US 12,331,722 B2
Blade monitoring by actively promoting blade vibrations
Anders Skafte, Egå (DK); Gustavo Oliveira Violato, Risskov (DK); and Fabio Caponetti, Åbyhøj (DK)
Assigned to VESTAS WIND SYSTEMS A/S, Aarhus N (DK)
Appl. No. 17/923,461
Filed by VESTAS WIND SYSTEMS A/S, Aarhus N. (DK)
PCT Filed Apr. 29, 2021, PCT No. PCT/DK2021/050135
§ 371(c)(1), (2) Date Nov. 4, 2022,
PCT Pub. No. WO2021/223823, PCT Pub. Date Nov. 11, 2021.
Claims priority of application No. PA 2020 70284 (DK), filed on May 4, 2020.
Prior Publication US 2023/0204010 A1, Jun. 29, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. F03D 7/02 (2006.01); F03D 1/06 (2006.01); F03D 7/04 (2006.01); F03D 17/00 (2016.01); G01M 5/00 (2006.01)
CPC F03D 7/0224 (2013.01) [F03D 1/06 (2013.01); F03D 7/024 (2013.01); F03D 7/042 (2013.01); F03D 7/045 (2013.01); F03D 17/011 (2023.08); F03D 17/013 (2023.08); F03D 17/014 (2023.08); F03D 17/015 (2023.08); F03D 17/017 (2023.08); G01M 5/0016 (2013.01); G01M 5/0066 (2013.01); F05B 2260/83 (2013.01); F05B 2270/331 (2013.01); F05B 2270/334 (2013.01); F05B 2270/807 (2013.01); F05B 2270/808 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A method of operating a wind turbine, the wind turbine comprising a rotor with at least one pitch adjustable rotor blade, where the at least one pitch adjustable rotor blade comprises a pitch actuator for adjusting a pitch angle, the method comprising:
applying a pitch actuation signal to the pitch actuator, the pitch actuation signal being conditioned to promote active blade vibration; and
determining at least one parameter relating to the active blade vibration, wherein promoting the active blade vibration is conducted by:
receiving an edgewise load signal for the at least one pitch adjustable rotor blade, the edgewise load signal being measured in a rotating reference frame;
applying an m-blade coordinate transformation to the edgewise load signal to transform the edgewise load signal to a whirling reference frame along a first and a second reference direction;
selecting a signal component of either the first or the second reference direction to obtain a selected signal component;
filtering the selected signal component at either a backward whirling frequency or a forward whirling frequency to obtain a filtered signal component;
applying an inverse m-blade coordinate transformation to the filtered signal component to obtain a pitch modification signal; and
setting the pitch modification signal the pitch actuation signal for the at least one pitch adjustable rotor blade to actively promote blade vibrations.
 
13. A control system for a wind turbine, the wind turbine comprising a rotor with at least one pitch adjustable rotor blade, where the at least one pitch adjustable rotor blade comprises a pitch actuator for adjusting a pitch angle; the control system comprising:
a pitch actuation unit being configured to actively promote blade vibration in response to a pitch actuation signal being applied to the pitch actuator; and
a control module being configured to determine at least one parameter relating to the active blade vibration, wherein promoting the active blade vibration is conducted by:
receiving an edgewise load signal for the at least one pitch adjustable rotor blade, the edgewise load signal being measured in a rotating reference frame;
applying an m-blade coordinate transformation to the edgewise load signal to transform the edgewise load signal to a whirling reference frame along a first and a second reference direction;
selecting p signal component of either the first or the second reference direction to obtain a selected signal component;
filtering the selected signal component at either a backward whirling frequency or a forward whirling frequency to obtain a filtered signal component;
applying an inverse m-blade coordinate transformation to the filtered signal component to obtain a pitch modification signal; and
setting the pitch modification signal the pitch actuation signal for the at least one pitch adjustable rotor blade to actively promote blade vibrations.