AU2021105137A4 - Method for diagnosing damage of wind turbine blade based on inherent frequency - Google Patents
Method for diagnosing damage of wind turbine blade based on inherent frequency Download PDFInfo
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- AU2021105137A4 AU2021105137A4 AU2021105137A AU2021105137A AU2021105137A4 AU 2021105137 A4 AU2021105137 A4 AU 2021105137A4 AU 2021105137 A AU2021105137 A AU 2021105137A AU 2021105137 A AU2021105137 A AU 2021105137A AU 2021105137 A4 AU2021105137 A4 AU 2021105137A4
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- damage
- blade
- wind turbine
- inherent frequency
- parameter
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- 238000000034 method Methods 0.000 title claims abstract description 10
- 230000004807 localization Effects 0.000 claims abstract description 11
- 238000013507 mapping Methods 0.000 claims abstract description 4
- 238000010586 diagram Methods 0.000 description 8
- 238000004364 calculation method Methods 0.000 description 4
- 238000003745 diagnosis Methods 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 238000004422 calculation algorithm Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- RLQJEEJISHYWON-UHFFFAOYSA-N flonicamid Chemical compound FC(F)(F)C1=CC=NC=C1C(=O)NCC#N RLQJEEJISHYWON-UHFFFAOYSA-N 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0033—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining damage, crack or wear
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D17/00—Monitoring or testing of wind motors, e.g. diagnostics
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/18—Complex mathematical operations for evaluating statistical data, e.g. average values, frequency distributions, probability functions, regression analysis
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- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Wind Motors (AREA)
Abstract
OF THE DISCLOSURE (Figure 1)
A method for diagnosing damage of a wind turbine blade based on an inherent frequency is
provided in the present disclosure, comprising the following steps: Si: establishing a parameter
of a single damage position of the wind turbine blade on the basis of a principle that a ratio or a
square ratio of a change of any second-order inherent frequency of a damaged wind turbine blade
is only related to a damage position; S2: establishing a database of parameters of different
damage positions on the basis of the parameter of the single damage position of the wind turbine
blade, extracting a blade damage locating parameter, and forming blade damage interval
localization; S3: achieving accurate localization in a blade damage interval on the basis of a
mapping relation between the blade damage locating parameter and a relative position of the
interval; and S4: obtaining a relational expression between the damage position and a damage
degree to accurately identify the damage degree on the basis of a principle that a ratio of a
change of a first-order inherent frequency of a damaged blade to the first-order inherent
frequency is only related to the damage degree of the blade. The present disclosure has the
benefit effects that the present disclosure may accurately localize the damage position and
identify the damage degree only by establishing a certain type of wind turbine blade and
measuring the inherent frequency of the online blade by means of a sensor, and that localization
method is simple and efficient.
1/8
DRAWINGS
S1: Establishing a parameter of a single damage position of the
wind turbine blade on the basis of a principle that a ratio or a
square ratio of a change of any second-order inherent frequency of
a damaged wind turbine blade is only related to a damage position
S2: Establishing a database of parameters of different damage
positions on the basis of the parameter of the single damage
position of the wind turbine blade, extracting a blade damage
locating parameter, and forming blade damage interval localization
S3: Achieving accurate localization in a blade damage interval on
the basis of a mapping relation between the blade damage locating
parameter and a relative position of the interval
S4: Obtaining a relational expression between the damage position
and a damage degree to accurately identify the damage degree on
the basis of a principle that a ratio of a change of a first-order
inherent frequency of a damaged blade to the first-order inherent
frequency is only related to the damage degree of the blade
FIG 1
1
Description
1/8 DRAWINGS
S1: Establishing a parameter of a single damage position of the wind turbine blade on the basis of a principle that a ratio or a square ratio of a change of any second-order inherent frequency of a damaged wind turbine blade is only related to a damage position
S2: Establishing a database of parameters of different damage positions on the basis of the parameter of the single damage position of the wind turbine blade, extracting a blade damage locating parameter, and forming blade damage interval localization
S3: Achieving accurate localization in a blade damage interval on the basis of a mapping relation between the blade damage locating parameter and a relative position of the interval
S4: Obtaining a relational expression between the damage position and a damage degree to accurately identify the damage degree on the basis of a principle that a ratio of a change of a first-order inherent frequency of a damaged blade to the first-order inherent frequency is only related to the damage degree of the blade
FIG 1
[0001] The present disclosure relates to the field of wind turbine fault diagnosis, and in particular, to a method for diagnosing damage of a wind turbine blade based on an inherent frequency.
[0002] Wind turbine blades are indispensable components of a wind turbine and also act as means for capturing wind energy. The blades will be subjected to damage of varying degrees during operation, and it is of great significance to accurately position and diagnose the damage of the blade. There are some limitations (for example, the position where a damage occurs and the degree of the damage cannot be accurately identified) in practical applications in the prior art. As a result, it is urgent to propose a novel method for simply identifying damage based on an inherent frequency with high positioning accuracy.
[0003] To solve the above technical problem, the present disclosure provides a method for diagnosing damage of a wind turbine blade based on an inherent frequency, which has a simple algorithm and high diagnosis accuracy. The method includes the following steps:
[0004] Si: by ignoring influences of an environment and damping on a structure and taking an influence of a damage position of a wind turbine blade structure on an inherent frequency into account, calculating a square ratio of a change of any second-order inherent frequency before and after damage of the wind turbine blade as follows:
5 (0) AkvsN(0) A~~~ Ar, N1
A N()Ak N(j)
T M$
[0005] it may be known from the above equation that a ratio or a square ratio of the change of any second-order inherent frequency of the blade structure is only related to the damage position
and is not related to a damage degree, and in the equation, Ao and A6 are squares of i-th
and j-th order inherent frequency variations of the wind turbine blade, M is a structural mass of the wind turbine blade, pi is an i-th-order mode of vibration, N(pi) is deformation of element N in the i-th-order mode of vibration, N is a damage element number, and AkN is a variation of element stiffness;
[0006] establishing a parameter Hn of a single damage position:
[0007] in the equation, Ois an i-th-order inherent frequency change ratio parameter, that is,
[0008] in the equation, o*' is an i-th-order inherent frequency of an undamaged blade, and o,
is an i-th-order inherent frequency of a damaged blade, and n is the damage position; and
[0009] setting a length of the blade to be L, and establishing a database of the parameter Hn of the single damage position of the blade, where in the database, a gap between adjacent damage positions is Ad, accordingly, a distance between the damage position and a root of the blade is: Lc(n)=Ad(n+l), (n=1,2,... NM), NM is the number of preset damage positions, and
[0010] it may be known according to inherent frequency characteristics of the damaged blade that a value of the damage position parameter Hn correspond to the damage position Lc(n) one to one, and when a type of the wind turbine blade is the same, a difference of the position parameter
Hn corresponding to damage of different damage degree at the same position is equal to 0 or tends to 0;
[0011] S2: with respect to the blade to be diagnosed, utilizing finite element software to calculate the inherent frequency of the damaged blade at Lc(n) and calculate an inherent frequency change ratio parameter C ' and the damage position parameter Hn at the same time,
and in order to prevent a simulation calculation error, with regard to the same damage position, setting various degrees of damage, and averaging calculated inherent frequency change ratio
parameters and damage position parameters to obtain and F, that is, obtain a database of
parameters of different damage positions, and
[0012] on the basis of the established database of the parameters of the damage position of the wind turbine blade, assuming that the damage position of the blade to be detected is at a position x from a root of the blade, and defining a damage localization parameter Pn,x of the wind turbine blade as:
r =| , - , C|1
[0013] Hx is a position parameter of the damage at the position x, C ' is the i-th-order inherent
frequency change ratio parameter corresponding to the damage position x, and
[0014] a positioning criterion is as follows:
[0015] (1) with respect to the blade with the damage at the position x, on the basis of the database, calculating the damage location parameter Pn,x of the wind turbine blade to obtain a damage position r corresponding to a minimum of Pn,x, and accordingly, listing the position at an adjacent interval of the position r, that is:
[0016] r, Pr,x=min{Pi,x, P 2 ,x,..., PNM,x}; and
[0017] (2) on the basis of the position r, obtaining a damage position t corresponding to the minimum of Pr-i,x and Pr+I,x, that is: r-1 Pr-1,x-<:Pr+1,x t=* r+1 Pr+l,x <,Pr-1x
[0018] according to the above equation, determining that the damage position to be detected is located within an interval between the position r and the position t, and is closer to a side r, and when Pr.i,x is closer to Pr+i,x, the damage is closer to the position r;
[0019] S3: with regard to the interval [r, r+1] of the damage position that is already located, assuming that the damage continuously moves at the location interval [r, r+1] to obtain a rule that the damage location parameters Pr,xand Pr+1,x change with the damage position, which are denoted as Pr(x) and P'r(x) respectively, Pr(x) being gradually incremented to a maximum from 0, and P'r(x) being gradually decremented to 0 from the maximum; considering that in all intervals, Pr(x) and P'r(x) do not have obvious common features, in order to obtain a consistent characteristic that values of Pr,x and Pr+1,x in each interval change with cracks, making a ratio of two curves of P r (x) and P'r (x), which is denoted as E n, that is:
P -(,x) "' PPx(xx
P W(x)
[0020] converting each interval into a parameter space [0, 1] to obtain a curve of the parameter space [0, 1], where the curve corresponding to each interval basically coincides at the moment, fitting the curve of each interval in the parameter space into a curve for accurately locating the damage in the interval, and calculating an inverse function value of an E n curve relation to obtain a damage relative position (; and
[0021] accurately localizing a position of an actual interval [r, r+1] where the damage is located by means of a conversion relation between the parameter space [0, 1] and the actual damage position interval, that is:
[0022] x=L c (r)+Ad.(; and
[0023] S4: on the basis that a ratio of the first-order inherent frequency variation to the first-order inherent frequency of the damaged blade is only related to the damage degree a of the blade, defining a damage degree parameter 6 as,
[0024] in the equation, Awo 1 is a variation of the first-order inherent frequency of the damaged wind turbine blade,
[0025] taking a plurality of different damage positions, fitting different damage degrees a at the same damage position and a value of the damage degree parameter 6 into a curve, where a curve equation is 6=aa b, finding out a relation between parameters a and b in the power function 6 and the damage position to obtain a curve for accurately identifying the damage degree, and accurately identifying the position of the damage degree by means of the step S3 to identify the damage degree.
[0026] The present disclosure has the benefit effects that the present disclosure may accurately localize the damage position and identify the damage degree only by establishing a certain type of wind turbine blade and measuring the inherent frequency of the online blade by means of a sensor, and that localization method is simple and efficient.
[0027] FIG.1 is an overall flow diagram according to the present disclosure.
[0028] FIG. 2 is a structural schematic diagram of a wind turbine blade according to an embodiment of the present disclosure.
[0029] FIG. 3 is an interval location diagram according to an embodiment of the present disclosure.
[0030] FIG. 4 is a schematic diagram of a relation of a difference between a damage position and two end points of a location interval according to an embodiment of the present disclosure.
[0031] FIG. 5 is a ratio diagram of each of curves according to an embodiment of the present disclosure.
[0032] FIG. 6 is a schematic diagram of a relation between the damage position and a damage degree according to an embodiment of the present disclosure.
[0033] FIG. 7 is a schematic diagram of a power function coefficient and the damage position according to an embodiment of the present disclosure.
[0034] FIG. 8 is a schematic diagram of a power function exponent and the damage position according to an embodiment of the present disclosure.
[0035] Considering a geometric model as shown in FIG. 2, a preset damage position is set at x=7.3 m, and a damage degree is 53%. A database of a damage position parameter of a type of blade is established, and then a damage inherent frequency parameter and the damage position parameter of the preset damaged blade are calculated. The damage inherent frequency parameter is compared with the damage position parameter. FIG. 3 shows a comparison result: when r=14, the damage position parameter is the smallest, moreover, P 15 (x)>P 13 (x), and therefore, a damage interval locating result is [7, 7.5] m, and is close to 7.5 m, which is consistent with an actual situation.
[0036] On the basis of the above database, a rule that the damage parameters P r,x and P r+1,x change along with the damage position is obtained, and a curve fitted based on the rule is denoted as P r (x) and P'r (x). FIG. 4 shows a part of the fitted curve.
[0037] FIG. 5 shows a relation between the damage position and the damage position interval obtained by calculating a ratio of two curves to obtain consistent characteristics of values of intervals P r,x and P r+1,x with the change of the damage position, and a ratio of the values of P r,x and P r+1,x is characterized as follows:
P(x
) E, Jl 'X)P( }< P,( xW Pr (x)
[0038] The interval [r, r+l] is converted into a parameter space, [0, 1], and curves, E n (), of various intervals are fitted into a curve as follows:
E {4.70945(-,+1)z 4.70945 "2638S 0 5 0.5 " 0.5 ; 1
[0039] The obtained function curve E n (() is used as a determination basis of accurate positioning in the damage interval, that is, a one-to-one correspondence between the damage position x and a function E n (() is established. A relative location of damage is determined on the basis of the following function:
P >P 1- 4.70945) 2-68 , P"' >P+'
[0040] According to the calculated preset damage position x=7.3 m, the damage position is accurately located at 7.2728 m by means of calculation based on the above equation, which is consistent with the actual damage position, and has high location accuracy.
[0041] With respect to the above damage degree determination and calculation method, with the wind turbine blade as an example, the damage degree is taken as (0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) respectively, and the damage position is taken at positions (2000, 3000, 4000, 6000, 8000, 10000, 12000) away from a fixed end respectively. Next, an inherent frequency, a first-order inherent frequency variation and a damage index of the blade are calculated respectively.
[0042] The damage at the above different positions and different damage degrees are fitted into a curve, which is shown in FIG. 6. The damage index increases in a power function with increase of the damage degree, and is denoted as6=a(O.1a) b,
[0043] where a coefficient a and a power exponent b of the power function6=a(O.la) b are related to the damage position. FIG. 7 and FIG. 8 show a relation between the power function coefficient and the damage position and a relation between the power function exponent and the damage position respectively.
[0044] Curvilinear functions of FIG. 7 and FIG. 8 are: ga=-2.07396-0.12266x'-0.03276x'2 and b=1.9659+0.18541x' respectively. According to accurate location of S3, a damage degree curve corresponding to the position may be determined respectively.
[0045] In the embodiment, the accurate location is 7.2728 m, and thus, a function expression of the damage degree curve is:6=0.0011187896(0.1a) 2.63912371.
[0046] By means of calculation, it may be known that the damage degree parameter of the preset damaged blade is6=0.087195567; and the damage degree is =5.209648x10 0 %=52.09648, which is consistent with the actual damage degree and has a higher identification accuracy.
Claims (1)
1. A method for diagnosing damage of a wind turbine blade based on an inherent frequency, comprising the following steps:
Si: establishing a parameter of a single damage position of the wind turbine blade on the basis of a principle that a ratioorasquareratio of a change of any second-order inherent frequency of a damaged wind turbine blade is only related to a damage position;
S2: establishing a database of parameters of different damage positions on the basis of the parameter of the single damage position of the wind turbine blade, extracting a blade damage locating parameter, and forming blade damage interval localization;
S3: achieving accurate localization in a blade damage interval on the basis of a mapping relation between the blade damage locating parameter and a relative position of the interval; and
S4: obtaining a relational expression between the damage position and a damage degree to accurately identify the damage degree on the basis of a principle that a ratio of a change of a first-order inherent frequency of a damaged blade to the first-order inherent frequency is only related to the damage degree of the blade.
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| AU2021105137A AU2021105137A4 (en) | 2021-08-09 | 2021-08-09 | Method for diagnosing damage of wind turbine blade based on inherent frequency |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113847212A (en) * | 2021-10-29 | 2021-12-28 | 中国华能集团清洁能源技术研究院有限公司 | Method for monitoring natural frequency of blades of wind turbine generator |
| CN114000989A (en) * | 2021-11-30 | 2022-02-01 | 中国华能集团清洁能源技术研究院有限公司 | Method and system for detecting aerodynamic performance attenuation of blades of wind generating set |
| CN114065429A (en) * | 2021-11-18 | 2022-02-18 | 哈尔滨工业大学 | Method for solving inherent characteristics of single-symmetrical-section wind turbine blade |
-
2021
- 2021-08-09 AU AU2021105137A patent/AU2021105137A4/en not_active Ceased
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113847212A (en) * | 2021-10-29 | 2021-12-28 | 中国华能集团清洁能源技术研究院有限公司 | Method for monitoring natural frequency of blades of wind turbine generator |
| CN113847212B (en) * | 2021-10-29 | 2023-05-02 | 中国华能集团清洁能源技术研究院有限公司 | Wind turbine generator blade natural frequency monitoring method |
| CN114065429A (en) * | 2021-11-18 | 2022-02-18 | 哈尔滨工业大学 | Method for solving inherent characteristics of single-symmetrical-section wind turbine blade |
| CN114065429B (en) * | 2021-11-18 | 2023-04-18 | 哈尔滨工业大学 | Method for solving inherent characteristics of single-symmetrical-section wind turbine blade |
| CN114000989A (en) * | 2021-11-30 | 2022-02-01 | 中国华能集团清洁能源技术研究院有限公司 | Method and system for detecting aerodynamic performance attenuation of blades of wind generating set |
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