This paper proposes a restricted earth fault protection based on the wavelet transform (REFW) for detecting ground faults close to transformer neutral point (turn-to-ground faults) and supporting conventional phase differential protection, which presents limitations in this kind of faults. The proposed REFW uses only high-frequency components instead phasor estimation, speeding up detection tur...

Power transformers in transmission network are utilized for increasing or decreasing the voltage level. Power Transformers fail to connect directly to the consumers that result in the less load fluctuations. Power transformer operation under any abnormal condition decreases the lifetime of the transformer. Power Transformer protection from inrush and internal fault is critical issue in power sy...

This paper presents the general knowledge, theory and methodology of life management that used in electric power transformer. The paper also discusses the basic failure theory and method to establish failure model of power transformer. Insulation ageing is a problem due to dielectric, chemical, thermal and electro-mechanic stresses, which is highly depending on operational conditions. Life mana...

This paper proposes a Flexible Power Electronic Transformer (FPET) for the application in the micro-grids. The low frequency transformer is usually used at the Point of Common Coupling (PCC) to connect the low voltage grid and utility network to each other. The conventional 50Hz transformer results in enhanced low voltage-grid power management system during grid-connected operation. In this pap...

Protection systems have vital role in network reliability in short circuit mode and proper operating for relays. Current transformer often in transient and saturation under short circuit mode causes mal-operation of relays which will have undesirable effects. Therefore, proper and quick identification of Current transformer saturation is so important. In this paper, an Artificial Neural Network...

this work studies the effect of neutral earth resistance on the controlling ferroresonance oscillation in the power transformer including MOV surge arrester. A simple case of ferroresonance circuit in a three phase transformer is used to show this phenomenon and the three-phase transformer core structures including nonlinear core losses are discussed. The effect of MOV surge arrester and neutra...