1,721,149 research outputs found
Control Lyapunov Function for Series and Parallel Compensators with Energy Storage Capabilities
No full textSliding-mode control of bidirectional dc-dc converter for supercapacitor energy storage applications
No full textA great interest in the last years has been paid in the literature to the application of supercapacitors in many existing or innovative systems. Bidirectional dc-dc converters chopper are intrinsic candidates to couple the supercapacitor devices to electric power systems. It might be very useful to adopt coupled-inductor configurations for increasing efficiency against high-voltage step-up ratio. In the paper, a sliding mode control technique is proposed in order to improve the performances of a certain dc-dc bidirectional converter topology. A numerical application is also performed with respect to a simple dc tramway system with a stationary supercapacitor storage device. The numerical results allow to remark that the sliding mode control is able to track a requested trajectory, which is determined by an optimization technique and exhibits the required robustness against the uncertainties and disturbances
On Hilbert transform methods for low frequency oscillations detection
No full textThis study tackles the issue of electromechanical modes identification through a measurement-based methodology employing a novel signal decomposition theorem based upon the Hilbert transform. The methodology aims to answer in a simpler and more pragmatic manner to the main weaknesses of the Hilbert-Huang transform with respect to the major refinements in the relevant literature. These weak points are discussed with sufficient detailed degree in the study. The main contribution of this study consists in combining a recent signal decomposition theorem for separating an assigned signal into elemental ones, each of them characterised by a single frequency component and a robust preliminary non-linear spectral analyser, named Lp periodogram. This procedure's results are very appropriate for analysing some critical cases of electromechanical oscillations, because of the Lp periodogram robustness against heavy-tailed noise and also its intrinsic ability in estimating closely spaced frequency components. The proposed approach is found to be inherently simple, reliable and consistent in performance as well as characterised by low computational burden. Some numerical applications validate the methodology and assess its own performance on synthetic signals, near real-life signals acquired by IEEE test networks and on a real measured signal from a wide-area monitoring system currently in operation
Design and control of an advanced PV inverter
No full textIn this paper the design and the control of an advanced PV (Photovoltaic) inverter is discussed. The input power stage consists of a dc–dc converter based on coupled-inductors boost topology. This circuital configuration guarantees the high voltage amplification needed in grid-connected PV applications. The second power stage is a three-phase inverter operated in order to exploit the functionality of a two legs configuration. The operation principle of the proposed circuit is analyzed and a proper PV panel model is used. The adopted control strategy is based upon sliding control technique in order to exploit its well-known properties of robustness. Furthermore, a Maximum Power Point Tracking (MPPT) approach based on the extremum seeking scheme has been employed for fast tracking the irradiation changes by performing an adaptive sliding surface. Moreover, a great attention has been devoted to the control of the inverter in order to obtain power factor correction, effective reduction of both unbalances and waveforms distortion. Finally, the numerical results reported in the paper permit to confirm the feasibility of the proposed design and control strategy
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