Search results for "transformer"
showing 10 items of 96 documents
Metrological performances of voltage and current instrument transformers in harmonics measurements
2018
In the new electrical system scenario, the increasing presence of non-linear loads and renewable energy sources makes the measurement of harmonics an essential task. The accuracy of harmonic measurement firstly depends on the used instrument transformers for voltage and current sensing. Since the behavior of instrument transformers in non-sinusoidal conditions is not always well defined, this paper presents an experimental study on the metrological performances of current and voltage instrument transformers (CTs and VTs) in the presence of harmonics. Proper tests procedures are defined and measurement setups are developed for both CTs and VTs calibration. The analysis is carried out by usin…
On the design of a high current power supply for superconducting magnet
2002
The purpose of the article is the description, considerations of design and presentation of experimental results of a high current (1000 A) and low voltage (up to 15 V) converter for the excitement of superconducting corrector magnets in particle accelerators. The power source, which is based on a ZVT converter, presents high efficiency, small output ripple, excellent regulation of line, and fulfilment of the EMC normative (VDE 0871 A).
Experimental Evaluation on Narrow Band Power Line Communication in Medium and Low Voltage Smart Grids
2013
The aim of this work is to perform a feasibility study on the power line communication for the development of a new generation of interface devices (IDs) for smart grid and energy storage applications. More in detail, this paper deals with one of the most important issues on this topic, which is the communication system. Among the existing communication technologies, the study is focused on power line communications (PLCs). After an analysis of the state of the art in the field, the main aspects are analyzed, concerning the open issues on the use of PLCs, especially for medium voltage (MV) and low voltage (LV) systems. In this work the use of PLC in MV-LV networks is investigated, by means …
Current transformers effects on the measurement of harmonic active power in LV and MV networks
2011
The harmonic active power is used to determine the location of polluting loads, the direction of harmonic power flow and to estimate how consequential a certain current harmonic source is. The highest uncertainties, when measuring harmonic active power, are introduced by the current and voltage transducers. This paper presents experimental results which show the impact of current transformers (CTs) on the accuracy of the harmonic power measurements. An expression for the evaluation of the power error in distorted conditions was developed which can be easily utilized in the case of linear current transducers. It is shown how CTs cannot be considered linear transducers and how the higher the …
Medium Voltage Smart Grid: Experimental Analysis of Secondary Substation Narrow Band Power Line Communication
2013
This paper is focused on the possibility of employing narrow band power line communication (PLC) in medium voltage (MV) distribution networks. The topic is investigated by means of both simulations and experimental tests, which were carried out in the distribution network of Ustica Island. In detail, a two-way MV communication was tested between two secondary substations connected by an MV cable power line. Each substation has a by-pass connection at MV bus-bars and an MV/LV oil filled power transformer. In this paper, the MV and the PLC systems under test are described and the experimental tests are presented, which were carried out to evaluate the parameters of the simulation model. The a…
Small-Signal Modeling of a Controlled Transformer Parallel Regulator as a Multiple Output Converter High Efficient Post-Regulator
2004
This paper presents a post-regulator based on the use of a controlled transformer, which adds or subtracts an additional voltage to the output filter of a converter in order to regulate its output voltage. So, their actuation is complementary to that of more known post-regulators, such as the magnetic amplifier (magamp) and synchronous switch post-regulator (SSPR), because the regulation is achieved by controlling the voltage across the filter inductor instead of its charge time. Besides, the post-regulator processes the power in parallel to the one flowing from input to output and only handles a percentage of it. The post-regulation by controlled transformer is suitable of being employed i…
Sound and reusable components for abstract interpretation
2019
Abstract interpretation is a methodology for defining sound static analysis. Yet, building sound static analyses for modern programming languages is difficult, because these static analyses need to combine sophisticated abstractions for values, environments, stores, etc. However, static analyses often tightly couple these abstractions in the implementation, which not only complicates the implementation, but also makes it hard to decide which parts of the analyses can be proven sound independently from each other. Furthermore, this coupling makes it hard to combine soundness lemmas for parts of the analysis to a soundness proof of the complete analysis. To solve this problem, we propose to c…
Fast fringe pattern phase demodulation using FIR Hilbert transformers
2016
This paper suggests the use of FIR Hilbert transformers to extract the phase of fringe patterns. This method is computationally faster than any known spatial method that produces wrapped phase maps. Also, the algorithm does not require any parameters to be adjusted which are dependent upon the specific fringe pattern that is being processed, or upon the particular setup of the optical fringe projection system that is being used. It is therefore particularly suitable for full algorithmic automation. The accuracy and validity of the suggested method has been tested using both computer-generated and real fringe patterns. This novel algorithm has been proposed for its advantages in terms of com…
Characterization of clamp-on current transformers under nonsinusoidal conditions
2009
This paper reports the performance of clamp-on current transformers under nonsinusoidal conditions. A set of experimental measurements helped to determine the ratio and the phase errors under two conditions: 1) sinusoidal excitation with frequencies from 45 to 1000 Hz and 2) nonsinusoidal excitation using the fundamental frequency and one harmonic, with adjusted phase shift. It was found that ratio and phase errors are affected by the phase angle between the harmonic and the fundamental and the harmonic amplitude. The effects of conductor location in the current transformer's window and of the air-gap width were also investigated. It was concluded that harmonic phase and ratio errors measur…
1/f noise in streaming electrification
2005
The paper presents the measurement results of the noise generated by static electricity. The tests were performed in the spinning-disk system. Insulation liquid (transformer oil) was used for electrostatic charge generation. The element measured was the current flowing to the disk surface. A stochastic term is present in the current. Existance of this term is due to the complex chemical constitution of the oil. A relaxation of the polar molecules has inertial character. The spreading of a large amount of the relaxation phenomena can lead to forming a compounded spectrum close in shape to 1/f noise. Power spectral density of the polarization was defined for periodic step function. The calcul…