Print Email Facebook Twitter The Immersion and Invariance Wind Speed Estimator Revisited and New Results Title The Immersion and Invariance Wind Speed Estimator Revisited and New Results Author Liu, Y. (TU Delft Team Riccardo Ferrari) Pamososuryo, A.K. (TU Delft Team Jan-Willem van Wingerden) Ferrari, Riccardo M.G. (TU Delft Team Riccardo Ferrari) van Wingerden, J.W. (TU Delft Team Jan-Willem van Wingerden) Date 2022 Abstract The Immersion and Invariance (II) wind speed estimator is a powerful and widely-used technique to estimate the rotor effective wind speed on horizontal axis wind turbines. Anyway, its global convergence proof is rather cumbersome, which hinders the extension of the method and proof to time-delayed and/or uncertain systems. In this letter, we illustrate that the circle criterion can be used as an alternative method to prove the global convergence of the II estimator. This also opens up the inclusion of time-delays and uncertainties. First, we demonstrate that the II wind speed estimator is equivalent to a torque balance estimator with a proportional correction term. As the nonlinearity in the estimator is sector bounded, the well-known circle criterion is applied to the estimator to guarantee its global convergence for time-delayed systems. By looking at the theoretical framework from this new perspective, this letter further proposes the addition of an integrator to the correction term to improve the estimator performance. Case studies show that the proposed estimator with an additional integral correction term is effective at wind speed estimation. Furthermore, its global convergence can be guaranteed by the circle criterion for time-delayed systems. Subject circle criterionConvergenceEstimationGeneratorsglobal convergence.Rotorstime-delayed systemTorqueWind speedWind speed estimatorwind turbineWind turbines To reference this document use: http://resolver.tudelft.nl/uuid:d67e169b-abc7-4cb7-88b9-5926478bf010 DOI https://doi.org/10.1109/LCSYS.2021.3076040 ISSN 2475-1456 Source IEEE Control Systems Letters, 6, 361-366 Part of collection Institutional Repository Document type journal article Rights © 2022 Y. Liu, A.K. Pamososuryo, Riccardo M.G. Ferrari, J.W. van Wingerden Files PDF The_Immersion_and_Invaria ... esults.pdf 1.47 MB Close viewer /islandora/object/uuid:d67e169b-abc7-4cb7-88b9-5926478bf010/datastream/OBJ/view