|T. Radil, P. M. Ramos, F. M. Janeiro, A. Cruz Serra - DSP based power quality analyzer for detection and classification of disturbances in a single-phase power system||483|
|B. D'Apice, C. Landi, A. Pelvio, N. Rignano - A multi-DSP based instrument for real-time energy and PQ measurements||495|
|P. Burnos, J. Gajda, P. Piwowar, R. Sroka, M. Stencel, T. Żegleń - Accurate weighing of moving vehicles||507|
|Janusz Gajda, Ryszard Sroka, Tadeusz Żegleń - Accuracy analysis of WIM systems calibrated using pre-weighed vehicles method||517|
|Jerzy Augustyn - Influence of the structure of signal conditioning circuits on the uncertainty of impedance measurement with algorithmic methods||529|
|Jerzy Hoja, Grzegorz Lentka - New concept of a measurement probe for high impedance spectroscopy||543|
|Umberto Pogliano, Bruno Trinchera - RMS voltage measuring system for precise evaluation of electric quantities||555|
|Aldo Baccigalupi, Annalisa Liccardo - Performance assessment of "Field programmable analog arrays"||563|
|L. Ferrigno, C. Landi, M. Laracca, C. Luongo - A study on the feasibility and effectiveness of digital filter application for harmonic and interharmonic measurement in compliance with IEC 61000-4-7||577|
|Jozef Petrík, Vojtech Špetuch - The dependence of brass hardness measurement system on time||595|
|Zbigniew Kłos, Jarosław Krysiak - Factors limiting extremely sensitive measuring ranges of contemporary picoammeter||603|
|Ludwik Finkelstein - Reflections on a century of measurement science as an academic discipline - A tribute to Prof. Dr. Eng. Andrzej Jellonek (1907-1998)||635|
|Janusz Mindykowski - Novelties in electrical measurements and instrumentation in the wake of IMEKO TC4 & TC 19 Symposia and ADC Workshop in Iasi, Romania, September 2007||639|
ABSTRACTS & FULL PAPERS
T. RADIL1, P. M. RAMOS1,2, F. M. JANEIRO1,3, A. CRUZ SERRA1,2
1Instituto de Telecomunicacções
Portugal, e-mail: firstname.lastname@example.org
2Technical University of Lisbon
Depeartment of Electrical and Computer Engineering
Portugal, e-mail: email@example.com, firstname.lastname@example.org
3Universidade de Évora
Departamento de Física
Portugal, e-mail: email@example.com
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
B. D'APICE, C. LANDI, A. PELVIO, N. RIGNANO
Seconda Università di Napoli
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
P. BURNOS, J. GAJDA, P. PIWOWAR, R. SROKA, M. STENCEL,
AGH - University of Science and Technology
Department o Measurement and Instrumentation
Kraków, Poland, e-mail: firstname.lastname@example.org
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
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: email@example.com
ACCURACY ANALYSIS OF WIM SYSTEMS CALIBRATED USING PRE-WEIGHED VEHICLES METHOD
Accuracy of WIM (Weigh-In-Motion) systems depends on several factors, of particular importance is the calibration procedure. Parameters of the calibration process have essential influence on accuracy of weighing results. There are many calibration methods to be used for weighing systems. The pre-weighed calibration vehicles method is the most commonly applied, because it is simple and applicable to various classes of WIM systems. There are a few estimators of calibration coeffcients possible to determine, according to the assumed criterion. This paper summarizes the results of estimator quality assessment, for a number of trucks and their passing cycles. Besides, the paper is intended to explore how parameters of the calibration process, the quality of the road surface, class and speed of calibration vehicles could influence the final accuracy of WIM systems. Such analysis requires a number of different tests in different conditions and is rather time consuming, that is why modelling and simulation methods were adopted instead.
Keywords: modelling and simulation, WIM, MS-WIM, calibration of WIM systems, pre-weighed
Kielce University of Technology
Faculty of Electrical, Automatic Control and Computer Engineering
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
JERZY HOJA, GRZEGORZ LENTKA
Gdansk University of Technology
Faculty of Electronics Telecommunications and Informatics, Poland
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 < |Zx | < 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 2o, respectively, in the whole range of measurement frequencies.
Keywords: impedance spectroscopy, high impedance measurement
UMBERTO POGLIANO, BRUNO TRINCHERA
Istituto Nazionale di Ricerca Metrologica (I.N.RI.M.)
e-mail: firstname.lastname@example.org, email@example.com
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
ALDO BACCIGALUPI1, ANNALISA LICCARDO2
University of Naples Federico II, Italy
1 Department of Computer Science
2 Department of Electrical Engineering
PERFORMANCE ASSESSMENT OF "FIELD PROGRAMMABLE ANALOG ARRAYS"
Field Programmable Analog Arrays (FPAAs) are reconfigurable analog modules introduced on the electronic market in the last decade. Their operation and, in particular, their programmability is achieved owing to the use of switched capacitors technology. At least in principle, they seem to be a very attractive and powerful tool to design analog circuits whose parameters have to be tuned to signal variations as in carrying out sensor conditioning systems. But the aim of exploiting their possibilities in the field of metrology requires complete characterization and performance assessment of the involved building blocks.
With this goal, in the paper, the metrological characterization of the most commonly blocks to be used in analog conditioning circuits, such as amplifiers and filters, is performed. These blocks have been characterized in terms of both frequency response and step response and the obtained experimental results have been compared with those expected from theoretic analysis. Concluding remarks are then deduced to furnish practical hints in the use of FPAAs in measurement applications.
Keywords: Measurements, analog filters, field programmable analog array, amplifiers
L. FERRIGNO1, C. LANDI2, M. LARACCA1, C. LUONGO1
1 DAEIMI - University of Cassino
Italy, e-mail: firstname.lastname@example.org
2 DII - Second University of Naples
Italy, e-mail: email@example.com
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
JOZEF PETRÍK, VOJTECH ŠPETUCH
Technical University of Košice,
Faculty of Metallurgy, Slovakia
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
ZBIGNIEW KŁOS, JAROSŁAW KRYSIAK
Wroclaw University of Technology
Institute of Electrical Machines, Drives and Metrology
Poland, e-mail: firstname.lastname@example.org
FACTORS LIMITING EXTREMELY SENSITIVE MEASURING RANGES OF CONTEMPORARY PICOAMMETERS
In the paper the principle of operation of contemporary picoammeters with analog conversion
of current into voltage has been presented. The influence of factors disturbing the i/u conversion
in a passive as well as in an active converter has been analyzed.
It has been shown that a picoammeter with the most sensitive ranges should base on active i/u conversion. In detailed considerations maximal errors coming from internal sources (i.e. input bias current, offset, noise currents and noise voltages of ampli.er and thermal noise of a high-ohm scaling resistor) as well as external disturbances (leakage currents of printed board and insulators and disturbances in leading cables) have been discussed and evaluated. From this analysis it can be concluded that on the extremely sensitive ranges the most leading impact on the accuracy of the current measurement have the following factors: the input bias current of the electrometric amplifier, accuracy of the scaling resistor and its thermal noise. These factors limit the extremely sensitive ranges of picoammeter to the level of 10÷20 pA with an accuracy of 1.2%. The presented considerations can be helpful for designers as well as for users of extremely sensitive picoammeters because they permit to avoid some errors caused by improper configuration of the measuring circuit and to distinguish disturbances coming from different sources.
Keywords: active i/u conversion, operational amplifier, scaling resistor
City University London
Measurement and Instrumentation Centre
UK, e-mail: email@example.com
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.