T. RADIL¹, P. M. RAMOS^1,2, F. M. JANEIRO^1,3, A. CRUZ SERRA<sup>1,2

1</sup>Instituto de Telecomunicacções
Portugal, e-mail: tomas.radil@lx.it.pt
²Technical University of Lisbon
Depeartment of Electrical and Computer Engineering
Portugal, e-mail: pedro.ramos@lx.it.pt, acserra@ist.utl.pt
³Universidade de Évora
Departamento de Física
Portugal, e-mail: fmtj@uevora.pt

DSP BASED POWER QUALITY ANALYZER FOR DETECTION AND CLASSIFICATION OF DISTURBANCES IN A SINGLE-PHASE POWER SYSTEM

This paper describes the prototype of a power quality analyzer designed for real-time detection and classification of disturbances that occur in a single-phase power system. The standalone DSP-based analyzer implements previously developed algorithms for detection and classification of power quality disturbances such as transients, waveform distortions, sags, swells and interruptions. Its performance was verified during long term monitoring of the power system.

Keywords: power quality, event detection, mathematical morphology, digital signal processor

Full paper (203kB)

B. D'APICE, C. LANDI, A. PELVIO, N. RIGNANO

Seconda Università di Napoli
Roma, Italy,
e-mail: biagio.dapice@unina2.it

A MULTI-DSP BASED INSTRUMENT FOR REAL-TIME ENERGY AND PQ MEASUREMENTS

The evaluation of electrical energy flows is at the base of all operations connected to commercial transactions on the energy market. Typically, the measurement apparatuses are made and characterized to work in ideal sinusoidal conditions. But, with increasing diffusion of power electronic devices, the typical characteristics of a power network are far from sinusoidal ones. With the aim to link the cost of energy to the level of power quality, it is necessary to determine the energy but also the indexes which characterize the power quality. In this paper the design and implementation of a multi-processor measuring instrument based on multiple digital signal processors (DSPs) is discussed. This system can embody a number of special signal processors and analog I/O modules, specifically designed to obtain the flexibility and scaling ability to meet the needs of real-time measurement applications and low cost. After a prototype description, part of the analysis algorithm is reported. The paper is completed by preliminary results of metrological characterization.

Keywords: power quality, real time measurement, multi-digital signal processor

Full paper (567kB)

P. BURNOS, J. GAJDA, P. PIWOWAR, R. SROKA, M. STENCEL, T. ŻEGLEŃ

AGH - University of Science and Technology
Department o Measurement and Instrumentation
Kraków, Poland, e-mail: jgajda@agh.edu.pl


ACCURATE WEIGHING OF MOVING VEHICLES

The paper deals with real-time Multi-Sensor Weigh - In - Motion System (MS-WIM). This system was designed in Poland in a period of 3 years from 2003 to 2006. The embodied system is equipped with 16 piezoelectric load sensors, in the form of narrow 4m long strips, provided by Measurement Specialties. The paper outlines the system structure and its elements i.e. the weighing site, the data acquisition system and data processing software. Experimental tests indicate that the designed MS-WIM system falls in accuracy class B+(7) in the speed range from 30 km/h to 80 km/h.

Keywords: WIM (weigh-in-motion), multiple sensors (MS) WIM, accuracy analysis

Full paper (254kB)

JANUSZ GAJDA, RYSZARD SROKA, TADEUSZ ŻEGLEŃ

AGH - University of Science and Technology
Faculty of Electrical Engineering, Automatics, Informatics and Electronics
Department of Measurement and Instrumentation
Cracow, Poland, e-mail: rysieks@agh.edu.pl

ACCURACY ANALYSIS OF WIM SYSTEMS CALIBRATED USING PRE-WEIGHED VEHICLES METHOD

Keywords: modelling and simulation, WIM, MS-WIM, calibration of WIM systems, pre-weighed vehicles method

Full paper (1312kB)

JERZY AUGUSTYN

Kielce University of Technology
Faculty of Electrical, Automatic Control and Computer Engineering
e-mail: etmja@tu.kielce.pl

INFLUENCE OF THE STRUCTURE OF SIGNAL CONDITIONING CIRCUITS ON THE UNCERTAINTY OF IMPEDANCE MEASUREMENT WITH ALGORITHMIC METHODS

The article presents an estimation of the impedance measurement uncertainty determined in the measurement circuit with a two-channel sampling transducer. Using the Monte Carlo method, the influence of dynamic error and quantization error on the probability distribution of the impedance components error has been analysed. Comparison of these errors propagation has been made for three structures of conditioning circuits of voltage and current signals on measured impedance. On the basis of the obtained probability distribution, the value of the expanded uncertainty of impedance components has been determined.

Keywords: uncertainty, conditioning circuits, measurement of impedance components, measurement algorithms

Full paper (1996kB)

JERZY HOJA, GRZEGORZ LENTKA

Gdansk University of Technology
Faculty of Electronics Telecommunications and Informatics, Poland
e-mail: hoja@eti.pg.gda.pl

NEW CONCEPT OF A MEASUREMENT PROBE FOR HIGH IMPEDANCE SPECTROSCOPY

The paper presents a new measurement probe working as the input circuit for a high impedance spectroscopy analyzer. The probe allows to measure impedance in the range of 100 Ω < |Z_x | < 100 GΩ. The probe extracts two signals proportional to current through and voltage across the measured impedance in a wide frequency range from 100 μHz to 1 MHz. By the use of a current-to-voltage converter the influence of capacitance of the shielded cables connecting the object under measurement on the result of the measurement is kept as low as possible. An analysis of the probe has been performed taking into account most important parameters influencing the measurement accuracy: parasitic capacitance and real-life parameters of operational amplifiers in use. The formula for calculation of the modulus and argument of the measured impedance has been developed taking into account the correction for real-life parameters of the probe. This allows to decrease the maximal measurement errors of the impedance modulus to ca. 1% and of the impedance argument to 2^o, respectively, in the whole range of measurement frequencies.

Keywords: impedance spectroscopy, high impedance measurement

Full paper (194kB)

UMBERTO POGLIANO, BRUNO TRINCHERA

Istituto Nazionale di Ricerca Metrologica (I.N.RI.M.)
Torino, Italy
e-mail: u.pogliano@inrim.it, b.trinchera@inrim.it

RMS VOLTAGE MEASURING SYSTEM FOR PRECISE EVALUATION OF ELECTRIC QUANTITIES

This paper is about a system for the measurement of RMS voltage. One or more of these systems can be employed as components for a wide range of applications for the measurement of electrical quantities in the field of electrical metrology. The first implementation has demonstrated its functionality and the possibility to reach a stability of the AC voltage measurement in a wide frequency range with an accuracy within 10 parts in 10⁶, limited only by the DC voltage accuracy of the DAC employed. A second implementation, now under investigation, aims at improving the accuracy of the system for high precision measurements.

Keywords: Thermal converters, RMS measurements, sampling technique, data acquisition

Full paper (708kB)

ALDO BACCIGALUPI¹, ANNALISA LICCARDO²

University of Naples Federico II, Italy
¹ Department of Computer Science
² Department of Electrical Engineering
e-mail:{baccigal, aliccard}@unina.it

PERFORMANCE ASSESSMENT OF "FIELD PROGRAMMABLE ANALOG ARRAYS"

Keywords: Measurements, analog filters, field programmable analog array, amplifiers

Full paper (258kB)

L. FERRIGNO¹, C. LANDI², M. LARACCA¹, C. LUONGO<sup>1

1</sup> DAEIMI - University of Cassino
Italy, e-mail: ferrigno@unicas.it
² DII - Second University of Naples
Italy, e-mail: carmine.landi@unina2.it

A STUDY ON THE FEASIBILITY AND EFFECTIVENESS OF DIGITAL FILTER APPLICATION FOR HARMONIC AND INTERHARMONIC MEASUREMENT IN COMPLIANCE WITH IEC 61000-4-7

Large scale monitoring of power quality in electrical power plants is nowadays a pressing need due to the liberalization of the electrical market in many countries and the deeper interconnections of electrical networks. Many instruments are today available on the market. Even if they provide good accuracy and measurement capability, they are generally developed for single point measurements. Their use in large scale monitoring leads to high costs. In this framework research activity, the authors aim at the realization of a measurement instrument for power quality monitoring in compliance with IEC 61000-4-30 and 61000-4-7 standards capable of granting good accuracy, satisfying repeatability, and cost effectiveness since the use in large scale monitoring is allowed. In this paper the attention is paid to the measurement algorithm to be adopted. The use of an alternative measurement approach with respect to the FFT one is proposed. Digital filters shaped on the harmonic group are thoroughly optimized for grouping measurements required by the IEC EN 61000-4-7 standard both in simulation and emulation environments. The obtained results confirm the advantages of the proposal.

Keywords: digital filters, power quality, waveform distortion analysis, power system measurement

Full paper (181kB)

JOZEF PETRÍK, VOJTECH ŠPETUCH

Technical University of Košice,
Faculty of Metallurgy, Slovakia
jozef.petrik@tuke.sk

THE DEPENDENCE OF BRASS HARDNESS MEASUREMENT SYSTEM ON TIME

Measurement system analysis (MSA) was used for estimation of hardness (HBS) measure- ment system capability. The time dependence of capability was evaluated. Experimental material Cu-Zn-Al cast alloy was used as shape memory alloy. The average and range method with 2 appraisers, 10 samples and 3 trials (indentations). was used to quantify repeatability (% EV), reproducibility (% AV) and part variation (% PV - variation between samples). The measurement was repeated 5 times in intervals of 7 days. As the values of %GRR are between 89.4% and 63.7% and values of "ndc" between 0.71 and 1.71 the used hardness measurement system is not capable and it depends heavily on the long-term variability.

Keywords: time dependence, % GRR method, shape memory alloy, hardness HBS

Full paper (120kB)

ZBIGNIEW KŁOS, JAROSŁAW KRYSIAK

Wroclaw University of Technology
Institute of Electrical Machines, Drives and Metrology
Poland, e-mail: zbigniew.klos@pwr.wroc.pl

FACTORS LIMITING EXTREMELY SENSITIVE MEASURING RANGES OF CONTEMPORARY PICOAMMETERS

Keywords: active i/u conversion, operational amplifier, scaling resistor

Full paper (258kB)

LUDWIK FINKELSTEIN

City University London
Measurement and Instrumentation Centre
UK, e-mail: l.finkelstein@sity.ac.uk

REFLECTIONS ON A CENTURY OF MEASUREMENT SCIENCE AS AN ACADEMIC DISCIPLINE-A TRIBUTE TO PROF. DR. ENG. ANDRZEJ JELLONEK (1907-1998)

The paper reflects on the development of measurement science as a discipline over the last hundred years, viewing the field through the work of Professor Andrzej Jellonek, a notable Polish scientist and educator. It considers present challenges to the discipline. The paper also pays a personal tribute to Professor Jellonek.

Full paper (32kB)