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A dual inverter based solar PV system is presented in this paper. To reduce the switching loss, the main inverter is switched at low frequency (square wave mode) while the other inverter operates at a higher frequency to compensate for the harmonics generated by the low frequency inverter. A new maximum power point tracking (MPPT) algorithm is proposed using only AC-side current and voltage signals...
This paper presents a model of typical three-phase, three-wire and two-level PWM controlled voltage-source converters (VSC) suitable to investigate the non-characteristic harmonic generation at dc- and ac-side of the converter under sinusoidal unbalanced voltage condition, e.g., third order current harmonic component of positive-sequence in the VSC ac-side current. The proposed model, based on instantaneous...
This work presents an adaptive nonlinear control strategy in a PI controller applied to a single-phase shunt active power filter. This strategy is based on a Gaussian-shaped function, where the control gains are defined as a nonlinear function of the input. The single-phase shunt active power filter application has two control loops, the DC bus voltage control loop and the compensating current control...
This paper presents experimental results of a sensorless control strategy for PWM rectifiers with active filtering function. The proposed technique, already presented for PWM rectifiers, has the capability to reject harmonic components from the grid, and can be employed for harmonic mitigation of shunt connected load. The mitigation of harmonics of the current shaping control is improved with a multiple...
The matrix converter (MC) is an alternative ac-ac power converter by connecting directly input to output phases through bidirectional switches and without using any dc-link or energy storing element, therefore is called an all-silicon converter. Two topologies of matrix converter are established such as direct topology and the indirect topology. This paper is devoting to presents the topology of the...
This study deals with a control system for voltage regulation of stand-alone generation systems based on self-excited induction generators (SEIG). It is considered a four-wire hybrid topology composed by switchable capacitor banks and distribution static compensator (DSTATCOM). While the switchable capacitor banks supply the most part of the reactive power for voltage regulation, the DSTATCOM is controlled...
Additional losses in transformers due to harmonic currents and voltages cause further heating in their structural parts, and damage its suitable operation, thereby reducing their lifetime. This paper proposes an energy efficiency study in a three-phase dry-type transformer, which compares temperature measurements obtained from a 10kVA three-phase dry transformer on both sinusoidal and non-sinusoidal...
The main objective of a photovoltaic (PV) inverter is inject the PV power into the grid. However, due to variations in solar irradiance, inverters have a current margin, which can be used in reactive power and harmonics compensation. This possibility, known as multifunctional operation, can be interesting in terms of power factor improvement and reduction of nonlinear loads impact at point of common...
Voltage waveform improvement has been the object of several investigations for many years and a manifold of different solutions have been proposed to reduce the harmonic content in Voltage Source Inverters (VSI) power application. In many cases this improvements have been obtained by modifying the reference voltage modulating signal. The recent introduction of cardinal B-spline functions, used as...
Distribution STATic synchronous COMpensators (DSTATCOMs) have been proved an effective approach to compensate reactive current in distribution network. With positive-sequence component, negative-sequence and zero-sequence component of unbalanced load current detected independently, selective reactive current compensation with individual phase control strategy can be realized. To improve the steady...
Every power converter needs a precise synchronization method to be able to connect to the utility grid. The synchronization impacts directly on the performance of the converter. Synchronization algorithms are often based on the well known Synchronous Reference Frame Phase Locked Loop (SRF-PLL). These are usually implemented in software on Digital signal Processors (DSP) or Microcontrollers and the...
Design criteria are addressed to select the parameters of an asymmetric multilevel shunt active power filter based on a Cascaded H-Bridge topology. The proposed approach is meant to simultaneously compensate both fundamental reactive power and current harmonics. The presented methodology allows to systematically design the main parameters of the power converter, particularly the inductive filter,...
This paper discusses the Brazilian photovoltaic grid-connected inverters standard comparatively with their European and North American counterparts. The electrical characteristics between the photovoltaic grid-connected inverter system and the electrical distribution network, required by the ABNT NBR 16149 standard, are described in detail. A comparison with its related standards in Europe (IEC Std...
This paper describes the topology and control scheme of a photovoltaic system for two-phase three-wire residential consumers. The system is composed basically of a photovoltaic array, dc-link and a grid-interface three-phase voltage sourced converter. The paper describes in detail how this system can work in an installation that uses two-phases and neutral derived from a three-phase distribution system...
The use of series-resonant converters (SRC) in light emitting diodes (LEDs) drivers has increased due to its simplicity and high efficiency. Furthermore, the use of SRC provides a reduction of the low frequency (LF) ripple in the LEDs' current, originated by the voltage ripple in the output of the power factor correction (PFC) stage (bus voltage ripple). Thus, the attenuation of the ripple transmission...
Considering the three main infrastructure of the actual power system (generation, transmission and distribution), where the latter receives least attention towards the modernizing grid. However, in the new context of smart grid, the distribution network plays an important role and topics related to monitoring of the power quality parameters are of great relevance to achieve the so called smart distribution...
This paper presents a compression algorithm for power quality (PQ) signals, which does not separate the signal into stationary and transient components. The proposed algorithm is composed of a number of different compression techniques which are combined to improve both compression ratio and total computing time. This method is based on a sequence of three phases. The first phase transforms the signal...
This paper shows a scheme for improving the detection performance of the Fundamental-Frequency Positive-Sequence (FFPS) space vector through the Generalized Delayed Signal Cancellation Phase-Locked Loop (GDSC-PLL). The performance was improved by a new scheme that reduces the phase-angle error in the frequency adaptive scheme during grid frequency variations. In the new scheme we replaced the SRF-PLL...
This paper focuses on the estimation of the fundamental frequency in balanced three-phase power systems. Specifically, we propose a Maximum Likelihood Estimator (MLE) that exploits the multidimensional nature of electrical signals. For perfectly sinusoidal signals, we show that the MLE can be expressed according to the periodogram of the instantaneous positive component. For harmonic signals, we demonstrate...
The paper analyzes the behavior of a three-phase consumer, consisting of several personal computers connected to a transformer's secondary phases. The modalities of monitoring and recording of electrical quantities are presented in this work. The structure of the consumer is described. The recorded waveforms are analyzed. The Fast Fourier Transform (FFT) analysis allowed for the decomposition of the...
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