Journal Volume 11 Issue 1

Measuring accuracy of electric energy in HV power networks

E-mail Print PDF

Wiesław Jałmużny

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. The algorithm may be applied, with positive results, by the operating personnel of measuring circuits with instrument transformers.

altDownload full text

Sensitivity of electrical equipment to voltage sags and short interruptions: recommendations for testing

E-mail Print PDF

Saša Djokić, Jovica V. Milanović

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.

altDownload full text

Single-phase power active filter using instantaneous reactive power theory – Theoretical and practical approach

E-mail Print PDF

Juraj Altus, Jan Michalik, Branislav Dobrucky, L.H. Viet

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.

Read more...

Mitigation of voltage flicker by superconducting synchronous condenser (supervar)

E-mail Print PDF

Shu-Jen Steven Tsai, Yilu Liu, Michael R. Ingram

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.

Read more...

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

E-mail Print PDF

Antoni Różowicz

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.

Read more...

Analysis of Vienna rectifier

E-mail Print PDF

Grzegorz Radomski

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. The Vienna rectifier system is an unidirectional converter.

Read more...

Analysis of operation of class E ZVS resonant inverter

E-mail Print PDF

Elżbieta Szychta

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.

altDownload full text

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

E-mail Print PDF

Chunchun Xu, Zhian Zhong, Virgilio Centeno, Richard Conners, Yilu Liu

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. However, the high installation cost of PMUs limits their applications for wide area control and stability analysis of power system.

Read more...

An optimum reactance one-port compensator for harmonic mitigation

E-mail Print PDF

Ehab F. El-Saadany, Hatem H. Zeineldin

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. Passive filters are inexpensive compared with most mitigating devices.

Read more...

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

E-mail Print PDF

Piotr Mysiak, Piotr Jankowski

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. The 24-pulse nature of operation of the system is obtained using three sets of coupled three-phase power network reactors (CTR).

altDownload full text

Page 1 of 2

  • «
  •  Start 
  •  Prev 
  •  1 
  •  2 
  •  Next 
  •  End 
  • »