CN113447376B - Bending moment matching optimization method for wind power blade double-shaft fatigue test - Google Patents

Bending moment matching optimization method for wind power blade double-shaft fatigue test Download PDF

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Publication number
CN113447376B
CN113447376B CN202110756495.0A CN202110756495A CN113447376B CN 113447376 B CN113447376 B CN 113447376B CN 202110756495 A CN202110756495 A CN 202110756495A CN 113447376 B CN113447376 B CN 113447376B
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bending moment
blade
section
actual
value
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CN113447376A (en
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张磊安
李成良
于良峰
郑大周
刘卫生
魏修亭
黄雪梅
王渊博
文永双
夏昭航
白伟鹏
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Shandong University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0073—Fatigue
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Abstract

The fan blade is used as an important part for energy conversion in wind power generation, can bear huge external load during operation, and is easy to fatigue and lose effectiveness, so that the working capacity is lost, and serious consequences are caused. In order to ensure that the service life of the blade reaches the actual use strength requirement, the blade must be subjected to a fatigue test before being put into use formally. During testing, the testing bending moment, which is an index for measuring blade damage, on the blade is usually greatly different from the pre-designed target bending moment. In order to make the damage caused by the fatigue test to the blade close to the actual damage of the blade, a series of effective measures are needed to reduce the bending moment error before the test, and the process is called bending moment matching.

Description

Bending moment matching optimization method for wind power blade double-shaft fatigue test
Technical Field
The invention particularly relates to a bending moment matching optimization method for a wind power blade double-shaft fatigue test, and belongs to a wind power blade double-shaft fatigue test system.
Background
At present, the blade fatigue test experiment of mainstream is still wind-powered electricity generation blade unipolar fatigue test internationally, but this kind of mode, first, has no way to simulate the moment of flexure condition that receives of blade in the middle of the actual work, can not match out the moment of flexure when the stress simultaneously with blade two directions, and the fatigue test is matched to the biax moment of flexure, can realize waving and shimmy go on simultaneously, better simulation wind load, and the precision is very high. Secondly, after the uniaxial fatigue test is finished in one direction, the blade is turned for 90 degrees to continue the test, and the test is very troublesome and long in period compared with a biaxial one-time simultaneous loading method. In recent years, the size of the blade is gradually increased, a biaxial fatigue testing technology and a bending moment matching method of the large-sized blade become important researches, and the distribution of bending moment load during actual operation is required to be met along the blade spanwise direction during a fatigue test. An effective theoretical-actual blade double-shaft bending moment matching method is provided, a double-shaft wind power blade fatigue loading bending moment optimization mathematical model is established, a bending moment distribution verification algorithm is compiled, the quality and the quantity of balancing weights are optimized and verified, and the design of double-shaft bending moment distribution and test matching are guaranteed. Selection of counterweight position the selection of counterweight position is considered in combination with the position of the dangerous section of the blade. The excitation device is generally added at 70% of the blades, namely, a balancing weight is added at the position. The clump weights should not be added at the minimum or maximum dangerous sections, otherwise the life of the blade estimated by the test is deviated. When a biaxial fatigue test is carried out, the blades are simultaneously stressed by load pressure in two directions, and the stress is various.
Disclosure of Invention
According to the defects in the prior art, the technical problems to be solved by the invention are as follows: the error between the theoretical bending moment and the actual bending moment can be controlled within the range under the condition of double shafts, and the experimental efficiency is effectively improved.
The invention relates to a bending moment matching optimization method for a biaxial fatigue test of a wind power blade, which comprises the following steps of:
(1) The blade is divided into n discrete parts along the wing direction according to an equivalent substitution principle to obtain n +1 sections, meanwhile, the blade is reversed along the sections by a certain angle sigma, and in an experiment, the blade is driven by an inertial resonance vibration exciter to vibrate simultaneously along the swinging and shimmy directions, and an exciting force is generated simultaneously;
(2) Establishing a model:
only a bending moment model of the dead weight of the blade is considered,
T 1k =
Figure SMS_1
[/>
Figure SMS_2
] [1]
T 1k is the actual value of a certain section k (k =0,1, …, n) in the modelA bending moment value;
an actual bending moment model (neglecting the weight of the driving device) is established by considering the weight of the balancing weight after the balancing weight is added
Expressed as: t is 12k =P 1 (i)
Figure SMS_3
[/>
Figure SMS_4
]cos(/>
Figure SMS_5
) [2]
T 22k =P 2 (i)
Figure SMS_6
[/>
Figure SMS_7
]sin(/>
Figure SMS_8
) [3]
T 2k The actual bending moment values of a certain section in the model along the waving and shimmy directions respectively;
the coupling bending moment formula obtained by the model is expressed as follows:
T K =
Figure SMS_9
[4]
T k the actual total bending moment value of a certain section k (k =0,1, …, n) of the blade in the model is obtained;
(3) To calculate T k Mass m of each added weight; and the distance x from each counterweight to the blade root j The values (i.e. the positions of the weights) are unknown, and the known conditions are: according to the requirement of fatigue test, for any section k (k is more than or equal to 0 and less than or equal to n) of the blade, the actual total bending moment value T is k And the theoretical bending moment value T k The error of' needs to be controlled within a certain range, namely: adding counterweights to distribute blade bending momentsThe equivalent bending moment value of the blade fatigue is close to the equivalent bending moment value of the blade fatigue, and the equivalent bending moment value is controlled within a certain error range. Due to the fact that
This constraint function is as follows: min (Q) =
Figure SMS_10
-/>
Figure SMS_11
[5]
When the calculated bending moment value is larger than the equivalent bending moment,
(T 12k -T i )/T i ≤
Figure SMS_12
[6]
when the calculated bending moment value is smaller than the target bending moment value,
(T 12k -T i )/T i ≥
Figure SMS_13
[7]
in the formula: ti is the design bending moment value of each section; [ delta ] is 1 ,δ 2 ]The upper limit value and the lower limit value of the bending moment error of each section and the bending moment matching error interval are [ delta ] 1 ,δ 2 ]In addition, for the case of multiple groups of solutions, a group with a higher frequency is selected to reduce the test period; wherein, delta is an original set value;
and (5) carrying out optimization solution according to a formula [5] [6] [7], and finally obtaining the number, the quality and the position of the added balancing weights, wherein the number of the added balancing weights is the minimum.
The following optimization solving method is preferred in the invention, and the specific method comprises the following steps:
(1) Calculating the cross section with the maximum relative error between the actual total bending moment value and the theoretical bending moment value before adding no balancing weight, and setting the distance between the cross section and the root of the blade as s 1 (ii) a Adding from the blade tip, adding a balancing weight (i.e. making n = 1), the farther the balancing weight is from the section, the smaller the mass of the balancing weight is needed, but the farthest distance cannot exceed the requirement for meeting the errorObtaining a cross section; finding out the cross section with the minimum relative error between the actual total bending moment value and the theoretical bending moment value, and setting the distance between the cross section and the blade
The distance of the root of the sheet is
Figure SMS_14
；
(2) Determining the initial position of the balancing weight by adopting a bisection method:
according to the dichotomy principle, order
Figure SMS_15
To pick up/answer>
Figure SMS_16
Is x 1 Optionally, the initial values of section k, k =0,
1, …, n is the theoretical bending moment value T k ' associated with the actual value of the total bending moment T k Taking the minimum value of the difference as an objective function, taking the difference values of other section errors as inequality constraint conditions of the objective function, and establishing an objective optimization mathematical model as follows:
Min(Q)=
Figure SMS_17
-/>
Figure SMS_18
[8]
δ
Figure SMS_19
/>
Figure SMS_20
or
-δ
Figure SMS_21
/>
Figure SMS_22
[9]
When j =1, let:
P 1 (i)=a 0 p 10 +a 1 p 11 + …+a n p 1n [10]
P 2 (i)=b 0 p 20 +b 1 p 21 + …+b n p 2n [11]
wherein P = { P = 0 ，p 1 ，p 2 ，…，p n }
(T 1 2 k -T i )/T i ≤δ 1 [12]
(T 1 2 k -T i )/T i ≥δ 2 [13]
Setting P (i) as a correction coefficient of the actual bending moment, and respectively solving partial differential of Q;
Q(a 0 ,a 1 ,…,a n+1 )=
Figure SMS_23
[14]
Figure SMS_24
;
Q(b 0 ,b 1 ,…,b n+1 )=
Figure SMS_25
[15]
Figure SMS_26
;
if no solution exists, according to the dichotomy principle, the order is:
Figure SMS_27
(k=0,1,2,/>
Figure SMS_28
) [16]
the optimization of solution is carried out according to the dichotomy principle, so that the optimal number of the balancing weights added in the formula can be met, and the selection of the number and the positions of the balancing weights can be met.
All the rotation angles sigma from the blade tip to the blade root are measured through the angle sensor, data given by the sensor are used for directly drawing, and a sigma value closest to the theoretical value is found. The coupling bending moment formula is as follows:
Figure SMS_29
[17]
and optimizing the coupling bending moment formula under the condition of adding the correction coefficient.
Compared with the prior art, the invention has the advantages that:
1. according to the invention, the blade is divided into a plurality of sections, and the model precision of actual bending moment distribution is very high;
2. the invention simultaneously carries out bending moment matching on the blade flapping and shimmy directions, thereby greatly saving time and improving efficiency;
3. on the basis of the single-shaft blade bending moment matching, the theoretical bending moment and the actual bending moment can be finally controlled within a delta range by coupling the inclination angle and the correction coefficients of the two swinging directions.

Claims (1)

1. A bending moment matching method for a single-point double-shaft fatigue loading experiment of a wind power blade comprises the following steps:
(1) Dividing the blade into n discrete parts along the wing direction according to an equivalent substitution principle to obtain n +1 sections, turning over a certain angle sigma along the tangential direction, simultaneously driving the blade to simultaneously vibrate along the waving and shimmy directions through an inertial resonance vibration exciter in an experiment, and simultaneously generating an exciting force;
(2) Establishing a model: establishing an actual bending moment model only considering the self weight of the blade, which can be expressed as:
T 1k =
Figure QLYQS_1
[/>
Figure QLYQS_2
]
T 1k the actual bending moment value at a certain section k of the blade in the actual bending moment model only considering the self weight of the blade is taken into consideration, wherein k =0,1,2, … …, n;
turning over the blade along the cross section sigma, after adding the balancing weight, consider that the inclination on inclined plane can divide into two directions, the power that the balancing weight adds need not be decomposed, after considering these factors, actual moment of flexure model expression is:
T 12k =P 1 (i)
Figure QLYQS_3
[/>
Figure QLYQS_4
]cos(/>
Figure QLYQS_5
);
T 22k =P 2 (i)
Figure QLYQS_6
[/>
Figure QLYQS_7
]sin(/>
Figure QLYQS_8
);
T 2k in an actual bending moment model which does not consider the weight of the driving device but considers the weight of the balancing weight after the balancing weight is added, the blades at a certain section k are respectively along the swinging and swinging directions, wherein k =0,1,2, … …, n;
wherein i is the section number, j is the counterweight block number on the right side of the section k, n is the total number of all added counterweight blocks, p is the total number of the counterweight blocks on the right side of the section k, wherein p is less than or equal to n, ρ i is the linear mass density of each discrete part, bi is the length of the discrete part, and L ki Is the distance between the end section k and the center of gravity of the ith discrete part ρ i, g is the gravitational acceleration, and t is the end sectionThe distance from the surface k to the blade root, T is the vibration period of the blade, P (i) is the correction coefficient of the actual bending moment, and rho is above i 、b i 、D ki P, T are measured values, m j To add weight of counterweight, x j For adding clump weights according to the distance of the blade root, m j 、x j Is an unknown value;
(3) And (3) carrying out optimization solution according to the following formula, wherein the theoretical bending moment value is represented, k =0,1,2, … and n is an original set value, and finally obtaining the number, the mass and the position of the added balancing weight:
T K =
Figure QLYQS_9
;
tk is the actual total bending moment value of a certain section k (k =0,1, …, n) of the blade in the model; setting P (i) as the correction coefficient of the actual bending moment;
Q(a 0 ,a 1 ,…,a n+1 )=
Figure QLYQS_10
;
P 1 (i)=
Figure QLYQS_11
;
P 2 (i)=
Figure QLYQS_12
;
in the function Q, ai is subjected to partial differential solution, so that the correction coefficient of the section of n sections can be solved, and then the following dichotomy method is utilized to solve:
when the calculated bending moment value is larger than or equal to the equivalent bending moment,
(
Figure QLYQS_13
)/T i />
Figure QLYQS_14
;
when the calculated bending moment value is smaller than the equivalent bending moment,
(
Figure QLYQS_15
)/T i />
Figure QLYQS_16
;
finally, the number and the mass of the balancing weights can be obtained according to the original initial value of the delta.
CN202110756495.0A 2021-07-05 2021-07-05 Bending moment matching optimization method for wind power blade double-shaft fatigue test Active CN113447376B (en)

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US8621934B2 (en) * 2007-12-14 2014-01-07 Alliance For Sustainable Energy, Llc Dual-axis resonance testing of wind turbine blades
CN102410928B (en) * 2011-10-25 2013-07-31 中国科学院工程热物理研究所 Method for detecting fatigue damage of blade of horizontal axis wind turbine
CN103573552B (en) * 2012-08-02 2016-02-24 通用电气公司 The controlling method of wind turbine and reduction rotor unbalance thereof
KR20150119990A (en) * 2014-04-16 2015-10-27 한국기계연구원 Flapwise fatigue testing method and Dual-axis resornace fatige testing method of a wind turbine blade using excitation in horizontal direction
CN105508147B (en) * 2015-12-28 2017-12-08 山东理工大学 Wind electricity blade single-point fatigue loading tests moment of flexure matching process
CN110231162B (en) * 2019-07-22 2020-11-27 上海电气风电集团股份有限公司 Fatigue testing method for wind power blade
CN112161795A (en) * 2020-11-05 2021-01-01 武汉理工大学 Double-shaft cooperative loading measuring device for fatigue test of wind driven generator blade

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