This paper proposes a novel and simple positive sequence detector (PSD), which is inherently self-adjustable to fundamental frequency deviations by means of a softwarebased PLL (Phase Locked Loop). Since the proposed positive sequence detector is not based on Fortescue's classical decomposition and no special input filtering is needed, its dynamic response may be as fast as one fundamental cycle. The digital PLL ensures that the positive sequence components can be calculated even under distorted waveform conditions and fundamental frequency deviations. For the purpose of validating the proposed models, the positive sequence detector has been implemented in a PC-based Power Quality Monitor and experimental results illustrate its good performance. The PSD algorithm has also been evaluated in the control loop of a Series Active Filter and simulation results demonstrate its effectiveness in a closed-loop system. Moreover, considering single-phase applications, this paper also proposes a general single-phase PLL and a Fundamental Wave Detector (FWD) immune to frequency variations and waveform distortions.I.

No abstract

Considering the increasing demand on digital processing techniques for power electronics and power systems application, this paper deals with the use of a Recursive Discrete Fourier Transform (RDFT) for phase angle, frequency and magnitude identification of the grid fundamental voltages, irrespective to waveform distortions, frequency or amplitude deviations. It will be discussed that if the fundamental frequency of the measured voltages exactly matches the frequency for which the DFT has been designed, an ordinary RDFT algorithm is completely able to provide the necessary information about phase, frequency and magnitude. Two ad- Prof. Denis Vinicius Coury ditional algorithms have been proposed to ensure the correct performance if the frequency departs from its nominal value: one for phase correction and another for identification of the fundamental component magnitude. Moreover, it is important to point out that by means of the proposed algorithms, the fundamental component can be identified in less than 2 cicles, independently of the input voltage signal. The analysis of the RDFT has been performed by means of simulation results. In order to evaluate the behavior of the RDFT in a practical system, experimental results regarding to the synchronization of a small generator and the power grid will be presented.

The aim of this book is to provide an overview of recent developments in Kalman filter theory and their applications in engineering and scientific fields. The book is divided into 24 chapters and organized in five blocks corresponding to recent advances in Kalman filtering theory, applications in medical and biological sciences, tracking and positioning systems, electrical engineering and, finally, industrial processes and communication networks.

Considering the growing interest in distributed generation systems, this paper presents an alternative technique for the synchronization of independent generators, by means of Kalman Filter (KF) for the identification of amplitude, phase angle and frequency of the grid and generator fundamental voltages, even considering waveform distortions. Based on the assumption of sinusoidal voltage signals for a general power grid, two methods have been proposed and developed using state variables: one for single phase systems and another for three phase systems. A simplified method for fundamental frequency identification is also proposed by means of the measure of the instantaneous phase angle. Considering different conditions of the input voltage signals, it has been shown that although the filtering dynamic dependence of noise parameters of measurement and processing, as well as from initial conditions, the proposed algorithms are perfectly capable of identifying the required information. In order to confirm the expectations of the behavior of the KF, experimental results have been obtained by means of a practical acquisition and processing system, during the connection of a small synchronous generator with the power grid.