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WIND POWER PLANTS. Wind turbines
INVENTION
Patent of the Russian Federation RU2075636

Windmill

Windmill

The name of the inventor: Zabegaev AI; Gorbunov Yu.N .; Zabegayev N.I .; Anopov VM; Novak Yu.I.
The name of the patent holder: Limited Liability Partnership The company "Obshchemash-engineering"
Address for correspondence:
Date of commencement of the patent: 1995.01.24

Usage: refers to wind power installations (WED) of autonomous use, to wind turbines with an adjustable blade angle and intended for use in an extended range of wind speed, mainly in low-speed wind flows. SUMMARY OF THE INVENTION: The wind turbine comprises a shaft kinematically connected to the electric generator by pivoting blades with mahas attached to rotary bushings mounted on the shaft, a paddle rotation drive kinematically connected to the pivoting bushings, and a blade rotation control system associated with the drive each blade in the rotation cavity Wind turbine is installed with the channel in the direction of rotation, the angle of inclination being formed by the longitudinal axes of the blade and the bushing, and its value lies in the range of 0.5 ... 2.0 degrees, the blades are made with the twist of the sections relative to the twist axis combined with the longitudinal axis of the blade, Shifted from the chord of the section towards a greater curvature of the profile of the blade, and the leading edge of the blade is located relative to the longitudinal axis of the blade at a distance 0.2 ... 0.25 of the magnitude of the chord of the corresponding sections of the blade. An additional difference of the claimed device is the performance of a blade blade with an end cut at an angle of 0.5 ... 2.0 degrees relative to a plane perpendicular to the longitudinal axis of the sleeve, and that the amount of the twist axis displacement can be chosen to be constant along the blade length for all sections Blade or a variable monotonically varying along the length of the blade, and it can be specified either as a constant in absolute values ​​or constant with respect to the current thickness of the blade profile. The blade of the windmill can be made inclined due to the inclined cutoff of the end of the sleeve, relative to the plane perpendicular to the radial axis of the blade.

DESCRIPTION OF THE INVENTION

(EN) The invention relates to wind power generation to wind turbines (WWF) of autonomous use, specifically to wind turbines with an adjustable blade angle and intended for use in an extended range of wind speed, mainly in low-speed wind flows.

There is a wind turbine known as. USSR N 1325189, cl. F 03 D 7/04, 1986, BI No. 27, 1987), which comprises a control system provided with a motor, kinematically coupled to the rotary blades, a wind speed sensor and a centrifugal regulator, a clutch in the form of a friction disk attached to the motor shaft and interacting with it Clamping collar.

The work of this known device is based on the fact that, for example, when the wind speed is increased, the power generated by the generator increases, which leads to an increase in the rotational speed of the generator shaft and the windmill, the frequency of the current being generated is thereby increased.

With the help of an electric motor fed from a generator with an increased frequency of the generated current, through the lever and thrust by means of a crank mechanism, the blades are rotated towards a decrease in the power drawn from the wind power, which leads to a decrease in the speed of rotation of the windmill and the restoration of the frequency of the current produced.

This known device has the following drawbacks:

  • When working in low-speed wind flows, the angle of the blades must be changed within 2.3 degrees, which, under increased gust of wind flow, can lead to self-oscillating processes in the "wind-driven traction system, the crank-link mechanism of the motor" due to the appearance of elasticity in the drive mechanism for turning the blades, Through the lever elements, which, as a rule, lead to a decrease in the kinematic rigidity and increased elastic compliance of the mechanism;
  • The known device does not provide any solutions for stabilizing the position of the pressure center during operation of the wind turbine in the extended range of wind speed, which, on the one hand, leads to increased drive wear due to work in a narrow range of displacements at low wind speeds, and on the other hand , Requires increased drive power at high wind speeds, due to increased aerodynamic loads on the blades of the windmill.

This limits the technical possibilities of using this known device.

A wind turbine is known that contains a hollow shaft kinematically connected to an electric generator, blades fixed on bushings mounted on the shaft, a paddle rotation drive kinematically connected with pivoting bushings, according to a.c. USSR N 1612107, cl. 7/02, 1985.

This device is the closest to the declared on the technical essence and the achieved result and is therefore accepted for the prototype.

The disadvantage of this known device is that its operation is accompanied by considerable loads on the mechanism for driving the rotation of the blades, which requires an increase in drive power and increases wear.

When the wind turbine is operating due to various modes of flow around the blade at different wind speed, the pressure center position shifts and, as a consequence, the aerodynamic loads that overcome the blade rotation mechanism are increased. To avoid the development of aeroelastic - flutter modes of vibrations, the center of pressure is displaced along the chord back from the axis of rotation, which significantly increases the aerodynamic moment.

Even more strongly the moment increases under storm loading regimes, when due to disturbance of flow modes, the pressure center shifts to the middle of the chord.

As a result, for example, for modern wind power plants with a capacity of 150.250 kW to overcome aerodynamic loads, a drive of up to 8 kW or more is required, which, however, does not exclude emergencies that may occur due to insufficient drive power.

For example, in 1993, in Ukraine in the operation of a wind turbine, a number of crashes of a 250 kW wind power plant occurred, which was caused, as shown by the analysis, mainly by the impossibility of turning the blades of the windmill during operation due to increased loads. Blades with a running wind turbine jammed at the corners of the power take-off and the windmill accelerated to unacceptable speeds followed by an accident.

The economics and reliability of the wind turbine using the well-known as. USSR N 1612107, cl. 7/02, 1985 the technical solution (prototype) when operating in the extended range of wind speeds is insufficient.

For the selection of maximum power from low-speed wind flows, it is necessary to constantly monitor the optimal angle of the blade installation after changing the speed of the wind flow, which, moreover, has increased gustiness with respect to high-speed wind flows.

The proportion of winds having speeds in the range up to 2.5 m / s is up to 60. 70% of the time in a year, while a period of strong winds exceeding 10 m / s does not exceed 12.15% of the total time resource in a year.

In the practice of designing a wind turbine at wind speeds V nominal speed, at which the wind turbine goes to nominal power, the angle of installation of the blades, as a rule, is not regulated. Thus, the number of operating strokes of the blade rotation drive system is relatively small.

Switching to work and regulation in the area of ​​low-speed flows increases the number of operating strokes of the drive by almost dozens of times and, especially unfavorably, this operating time occurs in a narrow range of rotation angles, which leads to increased wear of the drive.

In the absence of control on the section of the curve "power speed" before reaching the rated power, there is a shortage of power. Given the large percentage of low wind speeds in the overall picture of the distribution of wind speeds over time in a year, working in low-speed flows makes it possible to increase the generation of energy by a wind farm.

It is important to emphasize that when using wind turbines as an autonomous source of energy supply, and in the Russian Federation and the CIS, only 40% of the territory is covered by industrial and local networks, economy and reliability is of paramount importance.

The economy is primarily due to the fact that during the start-stop stages the wind turbines use their own energy source, mainly a battery of limited capacity, and the total energy consumption for the own needs of the windmill reaches 10.20% of the installed capacity.

Reliability because in an autonomous version of use, the wind turbine is the main source of energy, therefore, interruptions in its operation increase the cost of power supply and worsen the payback of the wind turbine because Require the connection of a backup power source.

Therefore, the task of creating a wind turbine with an aerodynamically "unloaded" wind turbine with a low power consumption and high reliability is an actual and complex engineering task.

This task is especially important in the development of wind turbines, which are designed to operate in an extended range of wind speeds. While the wind turbine is projected to work in a power recoil mode at low wind speeds, and at medium and high speeds, the aerodynamic loads increase substantially, which can lead to inability to control the wind turbine or will require an excessively high drive power.

The practical solution of these issues with the use of known technical solutions, including the use of as. USSR N 1612107, is essentially impossible or very difficult, new approaches are required, due to the peculiarities of work in low-speed wind flows.

The object of the invention is:

  • Increase in efficiency of wind turbines due to providing work in the extended range of wind speeds, mainly towards low speeds in the mode of maximum power output;
  • Increase in the life of the windmill by reducing the load on the mechanism for driving the rotation of the blades and actually on the wind turbine as a whole and reducing wear;
  • Increase in economy of wind turbines due to reduction of power consumed for control in the extended range of wind speeds;
  • Increasing the reliability of the windmill by reducing the loads acting on the mechanism for turning the blades and the wind wheel while moving the blades from the worker to the fender position and back.

The goal is achieved due to the fact that in a windmill containing a shaft kinematically connected to an electric generator, rotary blades with mahas fixed on rotatable bushings mounted on the shaft, a paddle rotation drive kinematically connected to the pivoting bushings, and a blade rotation control system coupled With the drive, each blade in the plane of rotation of the wind turbine is installed with a slope in the direction of rotation, the angle of inclination being formed by the longitudinal axes of the blade and the sleeve, and its value lies in the range 0.5. 2.0 degrees, the blades are made with a twist of the sections relative to the twist axis combined with the longitudinal axis of the blade shifted from the section chord towards the greater curvature of the blade profile and the leading edge of the blade is located relative to the longitudinal axis of the blade at a distance 0.2.0.25 of the chord corresponding Section of the blade.

An additional difference of the claimed device is that the blade of the blade is made with an end cut at an angle of 0.5.2 degrees with respect to the plane perpendicular to the longitudinal axis of the sleeve, and that the amount of the twist axis displacement can be chosen to be constant along the blade length for all sections of the blade Or a variable monotonically varying along the length of the blade, and it can be given as a constant in absolute values, and constant with respect to the current thickness of the profile of the blade.

The blade of the windmill can be made inclined due to the inclined cutoff of the end of the sleeve, relative to the plane perpendicular to the radial axis of the blade.

The attached drawings depict

Windmill

FIG. 1 wind turbine, general view, blade rotation drive circuit.

In Fig. 1 denotes:

10 the blade rotation drive reducer,

11 a rotating part of the pusher of the paddle driving mechanism,

12 the nonrotating part of the pusher of the paddle driving mechanism,

13 node decoupling the rotating and non-rotating parts of the pusher.

14 of the blade rotation drive arm,

15 an electric generator connected to the shaft 1 via a transmission.

FIG. 2 wind turbine, a diagram illustrating the inclination of the blade in the plane of rotation by the angle " a ".

FIG. 3 blade of the windmill, view B, see Fig. 2

In Fig. 2, 3 is indicated:

"D" the end section of the blade of the windmill,

"R" root section of the blade of the windmill,

"K" the distance from the leading edge of the blade to the axis of rotation of the blade,

"F" of the chord of the blade,

" D " displacement of the twist axis and rotation of the blade relative to the chord,

" B " is the angle of installation of the section relative to the plane of rotation of the windmill,

"B" the rotation plane of the windmill.

FIG. 4 is a diagram illustrating the geometry of the cross sections of the wind turbine blade when the maximum power for low speed winds is set in the angular range I of changing the angles B and when operating in the power limit mode in the range of 2 angular variations B (V).

In Fig. 4 denotes:

1 the position of the center of the twist and the longitudinal axis of the blade relative to the blade section, resulting from the inclination of the blade by an angle " a ". The contour of the section of the blade corresponding to this position is indicated by a dotted line.

1 'position of the point 1 in the section of the blade before it tilts in the plane of rotation,

(1-1 '), the value of the displacement of point 1' due to the inclination of the blade

L 1-1 ў = r 1-1 'Ça

2 the position of the pressure center at low wind speeds behind the longitudinal axis of the blade,

2 'displacement of the center of pressure forward with respect to the radial axis of the blades of the windmill due to the inclination of the blade,

(2'-2) the displacement value of point 2 'due to the inclination of the blade,

2 2 ў the displaced position of the pressure center forward from point 2 'with increasing speed of flow and increasing the number Re,

2 2 backward displacement of the center of pressure due to the rotation of the inclined blade,

L 22 shoulder action force Q 22 .

FIG. 5 the dependence of the installation angles of the cross sections B (shown for the end section of the blade) on the speed v of the wind flow.

Range I for maximum power output.

Range 2 for power limit operation.

The claimed device is a wind turbine comprising a shaft 1 kinematically connected to an electric generator, rotary blades 2 with mahs fixed to rotatable sleeves 3 mounted on a shaft 1, a blade rotation drive 4 kinematically connected to the sleeves 3 and a blade rotation control system 5 connected With the drive 4, each blade 2 in the plane of rotation of the windmill is installed with a slope in the direction of rotation, the inclination angle " a " being formed by the longitudinal axes 6 of the blade and the sleeve 7, and its value lies in the range of 0.5.2.0 degrees, the blades 2 are made with By twisting the sections relative to the twisting axis 8 aligned with the longitudinal axis 6 of the blade shifted from the section chord towards the greater curvature of the profile of the blade, and the leading edge of the blade is located relative to the longitudinal axis of the blade at a distance 0.2.0.25 of the chord length of the respective blade sections, Is made with a cut end 9 at an angle of 0.5.2.0 degrees.

In the claimed windmill, the value Of the displacement of the twist axis 8 can be chosen to be constant along the length of the blade for all sections of the blade or variable monotonically varying along the length of the blade, the amount of displacement being specified both as a constant in absolute values ​​and constant with respect to the current thickness d of the blade profile.

The inclination of the blade in the windmill can be made by tilting the end of the sleeve end with respect to the plane perpendicular to the radial axis of the blade at an angle of 0.5.2.0 degrees.

Wind turbine works as follows.

With the help of the mechanism of the drive of rotation, the blades are set to the angles of power take-off and the windmill is accelerated. In Fig. 5 shows the change in the angles of setting the cross sections B (V) in the area of ​​acceleration of the windmill. After acceleration, the blades are kept at optimal angles by the angles of selection of the maximum power, depending on the speed of the wind flow. At the same time, in the wind speed range V 0 .V , the angle (B) V varies within a small range from 0.5 to 2-3 degrees. With an increase in wind speed above Vnom , the range of variation of the angles B (V) increases and with increasing V, for example, up to 20 m / s, the angle B (V) increases by 20 degrees with respect to V nom .

When the wind turbine is in operation, the angle B (V) is constantly changed in accordance with the change in wind speed, provided by the mechanism for driving the rotation of the blades according to the commands of the control system.

(The implementation of the blade rotation drive mechanism in this application is not considered, since it is an independent solution: for example, the blade rotation drive for the claimed wind turbine is considered in the same applicant's application for "Windmill Management Method and Wind Power Plant," ref.N 92 / 12- 94 dated 16.12.94 of the VNIIGPE of 29.12.94).

Load on the blade rotation drive The aerodynamic torque arising from the operation of the windmill depends on the amount of the aerodynamic force Q (the forces Q, Q in Figure 4) and the arm of the action of this force with respect to the radial axis "qq" (see Figure 2).

By tilting the longitudinal axis of the blade at an angle " a " forward in the direction of rotation, a "controlled" predetermined displacement of the position of the pressure center with respect to the radius of the axis of the blade is achieved.

We introduce terminological notation.

The radius axis of the blade is the axis passing through the shaft of the wind wheel and the base of the rotary sleeve. It coincides with the longitudinal axis of the sleeve in the area before the blade is tilted in the plane of rotation of the wind wheel, is designated "qq" in FIG. 2.

The longitudinal axis of the blade is the axis around which the blade rotates while the windmill is running. It lies in the plane of the chords of the sections or in a plane parallel to the chord plane. The last execution in the declared decision.

The axis of the twist is the axis around which the geometry of the blade is constructed: the sections are tied and twisted. In the claimed solution, the twist axis coincides with the axis of rotation with the longitudinal axis of the blade.

Depending on the flow regime, the position of the center of pressure along the chord of the section of the blade changes. At low wind speed, the center of pressure lies at a distance from 0.25 to 0.3 chord, counted in sections from the leading edge of the blade. With increasing flow velocities and corresponding Re numbers, a partial flow turbulence occurs, the flow regime changes, the pressure center moves forward.

When creating wind turbines working in the area of ​​low-speed wind flows, the problem arises of ensuring the durability of the windmill, in particular the drive mechanism of the blades, as well as other elements of the windmill. This is due to the fact that operation in the low-speed wind range dramatically increases the number of loading cycles experienced by the wind turbine design when operating in a power recoil mode. In addition, as studies have shown, to remove the maximum power in the wind speed range from 1.5 to 6.0 m / s, the angle of the section of the blades should vary within the limits up to 2.3 degrees. In the range of wind speeds from 6.0 to 20.0 m / s this change reaches 20 degrees.

The operation of the wind turbine in the extended range of wind speed leads to an expansion of the range of loads acting on the blades.

Thus, for wind turbines with "classical" variants of construction, the number Re for the range V = 10.30 m / m changes by a factor of 3, while for the considered class of wind turbines operating in the speed range, for example, from 3.0 to 30 m / s The number Re varies by a factor of 10. This results in an increased range of displacement of the pressure center position and, accordingly, an increase in the aerodynamic moments acting on the blade and the load on the blade rotation drive mechanism at high wind speeds.

It should be noted that the mode of operation of the windmill is important in the transition to the vane position of their worker and vice versa from the weathervane to the working one. This is due to the fact that in the flow around the blades of the windmill, which is in an inoperative state, the blades can be in an arbitrary direction that is not oriented with respect to the wind flow, including at the angles of maximum power takeoff, but also in the vane position. The center of pressure can be located in the middle of the chord of the blade, which creates an increased aerodynamic moment acting on the blade rotation drive. The mechanism for driving the rotation of the blades should ensure that the blades are installed in the vane position at wind speeds of up to 52.60 m / s or that the blade is moved to the working position at wind speeds up to 25.30 m / s.

In the claimed device, the problems considered are of principal importance due to the following approaches:

  • Setting the position of the longitudinal axis of the blade relative to the leading edge at a distance of 0.2.0.25 chords in the corresponding sections;
  • Inclination of the blade forward in rotation of the windmill by 0.5.2.0 degrees;
  • The execution of the blade hub with a cut of the end windmill near the shaft at an angle of 0.5.2.0 degrees;
  • The alignment of the twist axis and the longitudinal axis of the blade and their displacement relative to the section chord towards a greater curvature of the profile of the blade.

When the flow around the blade profile by a low-speed flow, the pressure center is at a distance of 0.25.0.33 chords from the leading edge of the blade. When the blade is installed with a forward inclination in the plane of rotation by an angle of 0.5.2 degrees, the pressure center aligns with the radial axis "qq", see Fig. 2, as a result of which, when operating in the low-speed range of the wind currents, the aerodynamic moment acting on the blade decreases almost to zero and the wear of the blade rotation drive mechanism during operation in this range practically ceases. The power consumed by the drive is reduced, which is very important for autonomous operation modes of the wind turbine, when start-up and operation operations at low wind speeds are made on its own power source, and the generated power is low.

With an increase in wind speed, the power developed by the wind turbine increases, and for V> V nom a power limitation is necessary, which is achieved by rotating the blades at increased angles b, see Fig. 4, the angle of attack of the section with respect to the wind flow is thereby reduced, as a result of which the power taken from the wind flow is limited. When the blades rotate at significant angles, the displaced position of the longitudinal axis of the blade and the inclination of the end face of the blade lead to a complex motion of the blade: its longitudinal axis moves along the lateral surface of the truncated cone, whose radius in the small base is equal to the displacement of the longitudinal axis of the blade from the chord, and the radius in the large base

R R lh f in

Where R is the radius of the blade from end to canted end face;

F into the cutoff angle of the end face.

Due to this, the shoulder of the action of the aerodynamic force decreases, as shown in FIG. 4, despite the shift of the pressure center forward

L 22 <L 22

And the danger of the occurrence of aeroelastic oscillation modes (such as the flutter of the blade) is reduced.

When the blades are moved from the vane position to the working position, and also when moving from the working to the weathervane, the pressure center with the wind turbine idle is located approximately in the middle of the section chord, which in the "classical" designs requires a high drive power. Especially dangerous is the practice of wedging the blades at the power takeoff angles, when, due to increased loads, the blade rotation drive is not able to overcome the current aerodynamic loads and friction in the bearings. As a result, an emergency situation occurs. In the claimed solution, the inclination of the blade forward brings the pressure center in this flow regime to the radial axis of the blade, which reduces the load acting on the blade drive and the required drive power. As the calculations have shown, for the wind turbines of the middle class with a power of 100.150 kW, the claimed solution makes it possible to reduce the load in the mode of detaching the blade into the vane position when the wind turbine is idle by 30.50%, and makes it possible to perform blade setting operations in the required position, even in the case of storm winds at wind speeds of 52.60 m / S on an autonomous power source.

The effect of reducing the aerodynamic load created by the displacement of the longitudinal axis of the blade from the chord of the section when turning the blade can be quantitatively regulated depending on the configuration of the blade, the profile used, the speed of rotation of the windmill.

When setting the constant value of the displacement along the entire length of the blade, the displacement effect is most pronounced for the peripheral most velocity part of the blade, since in relative terms for the peripheral part of the blade the displacement is greater than in the root part, for example for a blade with characteristics (see table).

With a displacement value of dc of 0.028 m in the root part and in the end part, respectively



When setting the displacement value constant in relative coordinates Or variable, for example, according to a monotonically changing law, the effects achieved by shifting the longitudinal axis of the blade relative to the chord toward a greater curvature of the profile of the blade can be adjusted.

The complex motion of the blade during rotation can be realized not only due to the performance of a blade blade with a cut of its end at an angle of 0.5.2 degrees relative to the plane perpendicular to the longitudinal axis of the sleeve, but also by making the ends of the sleeve with a cut relative to the plane perpendicular to the longitudinal radius Axis of the blade at an angle of 0.5.2.0 degrees.

The most technologically feasible is the embodiment of a blade blade with a cut end, included in the main body of the claims.

Application of the claimed solution allows to provide the estimated life of the blade rotation drive system for 15 years before major repairs, including taking into account work in the low-speed wind flow area, which is practically not achieved by any of the known technical solutions that can be used for practical use in the wind turbine designed To work as an autonomous source of energy.

The power of the drive is reduced several times and for the wind power class of 100.150 kW it is 1.5 kW.

The technical solutions of analogues require a drive with similar characteristics for power control of 6.8 kW.

Thus, the claimed solution is successfully combined with the possibility of implementing reduced loads in the blade rotation drive in all vital operating modes, including:

  • At low speeds up to 5-6 m / s;
  • At high speeds of 10.30 m / s, as well as in the modes of transferring the blades into the vane position and back in high-speed and storm modes, and allows to receive thus a positive effect, which consists in the following:

    • Increase in efficiency of wind turbines due to providing work in the extended range of wind speeds, mainly towards low speeds in the mode of maximum power output;

    • Increase in the service life of computers by reducing the load on the mechanism for driving the rotation of blades and actually on the wind turbine as a whole and reducing wear;

    • Increase in economy of wind turbines due to reduction of power consumed for control in the extended range of wind speeds;

    • Increasing the reliability of the windmill by reducing the loads acting on the mechanism of rotation of the blades and the wind wheel while moving the blades from the worker to the fender position and back.

CLAIM

1. A wind turbine comprising a shaft kinematically connected to an electric generator, pivoting blades with mahas attached to rotary bushings mounted on a shaft, a paddle rotation drive kinematically connected to pivoting bushings, a pivot drive control system associated with the drive, characterized in that each The blade in the plane of rotation of the wind turbine is installed with a slope in the direction of rotation, the angle of inclination being formed by the longitudinal axes of the blade and the bushing, and its value lies in the range of 0.5 to 2.0 ° , the blades are made with a twist of the section relative to the twist axis combined with the longitudinal axis of the blade , Shifted from the section chord towards the greater curvature of the profile of the blade, the leading edge of the blade is located relative to the longitudinal axis of the blade at a distance 0.2-0.25 of the magnitude of the chord of the corresponding sections of the blade.

2. Wind turbine according to claim 1, characterized in that the blade is inclined by the inclined cut of the blade end face.

Wind turbine according to. 1 and 2, characterized in that the blade end face is cut at an angle of 0.5 2.0 ° to the plane perpendicular to the longitudinal axis of the sleeve.

4. The wind turbine according to claim 1, characterized in that the blade is inclined by the inclined cutoff of the end of the sleeve.

5. The wind turbine according to claim 1, characterized in that the amount of the twist axis displacement is selected to be constant along the blade length for all blade sections.

6. Wind turbine according to claims 1 and 5, characterized in that the displacement value of the twist axis is selected by a variable monotonically varying along the length of the blade.

7. Wind turbine according to claims 1 and 5, characterized in that the amount of displacement of the twist axis relative to the thickness of the profile of the blade in the sections is chosen to be constant.

print version
Date of publication 02.04.2007gg