Transformer insulating oil nanofluid is made to improve dielectric and thermal properties of the oil by employing nanoparticles with proper properties. In the current work, nanofluids based on transformer mineral oil were prepared by three procedures using diamond nanoparticles with high thermal conductivity, as well as high dielectric properties. It was tried to consider the impacts of surfact...

Magnetic core saturation of transformers and rotating machines generate harmonics. Harmonics are integer multiples of the fundamental frequency. Harmonics is caused by nonlinear devices in the power system. Due to the non-linear loads, power frequency harmonics exist mainly in distribution systems. The current harmonics cause voltage harmonics, hence resulting in nonsinusoidal supply voltage in...

The delta primary transposed zigzag secondary (DTz) transformer has been designed and used to reduce the bad impacts of the harmonic in the distribution power system. The DTz transformer is constructed with delta connection in primary winding and the three transposed windings at the different core legs of secondary winding. The harmonic reduction method of the DTz transformer applies two basic ...

The power supply analysis and design results of Sherman and Hamacher are extended to include approximate solutions to the nonlinear equations that define the rectifier turn-on angles. Additionally, peak rectifier current solely as a function of ripple factor, as well as the inverse relationship, i.e., ripple factor as a function of peak rectifier current, are also provided. Simplified exact equ...

This paper presents a novel fault location method for series compensated transmission lines. It is established based on synchronized voltages sampling and Thevenin impedance from both ends of series compensated transmission line. The method is based on the use of phasor measurement units (PMU) technology which is aimed to be independent of current measurements, fault type, fault resistance, fau...

Photovoltaic systems integrated to the grid have received considerable attention around the world. They can be connected to the electrical grid via galvanic isolation (transformer) or without it (transformerless). Despite making galvanic isolation, low frequency transformer increases size, cost and losses. On the other hand, transformerless PV systems increase the leakage current (common-mode c...

In this paper a modular power electronic transformer (PET) for feeding critical loads is presented. The PE based transformer is a multi-port converter that can connect to medium voltage levels on the primary side. Bidirectional power flow is provided to the each module. The presented structure consists of three stages: an input stage, an isolation stage, and an output stage. The input current i...

In this paper, a differential protection schemes using fuzzy inference system (FIS) for power transformer protection is presented. First we review the concept of differential protection, and illustrate the magnetizing inrush current as they belong to the causes of the protection maloperation. Then relay logic and the algorithm that uses Discreet Fourier transformer for extraction of fundamental...

This paper takes a typical 220 kV three-phase three-limb oil-immersed transformer as an example, this paper building transient field-circuit coupled model and 3D coupled magneto -fluid-thermal model. Considering a nonlinear B–H curve, the magneto model uses the field-circuit coupled finite element method (FEM) to calculate the magnetic flux distribution of the core and the current distribution ...