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The estimations of amplitude and phase are of great importance in the synchronous phasor measurement for power systems. In addition to the off-nominal frequency, the amplitude and phase estimations accuracy level of the power system signal is affected by the inevitable noise. In this article, the effect of white noise on amplitude and phase estimations provided by DFT-based frequency shifting and filtering algorithm (FSF) is analyzed. With the help of the equivalent weighting filter’s merits, i.e., equivalent noise bandwidth and overlap correlation, the FSF-based amplitude and phase variance expressions are derived theoretically by considering the overlap of two processed samples. The effectiveness of the proposed amplitude and phase variance expressions are verified through computer simulations.

The frequency shifting and filtering (FSF) algorithm, a variant of DFT, has the merit of high efficiency for frequency analysis thanks to its simple implementation in the time domain. However, the inevitable white noise injected by various factors leads to inaccurate frequency estimation in practical measurement. This article investigates the influence of a stationary white noise on FSF-based frequency estimation of the power system. The variance expression of the frequency estimator is derived theoretically and compared to its unbiased Cramer–Rao lower bound (CRLB). The obtained results are validated by several computer simulations.

Medium-voltage cable joints are one of the critical components of the distribution networks. They represent the first cause of faults and outages. Among the others, partial discharge, dielectric, and temperature measurements are the typical tests performed for investigating over the early aging of such critical components. In this paper, a new study has been completed correlating the cable joint tangent delta (Tan $\delta$ ) value to the external pressure applied on the insulating material surrounding the joint. Results confirm the presumed correlation. In fact, an increase of pressure results in a Tan $\delta $ decrease, hence in an extension of the cable joint working life.

This paper presents the study of the propagation of the effects of uncertainties in a typical measurement system for modern power networks. Nowadays there is a strong demand from the electricity industry of simple and ready-to-use solutions for calculating uncertainty in such ``new'' measurement systems. To this purpose a simplified approach is presented whose results are shown to be in good agreement with those provided by conventional but more complex methods. Two applications, rather simple but very common, are considered in this paper. In the first one, the measurement of a voltage phasor is considered and the measurement chain is made by an low power instrument transformer (LPIT) and a converter used for adapting the level of signals from the LPIT to the inputs of intelligent electronic device. The second application deals with the measurement of active power of a system made by a low power voltage transformer (LPVT), a low power current transformer and a powermeter.

In this paper, the measuring and calibration techniques useful for ensuring the traceability of nonconventional voltage transformer (VT), used in ac power plant up to 52 kV, are described and discussed. In particular, a setup made by commercially available devices is presented and an in-depth accuracy analysis is performed by considering all the uncertainty sources located in the measurement chain. The obtained results prove that it can be used for the calibration of 0.5 accuracy class low-power VTs. In addition, the sources that contribute more to the uncertainties on the ratio and phase errors are highlighted and suggestions on where to act to further improve the accuracy of the presented setup are given.

Current measurement is required to ensure the correct operation of power systems. Conventional current transformers are still widely employed in such networks, but their well-known limits make them not suitable for the incoming smart meters. In this paper, a current sensor based on proper measurements of the magnetic field produced by the primary current is proposed. Its main feature is the capability, owing to its particular geometry, of neglecting the effect of external fields without using traditional coil structure. An experimental analysis of its performance in both time and frequency domains is presented and discussed.

Flicker annoyance measurement, regardless if it is performed by processing the supplying voltage or by evaluating the light emitted by the lamp, relies on the assumption of a proper model of the behavior of the complex eye-brain system in the presence of fluctuating light. The only experimental data available are the ones obtained, for a certain incandescent lamp, by asking several people to report their perception about the flicker to which they were subjected. In this paper, the possibility of achieving an ldquoobjectiverdquo evaluation of the flicker effects on a human subject is investigated. In particular, the increment of the blood flow in a vessel at the optic nerve is considered and taken as a possible index of annoyance due to flicker.

The Remote Didactic Laboratory Laboratorio Didattico Remoto - LA.DI.RE. ldquoG. Savastanordquo is the e-learning measurement laboratory supported by the Italian Ministry of Education and University. It involves about 20 Italian universities and provides students of electric and electronic measurement courses with access to remote measurement laboratories delivering different didactic activities related to measurement experiments. In order to demonstrate the versatility for didactic use, the overview of some experiments is given. The didactic experiments summarized in this paper concern measurement characterization of instruments and communication systems, measurement devices for remote laboratories, basic electrical measurements, magnetic measurements, electromagnetic-interference measurements, and signal processing for measurement applications.

The instruments dedicated to the characterization of transient disturbances affecting the power supply contain an event-detection block that activates the storage and processing functions only when necessary. A simple, robust, and fast algorithm that can easily be loaded on a DSP board to implement the above block was proposed by the authors in a previous contribution. In this paper, a study on the effects of the DSP characteristics on the algorithm performance has been developed. This paper leads to a conclusion that has been validated by means of experiments and provides optimization rules that are presented

A statistical approach to estimate the trend, over a long time interval, of electrical parameters is proposed in this paper. The trend is determined by processing a limited number of parameter values measured at instants randomly chosen. Experimental results are reported, which show the good performance of the method proposed when it is applied to estimate customers' loads profiles and the trend of some parameters providing information on power quality.

A broadband digital harmonic vector voltmeter proposed previously and studied theoretically by the authors was implemented using a special-purpose, random sampling strategy, to avoid the bandwidth limitations due to the finite conversion time of the sample-and-hold and analog-to-digital-conversion (S/H-ADC) devices. The experimental results have shown that the bandwidth of the instrument is not limited by the finite conversion time of S/H-ADC devices, since good accuracy can be achieved even when the average sampling frequency is much lower than the signal bandwidth. The amplitude and phase uncertainty, with sinusoidal test signals up to 1 MHz and an average sampling rate of 10 kHz, was found to be lower than 3% and 0.03 rad, respectively. For more careful testing of the broadband performance of our instrument, we also carried out two-frequency, variable order harmonic measurements, which showed good accuracy (amplitude error less than 1.5% and phase error less than 0.03 rad) with harmonics up to 300 kHz. Reasonable accuracy (i.e., sufficient to correctly reconstruct the actual signal waveform) was also found with a highly distorted square-wave signal.

The IEEE International Workshop on Applied Measurements for Power Systems (AMPS) is the main event promoted by TC-39 of the Instrumentation and Measurement Society (Measurements in Power Systems). It was held in Aachen, Germany, from September 28 to 30, 2016, and in its seventh edition was hosted again by the E.ON Energy Research Center, RWTH Aachen University. In the recent years, the workshop has continuously shown increasing numbers. It was, once more, a fruitful scientific meeting involving attendees from both industry and academia.

The six papers in this special section are extended versions of papers presented at the Second IEEE International Workshop on Applied Measurements for Power Systems (AMPS), held at the E.ON Energy Research Center, RWTH Aachen University, Germany, on September 28-30, 2011.

This paper addresses one of the new and most important issues arising when low-power voltage transformers (LPVTs) are used in power network substations for evaluating, among others, the residual voltage measurement. Conversely to open-triangle inductive instrument transformers, the use of phase voltage transformers for measuring the residual voltage gets challenging due to the very high accuracy required for the three LPVTs. In this paper, a general expression to estimate the residual voltage measurement uncertainty, starting from the LPVTs accuracy, is presented. The effectiveness of the proposed approach is then confirmed with both Monte Carlo simulations and actual measurements on a general three-phase system.