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The computation of circulating currents between parallel conductors is a difficult problem in reactor and transformer design. A direct field-circuit coupling FEM model has been established to analyze the magnetic field of air core power reactor. And the circulating current losses has been calculated based on the magnetic field distribution.
This paper presents a dual-buck full-bridge inverter (DBFBI) with different inductor structures. All power devices operate at each half line cycle, and the freewheeling current flows through the independent diodes instead of the body diodes of the switches. Shoot-through problem does not exist. However, the DBFBI has four inductors, so the weight and volume of the inverter may be large. In order to...
The DFIG is excited by converter which is connected rotor. The performance of wind turbine is depended on the matching conditions of the DFIG and converter. And the DFIG equivalent circuit parameter will influence the generator electromagnetic design. Based on the equivalent circuit and the test data, this paper put forward a kind of theory and calculation method to separate the equivalent circuit...
Any failures in these equipments directly reduce network reliability and increase maintenance costs. Consequently, the preventive maintenance techniques are increasingly developed. In this regard, frequency response analysis is an appropriate method in order to diagnose any change which occurs in transformer physical construction. This contribution has been concentrated on fault diagnosis by use of...
Under the effects of DC voltage and polarity reversal voltages, electric field distribution in valve winding of converter transformer gets more complicated than common power transformer. The polarity reversal electric field of converter transformer is computed by finite element software. The effects of insulation material resistivity to polarity reversal electric field are analyzed.
A power transformer operating in electric network is supplied by voltage source. When analyzing leakage flux and magnetic forces of the power transformer applied to windings, the field-circuit coupled 3D finite element method is needed because of the drawbacks of magnetic dipole model and 2D finite element method. The models were used for simulating and analyzing leakage flux and magnetic forces data...
Six-phase motors are widely used in industry, for they can be useful in increasing motor capacity with limit voltage level, and be more reliable in continuous operating and be more robust in performance controlling. Up to the present, there have been many researches on six-phase motors, and they are usually analyzed by analytical methods. However, most of six-phase motors are used with variable frequency...
With the increase of switching frequency, dissipation of switching device became one of the most important factors which constrained the efficiency of DC-DC converter. A phase-shifted full-bridge circuit which based on the phase-shifted quasi-resonant converter was introduced in this paper. We developed a switching power supply prototype for 1000W. Some specific circuits, waveforms from the saber...
Monitoring the loss of distribution transformer is very significant for the energy conservation and economic operation of transformer. Off-line approach is the main way used in loss detection in China. In this paper, an on-line detecting method for transformer loss is proposed. The equivalent circuit of transformer is created. Based on the structure and working principle of transformer, the formulas...
Two experimental high temperature superconducting transformers has been designed and built using Bi2223 HTS tape. The transformers are unique in that the magnetic circuit is comprised of air and a silicon steel partial core. The first transformer failed during a full load endurance run and an investigation was carried out to determine the cause of the failure. The cause was believed to be from operating...
This article uses the BEM electromagnetic field calculation way to simulate the internal electric field distribution of shunt reactor, and discusses the internal electric field impact of reactor about shunt reactor sealed surface insulation cracking and the installation position of multi-tap arc-suppression coil. Simulation results show that sealed surface crack is not only easy to cause the sealed...
Details regarding performance can be obtained by detecting the important parameters of transformer. One of the important parameters of transformer is the capacity. The transformer load can be adjusted in time according to the real capacity. Off-line measures are mainly taken in power industry, however, these methods have many disadvantages. In this study, we proposed an on-line capacity detection...
Axial Flux Permanent Magnets (AFPM) machines are a new kind of permanent magnet machines receiving more attention in the two recent decades. Many different structure of this machine was made. Axial flux machine has better "power to weight ratio", "efficiency", "smaller size" and "adjustable air gap" in compare whit radial flux machine. This article tries to...
As the power transformer has been to the direction of high voltage and large capacity. Therefore, the calculation of major insulation and longitudinal insulation has been played a more and more important role in transformer design. Use the simplified equivalent circuit as the calculated model. The calculation software for wave process of power transformer winding is developed with Matlab language...
Two kinds of different arrangements on harmonic-suppressed winding with LC filters is studied in this paper, based on the principle of CRT with simplex control winding. According to the analysis of Equivalent circuit of three-winding transformer, the effect of harmonic-suppressed is optimum when harmonic-suppressed winding is placed between control winding and work winding.The Simulation model of...
Plasma has been formed by exploding a wire in an inductively coupled circuit. Capacitors are discharged through air-cored mutually coupled coils. The exploding wire section of the electrically isolated coil is 0.2 mm diameter copper wire. The energy source is a 21.4 μF capacitor bank, charged to 21.5 kV, producing 0.5 m of plasma discharge in a single turn. Waveforms of voltage and current for the...
Through the analysis of the electromagnetic properties for the rotor coil of turbine generator, we obtained the main magnetic field variation characteristics for the rotor winding and put forward the short circuit fault between rotor inter-turns causing the potential difference and circulation between the parallel branches of generation stator winding spectral method was applied on the spectrum analysis...
In the process of determining and investigating the reasonable operation mode of transformer, how to consider reliability and economic operation of transformer is a very important and necessary work. This dissertation chiefly studies the topic of accounting reliability and economic operation of transformer. Economy and reliability are the most two important index of Power System, but also contradictory...
1000kV/1000MVA UHV the scene of the transformer no-load test for the first time at home and abroad, in particular test voltage of 380V, Measuring mA current level, the corresponding test technology research is very difficult. In addition the transformer core remanence of the impact test results, effectively to demagnetizating UHV transformers is the key to the trial. In this study, using the method...
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