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Distributed power generation systems may be required to work in both grid-connected and stand-alone modes for ensuring the supply of critical local loads, maybe organized in micro-grids. Every time the micro-grid is disconnected and reconnected from the grid, a change in the control scheme is required leading to undesired transients and even lost of stability. In this paper, the use of the droop control...
Wind Turbine (WT) systems based on Permanent Magnet Synchronous Generators (PMSG) have become important mainly due to their high power factor and high efficiency. In order to reduce costs, maintenance and complexity, speed and position estimators can be used to replace the corresponding sensors in low and high power WT. This paper studies a PMSG flux observer, which is used along with a PLL to estimate...
This paper introduces a novel approach to estimate the initial rotor position in permanent magnet synchronous generator (PMSG) sensorless drives. The main problems of sensorless techniques appear at low speeds and also at standstill. To ensure a stable starting, this paper presents firstly an overview of several techniques for initial rotor position estimation (IRPE) proposed previously by other authors,...
Power electronic converters used in distributed power generation systems need grid synchronization systems. These synchronization methods can be divided into two fundamental parts. Whereas the first part proposes detecting grid signal sequences and harmonics, the second one is based on a PLL (Phase Locked Loop). DSC (Delay Signal Cancellation) y DSOGI-QSG (Dual Second Order Generalized Integrator-Quadrature...
In this paper, a space-vector discrete-time Fourier transform is proposed for fast and precise detection of the fundamental-frequency and harmonic positive- and negative-sequence vector components of three-phase input signals. The discrete Fourier transform is applied to the three-phase signals represented by Clarke's αβ vector. It is shown that the complex numbers output from the Fourier transform...
In this paper, a discrete-time algorithm for separately detecting the positive- and negative-sequence harmonic space-vector components of a three-phase signal is presented. The discrete Fourier transform is applied to the three-phase signals represented by the Clarke's a?? vector. The proposed transform outputs the instantaneous values of the fundamental frequency and harmonic component vectors of...
In this paper, two current controller schemes, based on repetitive controllers and proportional+resonant controllers using second order generalized integrators connected in parallel, are proposed and compared for shunt active power filters. Both controllers are well suited due to their optimum tracking and harmonic rejection capability. The objectives of this paper are: to analyze both controllers...
A new frequency adaptive method for detecting the Fundamental Frequency Positive Sequence (FFPS) voltage vector is proposed in this paper. The analytical developments demonstrate that the proposed method allows obtaining the FFPS alphabeta voltage vector canceling the effects of fundamental-frequency negative-sequence components, as well as the influences of all harmonic voltage vectors up to 24th...
This paper describes the hardware and software modules of a remote Internet-based laboratory for experimentation with a 120 KVA multilevel power converter. The key feature of this laboratory is the utilization of a multilevel converter that can be controlled and supervised remotely in a secured way. A wide variety of laboratory experiments are supported, from grid connection to ac motor control. The...
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