Search results for "harmonics"
showing 10 items of 199 documents
The Measurement of Reactive Energy in Polluted Distribution Power Systems: An Analysis of the Performance of Commercial Static Meters
2008
This paper presents a comparative analysis of the performances of both a traditional induction meter and various types of commercial static meters for reactive energy in the presence of harmonic distortion. This is a topical issue, since there are several types of static meters on the market, based on different principles of construction. In accordance with current standards, these meters are designed to operate in sinusoidal conditions and their performance is not tested in the presence of harmonic distortion. However, with the increase of pollution levels in power systems, the meters may be used even in the presence of distorted voltages and/or currents; in such cases, their accuracy may …
A novel approach based on nonactive powers for the identification of disturbing loads in power systems
2007
In this paper, a new approach is proposed for the detection of harmonic sources in polluted power systems. It is a single- point strategy, based on a comparison among different "nonactive" power quantities proposed in literature that, in the same working conditions, assume different values at the same metering section. Some simulations tests were carried out on a standard IEEE test system proposed by other authors as a benchmark system for the analysis of multipoint measurement techniques for harmonic pollution monitoring. The obtained results show that the proposed single-point approach is in agreement with other strategies already proposed in the literature and can provide useful indicati…
A Time-Domain Approach Based on the IEEE Std 1459-2000 for the detection of Loads Producing Harmonic Distortion
2008
This paper presents a novel strategy for the detection of harmonic sources in power systems for both the single-phase and the three-phase systems. It is based on the IEEE Std. 1459-2000 approach and it is based only on the separation of the fundamental components from the harmonic content of voltage and current. The proposed strategy do not require any spectral analysis of voltages and currents and it can be entirely implemented in the time domain. In the paper, the formulation of the novel approach is given and some simulation results are presented.
Detection of disturbing loads in distorted and/or unbalanced power systems: a technique based on a comparison among nonactive powers
2007
This paper presents an innovative technique for the detection of disturbing loads in distorted power systems. It is a single-point strategy, based on a comparison among different "nonactive" power quantities already proposed in literature, that are measured at the same metering section. In the paper, the results obtained with the application of the proposed technique are compared with those of other techniques for the monitoring of the harmonic pollution, both single-point and multi-point. Moreover, the effectiveness of the strategy is discussed, considering also the errors of the measurement transducers.
Comparison of Nonactive Powers for the Detection of Dominant Harmonic Sources in Power Systems
2008
This paper deals with an innovative technique for the detection of disturbing loads in distorted power systems. The technique is a single-point strategy based on a comparison among different ldquononactiverdquo power quantities already proposed in the literature, which are measured at the same metering section. In this paper, the effectiveness of the strategy is discussed, which also considered the errors of the measurement transducers; the analysis is supported by simulation tests, which were carried out on both a simple single-phase system and an IEEE standard three-phase test power system. The latter was used by other authors as a benchmark system for the analysis of multipoint measureme…
Mixed Harmonic Elimination Control for a Single-Phase 9 Level Grid-Connected Inverter
2018
The power quality requirements are increasingly stringent, due to the continuous growth of devices connected to the grid that introduce harmonics. These devices include DC to AC energy conversion systems, i.e. grid connected inverters. The design, control and operation of these systems must take into account the rules of interconnection to the electricity grid. To improve the quality of the output waveform of the grid-connected inverter, Multilevel Converters (MC) with selective harmonic elimination modulation technique can be used. This paper presents a single-phase nine level grid-connected inverter with DC/DC input stages. The obtained switching angles for THD minimization are independen…
Practical Implementation of a Synchronous PWM Strategy for Low Switching Frequency FOC of im Drives with ATSAM3X8E Microcontroller
2021
This paper presents a practical implementation of synchronous PWM modulation algorithm for an induction motor field oriented control powered by a DC/AC inverter and implemented on a low-cost microcontroller, the ATSAM3X8E. In particular, a simple algorithm, capable to calculate automatically an optimized set of frequency modulation indexes will be presented. Hysteresis bands are also introduced in the algorithm in order to avoid multiple changeovers during modulation index transitions. Experimental tests and their results will be shown and discussed, highlighting the benefits of the present algorithm, such as reduction of current harmonic content, reduction of current ripple and, consequent…
Correlated Event-by-Event Fluctuations of Flow Harmonics in Pb-Pb Collisions at √sNN = 2.76 TeV
2016
We report the measurements of correlations between event-by-event fluctuations of amplitudes of anisotropic flow harmonics in nucleus-nucleus collisions, obtained for the first time using a new analysis method based on multiparticle cumulants in mixed harmonics. This novel method is robust against systematic biases originating from nonflow effects and by construction any dependence on symmetry planes is eliminated. We demonstrate that correlations of flow harmonics exhibit a better sensitivity to medium properties than the individual flow harmonics. The new measurements are performed in Pb-Pb collisions at the center-of-mass energy per nucleon pair of √=2.76 TeV sNN p ¼ 2.76 TeV by the ALI…
Spherical harmonic expansion of fundamental solutions and their derivatives for homogenous elliptic operators
2017
In this work, a unified scheme for computing the fundamental solutions of a three-dimensional homogeneous elliptic partial differential operator is presented. The scheme is based on the Rayleigh expansion and on the Fourier representation of a homogeneous function. The scheme has the advantage of expressing the fundamental solutions and their derivatives up to the desired order without any term-by-term differentiation. Moreover, the coefficients of the series need to be computed only once, thus making the presented scheme attractive for numerical implementation. The scheme is employed to compute the fundamental solution of isotropic elasticity showing that the spherical harmonics expansions…
Metrological performances of voltage and current instrument transformers in harmonics measurements
2018
In the new electrical system scenario, the increasing presence of non-linear loads and renewable energy sources makes the measurement of harmonics an essential task. The accuracy of harmonic measurement firstly depends on the used instrument transformers for voltage and current sensing. Since the behavior of instrument transformers in non-sinusoidal conditions is not always well defined, this paper presents an experimental study on the metrological performances of current and voltage instrument transformers (CTs and VTs) in the presence of harmonics. Proper tests procedures are defined and measurement setups are developed for both CTs and VTs calibration. The analysis is carried out by usin…