ISSN 1335-4205






Doc. Ing. Juraj Altus PhD., Doc. Ing. Milan Novak PhD., Doc. Ing. Alena Oteensova PhD., Doc. Ing. Michal Pokorny, PhD.

 Department of Electric Traction of Electrics, Faculty of Electrical Engineering, University of Źilinia, Vel’ky Diel, 010 26 Źilina, Slovak Republic.

 Dr Eng. Adam Szeląg MIEE

 Depratment of Electrical Traction and Energetics, Faculty of Electrical Engineering, Warsaw University of Technology, Plac Politechniki 1, 00-661 Warsaw, Poland

The paper analyses the most relevant unfavourable impact of AC electric traction on the quality parameters of supplied electric energy. These are: power factor of fundamental harmonic and power factor, voltage a current harmonic components, unbalance and power factors in asymmetrically loaded lines and flicker. To confirm some proposi­tions, the paper presents results of measurements in traction transfor­mer substation ŹSR Nove Zamky. Also, the possibilities of unfavourable impact elimination using filtering and compensating substation and power active filters are mentioned.

 1. Introduction

Various parts of electrical equipment are mutually affected. Each appliance is less or more able to operate satisfactorily in its electromagnetic environment without introducing intolerable elec­tromagnetic disturbances to other appliances placed in the same location. An inter-disciplinary scientific branch generally called Electromagnetic Compatibility (EMC) deals with mentioned pro­blems. One of its parts is the domain dealing with the quality of electricity.

The supplier (distributing company) always guarantees quality of electricity, even in the case when the quality deterioration is caused by the electrical installation owned by a consumer. Hence a cooperation of both parties involved (supplier, consumer) is re­quired during the process of creating an agreement for electricity supply. But the market principles are not the only criterion; a sup­plier also has to protect its own priorities, and the interests of other consumers. It could come to fruition through the established con­ditions for connecting electric installations (appliances and electri­city sources), international standards and measurement of various quality parameters.

The quality parameters of electricity are defined in the Slovak standard STN 50160 ‘Voltage characteristics of electricity supplied by public distribution systems" 151, together with their compatibi­lity levels, i.e. acceptable values for LV and MV voltage systems.

The following parameters are considered as the quality para­meters of electricity:

  • voltage and its deviation limits,
  • short-time voltage interruptions, dips and swells (as related to the voltage nominal value),
  • power factor of the fundamental harmonic,
  • frequency,
  • voltage unbalance,
  • content of voltage and current harmonics,
  • interharmonics,
  • rapid voltage changes and fluctuations, rate of flicker.

Mentioned quality parameters of electricity and negative influ­ences of non-linear appliances upon the electric network were not universally monitored. Present needs for the highest quality para­meters force the electricity suppliers to measure and evaluate these quantities.

 Literatura - References

[1] OTCENASOVA, A., TABAĆEK, R.: Methodology of Calculation of Current Harmonics in Traction Overhead Lines Propagation, Works and Studies of VSDS Żilina, Electro Series, Vol. 20, Żilina 1996, pp. 115-124

[2] ALTUS, J„ NOVAK, M., OTCENASOVA, A., POKORNY, M.: Analysis of AC Traction Influence upon the Electric Network, Procee­dings of MET ’99 - 4th International Conference “Drives and Supply Systems for Modern Electric Traction Warszaw 1999, pp. 30-35

[3] DOBRUCKY B„ OTCENASOVA, A., POKORNY, M„ TABAĆEK, R.: The New Possibilities of Dynamic Compensation and Rege­neration of Energy in Electric Traction, Communications - Scientiffice Letters of the University of Żilina, No. 1/99, pp 5-12

[4] IEC 1000-2-4 Electromagnetic compatibility (EMC) - Part 2: Environment - Section 4: Compatibility levels in industrial plants for low- frequency conducted disturbances, 1994

[5] STN EN 50160 Voltage Characteristics of Electricity Supplied by Public Distribution Systems, 1998

[6] AKAGI, H.: New Trendsin Active Fillers, Proceeding of EPE ’95 Conference, Sevilla 1995, pp. 0.017-0.026

[ 7] RAĆEK, V., DOBRUCKY, B., VITTEK, J„ POKORNY, M.: Time Sub-Optimal Analysis and Control of Fast Three-Phase Active Filter Acting in One Sixth of Period, Proceedings of APEC '98, Anaheim 1998, pp. 979-985

[8] SMOLA, A.: Compact Fluorescent Lamps, EE - A Technical Journal for Electrical and Power Engineering, No. 3/1995. pp. 30-34