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Rotor imbalance determination fit for Condition Monitoring. Jenny Niebsch (RICAM, Linz, Österreich) Michael Melsheimer (BerlinWind GmbH) EWEA Vienna, 7. February 2013 Founded by Österreichische Forschungsförderungsgesellschaft mbH (FFG). Introduction and Aims. Problem
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Rotor imbalancedeterminationfit for Condition Monitoring Jenny Niebsch (RICAM, Linz, Österreich) Michael Melsheimer (BerlinWind GmbH) EWEA Vienna, 7. February 2013 Founded by Österreichische Forschungsförderungsgesellschaft mbH (FFG)
Introduction and Aims • Problem • Imbalanced rotors cause serious problems in the operation of Wind Energy Converters (WEC) • Lifespan of components decreases • State-of-the-art balancing methods are expensive • Aims • Includeimbalance determination in Condition Monitoring System (CMS) • Compute absolute value and position from lateral vibration
Introduction • State of the art • Signal processing methods generate alarm system [1] • computation of actual value and position of imbalance not possible • Field measurements with test weights (BerlinWind GmbH) • elaborate and expensive [1] Caselitz, Giebhardt (2005)
General idea • Mathematical formulation of the problem • Replace the experimental model by a mathematical model • Imbalance load p and vibration u coupled by equation • Computation of imbalance from vibration data Inverse Problem
Procedure Forward Problem: How to get A ? • M, S Mass and stiffness matrix derived from FE-model of WEA • mr absolute value • φ position of imbalance • Solution of vibration equation
Procedure • Inverse problem • vibrationdata u measured with additional sensor in nacelle • rotational frequency ω constant during measurement • compute mr and φ in p Imbalance and balancing weights Raw data Preprocessed data
Field tests • WEC types • Südwind S77-1.5MW (85 m) • Vestas V80-2MW (78 m) • Vestas V82-1.65MW (80 m) • Vestas V90-2MW (105 m) • Measurements
Field test results Absolute value of imbalance in kgm
Conclusion • all test results within the confidential interval of BerlinWind • new method reliable to quantify mass imbalance • fit for implementation in CMS • Outlook • Test for angle reconstruction • expansion of method to aerodynamic imbalances (pitch angle deviation) • methods for non-stationary frequency data