EPQU Journal - Volume 11 Issue 1
By HDK / Published on Fri, 2009-05-29 07:58
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By Isabelle Heriakian / Published on Sat, 2005-02-12 18:07
This article presents the effect of secondary circuits of inductive current and voltage transformers on measuring accuracy in HV power networks. The basic parameters of instrument transformers were defined, such as errors or rated output. The impedance effect of the leads connecting secondary terminals with measuring instruments and the impact of burden power on the energy measuring error were analyzed. The calculation samples illustrate the procedure when assessing energy (power) measuring error.
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By Isabelle Heriakian / Published on Fri, 2005-02-11 18:13
General testing procedures for testing different types of electrical equipment against various types of voltage sags and short interruptions are proposed and described in this paper. The recommendations for testing are discussed with respect to a number of sag and interruption parameters, non-ideal voltage supply characteristics, type of equipment, operating/loading conditions of the equipment and multiplicity of the malfunction criteria of the equipment. Presented analysis is illustrated using the examples of equipment sensitivity identified in tests.
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By Isabelle Heriakian / Published on Thu, 2005-02-10 18:18
The paper deals with the new method of analysis, synthesis and experimentation of single-phase power active filters. By using a new particular transformation theory, the ordinary single-phase system can be transformed into an equivalent two-axes orthogonal one. The new original thought is based on the idea that ordinary single-phase quantity can be complemented by fictitious second phase so that both of them will create an orthogonal system, as is usual in three-phase systems.
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By Isabelle Heriakian / Published on Wed, 2005-02-09 18:22
Voltage flicker caused by the electric arc furnace (EAF) and the mitigation using the superconducting synchronous condenser (SuperVAR) by the American Superconductor Corp. are considered in this paper. The modeling of EAF, SuperVAR and the system used are discussed. Fast reactive power support to reduce voltage flicker problem by an EAF is desirable. We use the voltage fluctuation amplitude as an index to evaluate the effectiveness of SuperVAR for two different MVar levels.
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By Isabelle Heriakian / Published on Tue, 2005-02-08 18:31
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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By Isabelle Heriakian / Published on Mon, 2005-02-07 18:40
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. In addition the Vienna rectifier is the three voltage level system with less current ripples than in the case of the PWM converter. However, it has some disadvantages.
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By Isabelle Heriakian / Published on Sun, 2005-02-06 18:45
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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By Isabelle Heriakian / Published on Sat, 2005-02-05 01:00
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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By Isabelle Heriakian / Published on Fri, 2005-02-04 01:00
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. There are two types of harmonic filters: passive filters and active filters.
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By Isabelle Heriakian / Published on Thu, 2005-02-03 01:00
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. The presented converter allows significant reduction of undesirable higher harmonics in the power network current, including the elimination of harmonics of an order 23 and 25.
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By Isabelle Heriakian / Published on Wed, 2005-02-02 01:00
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. Moreover they make it possible to take into account functional dependences among them and, consequently, to improve the analysis of unbalanced operation states of EAF, as well as their balancing.
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By Isabelle Heriakian / Published on Tue, 2005-02-01 01:00
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. The obtained optimal location and size prove to depend strongly on the given conditions.
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