Reliability of a power system is considerably influenced by its equipments. Power transformers are one of the most critical and expensive equipments of a power system and their proper functions are vital for the substations and utilities. Therefore, reliability model of power transformer is very important in the risk assessment of the engineering systems. This model shows the characteristic...

In this study, a disk-shaped piezoelectric transformer was fabricated using lead-free (K,Na)NbO(3)-based ceramics with high mechanical quality factor. The transformer can operate in the fundamental or the third radial vibration mode. The transformer is poled along the thickness direction. The top surface is covered by ring/dot silver electrodes separated by an annular gap which serve as the inp...

Abstract The flexible on-load transformer can be adapted to different application scenarios by adding power electronic converter structures through the use of existing transformers. In this paper, a regulator structure based on floating capacitor multi-level AC/AC is proposed, which compensate input voltage primary side in same direction or opposite direction, combine with tap-changer, and also...

electric arc furnaces (eafs) are unbalanced, nonlinear and time varying loads, which can cause many problems in the power system quality. in steel industries, the two arc furnaces often perform in parallel and stand on a single bus, which surely deteriorate the power quality. in this paper, in order to study and analyze the harmful effects of parallel operation of eafs, first, a three phase arc...

Risk assessment for power transformer is an important means to guide the condition based maintenance of transformer and enhance the reliability of power system operation, but also to strengthen the power transformer to provide an important basis for quality control. In this paper, an index system for comprehensive evaluation of transformer is put forward and a risk assessment model for power tr...

In this paper, a new model based on the thevenin equivalent circuit for investigating the ultra-saturation phenomenon during the energization of a loaded power transformer is presented and its effect on the differential protection of the transformer is considered. The ultra-saturation phenomenon causes the mal-operation of the power transformer differential protection. So, the description a...

An electronic current transformer with a B-dot sensor is proposed in this study. The B-dot sensor can realize the current measurement of the transmission line in a non-contact way in accordance with the principle of magnetic field coupling. The multiple electrodes series-opposing structure is applied together with differential input structures and active integrating circuits, which can allow th...