# US 9,752,561 B2 · Detecting a pitch angle adjustment fault

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- Number: US 9,752,561 B2
- Document ID: US9752561B2
- Status: Granted
- Kind: B2
- Application number: 14/561,650
- Filed: 2014-12-05
- Published: 2015-06-25
- Granted: 2017-09-05
- Earliest claimed: 2013-12-20
- Assignees: Siemens Aktiengesellschaft
- Applicants: Siemens Aktiengesellschaft
- Inventors: Per Egedal; Gustav Hoegh; Bjarne Skovmose Kallesoee
- Web page: https://patentgrep.com/patent/US9752561B2

## CPC

- F03D 17/00: Monitoring or testing of wind motors, e.g. diagnostics (testing during commissioning of wind motors F03D13/30)
- F03D 7/0224: {Adjusting blade pitch}
- F03D 7/044: {with PID control}
- F03D 7/024: {of individual blades}
- F05B 2260/821: Parameter estimation or prediction
- F05B 2260/83: Testing, e.g. methods, components or tools therefor
- F05B 2270/309: Rate of change of parameters
- F05B 2270/328: Blade pitch angle
- Y02E 10/72: Wind turbines with rotation axis in wind direction
- F03D: WIND MOTORS
- F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A method for detecting a rotor blade pitch angle adjustment fault of a rotor blade of a wind turbine is provided, the method includes measuring a rotor blade pitch angle speed; predicting, based on an actual rotor speed, a rotor blade pitch angle speed; indicating a fault, if a first criterion is satisfied, wherein the first criterion is satisfied, if deviation between the measured rotor blade pitch angle speed and the predicted rotor blade pitch angle speed exceeds a speed threshold.

## Claims

### Claim 1

A method for detecting a rotor blade pitch angle adjustment fault of a rotor blade of a wind turbine, the method comprising:
measuring a rotor blade pitch angle speed during operation of the wind turbine wherein the rotor blade pitch angle speed is a speed or velocity with which a rotor blade pitch angle changes with time;
predicting, based on an actual rotor speed, a predicted rotor blade pitch angle speed; and
indicating a fault, if a first criterion is satisfied,
wherein the first criterion is satisfied, if deviation between the measured rotor blade pitch angle speed and the predicted rotor blade pitch angle speed exceeds a speed threshold wherein indicating the fault further comprises activating a safety system which increases the rotor blade pitch angle.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the measured rotor blade pitch angle speed is taken as an average rotor blade pitch angle speed or a maximum rotor blade pitch angle speed among at least two rotor blades of the wind turbine.

### Claim 3 (depends on 1)

The method according to claim 1, wherein predicting the predicted rotor blade pitch angle speed is further based on a rotor acceleration and/or the rotor blade pitch angle of a respective rotor blade.

### Claim 4 (depends on 1)

The method according to claim 1, wherein predicting the predicted rotor blade pitch angle speed includes computing a derivative of a predicted rotor blade pitch angle.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the predicted rotor blade pitch angle speed is derived based on a deviation between a reference rotor speed and the actual rotor speed.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the predicted rotor blade pitch angle speed is derived based on an instantaneous and a time integrated deviation between a reference rotor speed and the actual rotor speed.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the predicted rotor blade angle speed is derived based on a predicted rotor blade pitch angle (ref) defined according to:
ϑ
ref
=
G
⁡
(
ϑ
)
·
(
K
p
⁢
δ
+
∫
0
t
⁢
K
i
⁢
δ
⁢
⁢
d
⁢
⁢
t
)
wherein
G() is a gain function depending on a filtered blade pitch angle ,
δ is a deviation between a reference rotor speed and the actual rotor speed,
Kp is a proportional gain, and
Ki is an integrative gain.

### Claim 8 (depends on 1)

The method according to claim 1, wherein,
if the predicted rotor blade pitch angle speed is greater than a maximum controller pitch angle speed, the predicted rotor blade pitch angle speed is reset to the maximum controller pitch angle speed, the maximum controller pitch angle speed being a maximum speed the controller is able to change the pitch angle.

### Claim 9 (depends on 1)

The method according to claim 1, wherein
a fault is not indicated, if the measured rotor blade pitch angle speed, that is in a direction to increase the rotor blade pitch angle, is greater than a minimum rotor blade pitch angle speed threshold.

### Claim 10 (depends on 1)

The method according to claim 1, wherein
a fault is not indicated, if the rotor speed is smaller than a minimal rotor speed threshold.

### Claim 11 (depends on 1)

The method according to claim 1, wherein
the fault is indicated, if at least one of the first criterion and a second criterion is satisfied,
wherein the second criterion is satisfied, if the rotor speed is greater than a maximum rotor speed threshold.

### Claim 12 (depends on 1)

The method according to claim 1,
wherein the fault is indicated, if at least one of the first criterion and a second criterion and a third criterion is satisfied,
wherein the second criterion is satisfied, if the rotor speed is greater than a maximum rotor speed threshold,
wherein the third criterion is satisfied, if the following holds:
rotor speed>PitchRunAwayEnableSpeed
AND
(ABS(Pitch_A_Pitch_B)>MaxPitchDeviation) OR
ABS(Pitch_B_Pitch_C)>MaxPitchDeviation) OR
ABS(Pitch_A_Pitch_C)>MaxPitchDeviation))
wherein
the PitchRunAwayEnableSpeed is a rotor speed threshold,
the Pitch_A is the rotor pitch angle of a first rotor blade,
the Pitch_B is the rotor pitch angle of a second rotor blade,
the Pitch_C is the rotor pitch angle of a third rotor blade,
the first, second and third rotor blades being connected to a shaft of the wind turbine, and
the MaxPitchDeviation is a pitch angle deviation threshold.

### Claim 13 (depends on 1)

A software program stored on a non-transitory computer-readable medium, adapted, when executed on a computing system, to carry out a method according to claim 1.

### Claim 14 (depends on 1)

The method according to claim 1, wherein the measured rotor blade pitch angle speed is taken as an average rotor blade pitch angle speed or a maximum rotor blade pitch angle speed among all rotor blades of the wind turbine.

### Claim 15 (depends on 1)

The method according to claim 1, wherein the measured rotor blade pitch angle speed is continuously measured or continuously sampled during the operation of the wind turbine.

### Claim 16

A wind turbine controller comprising: an arrangement including a processor for detecting a rotor blade pitch angle adjustment fault of a rotor blade of a wind turbine, the arrangement of the wind turbine controller configured to:
receive a measured rotor blade pitch angle speed and to receive an actual rotor speed wherein the measured rotor blade pitch angle speed is a speed or velocity with which a rotor blade pitch angle changes with time:
predict, based on the actual rotor speed, a predicted rotor blade pitch angle speed and determine that a first criterion is satisfied, if a deviation between the measured rotor blade pitch angle speed and the predicted rotor blade pitch angle speed exceeds a speed threshold; and
transmit a signal to a safety system which indicates a fault, if the first criterion is satisfied wherein the safety system causes a change in the rotor blade pitch angle of the rotor blade.

### Claim 17 (depends on 16)

The wind turbine controller according to claim 16, wherein the predicted rotor blade angle speed is derived based on a predicted rotor blade pitch angle (ref) defined according to:
ϑ
ref
=
G
⁡
(
ϑ
)
·
(
K
p
⁢
δ
+
∫
0
t
⁢
K
i
⁢
δ
⁢
⁢
d
⁢
⁢
t
)
wherein
G() is a gain function depending on a filtered blade pitch angle ,
δ is a deviation between a reference rotor speed and the actual rotor speed,
Kp is a proportional gain, and
Ki is an integrative gain.