Pietro Vincenzo Barbaro, Antonio Cataliotti, Valentina Cosentino, Salvatore Nuccio
A NEW TECHNIQUE TO DETECT HARMONIC SOURCES IN POLLUTED POWER SYSTEMS

This paper presents a comparative analysis among different nonactive power quantities proposed in literature in nonsinusoidal conditions; with respect to this, a new single-point approach is proposed, for the detection of the dominant harmonic sources in polluted power systems. It is based on the observation that in the same distorted working condition the analyzed power quantities present a different behavior. In order to verify the theoretical assumptions, some simulations tests were carried out on a standard IEEE test system, proposed as a benchmark for harmonic propagation studies. Simulation results show how the approach based on a comparison of different definitions of nonactive powers can give some useful information for the detection of dominant harmonic sources.

Dušan Agrež
FAST MEASUREMENT OF POWER SYSTEM FREQUENCY IN THE FREQUENCY DOMAIN

In paper, an algorithm for fast measurement and estimation of power system frequency is presented. The frequency is calculated by an interpolation of the amplitude coefficients of the discrete Fourier transform (DFT). An analysis is made to study the influence of the leakage effect when the rectangular window and the Hanning window are used. Interpolations with longer time of measurement and with larger number of points decrease the systematic errors. The proposed method achieves accuracy in measuring the frequency under a hundredth of Hertz.

E. Hristoforou, E. Kayafas
ON THE MAGNETIC AND MAGNETOELASTIC UNIFORMITY MEASUREMENTS OF MAGNETOSTRICTIVE RIBBONS AND FIBERS

In this paper we present results on magnetic and magnetoelastic uniformity measurements of magnetostrictive ribbons and fibers. Both magnetic and magnetoelastic measurements are based on the magnetostrictive delay line (MDL) response. Measurements were realized by using an automatic instrumentation device, with parametric control of field and frequency. The device has been calibrated with respect to standard Ni wires. Indicative results are given concerning amorphous magnetostrictive ribbons and fibers, showing a good agreement with other measuring techniques.

Marcos Flavio de Campos
ANISOTROPY OF STEEL SHEETS AND CONSEQUENCE FOR EPSTEIN TEST: I THEORY

ODF – Orientation Distribution Function – Theory allow the prediction of the average magnetic properties of electrical steels when crystalline symmetry of cubic bcc iron and the orthorhombic sheet symmetry are taken into account. The crystallographic texture can be related to the magnetocrystalline anisotropy by means of a very simple expression. The dependence of the variables: Magnetic Induction, coercivity, permeability and iron losses with texture is discussed. Magnetic Induction at high fields - B₂₅ and B₅₀ - can be directly scaled to magnetocrystalline anisotropy. Effects of demagnetizing field on the Magnetic Induction are commented. Permeability and power losses are not directly related to magnetocrystalline anisotropy, mainly due the existence of domain wall displacement phenomena. The domain wall structure is function of the crystalline orientation and also contributes for the anisotropy of iron losses. As consequence of the theoretical analysis, it is suggested that the traditional Epstein arrangement (50% RD-Rolling Direction plus 50% TD–Transverse Direction), be changed for 3 separate measurements in the RD, TD (i.e., 90o) and 45° directions.

Pasquale Arpaia, Juan Garcia Perez, Alessandro Masi, Giovanni Spiezia
METROLOGICAL CHARATERIZATION OF A FAST DIGITAL INTEGRATOR FOR MAGNETIC MEASUREMENTS AT CERN

A Fast Digital Integrator (FDI) was designed to satisfy new more demanding requirements of dynamic accuracy and trigger frequency in magnetic measurements based on rotating coil systems for analyzing superconducting magnets in particle accelerators. In particular, in flux measurement, a bandwidth up to 50-100 kHz and a dynamic accuracy of 10 ppm are targeted. In this paper, results of static and dynamic metrological characterization of the FDI prototype and of the Portable Digital Integrator (PDI), heavely used at CERN and in many sub-nuclear laboratories, are compared. Preliminary results show how the initial prototype of FDI is already capable of both overcoming dynamic performance of PDI and covering operating regions inaccessible before.