This paper presents the design and analysis and of the proposed zero voltage zero current switching (ZVZCS) full bridge dc-dc converter with transformer isolation and current doubler rectifier for high power and high performance by introducing ZVS for lagging leg and ZCS for leading leg operation It has a simple and robust structure with asymmetrical shifted pulse width modulation technique. Th...

This paper proposes a wireless ZigBee technology to monitor the parameters of the transformer. The transformer parameters such as voltage, current, power factor and temperature can be monitored through wireless ZigBee technology. Embedded Ethernet is used to develop client and server applications. Acquisition of voltages, currents, temperatures, active and reactive power, controlling the switch...

harmonics have become an important issue in modern power systems. the widespread penetration of non-linear loads to emerging power systems has turned power quality analysis into an important operation issue under both steady state and transient conditions. this paper employs an extended harmonic domain (ehd) based framework for dynamic analysis of long term analysis over voltages during the tra...

Original scientific paper Measurement of grid voltage harmonic components is an important part of power quality measurements. Current high voltage transformers with iron core are not linear and cannot easily be used for accurate measurement of "polluted" voltages in wide frequency range. In this paper, design details of a new coreless voltage transformer for power quality measurement are given....

This article puts forward a new algorithm based on Kullback–Leibler divergence (KLD) for discriminating inrush and internal fault currents in power transformers. Specifically, the main idea of this is to utilize current signal discrepancy distribution with ideal waveforms. To such an aim, proposed index reproduces differential signal. Utilizing fast modified least squares technique, generated. ...

More and more sub-stations are retrofitted with numerical relays, meters and monitoring devices. Most often, the older relay gets replaced with a newer relay with the rest of the installation such as Current Transformer (CT) and lead remaining undisturbed. Utilities have standardized on their older current transformers and want to maintain the same current transformer specifications throughout ...

This paper deals with diagnostic methods of the internal faults in power transformers. The diagnostic process uses some of the current diagnosis methods (e.g. oil test, dissolved gases analysis (DGA), partial discharge (PD), etc.) to determine the condition of the transformer. In this process, the most frequent diagnostic methods were listed and applied practically to be compared. A conventiona...

Among the most noticeable root causes of improper performance in power transformers, internal short circuit faults can be noted and if not quickly be identified and addressed in the accepted time interval, irrecoverable damages such as interruption or even collapse of the network connected to the power transformer would happen. In this contribution, three-phase transformer behaviors under magne...

(Received: October 30, 2011; Accepted: December 8, 2011) Abstract: This paper presents a novel technique for transformer differential protection to prevent incorrect operation due to inrush current. The proposed method in this paper is based on time-frequency transform known as the Wavelet transform. The discrete Wavelet transform is used for analysis the differential current signals in time an...

Electromagnetic forces in power transformer windings are produced by interaction between the leakage fluxes and current passing them. Since the leakage flux distribution along the windings height is in two axial and radial directions, so the electromagnetic forces have two components, radial and axial. There is a risk that a large electromagnetic force due to the short circuit or inrush current...