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Next-generation phasor measurement units (PMU) are expected to be more accurate than existing ones, especially to address the stricter requirements of future active distribution grids. From this perspective, the influence of acquisition wideband noise (which includes multiple contributions both in amplitude and in phase) has to be carefully evaluated. In this context, the contribution of this paper is twofold. First, it provides a general framework to evaluate the effect of wideband noise on synchrophasor amplitude, phase, frequency, and rate of change of frequency (ROCOF) estimation. The results of this analysis show that the influence of wideband noise can become critical for compliance with the requirements reported in the IEEE standards C37.118.1-2011 and C37.118.1a-2014, especially for frequency and ROCOF estimation. In addition, this paper reports general guidelines to choose the PMU effective resolution and sampling rate for which the impact of wideband noise on both P Class and M Class PMUs is negligible. [ABSTRACT FROM PUBLISHER]

Radiative transfer models (RTM) are used to calculate spectral and broadband irradiance, given a set of input parameters that are representative of the atmospheric state. While many studies exist on their accuracy, there is still a research gap in the assessment of their uncertainty, due to the nonlinear and not differentiable nature of the Radiative Transfer Equation, which is the core of a RTM. This study evaluates the uncertainty of both spectral and broadband irradiance calculated with the radiative transfer model SDISORT implemented in the tool UVSPEC within the range 280–2500 nm. A set of input values representing the atmospheric state at Kanzelhöhe Observatory (Austria) site at 10:00 on April 25th, 2013 is taken as reference and a Monte Carlo technique is used to propagate the uncertainty of input parameters to the model output. Both the effects of single input parameter uncertainty and of their combination are evaluated, as well as the influence of the deviation of input values from the reference set. Results show that ozone column is an important source of uncertainty in the UV-B region, while the uncertainties of Ångström aerosol turbidity coefficient and extraterrestrial spectrum affect the whole spectral range. Considering a reasonable variability range for all involved input parameters, the overall uncertainty of broadband global horizontal irradiance is between 2.9% and 5.9%. These values are higher, but still comparable, to typical uncertainty values of outdoor-deployed spectroradiometers. [ABSTRACT FROM AUTHOR]

As known, phasor measurement units (PMUs) greatly enhance smart grid monitoring capabilities with advantageous impacts on power network management. Generally, PMUs accuracy is expressed in terms of total vector error, which comprises the joint effect of both angle and magnitude errors, thus possibly concealing the algorithm ability to measure phase. Some recent research works emphasize the importance of measuring current or voltage phasor angle with high accuracy (in the order of a few milliradians) at the distribution level. Because this issue is seldom considered in the literature, in this paper the phase measurement accuracy of three algorithms, namely the basic DFT, the windowed Taylor–Fourier filter, and the interpolated dynamic DFT ( \mathrmIpD^2 FT) estimator, is extensively analyzed by means of simulations performed in various conditions described in the Standards IEEE C37.118.1:2011 and EN 50160:2010. In addition, some meaningful considerations about the uncertainty contributions due to imperfect synchronization are reported. [ABSTRACT FROM PUBLISHER]

Transient amplitude or phase changes in current or voltage waveforms may seriously affect synchrophasor estimator's accuracy and responsiveness. The IEEE Standard C37.118.1-2011 specifies test conditions as well as accuracy and response delay limits for different types of disturbances. In this paper, the performances of three state-of-the-art techniques based on phasor Taylor's series expansion specifically conceived to track phasors in dynamic conditions are analyzed and compared with the one-cycle discrete Fourier transform estimator under the effect of amplitude step changes, phase step changes, and linear frequency variations. Several simulation results show that the total vector error (TVE) tends to increase linearly with the step size. However, the peak TVE increments for a given step size are quite similar for all the considered techniques and are dominated by amplitude or phase errors, depending on whether the step affects the waveform amplitude or its phase, respectively. In this paper, the response times of the considered estimators for two different TVE thresholds are also analyzed and compared as a function of the step size, to assess their compliance to the requirements of the standard. Further simulation results show that in the case of linear frequency variations, responsiveness is not an issue and the TVE values of all estimators lie within the same worst case boundaries as those related to the case of static off-nominal frequency offsets. [ABSTRACT FROM AUTHOR]

The real-time high-accuracy measurement of waveform phasors is one of the many open challenges that need to be addressed in future smart grids. In this paper, the accuracy of four recently proposed synchrophasor estimators is analyzed and compared with the well-known one-cycle discrete Fourier transform estimator under the effect of static frequency offsets, amplitude modulation, phase modulation, harmonic distortion, and wideband noise. Two of the considered techniques track the phasor variations through finite-difference equations that estimate the first- and second-order derivatives of the phasor itself. The other two methods are instead based on a least squares estimation of the coefficients of the phasor Taylor's series expansion. The analysis reported in this paper covers the main scenarios described in the Standard IEEE C37.118.1-2011. In particular, the influence of different signal parameters on the total vector error (TVE) values is quantified and used to determine the maximum TVE increments associated with distinct parameters and the corresponding upper bounds. [ABSTRACT FROM AUTHOR]