This paper proposes a transformer-assisted pulsewidth-modulation zero-voltage-switching neutral-pointclamped (NPC) inverter. With the assistance of a transformer-assisted small-rating lossless auxiliary circuit, the main switches work with zero-voltage switching without suffering from any voltage/current spikes, under simple explicit control. The technique allows for higher operating frequency ...

Power systems and transformer are intrinsic apparatus, therefore its reliability and safe operation is important to determine their operation conditions, and the industry uses quality control tests in the insulation design of oil filled transformers. Hence the service period effect on AC dielectric strength is significant. The effect of aging on transformer oil physical, chemical and electrical...

This paper presents an artificial neural network (ANN) approach to predicting and classifying distribution transformer specific iron losses, i.e., losses per weight unit. The ANN is trained to learn the relationship of several parameters affecting iron losses. For this reason, the ANN learning and testing sets are formed using actual industrial measurements, obtained from previous completed tra...

Significance: Dec 29, 2001 Identified By: NRC Item Type: FIN Finding DEGRADED AND INADEQUATELY TESTED TRANSFORMER AND PROTECTIVE RELAYING RESULTS IN INCREASE IN TRANSIENT AND LOSS OF OFFSITE POWER INITIATING EVENT FREQUENCIES On August 2, 2001, Unit 2 experienced a transformer failure, reactor scram, and loss of offsite power. The inspectors determined that a lightning strike in conjunction wit...

This paper describes interconnection between technical and economical making decision. The reason of this dealing could be different: poor technical condition, change of substation (electrical network) regime, power transformer owner budget deficit and increasing of tariff on electricity. Establishing of recommended practice as well as to give general advice and guidance in economical sector, t...

Abstruct-This paper proposes a transformer assisted PWM zero voltage switching Neutral-Point-Clamped (NPC) inverter. With the assistance of a transformer assisted small rating lossless auxiliary circuit, the main switches work with zero voltage switching without suffering from any voltage/current spikes, under simple explicit control. The technique allows for higher operating frequency and bett...

This paper presents the use of Artificial Neural Networks (ANN) as a pattern classifier for the combined differential protection of generator-transformer unit with an aim to build a backup protection system to improve the overall reliability of the system. The proposed neural network model is trained and tested with an efficient Resilient Back propagation (RPROP) algorithm and Genetic Algorithm...

Generation, transmission and distribution of electric energy are to be characterized by a very high degree of reliability. Reliability level is directly related to the quality of the equipment used and the periodic maintenance carried out on the system. In our country, the distribution system is the most neglected part, which is being given some importance only in the recent years. Distribution...

power system overvoltages due to switching, lightning and other disturbances are the main problem for designers of the power transformers. once some frequencies of the incoming surges match with some of the natural frequencies of transformer winding, the resonance phenomenon is expected in transformer winding. the resonant overvoltages may destroy the insulation between turns and cause to insul...

Frequency response analysis (FRA) is a sensitive ‎method established for testing the mechanical integrity of ‎transformers. However, interpretation of FRA signature still ‎needs expert opinions and there is no FRA interpretation code ‎generally accepted. Various mechanical faults with different ‎extents on power transformers are required to aid FRA ‎interpretation. To address this challenge, in...