This thesis describes how to provide standardized, current based, differential protection for any three-phase power transformer, including phase-shifting transformers with variable phase angle shift and transformers of all construction types and internal on-load tap-changer configurations. The use of standard transformer differential protection for such applications is considered impossible in ...

The algorithms of the present generation practical differential relays are based on two methods. first method is ratio harmonic content current, and second one length time interval between zero-crossing points called gap-detection method. However, these methods suffer from installation fault current limiters (FCLs) in power system transformer (CT) saturation phenomenon. This paper deals with a ...

The more sophisticated a protection algorithm, the more information on both steady-state and transient behavior of a protected element required for proper designing, setting and testing of a given relay. In the case of a power transformer, the most important phenomena to be modeled from the standpoint of protective relaying are: magnetizing inrush including initial, recovery and sympathetic inr...

Abstract In power systems, busbars connect important components such as generators, transmission lines, and loads. A typical fault occurrence on the busbar may result in isolation of faulty sections from other normally operating parts system resulting differential protection operation. Although main busbars' scheme is protection, its operation significantly affected by magnetic saturation curre...

This study presents a novel technique based on Support Vector Machine (SVM) for the classification of transient phenomena in power transformer. The SVM is a powerful method for statistical classification of data. The input data to this SVM for training comprises fault current and magnetizing inrush current. SVM classifier produces significant accuracy for classification of transient phenomena i...

this paper presents a new arc starter circuit that is usable in manual metal arc welding (mma) power supplies. the proposed circuit uses an auxiliary circuit and a series coupling transformer for adding high frequency spikes to output dc voltage during arc striking. the proposed circuit is usable in inverter based arc welding supplies and it could result in a decrease of weigh, volume and expen...

Multilevel inverters are a source of high power, often used in medium-voltage application. Multilevel converters have received increased interest recently due to high quality output waveform and decrease the harmonic distortion in the output waveform without decreasing the inverter power output. A multilevel inverter uses a series of semiconductor power converters, thus generating higher voltag...

This research studies the forces on the windings of transformer due to inrush current. These forces are compared with the corresponding forces due to short-circuit of the windings. Twodimensional finite element computation of a single-phase shell-type transformer is carried out based on the maximum permissible inrush current value where its amplitude is the same as the rated shortcircuit curren...

ac railway traction loads are usually huge single phase loads. as a result, a significant amount of negative sequence current (nsc) is injected into utility grid. moreover, harmonics and consumption ofreactive power are further power quality problems that the supply network is encountering. in this paper, acompensation strategy with the aid of railway power conditioner (rpc) is proposed to over...

The objective of this research is to compute the mechanical stresses in power transformer resulting from the currents more than rated value during its operation. Due to this high fault current, mechanical stresses are produced indifferent directions which may cause the damage of winding insulation. Various techniques have been adopted to analyze the stresses on transformer windings. For the acc...