Search

The phase estimation accuracy level of voltage and current signals of the power network is affected by the inevitable noise. In this paper, the effect of the white noise on phase estimation provided by frequency shifting and filtering (FSF) is analyzed. With the help of the Equivalent Weighting Filter's merits, viz., Equivalent Noise BandWidth and Overlap Correlation, the FSF-based phase variance expression is derived theoretically by considering the overlap of two processed samples. The effectiveness of the proposed phase variance expression is verified through computer simulations.

The use of Low-Power Instrument Transformers is spreading among the network and Standards are providing all the necessary information for their usage. However, practical applications adopt such definition with a certain delay (which could be years) with respect to their publication. To this purpose, the paper presents a simple Rogowski modelling procedure, for nonexperts, to predict the Rogowski output when used under nonstandard conditions. In addition, the procedure allows to have a clear knowledge of each device for further testing. Provided measurement results confirm the effectiveness of the proposed procedure.

The paper presents a study on electrical energy meters. The huge installation along the distribution network of these devices made them a key element to measure the electrical quantities of the grid. The meters operation is regulated by different Standards, which do not always coincide and prescribe the same rules. To this purpose, the paper provides a brief comparison between the latest Standards and afterwards a new set of tests are proposed. Such tests, focused on the role of the frequency in the energy measured by the meters, have been applied on two off-the-shelf class B meters.

The paper deals with the evaluation of the accuracy variation of inductive current transformers vs. ambient temperature. There is a lack of information regarding if and how the accuracy of inductive current transformers changes with respect to temperature variations. To this purpose, in this paper a proper setup is presented and used for evaluating the performance of two inductive current transformers available on the market used for billing purposes. Such a topic is of paramount importance given that, at present, inductive current transformers are commonly still used for the specific tariff and pricing.

The paper addresses one of the new and most important issues arising when Low Power Voltage Transformers (LPVT) are used in power network substations for evaluating, among others, also the residual voltage. 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 the paper, an analytical study will be presented along with simulation results in order to show the relationship between the accuracy class and the uncertainty affecting the residual voltage value.

The diffusion of LED lamps on the market is becoming increasingly wide and it is expected that, in a few years, they become a sort of standard de facto for lighting of houses as well as offices. As a consequence, they can be considered for replacing the incandescent bulb in the international standard for flicker measurement given that, as it is well known, this last lamp is banned from the market and hence the measurement of flicker severity is no more related with the actual annoyance caused by the light fluctuation. In this connection, this paper will investigate the behavior of several same-power LED bulbs under nonsinusoidal voltage conditions to verify if it is possible to choose a specific LED source as a reference for flicker evaluation.

This paper deals with the problem of synchronizing phasor measurements in different nodes of a power network. Usually, this issue is faced by using a synchronization signal provided by wired or wireless communication infrastructure. As it is well known, the most common implementation of such a solution is the so-called Phasor Measurement Unit (PMU) which relies on a time reference signal coming from the GPS system. In this work, an alternative approach based on asynchronous measurements is presented and discussed. In particular, it is firstly shown how an equivalent synchronization among different nodes can be obtained by performing voltage and current measurements in all the nodes of the considered network. After that, an equivalent synchronization when only 75% of the nodes are monitored, is presented.

In this paper authors present the result of a study oriented to assess the metrological characteristics of measuring systems used for verifying the variation of the ratio errors and phase displacements of inductive voltage transformers vs. temperature. Experimental results show that the designed equipment as well as the set up realized can be considered as a benchmark for the verification of the variations of ratio errors and phase displacements of up to 0.1-accuracy class voltage transformers vs. temperature. In addition, the sources that more contribute to the uncertainties on the ratio and phase errors have been investigated and discussed in the paper along with suggestions on where to act to further improve the accuracy of the presented set up.