1,721,101 research outputs found
FPGA-based compensation of current transformers
No full textVoltage and current transformers are the most installed transducers in electrical power system and typically they are constructed to operate at industrial frequency, 50/60 Hz. On the other hand power quality analyses in the last years has assumed more and more heaviness in industrial environments, due to the presence of non-linear loads: they require measuring instrumentation with large bandwidth. Therefore in this paper a real-time digital technique for the compensation of current transformers, based on field programmable gate array, is presented: it implements a digital filter with a frequency response equal to the inverse one of CT. The compensated CT continues to be an analog device since the FPGA board is opportunely equipped with analog to digital and digital to analog converters. Experimental results have shown that the compensated CT improves performances of the original CT of a factor 24
Experimental evaluation of the incidence of operating conditions on measurement uncertainty of conducted emissions by power drive systems
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Accuracy Analysis of Algorithms Adopted in Voltage Dip Measurements
No full textThis paper analyzes the accuracy of algorithms commonly adopted in instruments devoted to the detection and the characterization of voltage dips (also called sags). This analysis is particularly interesting because the results of dip measurements are utilized for calculation of severity levels and site indexes that are important parameters in the assessment of quality level of power supply but also for selecting equipment with proper intrinsic immunity. Anyway, instruments for dip measurement still have unresolved technical and theoretical issues related to the characterization of their metrological performances, so, it can be found that different instruments are significantly in disagreement in some actual measurements. This paper moves a step into the direction of deepening the knowledge about the measurement of voltage dips, pointing out the limits incident to the adoption of the detection algorithms indicated in the standards. It starts with a discussion about parameters that characterize voltage dips, in agreement with standard. Then, the analytical calculations of some systematic deviations in the event characterization, introduced by the most diffused dip detection algorithms, in simplified measurement situations, are presented, underlining their remarkable impact. The obtained relations are experimentally verified on a commercial power quality instrument, forecasting its systematic deviations
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