The Experts below are selected from a list of 15972525 Experts worldwide ranked by ideXlab platform
Giri Venkataramanan - One of the best experts on this subject based on the ideXlab platform.
-
A fault tolerant doubly fed induction generator wind turbine using a parallel grid side rectifier and series grid side converter
IEEE Transactions on Power Electronics, 2008Co-Authors: Patrick S. Flannery, Giri VenkataramananAbstract:With steadily increasing wind turbine penetration, regulatory standards for grid interconnection have evolved to require that wind generation systems ride-through disturbances such as faults and support the grid during such events. Conventional modifications to the doubly fed induction generation (DFIG) architecture for providing ride-through result in compromised control of the turbine shaft and grid current during fault events. A DFIG architecture in which the grid side converter is connected in series as opposed to parallel with the grid connection has shown improved low voltage ride through but poor power processing capabilities. In this paper, a unified DFIG wind turbine architecture which employs a parallel grid side rectifier and series grid side converter is presented. The combination of these two converters enables unencumbered power processing and robust voltage disturbance ride through. A dynamic model and control structure for this architecture is developed. The operation of the system is illustrated using computer simulations.
-
evaluation of voltage sag ride through of a doubly fed induction generator wind turbine with series grid side converter
Power Electronics Specialists Conference, 2007Co-Authors: Patrick S. Flannery, Giri VenkataramananAbstract:With steadily increasing wind turbine penetration, regulatory standards for grid interconnection have evolved to require that wind generation systems ride- through disturbances such as faults and support the grid during such events. Conventional ride-through accommodations result in high currents and torque or are unable to ride-through down to zero volts. This paper explores two DFIG configurations in which a series grid side converter (SGSC) is employed exclusively for voltage sag ride-through. A control strategy applicable to both configurations is developed whereby the SGSC engages to stabilize the stator flux at the beginning and resolution of the sag event. Simulation results show excellent zero voltage ride-through response.
Jongwoo Lim - One of the best experts on this subject based on the ideXlab platform.
-
rovo robust omnidirectional visual odometry for wide baseline wide fov camera systems
International Conference on Robotics and Automation, 2019Co-Authors: Hochang Seok, Jongwoo LimAbstract:In this paper we propose a robust visual odometry system for a wide-baseline camera rig with wide field-of-view (FOV) fisheye lenses, which provides full omnidirectional stereo observations of the environment. For more robust and accurate ego-motion estimation we adds three components to the standard VO pipeline, 1) the hybrid projection model for improved feature matching, 2) multi-view P3P RANSAC algorithm for pose estimation, and 3) online update of rig extrinsic parameters. The hybrid projection model combines the perspective and cylindrical projection to maximize the overlap between views and minimize the image distortion that degrades feature matching performance. The multi-view P3P RANSAC algorithm extends the conventional P3P RANSAC to multi-view images so that all feature matches in all views are considered in the inlier counting for robust pose estimation. Finally the online extrinsic calibration is seamlessly integrated in the backend optimization framework so that the changes in camera poses due to shocks or vibrations can be corrected automatically. The proposed system is extensively evaluated with synthetic datasets with ground-truth and real sequences of highly dynamic environment, and its superior performance is demonstrated.
Patrick S. Flannery - One of the best experts on this subject based on the ideXlab platform.
-
A fault tolerant doubly fed induction generator wind turbine using a parallel grid side rectifier and series grid side converter
IEEE Transactions on Power Electronics, 2008Co-Authors: Patrick S. Flannery, Giri VenkataramananAbstract:With steadily increasing wind turbine penetration, regulatory standards for grid interconnection have evolved to require that wind generation systems ride-through disturbances such as faults and support the grid during such events. Conventional modifications to the doubly fed induction generation (DFIG) architecture for providing ride-through result in compromised control of the turbine shaft and grid current during fault events. A DFIG architecture in which the grid side converter is connected in series as opposed to parallel with the grid connection has shown improved low voltage ride through but poor power processing capabilities. In this paper, a unified DFIG wind turbine architecture which employs a parallel grid side rectifier and series grid side converter is presented. The combination of these two converters enables unencumbered power processing and robust voltage disturbance ride through. A dynamic model and control structure for this architecture is developed. The operation of the system is illustrated using computer simulations.
-
evaluation of voltage sag ride through of a doubly fed induction generator wind turbine with series grid side converter
Power Electronics Specialists Conference, 2007Co-Authors: Patrick S. Flannery, Giri VenkataramananAbstract:With steadily increasing wind turbine penetration, regulatory standards for grid interconnection have evolved to require that wind generation systems ride- through disturbances such as faults and support the grid during such events. Conventional ride-through accommodations result in high currents and torque or are unable to ride-through down to zero volts. This paper explores two DFIG configurations in which a series grid side converter (SGSC) is employed exclusively for voltage sag ride-through. A control strategy applicable to both configurations is developed whereby the SGSC engages to stabilize the stator flux at the beginning and resolution of the sag event. Simulation results show excellent zero voltage ride-through response.
Hochang Seok - One of the best experts on this subject based on the ideXlab platform.
-
rovo robust omnidirectional visual odometry for wide baseline wide fov camera systems
International Conference on Robotics and Automation, 2019Co-Authors: Hochang Seok, Jongwoo LimAbstract:In this paper we propose a robust visual odometry system for a wide-baseline camera rig with wide field-of-view (FOV) fisheye lenses, which provides full omnidirectional stereo observations of the environment. For more robust and accurate ego-motion estimation we adds three components to the standard VO pipeline, 1) the hybrid projection model for improved feature matching, 2) multi-view P3P RANSAC algorithm for pose estimation, and 3) online update of rig extrinsic parameters. The hybrid projection model combines the perspective and cylindrical projection to maximize the overlap between views and minimize the image distortion that degrades feature matching performance. The multi-view P3P RANSAC algorithm extends the conventional P3P RANSAC to multi-view images so that all feature matches in all views are considered in the inlier counting for robust pose estimation. Finally the online extrinsic calibration is seamlessly integrated in the backend optimization framework so that the changes in camera poses due to shocks or vibrations can be corrected automatically. The proposed system is extensively evaluated with synthetic datasets with ground-truth and real sequences of highly dynamic environment, and its superior performance is demonstrated.
N A Vovos - One of the best experts on this subject based on the ideXlab platform.
-
a genetic algorithm based low voltage ride through control strategy for grid connected doubly fed induction wind generators
IEEE Transactions on Power Systems, 2014Co-Authors: T D Vrionis, X I Koutiva, N A VovosAbstract:This paper proposes a new computational intelligence-based control strategy, to enhance the low voltage ride-through capability of grid-connected wind turbines (WTs) with doubly fed induction generators (DFIGs). Grid codes world-wide require that WTs should supply reactive power to the grid during and after the fault, in order to support the grid voltage. The conventional crowbar-based systems that were initially applied in order to protect the rotor-side converter at the occurrence of grid faults, do not fulfill this requirement, as during the connection of the crowbar, the DFIG behaves as a squirrel cage machine, absorbing reactive power from the grid. This drawback led to the design of control systems that eliminate or even avoid the use of the crowbar. In order to conform to the above-mentioned requirement, this paper proposes a coordinated control strategy of the DFIG converters during a grid fault, managing to ride-through the fault without the use of any auxiliary hardware. The coordination of the two controllers is achieved via a fuzzy controller which is properly tuned using genetic algorithms. To validate the proposed control strategy, a case study of a 1.5-MW DFIG supplying a relatively weak electrical system is carried out by simulation.
