CN102287329B - Wind generating set variable pitch method - Google Patents

Abstract

The invention discloses a wind generating set variable pitch method, which comprises the following steps of: a, measuring an air incoming flow wind speed and the linear speed of a blade element at a hub in a set period so as to obtain a synthesized wind speed and an attack angle alpha, and calculating the wind speeds of heights of centre-of-gravity positions of three blades, wherein v0 is the synthesized wind speed of the height h0 of the hub; b, ensuring that the calculated wind speeds v correspond to set values of blade pitch angles, adjusting the respective pitch angle to the set value by using three variable pitch systems according to the wind speeds at the respective centre-of-gravity positions of the three blades, and dynamically adjusting the pitch angles in the process of rotating the blades; and c, adjusting the set period in the step a according to the difference of the air incoming flow wind speeds of the blades on the highest and lowest parts. The invention has the advantages that: the load of the hub can be effectively reduced, the service life of the hub is prolonged, and time for replacing the hub can be greatly shortened in the process of subsequently maintaining a fan.

Description

A kind of Wind generating set variable pitch method

Technical field

The present invention relates to a kind of Wind generating set variable pitch method.

Background technique

The pitch-controlled wind-driven generator group refers to that whole blade around the rotation of blade central shaft, changes attack angle of blade, so that regulation output power is no more than the design admissible value in certain limit (general 0 °～90 °).When unit breaks down, need emergency shutdown, generally should make first the blade feathering, stressed little in the set structure like this, can guarantee the safety reliability of unit operation.The general leaf of feather blade is wide little, and blade is light, and the head quality is less than stall unit, does not need very large brake, and startability is good.Still can reach rated power in low air density area, after rated wind speed, output power can keep relative stability, and guarantees higher generated energy.But owing to increased by a cover pulp distance varying mechanism, increased the probability that fault occurs, and it is large to process pitch-changing mechanism blade bearing fault difficulty.The displacement unit relatively is suitable for the low area operation of plateau air density, has avoided after stall machine established angle is determined, it is low to generate electricity summer, and surpasses the problem of sending out winter.The feather unit is suitable for the more area of the above wind speed of rated wind speed, and the raising of generated energy is apparent in view like this.

At present, the horizontal axis blower fan of main flow all adopts the mode of synchronous change oar to carry out the variation of propeller pitch angle both at home and abroad.This is because in initial fan design process, design wind speed is with constant calculating in the whole wind wheel face.

The shortcoming of general change oar mode is as follows: become oar in general change oar mode, wind wheel blade only reaches the designed angle of attack when a certain height point position, other point does not then reach the design angle of attack, can make like this wind wheel blade stressed inhomogeneous in the wind wheel swept surface, increase the asymmtric load of wind wheel inside, affect the wind wheel life-span.

Summary of the invention

For solving above technical deficiency, the invention provides and a kind ofly can accurately become oar, thereby make the wind wheel internal load symmetrical, prolong the Wind generating set variable pitch method in wind wheel life-span.

The present invention is achieved by the following measures:

A kind of Wind generating set variable pitch method of the present invention may further comprise the steps:

A. setting cycle is measured the air incoming flow wind speed of wheel hub

Linear velocity with foline

Draw resultant wind velocity

Angle of attack is resultant wind velocity

The angle of direction and plane of rotation deducts propeller pitch angle, according to formula:

Calculate the wind speed v of three blade center-of-gravity station height h, wherein v ₀Be hub height h ₀Resultant wind velocity

B. the wind speed v that calculates be to should there being the setting value at blade pitch angle, three pitch-controlled systems respectively according to three blades separately the position of centre of gravity place wind speed separately corresponding propeller pitch angle adjust to setting value, and in the blade rotary process, dynamically adjust propeller pitch angle;

C. according to the difference of blade at highest point and lowest part air incoming flow wind speed, the setting cycle among the set-up procedure a.

The invention has the beneficial effects as follows:

The present invention can be applied in the high-power blower running.Regard each blade as an independent individuality, and that each blade becomes oar more synchronously to the load of wind wheel is more even, is conducive to the raising in axial fan hub life-span.Although this kind method has increased for the requirement that becomes oar actuator, but the lifting for the wheel hub life-span is favourable, and under present manufacturing level, when safeguarding such as the later stage, the cost of changing blade pitch device is little more than the cost of changing wheel hub, and to change that used time of blade pitch device and the whole wheel hub of replacing compare also be less a lot.Can effectively reduce the load of wheel hub, increase its life-span, in blower fan later maintenance process, can greatly shorten the replacing wheel hub and expend time in.

Description of drawings

Fig. 1 is workflow block diagram of the present invention.

Embodiment

Be described further below in conjunction with embodiment:

Here need the three basic knowledge point:

Consider from the foline theory that (1) the suffered load of a certain specific foline is:

$\mathrm{\δ}{F}_L=\frac{1}{2}\mathrm{\ρ}{\left|V\right|}^2{C}_L\·c\·\mathrm{\δr}$

$\mathrm{\δ}{F}_D=\frac{1}{2}\mathrm{\ρ}{\left|V\right|}^2{C}_D\·c\·\mathrm{\δr}$

δ F in the formula _LBe the suffered lift of foline, δ F _DBe the suffered resistance of foline, C is chord length, and δ r is foline length, lift coefficient C _LWith resistance coefficient C _DDetermined by angle of attack.Carry out integration in the whole length of blade and can get whole vane stress, calculate the stressed of whole wind wheel according to composition of force again.

(2) foline place wind speed is calculated as follows:

In the formula

Be air incoming flow wind speed,

Linear velocity for foline.Resultant wind velocity wherein

The angle of direction and surface of revolution deducts propeller pitch angle and is angle of attack.Pitch-controlled system changes the size of attack angle of blade by the size that changes propeller pitch angle.

(3) owing to there is wind shear, wind speed is different on the different heights, the height of wind speed and velocity relationship general satisfaction: $\frac{v}{v_0}={\left(\frac{h}{h_0}\right)}^{\mathrm{\α}}$

In the formula, v ₀Be reference altitude h ₀Wind speed.

One, the early-stage preparations stage:

This stage is the preparatory stage of asynchronous change oar, and in the cycle, moment of torsion is basicly stable at a certain measuring wind speed, and three blade pitch angles equate that master control obtains the wind wheel rotational position by encoder.This stage and common change oar indifference.

Two, the asynchronous change oar stage:

May further comprise the steps:

A. setting cycle is measured the air incoming flow wind speed of wheel hub

Linear velocity with foline

Draw resultant wind velocity

Angle of attack is resultant wind velocity

The angle of direction and plane of rotation deducts propeller pitch angle, according to formula:

Calculate the wind speed v of three blade center-of-gravity station height h, wherein v ₀Be hub height h ₀Resultant wind velocity

B. in Technical specifications, stipulated wind speed-propeller pitch angle table of comparisons, the corresponding corresponding propeller pitch angle setting value of great wind speed namely, the wind speed v that each blade calculates is to there being the setting value at blade pitch angle, three independent pitch systems detect respectively first the propeller pitch angle of each blade of controlling, three pitch-controlled systems respectively according to three blades separately the wind speed inquiry wind speed-propeller pitch angle table of comparisons at position of centre of gravity place obtain the poor of instantaneous propeller pitch angle and setting value, again by controller just separately corresponding present propeller pitch angle adjust to set angle.This moment, each blade all was in the adjusting stage, and finally a period of rotation by wind wheel makes three blade pitch angles identical with setting value respectively.The variation of one-period will be carried out in the wind wheel blade pitch angle that whenever rotates a circle thereupon.

Three, wind speed changes the stage:

After wind speed changes, the rotation speed change of blade, blade is at the generation difference of highest point and lowest part air incoming flow wind speed, the setting cycle of the measuring wind among the set-up procedure a.Can start any stage in fan operation, the measuring wind speed cycle is that blower fan control system changes insensitive stage for wind speed in certain time period, and the supposition wind speed is constant in this cycle, and moment of torsion remains unchanged substantially.The method is different from traditional change oar method, regards blade as independent individuality, but the load of whole wind wheel has been carried out balance;

Measuring wind speed is to lean on the recording anemometer of rear end, cabin to carry out for blower fan, and its height can be by hub height.Can suppose when becoming oar that wind speed v is constant in the whole wind wheel face.But actual conditions wind speed in whole wind wheel face is to be exponential distribution.For example the axial fan hub height is 70, and hub height place wind speed is 15m/s, and rotor diameter is 72m, and position of centre of gravity is at distance blade root 1/3 length of blade place.Then blade is poor at the air incoming flow wind speed of highest point and lowest part is 0.736m/s.According to each blade center of gravity place wind speed, can change by corresponding propeller pitch angle.

Above-described embodiment is described to be to specify this patent; though describe by specific term in the literary composition; but can not limit with this protection domain of this patent; being familiar with the personage of this technical field can be after the spirit of understanding this patent and principle change or revises it and reach equivalent purpose; and this equivalence change and modification all should be covered by the claim scope and define in the category.

Claims (1)

1. a Wind generating set variable pitch method is characterized in that, may further comprise the steps:

A. setting cycle is measured the air incoming flow wind speed of wheel hub

Linear velocity with foline

Draw resultant wind velocity

Angle of attack is resultant wind velocity

The angle of direction and plane of rotation deducts propeller pitch angle, according to formula:

Calculate the wind speed v of three blade center-of-gravity station height h, wherein v ₀Be hub height h ₀Resultant wind velocity

B. the wind speed v that calculates be to should there being the setting value at blade pitch angle, three pitch-controlled systems respectively according to three blades separately the position of centre of gravity place wind speed separately corresponding propeller pitch angle adjust to setting value, and in the blade rotary process, dynamically adjust propeller pitch angle;

C. according to the difference of blade at highest point and lowest part air incoming flow wind speed, the setting cycle among the set-up procedure a.

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