Considerations on power quality measurements and measurement instrumentation

Abstract

Absfract-The tnherent differences in the accuracy of measunnglmonitoring power quality (PQ) instrumentation has led the Brazilian Transmission Independent System Operator (ONS -Brazilian ISO) ONS to conduct a comprehensive field campaign and laboratory tests. These tests have allowed for evaluation of the accuracy and measurement methodology for a large number of commercially available instruments. This paper presents the laboratory test results for the performance of the different instrumensts. AN of the instruments were simultaneously fed the same voltage signal. Lab tests were conducted which included most commom power quality indices such as: steady state voltage, frequency variation, unbalance voltage, voltage fluctuation and short duration voltage variation (sag).

An overview of probabilistic aspects of harmonics: state of the art and new developments

“…The technical publication also covers probabilistic indices for harmonic distortion, characterization of multiple electronic loads, accuracy of commercial measuring instrumentation, which indicated the need for careful considerations when dealing with voltage fluctuation and time-varying harmonic distortion [13]. Also the possible utilization of fuzzy logic in diagnostic system procedures and time-varying flexible limits are considered (see Figure 7 below -with IEEE 95% THD limits, maximum 95% THD, and short-duration bursts) [14].…”