February 8th

On the thickness of phosphor coating in fluorescent lamps and its impact on selected light parameters

This article presents the results of research carried out on the formation of light parameters of the phosphor coatings and surfaces of fluorescent lamps. Particular attention has been paid to those parameters which influence the formation of light parameters such as light efficacy and ripple. The results of the measurements of light efficacy and light ripple are given in terms of the thickness of coatings and some of the physical parameters of phosphors used in AC powered mains frequency fluorescent lamps.

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February 7th

Analysis of Vienna rectifier

It is common to find the inexpensive but robust electric power rectification method to fulfil the demands of clean power conversion. The Vienna rectifier structure is one of the hopeful construction to fulfil these demands. It may be classified as the Clean Power Converter. It lets us obtain PFC rectification in simpler than the PWM converter system. The Vienna rectifier has three control points.

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February 6th

Analysis of operation of class E ZVS resonant inverter

The article discusses class E zero-voltage-switching resonant inverter (ZVS). The resonant circuit of the inverter is subject to mathematical analysis using the method of state variables with the aid of MATLAB software. Results of simulation testing, based on Simplorer software, of an inverter at the operating frequency of 100kHz are presented.

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February 5th

Practical issues in frequency disturbance recorder design for wide-area monitoring

To maintain power system operation in a balanced and stable condition, the frequency deviation and the rate of frequency change information are highly desired in monitoring and protection applications of the power grid. How to obtain frequency information more accurately and efficiently has been the topic discussion for decades. PMUs (Phasor Measurement Unit) are the most widely-used devices for measuring phase angle differences and they also provide very accurate frequency information.

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February 4th

An optimum reactance one-port compensator for harmonic mitigation

The installation of electronic devices, digital equipment, and nonlinear loads in both industrial and domestic applications have dramatically increased in recent years, which in turn increased the level of harmonics in the system. Harmonic distortion is widely recognized as a significant cause of damage to, and mal-operation of electrical equipment. A harmonic filter can eliminate the potentially dangerous effects of harmonic currents created by nonlinear loads.

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February 3rd

A multi-pulse diode rectifier with a coupled three-phase reactor

The article presents the principle of operation, design method, and results of laboratory and simulation tests of a 24-pulse power network converter system with direct-voltage output, the concept and practical realisation of which was worked out within the framework of a research project financed by the State Committee for Scientific Research.

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February 2nd

Advantages of changing 3-phase arc furnaces asymmetry estimation criteria in international and european standards

The criteria for estimating the asymmetry of arc furnace circuit impedances, referring to the theory of symmetrical components, have been presented. In contrast to the criteria recommended as yet by IEC and CENELEC, they give homogeneous estimation of asymmetry of circuit impedances, heating powers and unbalance of arc currents.

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February 1st

Passive Filters for Minimum Life Cycle Cost

Harmonic currents can originate from systems that do not contain energy and in which the sign of the current matches that of the voltage throughout the cycle (e.g. a phase-angle controller for an incandescent lamp). The term ‘wattless current’ is sometimes applied to harmonic currents that do not have substantial voltage harmonics of the same orders to multiply them. The result is a product of current and voltage that is zero. Those harmonic currents have a lot in common with reactive currents:

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Optimal placement and sizing of distributed generator units using genetic optimization algorithms

In this article the authors describe how genetic optimization algorithms can be used to find the optimal size and location of distributed generation units in a residential distribution grid. Power losses are minimized while the voltage profile is kept at an acceptable level. The methods is applied on a system based on an existing grid topology with production and residential load data based on measurements. Different scenarios are chosen to run the algorithm.

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