Milan Simic

Development of a Data Acquisition System for the Testing and Verification of Electrical Power Quality Meters

This paper presents the development of a software supported acquisition system for metrological verification and testing of the equipment for monitoring and analysis of the basic electrical power quality parameters. The described procedure consists of two functionally connected segments. The first segment involves generation of the reference three-phase voltage signals, including the possibility of simulation of the various power quality disturbances, typical for electrical power distribution networks. The second part of this procedure includes the real-time recording of power quality disturbances in three-phase distribution networks. The procedure is functionally supported by the virtual instrumentation concept, including a software application developed in LabVIEW environment and data acquisition boards NI 6713 and NI 9215A. The software support of this system performs graphical presentation of the previously generated and recorded signal waveforms. A number of the control functions and buttons, implemented on the virtual instrument front panels, are provided to adjust the basic signal acquisition, generation and recording parameters.

Generation of the power quality disturbances in LabVIEW software environment

Software controlled procedure for classification and generation of the typical power quality disturbances, is presented in this paper. Generation procedure is functionally based on the virtual instrumentation concept, including software application developed using graphical programming package LabVIEW and D/A data acquisition card NI PCI 6713, installed in standard PC environment. Besides standard undisturbed three-phase voltage signal waveforms, six different categories of the PQ disturbances characteristic for real-time power distribution networks, can be simulated on the basis of developed virtual instruments: voltage swells, sags, interruptions, high-order voltage harmonics, swells with harmonics and sags with harmonics. Each of simulated PQ disturbances can be predefined and easily changed according to user requirements, using various combinations of the knobs and controls implemented on the virtual instrument front panel. Data acquisition 8-channel card NI 6713 provides real-time generation of the disturbances using analog output channels, which can be applied for testing and verification of the instruments developed for measurement and processing of the basic PQ parameters.

Signal conditioning for power quality

In every computer-based power quality measuring system it is necessary to adapt the power line signals to the data acquisition (DAQ) card modules. Proper dimensioning of the signal conditioning circuit is essential because it strongly affects the measuring uncertainty of the system. The signal conditioning modules provide several functions, such as: attenuation, galvanic isolation, filtering, A/D conversion etc. In this paper, directions for proper dimensioning of the signal conditioning modules and proper selection of the sampling frequency and observation interval are given. Additionally, a prototype realization of a signal conditioning circuit and its characteristics are given.

On the design of power quality signal amplifier

Design and realization of power quality signal amplifier is described. The amplifier is intended to amplify a digital-to-analog converter output signal to the nominal power line voltage levels. Such an amplifier is commonly used to simulate power quality disturbances in order to test instrument performances, or to analyze the behavior of different electronic devices. The amplifier is designed according the power quality standard EN50160, i.e. the passband of the amplifier is up to the 50th harmonic of the nominal power line frequency. In the paper, experimental tests on commercial power quality instrument are presented.

Virtual instrumentation software applied to integrated circuit testing procedure

Laboratory measurement and acquisition system based on the LabVIEW virtual instrumentation software package, applied to automated procedure for integrated circuit parameter testing, is presented in this paper. Described software controlled procedure is performed on CMOS inverter integrated circuit HCF 4007 UB Hardware configuration of developed solution includes data acquisition card PCI NI 6251 and model of tested integrated circuit, controlled by LabVIEW programming application in PC environment. Multi-channel acquisition card provides generation of test voltage waveforms for inverter circuit inputs and receives voltage signals from integrated circuit outputs. Control software application, developed in LabVIEW 8.0 programming package, performs automated recording and presentation of circuit transfer characteristics, recorded for different supply voltages, including measurement, software analysis and graphic presentation of basic circuit parameters, according to user requirements. This solution eliminates demands for manual measurement of output voltage for each input voltage changing point in circuit transfer characteristic recording procedures, due to providing complete software based automation of these processes. Such approach gives possibility for development of software controlled automated test subsystem or measurement module applicable as a part of more complex ATE systems used in integrated circuit industry production and testing.

Remote Wireless Calibration of Equipment in the Distributed Measurement Systems

This paper presents possibilities of the GSM/GPRS communication network for remote wireless calibration of the measurement equipment used for metrological assurance of the distributed measurement systems. An automated calibration procedure is performed by the measurement data transmitting between calibrator unit in the control center and fixed or mobile remote measurement stations, using synchro timing distribution system. Such calibration procedure is implemented in distributed system for metrological support of power quality monitoring and analyzing, aimed to increase an efficiency of energy delivery and consumption. By means of the Lab VIEW application software, a virtual instrument for the measurement, recording and statistical processing of the measured power quality parameters, defined according to the relevant European quality standard EN 50160, is developed and implemented in this system.

Generation of Long-time Complex Signals for Testing the Instruments for Detection of Voltage Quality Disturbances

Abstract Software supported procedure for generation of long-time complex test sentences, suitable for testing the instruments for detection of standard voltage quality (VQ) disturbances is presented in this paper. This solution for test signal generation includes significant improvements of computer-based signal generator presented and described in the previously published paper [1]. The generator is based on virtual instrumentation software for defining the basic signal parameters, data acquisition card NI 6343, and power amplifier for amplification of output voltage level to the nominal RMS voltage value of 230 V. Definition of basic signal parameters in LabVIEW application software is supported using Script files, which allows simple repetition of specific test signals and combination of more different test sequences in the complex composite test waveform. The basic advantage of this generator compared to the similar solutions for signal generation is the possibility for long-time test sequence generation according to predefined complex test scenarios, including various combinations of VQ disturbances defined in accordance with the European standard EN50160. Experimental verification of the presented signal generator capability is performed by testing the commercial power quality analyzer Fluke 435 Series II. In this paper are shown some characteristic complex test signals with various disturbances and logged data obtained from the tested power quality analyzer.

Metrological evaluation of computer-based electrical power quality signal generator

Metrological evaluation of electrical power quality signal generator, designed for reproducing the standard power quality disturbances, is presented in this paper. This generator is functionally based on the virtual instrumentation software, data acquisition card and power amplifier for scaling the output voltage to the nominal power line voltage level (230 V). The realized computer-based signal generator can be used as suitable and cost effective alternative to the various instruments for testing the power quality meters and analyzers. Metrological assessment of signal generator includes calculation of measurement uncertainty components and final presentation of measurement uncertainty budget. Procedure for calculation of Type A, Type B, combined and expanded measurement uncertainty, according to the Guide to the Expression of Uncertainty in Measurement, is proposed.

Realization and testing of PC-based power quality signal generator

The paper elaborates the design and evaluation aspects of power quality signal generator. The system is capable of reproducing the power quality (PQ) disturbances in accordance with European standard EN50160. The signal generator is divided in two functional parts: LabVIEW virtual instrumentation software, and hardware electronics for signal generation (data acquisition card and signal amplifier). By using the developed signal generator, a number of experimental test signals with various PQ disturbances typical for real power distribution systems are presented. The pQ analyzer Fluke 435 is used as the reference instrument suitable for measurement of PQ parameters from signal generator output. This paper summarizes the software architecture of the PQ generator, and some experimental results obtained with the reference instrument.

Calculation of uncertainty in electrical power quality measurement supported by LabVIEW software

Procedure for software supported calculation and analysis of standard uncertainty components in electrical power quality measurement is presented in this paper. Experimental system developed for measurement of typical PQ (power quality) parameters and disturbances is functionally supported by the LabVIEW virtual instrumentation software. Reference voltage signals are provided by using generator of standard three-phase waveforms with possibility for simulation of standard network disturbances, recently developed and presented in some previous papers. Instrument applied for measurement of reference voltage quality parameters is standard three-phase PQ analyzer - Fluke 435 Series II. Application software controls complete procedure, including measurements, periodical recording, presentation and statistical analysis of measurement results, related to parameters of reference voltage signals. Statistical analysis of measurement data includes graphical presentation of previously recorded time diagrams and histograms of measured signal quality parameters. Specific calculation of standard measurement uncertainties is performed according to the relevant international document - ISO Guide to the Expression of Uncertainty in Measurement.