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This paper proposes models for the reference phasor in the context of phasor measurement unit calibration, under conditions of step discontinuities in magnitude and phase, along with methods to estimate the model parameters. Two parametric mathematical models, which are proposed to represent these signals, are fitted to signal samples via an iterative numerical method. The proposed approach does not require any time adjustment of the analysis window to skip the discontinuity. The estimated parameters can be used to calculate the frequency, the magnitude, and the phase during magnitude or phase steps. During a window with the step transient, we propose reference phasors with an appropriate definition. Moreover, we quantify the errors of the phasor-related estimates, for both computer-simulated cases and laboratory measurements. [ABSTRACT FROM AUTHOR]

This paper describes three impedance bridges in operation at INMETRO: the two- and four-terminal-pair coaxial bridges and a digital quadrature bridge, including several comparisons among them in the nanofarad capacitance range. These comparisons have the objective to verify the performance and reliability of the coaxial bridges between themselves and to infer on the capabilities of a digital one, recently put in operation. The results obtained indicate that the more accurate coaxial systems are compatible with one another in the 10−7 level. The digital bridge is in agreement with the coaxial ones within a few parts in 106 or even less in some cases. [ABSTRACT FROM AUTHOR]

This paper describes a five-terminal (four terminal with shield) digital impedance bridge aided by digital adaptive phase regulation. It allows the comparison of ac resistances and capacitances with outstanding accuracy and with measurement uncertainties bearing only some 10−6 Ω/Ω, as corroborated by extensive experimental investigations. [ABSTRACT FROM AUTHOR]

For high-accuracy electrical measurements, sampling errors can contribute significantly to increase the incertitude. The fractional delay (FD) sampling technique is a simple and very efficient technique to reduce sampling errors, improving the measurement accuracy. Here, we combine the FD sampling technique with principal component analysis, applying this technique to high-accuracy ac voltage measurements, more specifically to the harmonic estimation of periodical signals. Theoretical results are backed by simulations and experimental results. [ABSTRACT FROM PUBLISHER]