Effects of Harmonic Pollution on Three-Phase Electrical Motors

Transcription

1 t nternational Conference on Electrical and Electronics Engineering (CEEE-7) Oct. -, 07 Bali (ndonesia) Effects of Harmonic Pollution on Tree-Pase Electrical Motors Eleonora. Darie, Emanuel. Darie Abstract Tis paper presented te effects of te distortion penomenon of electrical current and electric voltage curves on tree-pases electric motors as well as te metods of evaluation of te extra losses from tree-pases electric motors due to armonics. Tere are also some entries useful for te armonic analysis of a consumer driven by a tree-pase asyncronous motor. Keywords Deforming Regime, Harmonic Analysis, Power Quality, Tree-Pases Electrical Motor. T. NTRODUCTON HE distortion of te voltage and current curves is damaging te equipment of bot producers and users of electricity. Te results of te presence of armonics and inter armonics of electric and / or voltage in electrical networks are []: increased losses in electricity transmission and distribution networks; increased losses in consumer electricity networks, overstressing and aging of electrical network and equipment insulation; termal overload of te neutral conductor in low voltage installations; interference wit command and protection signals on power lines, disturbances in telecommunication networks. Te actions (effects) of armonic distortions on te components of an electro-energetic system are not fully known.. EFFECTS ON ELECTRC MOTORS Te most important effects due to te presence of armonics in te electrical network on electric motors are: increased losses in conductors and magnetic materials; increasing te temperature of te windings and te magnetic core, due to additional losses in conductors and magnetic materials; te occurrence of couples wit a rotational speed corresponding to te frequency of te armonics (in te supply voltage curve); reducing te life of electric cars, lowering te efficiency of electric cars. A. Additional losses due to te flow of armonic currents Harmonic currents and voltages cause ig termal effects due to additional power losses: losses in conductive materials; losses in magnetic materials; dielectric losses [9]. Eleonora. Darie, Tecnical University of Civil Engineering, Bucarest, Romania ( eleonora.darie@gmail.com). Emanuel. Darie, was wit Police Academy, Bucarest, Romania. He is now a collaborator of te same university ( edarie@gmail.com). B. Analysis of Harmonic Components n te voltage curve of te electric motors, tere may appear: armonic ranks: =3 k (k integer number), tey beave like symmetrical zero-sequence (omopolar) sequences; armonic rank: =3 k +, wic beaves as te positive (direct) symmetric components; armonic rank =3 k+, wic beaves as symmetrical components of negative (indirect). n relation to te rotor rotating at te speed corresponding to te fundamental armonics, te armonics of rank =3 k +, determines couples in te direction of rotation of te electric macine, and te armonics of rank: =3 k +, causes couples in te opposite direction to te direction of rotation of te electric macine []. Te operation of non-sinusoidal electric motors is equivalent to te operation of several electric motors (te number of wic is equal to te number of armonics present in te non-sinusoidal supply voltage) coupled to te same axle and rotating at te same speed, only powered by actual value voltages and different frequencies U, U,, U, respectively f, f,, f, were is te rank of te armonica. Eac armonic will determine active or resilient couples (wic are added or subtracted to te main torque generated by te fundamental armonic) []. Te presence of current armonics in te motor windings also leads to an increase in te acoustic noise produced by te engine [], [9]. C. Engine Power Denomination n accordance wit EC : 00 [6], alternating voltage electric motors must be able to operate smootly in electrical networks aving a armonic voltage (FA) factor of less tan or equal to % and being calculated wit te relationsip [8]: U FA. () U n tis relation, te tird armonic is excluded. f te power supply network is caracterized by a greater distortion, it may be necessary to reduce te load on te macine (a denomination of macine power). A particular problem occurs in te case of electric motors powered by static frequency converters (wic produce a strongly distorted voltage), wic can lead to strong termal and mecanical stresses of te electric motor [7]. n tese situations, it is necessary to carry out an analysis of te practical possibilities of reducing te perturbations and te load limits of te electric motor. ttps://doi.org/0.7758/era.p0075 6

2 t nternational Conference on Electrical and Electronics Engineering (CEEE-7) Oct. -, 07 Bali (ndonesia). POWER QUALTY NDCATORS A. Quality indicators of te electrical energy Te evaluation of armonics and inter-armonics of voltage and currents in te electrical networks is based on electricity quality indicators, establised according to international standards: EN 5060 [], [], CE [] and CE [], []. Te armonics of te electrical voltage are individually evaluated [4] (by teir relative amplitude U (%)) and global (troug te total armonic distortion factor, THDU), wit te elp of relationsips [], [4]: U U(%) 00. () U ( = f ); te pase sift armonics, to te fundamental; c m - te amplitude of te inter-armonic frequency component f = f ; m te pasing of te interarmonics m, to te fundamental. V. ARMONC ANALYSS OF A CONSUMER ACTONED BY A ASYNCHRONOUS THREE-PHASE MOTOR, 400/30 V, 60 KW A. Te voltage recorded on te tree power lines is sown in Figure. 40 U THDU. (3) U Te armonics of electricity are evaluated by relationsips: (%) 00. (4) THD 40. B. Evaluation and measurement of armonics Te most important international standards, wic establis te metods, procedures for measuring and evaluating te armonics and inter armonics in te electrical networks, as well as te requirements, wic must be met by te equipment used for tis purpose, are te following: CE :08 [3], [5] and CE :00 [3], [6]. Current measurement systems of voltage and currents in electrical networks use numerical tecniques to measure analogue sizes and to process measured values. For numerical processing, te analog signals taken from te electrical networks are sampled. Te processing of te samples resulting from te measurements for te armonic analysis of te distorted voltage and current curves is done by means of te Fourier transform (made wit discrete values of te analyzed size), called Discrete Fourier Transform (DFT) and a fast processing algoritm, known as Fast Fourier Transform (FFT) []. Non-sinusoidal quantities in te power system are defined by a function aving te sape: f ( t) c c sin t 0 c sin m t. m in wic: te first part of (6) refers to te armonics and te second part to te inter-armonics; c 0 - continuous component; c - te amplitude of te armonic frequency component f = f ; - te pulse of te fundamental component m (5) (6) Fig. Variation of te supply voltage (V) wit te electrical energy on te tree lines, witin te time considered. B. Te voltage recorded on te tree pases is sown in Figure. Fig. Variation of te supply voltage (V) wit te electrical energy on te tree pases, witin te time considered. ttps://doi.org/0.7758/era.p0075 6

3 t nternational Conference on Electrical and Electronics Engineering (CEEE-7) Oct. -, 07 Bali (ndonesia) C. Te voltage recorded on te neutral conductor is sown in Figure 3. F. Te currents recorded on te tree power lines are sown in Figure 6. Fig. 3 Voltage variation on te neutral conductor over te time considered. D. Voltage armonics of te 3 rd, 5 t, 7 t, 9 t and 0 t order Fig. 6 Variation of te currents (A) on te tree power lines witin te considered time frame. G. Te current recorded on te neutral conductor is sown in Figure 7. Fig. 4 Voltage armonics of te 3 rd, 5 t, 7 t, 9 t and 0 t order E. Total armonic voltage distortion factor THDU (expressed as a percentage) on te tree power lines. Fig. 7 Current variation (A) on te neutral conductor, witin te time interval considered. H. Current armonics of te 3 rd, 5 t, 7 t, 9 t and 39 t order from te current spectrum are: Fig. 5 Total armonic voltage distortion factor THDU (expressed as a percentage) on te tree power lines. Fig. 8 Current armonics of te 3 rd, 5 t, 7 t, 9 t and 39 t order from te current spectrum ttps://doi.org/0.7758/era.p

4 t nternational Conference on Electrical and Electronics Engineering (CEEE-7) Oct. -, 07 Bali (ndonesia). Te current armonics of te nd, 4 t, 6 t, and 40 t order, present in te current spectrum. L. Te distortion factor of te electric current, THD Fig. 9 Te current armonics of te nd, 4 t, 6 t, and 40 t order (expressed as a percentage), present in te current spectrum. J. Te current armonics of te nd, 3 rd, 4 t, 7 t, and 9 t order, present in te current spectrum 3. Fig. Te distortion factor of te electric current, THD (expressed as a percentage). M. Total electric current distortion factor TDD (expressed as a percentage), of te load. Fig. 0 Te current armonics of te nd, 3 rd, 4 t, 7 t, and 9 t order (expressed as a percentage) present in te current spectrum 3. K. Te current armonics of te nd, 3 rd, 4 t, 7 t, and 9 t order, present in te current spectrum N. Fig. Te current armonics of te nd, 3 rd, 4 t, 7 t, and 9 t order (expressed as a percentage) present in te current spectrum N. Fig. 3 Total electric current distortion factor TDD (expressed as a percentage), of te load. Te metod of measuring te armonics is in accordance wit te actual regulations in force (te standard: EN 5060, CE ) and te measurements were made wit Power Analyzer (software Metrel Power View, v.3.0). V. CONCLUSON Te existence of armonic currents leads to te increase of te actual values of te currents in te conductors of te electric lines and in particular from te neutral conductor [4]. From te analysis of te measured measurements, it is observed tat te limits of te individual voltage armonics values in te low voltage electric networks, at te supply terminals, for ranges up to 5 (in percent) compared to te fundamental voltage U (te standard: EN 5060; CE ), and te limit values for te armonics of electricity emitted in low-voltage installations of tree-pase equipment s (te standard CE ), is not fully respected. t is empasizes te need to carry out as many measurements as possible (according to te standards and regulations in force) for different time periods (up to one ttps://doi.org/0.7758/era.p

5 t nternational Conference on Electrical and Electronics Engineering (CEEE-7) Oct. -, 07 Bali (ndonesia) week) in order to obtain te largest and most consistent amount of information [4]. Witout measurements (it is advisable to use te most efficient analyzers), one cannot: know te real complexity of te deformation penomenon analyzed; establis measures to attenuate te deforming penomenon and subsequently evaluate te effectiveness application of te attenuation measures. REFERENCES [] F. Vatră, P. Postolace a.o., Calitatea energiei electrice. Manual pentru profesioniști. Volumul, SER Publising House, Bucarest, 05, SBN [] Vatră, P. Postolace a.o., Calitatea energiei electrice. Manual pentru profesioniști. Volumul, SER Publising House, Bucarest, 03, general SBN , volume SBN: [3] Vatră, P. Postolace a.o., Calitatea energiei electrice. Manual pentru profesioniști. Volumul, SER Publising House, Bucarest, 03, general SBN , volume SBN: [4] ordănescu,., Postolace, P., Toader, C., Jișa, M., Fenomenul deformant în instalațiile electrice și eficiența măsurilor de atenuare. Ed. AGR, București, 0. [5] Eurelectric, Power Quality in Europeean Electricity Supply Network, Ref [6] CE :008, Electromagnetic Compatibility (EMC) Part 4-30: Testing and measurement tecnique Power Quality measurements metods. [7] CE :008, Electromagnetic Compatibility (EMC) Part 4-7: Testing and measurement tecnique General gide on armonics and interarmonics measurements, for power supply systems and equipment. [8] A. Baggini, Z. Hanzelka, Voltage and Currents Harmonics Capter 7 from Handbook of Power Quality, Jon Willey & Sons, Ltd. 008, SBN: [9] A. Arie, E. Neguș a.o., Poluarea cu armonici a sistemelor electroenergetice funcționând în regim permanent simetric, Editura Academiei, Bucarest, 994. ttps://doi.org/0.7758/era.p