The power quality of three-phase grid-connected inverters has drawn attention with the increasing numbers of distributed generation systems. In order to effectively eliminate the harmonics in output currents, a hybrid...
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The power quality of three-phase grid-connected inverters has drawn attention with the increasing numbers of distributed generation systems. In order to effectively eliminate the harmonics in output currents, a hybrid system based on proportional-integral (PI) control and repetitive control (RC) implemented in the synchronous referenceframe (SRF) is presented. Based on the referenceframe transformation, the use of a repetitive controller is not for achieving fundamental reference current tracking but attaining the harmonics compensation, which is different from the RC designed in a static reference frame. In addition, analyses of the SRF-based hybrid controlled converter system, including stability constraints, harmonics rejection principles and the relationship between the PI controller and repetitive controller, are further developed in frequency domain and time domain. Finally, experimental results are demonstrated to validate the steady-state and dynamic performance of the proposed hybrid controlled system.
A local characterization of Schwarzschild metrics is made by showing the space-time is locally a 2 by 2 warped product and admitting a static reference frame on its certain open subsets under some assumptions on the g...
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A local characterization of Schwarzschild metrics is made by showing the space-time is locally a 2 by 2 warped product and admitting a static reference frame on its certain open subsets under some assumptions on the global analytic structure and stress-energy tensor of the space-time, such as, assuming the existence of solutions to certain partial differential equations and the existence of a radiation stress-energy tensor consistent with these solutions on the space-time. (C) 2002 Elsevier Science B.V. All rights reserved.
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