that the front and back of the secondary blade is limited and not along The wind turbine oscillates axially and plays a leading role in forming a preset wing profile. The preset wing section is similar in shape to the section of the corresponding main blade and has the same aerodynamic efficiency.

3 The left and right positioning rods and their track devices (see Annexes 1 and 4) are mounted on the trailing edge of the main blade, between the outer trailing edge of the main blade and the inner trailing edge of the auxiliary blade; the positioning bar has at least two juxtaposed ends, and its one end is positioned by a positioning rod. The slider is slidingly hinged with the track, and the other end is hinged with the back plate along the reinforcing plate;

4 Radial positioning lock card (see Annex 1) There are two near-radial positioning lock cards on the trailing edge of the main blade. When the auxiliary blade and the positioning rod are raised and lowered in position, the two near-distant lock cards respectively pass the positioning rod, and the secondary blades The rear edge is locked and cannot roll in the radial direction of the wind wheel. The far positioning lock card and the positioning rod together have auxiliary functions for the auxiliary blades and the unfolding support and the left and right positioning to form a preset wing-shaped section. The switch of the near-far lock card is controlled by a spring and a thin steel cord which is connected to and powered by a lock card motor mounted on the hinge frame through a pulley. In this way the switching power of the lock card can be sufficiently large.

5 There are two different structures in the steel rope limit sliding sleeve (see Annex 3.2), which is installed on the side of the main blade where the steel rope passes, to prevent the steel rope from shaking too much.

3.4 Deicing and Snow System

Deformation blades that may come into contact with ice and snow should be installed on the system to ensure smooth operation of the secondary blades and reduce the impact of ice and snow on power generation. The system has: 1 before and after the removal of ice and snow knife is located in the leading edge of the secondary blade slide rail and the two ends of the left and right positioning card slider, will remove most of the ice and snow along the front and rear edges of the main blade along with the lifting of the secondary blades; 2 steel rope is slow The moving device (see Appendix 2.1 for the assembly sketch) is a device that allows the wire rope to be drawn slowly and slowly with a slow moving motor in the root of the main blade when the temperature is below zero. The water in the gap between the track gap and the steel rope and its limit sleeve is not hard ice.

3.5 Electrical Control System

Obviously, the winch motor, lock card motor, and wire rope slow motor are all electric appliances that need automatic control. The switch of the wire rope slow motor circuit is controlled by a temperature-controlled switch, and other motor circuit switches pass a special centrifugal force associated with the fan speed. Switch and time relay control. The centrifugal electric switch (see Appendix 5 for its assembly sketch) is installed on the inner wall of the main blade, about 7 meters away from the center of the hub, to ensure that the secondary blades move up and down in time. In order to avoid frequent lifting, the secondary vanes were designed to rise after a delay of several hours after the wind speed dropped below about 6 m/s, and dropped when the wind speed rose to nearly 8 m/s. In addition, a remote control circuit is also provided for manual remote control under the wind tower.

3.6 Others

1 The lightning protection device connects the winch with the original lead wire at the root of the main blade. The lightning on the secondary blade can reach the original lightning wire along the steel wire and the joint. Since the lightning resistance calculated by the steel wire and the joint is less than 0.4 ohm and less than the experience value of the lightning protection circuit resistance of 2 ohms, even if all the thunder and lightning are passed from the steel wire, it is still safe, so no special lightning protection device is needed. . 2 The battery considers whether or not to share the prime mover battery with the main blade pitch, depending on the situation. 3 A total of 200 M6 screws are installed on the leading edge and trailing edge of the main blade; a total of 16 M16 bolts and 6 holes with 16 mm holes are installed in the root of the main blade with reinforced steel sleeves. Due to the design on the eve of installing the screws and rails on the edge of the main blade, the adhesive is injected into the screw hole and the bottom of the rail. Therefore, these minimally invasive effects on the strength of the main blade are negligible. 4 The total weight of a blade deformation device is about 510 kg, which is less than 9% of the weight of a main blade, which reduces the bending safety factor of the wind turbine generator main shaft and tower by less than 9%, but the safety factor of the shaft and the tower are both If it is far greater than the blade safety factor 2, it should not cause problems.

4 Project Benefits

4.1 Blade Deformation Device Manufacturer Benefits

Taking a set of 1.5 MW three-blade deformation device as an example, the manufacturing and on-site unloading costs total about 200,000 yuan, which can result in a significant increase in the efficiency of wind power companies and a selling price of 300,000 yuan, with a profit after tax of approximately 90,000 yuan per set. The profit after taxation per megawatt capacity is about 60,000 yuan.

4.2 New Benefits of Power Generation Enterprises

Incremental power generation estimation This prototype increases approximately 11 square meters in the windward area of ​​the section approximately 8 meters long near the main blade tip, which is equivalent to more than double the area of ​​the main blade of the section, and the contribution of the main blade of this section to the wind power is approximately 50%, in order to estimate the average wind speed of 6 meters / second when the power increase rate of about 0.28. The author of this article the author of the Guangxi Zixian County Jin Zishan wind power project (China's first high mountain wind power project) as an example, the first phase of the project Thirty-three 1.5-megawatt wind turbines have been installed. The actual power generation over the year is more than 95 million kilowatt-hours, or 2.88 million kilowatt-hours of electricity per 1.5 megawatts of capacity. The annual wind speed of 6 m/s and 1.5 MW average power generation capacity of 235 kW will be set if the wind speed is below 8 m/s for the whole year, and the average power will be 235 kW if the wind speed is less than 8 m/s. After loading the secondary blades, the power will increase by 235 kW x 0.28 = 66 In kilowatts, the annual power generation increase is 66 kilowatts x 8000 hours = 530,000 kilowatt-hours, and the increment is 530,000 degrees / 2.88 million degrees = 18.4 percent. Considering the increase of wind power for ice and snow, and the addition of additional components such as wire ropes and front and rear positioning plates, After the wind power, the total wind power increased by about 20%.

If 1.5 megawatts of wind power capacity, acquisition and renovation of unloading costs 300,000 yuan (equivalent to 1.5 megawatts of wind power, the general total investment of 10 million yuan in 3%), generating capacity increased by 20%, on-line wind power costs 0.55 yuan / degree (national pricing 0.5 Calculated to 0.6 yuan, you can get: 1 Newly added power generation efficiency of 317,000 yuan per 1.5 megawatt capacity. 2 Refitting Fees The payback period is about one year. 3 If 0.25 billion kilowatts (3.3% of the world's wind turbines) are converted into deformed vane machines each year after 2020, the annual new wind power benefit will be 5.28 billion yuan/year.

5 project implementation

Has signed a cooperation agreement with Guangxi Guiguan Power Investment Co., Ltd., a subsidiary of Datang Power, and also welcomes a number of wind power and venture capital companies or individuals with strong relevant energy to support cooperative R&D (mainly to provide one free site for wind power The large-scale old wind turbine was transformed into the world's first deformed blade wind power prototype), and the cooperation support method was not limited, and the patent benefit was shared.

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