Jurnal Teknologi HYBRID ACTIVE POWER FILTER METHOD IN FREQUENCY DOMAIN FOR QUALITY IMPROVEMENT IN VARIABLE FREQUENCY DRIVE APPLICATIONS.

Transcription

1 Jurnal Tenologi HYBRID ACTIVE POWER FILTER METHOD IN FREQUENCY DOMAIN FOR QUALITY IMPROVEMENT IN VARIABLE FREQUENCY DRIVE APPLICATIONS Min Hoang Hac Le, Kim-An Nguyen 2*, Viet Hung Ngo 3 R&D project, PowerMore Ltd. company, Danang, Vietnam ²CEA team, Faculty of Electrical Engineering, te University of Danang, University of Science Tecnology, Vietnam 3 Production Tecnical board - Power generation corporation 2 (GENCO2) - Vietnam Electricity (EVN), Vietnam Full Paper Article istory Received Received in revised form Accepted *Corresponding autor an.n@powermore.vn Grapical abstract x x 4 Abstract We present in tis paper a control metod of a novel ybrid parallel active power filter (HPAPF) used for armonic currents elimination reactive power compensation in te power system for tree-pase variable frequency drives (VFDs). Te HPAPF configuration is built from two filter components including armonics tuned passive filter active power electronics filter. Te active power electronics filter of tis proposed HPAPF system is controlled by a novel control algoritm tat maes use of Fourier analysis to facilitate accurate selective armonics targeting allowing te cooperation between passive active components. Wit te proposed topology, a coupling of te passive filter component te active filter allows significant reduction in current rating of te active filter component. Tis rating reduction sceme implies a great economic advantage of te proposed HPAPF compared to te metods wic are based only on traditional pure active power electronics filters. Te ardware design te control algoritm of te proposed HPAPF are verified by MATLAB/Simulin software. Keywords: Hybrid parallel active power filter; sunt active power filter; passive filter; selective armonics filtering; variable frequency drive. 25 Penerbit UTM Press. All rigts reserved. INTRODUCTION In recent years, te advancement of industrial product quality production precision require new breeds of accurate efficient equipment. Tis leads to te increase of nonlinear loads wic, in turn, creates a rapid deterioration of power quality in multiple industrial fields. Variable frequency drive (VFD) is among te most prominent sources of poor power quality including electric arc furnaces, induction furnaces, power rectifier, computing centers, etc. VFD is typically used in speed control, HVAC, flow rate control, factory pacaging transportation, etc. Nonlinear loads produce armonics [] consume a significant amount of reactive power [2]. Additionally, reactive power consumption of VFDs canges constantly over time resulting in sags, swells, flicer oter disturbances [3]. Serious current armonics pollution could affect te wole distribution grid by causing voltage armonics because of te fact tat bus bar voltage is coupled wit line current by line parasitic impedance [4]. Finally, reactive power is required to maintain te voltage to deliver active power. Toug reactive power is needed by many electrical devices, excessive fluctuation abnormal transients could lead to equipment damage [5]. Tis is wy most of researc wors concerning te power quality reported in te literatures are interested in te matter of current armonics cancellation dynamic reactive power compensation [6]. XX: (25) 6 eissn

2 2 Min Hoang Hac Le et al. / Jurnal Tenologi (Sciences & Engineering) 72: (25) 6 Over te past few decades, te istory of power filters as gone troug a canging process from passive power filters (PPFs) [7-8] to active power filters (APFs) [9-], recently, towards ybrid active power filters (HAPFs) [-3]. Different topologies of HAPF composed of active passive equipment ave been proposed, aiming to improve te compensation caracteristics of PPFs reduce te voltage /or current ratings cost of te APFs [4]. Jasmine Susila et al. ave implemented a series topology HAPF in [5], simulation results sowed improved power quality. However, teir proposed topology was not fully tested due to inadequate experimental setup. Medi Asadi et al. [6] proposed a HPAF wic comprises a b-sape C-type HAPF (bchapf) an active electromagnetic filter consisting of a Zig-Zag transformer a single-leg inverter, te topology performed well wit current armonics elimination but complex difficult to implement. In tis paper, a joint topology of active filter passive filter for current armonic cancellation power factor enancement in tree-pase power networs is proposed studied. Te topology is a parallel configuration of low order passive armonics filter selective sunt active power filter. Frequency domain Fourier Transform analysis robust PI controllers are used to design control algoritm. HPAPF performance is verified by modeling using Matlab/Simulin software for model simulations. 2. CONSTRUCTION OF PROPOSED HPAPF 2. Design of Passive Components Filter tuning frequency tuning angular frequency are calculated as,,. () 2 LC LC Te relationsip between filter inductance capacitance C is presented as, Z Z L L, C, 2 5Hz were Z L, impedances at passive branc, L, (2) ( ) C Z C, are filter inductor capacitor, 5Hz is te armonic order of te is te angular frequency at fundamental frequency. Filter quality factor Q is calculated as, ZL L Q, (3) R R C Wereas Z L is inductor impedance at fundamental frequency. In Figure, two PHF brances are connected in parallel tuned at 5 t 7 t Along wit armonics filtering functionality, te two passive brances also provide bacground reactive power compensation for power factor correction. ( L, C, R ). f2 f2 f2 Impedance (oms) Impedance ( L, C, R ) f f f Frequency (Hz) Figure 2 Branc Impedance versus Frequency diagram of a typical single tuned passive filter For power factor correction from an initial PFinitial to a desired value, te amount of reactive power produced by te passive component is calculated as follow: PF final Q filter Figure Single tuned passive filter diagram Single tuned topology is cosen to implement te passive components because it is simple to construct economically viable. Along wit ig pass double tuned filters, single tuned passive filter is one of te most commonly used type oarmonics filters in tree-pase systems. Te passive components of te joint topology are designed to eliminate te majority of te lower part of te armonic spectrum, typically 5t /or 7t armonics. Te quality factor of te filter Q is typically cosen in te range of 5 to 8 inversely proportional to filter branc resistance. Q P (tan[acos PF ] tan[acos PF ]) (4) filter load initial final Qfilter can also be calculated as, 2 Q Q Q Q. ( 5) filter C L 2 C Wen Q is obtained, C can be found as C describe in [6]. Finally, R can be calculated via selection of quality factor. Figure 2 sows te frequency response of a passive filter in wic te local maximum sows a parallel resonance between te filter grid due to grid parasitic impedance. Te filter impedance minimum situates at tuning frequency. L

3 3 Min Hoang Hac Le et al. / Jurnal Tenologi (Sciences & Engineering) 72: (25) Design of Active Component Te active component of te joint topology is a sunt APF wit small compensation current rating sown in Figure 3. As te active power filter is placed upstream of te passive components, it will only see ig order armonics wic are typically t, 3 t, since lower armonics are eliminated by te passive components. In VFD systems, armonics magnitudes tend to decrease as armonic order increases. [7] Wereas function i load n () t, i () t load represents te fundamental is te function oarmonic components. 3.2 APF Reference Current Calculation Control Loops For Compensation Current Generation Figure 4 Control algoritm for te active component Figure 3 Structure wiring diagram of a sunt APF In principle, te active filter stores electrical energy in its DC bus convert tis DC voltage into tree pase AC voltage AC current. Te control algoritm decides ow muc reactive power is being supplied to te grid by varying te output current pase amplitude. Tis can be acieved by estimating te correct amount of reactive power needed by te non-linear loads using voltage current feedbac signals measured at te point of common coupling (PCC) DC bus. Details about te control algoritm will be furter discussed in te next section. 3. CONTROL METHODOLOGY 3. Frequency Domain Analysis of Harmonics Current Fourier Transform is used to analyse load feedbac signal to provide flexible selective armonics compensation. Discrete Fourier Transform (DFT) is te digital form of Fourier Transform. DFT of a discrete signal sampled N times in a cycle is defined: N j2 n X x e. (6) X is defined as: Inverse DFT of j2 N x X e. (7) N Tis allows te selection oig order armonics wile omitting lower components. According to Fourier Transform, load current can be represented as: i t i t i ( t ), (8) load load load, n n 2 Figure 4 illustrates te control algoritm for te active component. Assuming a sampling rate of 28 Hz, wic is 256 samples/electrical cycle, te amount of frequency bin obtained by DFT is 256 bins. Tese bins represent 28 frequency components of load current. Reference current is computed by extracting ig order armonics from DFT analysis of load feedbac current, namely t to 28 t frequency bins, ten taes te inverse DFT of tis frequency range. A DC bus voltage PI regulator is included in order to eep DC bus stable at a reference value. Output of te DC bus PI regulator is ten added to armonics reference current along wit reactive power compensation reference current. Anoter PI controller is used to generate pulse widt modulation signals regulate APF output compensation current. PWM generation module is a Sinusoidal PWM wic creates PWM pulses at a specific switcing frequency, normally between 8 Hz to 5 Hz. 4. SIMULATION RESULTS 4. Case Study of a VFD System Figure 5 Basic electrical diagram of te cable car transport system using DC drives in Danang, Vietnam

4 4 Min Hoang Hac Le et al. / Jurnal Tenologi (Sciences & Engineering) 72: (25) 6 For te purpose of demonstrating te performance of te HPAPF, a case study is conducted at a cable car transport system as seen in Figure 5. Te cable car system is located in Danang, Vietnam. Power quality parameters fo te case study are obtained by an Elspec G45 Blacbox industrial monitor. In tis case, te armonics pollution exemplifies te armonics generating caracteristic of DC drives in an industrial application. Te electrical system at Station 6 consists of a pair of 575 W DC motors driven by two ABB DCS8 DC drives, supplied by a 2 MVA 22V/.4V Delta/Wye Transformer. Tese nonlinear loads ave been generating severe armonics wit current THD fluctuates between 26.3% 2.6%. Voltage THD is also ig, consistently above 3% peas at 26.3%. Figure 6 Measured armonics spectrum sows significant armonics at 5 t, 7 t, t 3 t orders Hig armonic current voltage ave dealt significant damages to te cable car system, interrupting te cable car lifting operation of te motors causing considerable business downtime. 4.2 Implementation of Proposed Topology for te Case Study For te case study, we propose a HPAPF topology in wic, bot of passive filter components active filter component are included configured as presented in Figure 7. Te existing power factor correction capacitor ban on site is removed because it was producing parallel resonance in te system, maing t 3 t armonics current unusually ig as seen in Figure 6. As initial power factor is.85, te amount of reactive power needed by te W DC motors oter loads,, could be calculated as, Qtotal Q total W (tan[acos.85 ] tan[acos.95 ]) 32 VAr. Te active component armonics rating is selected to be 22Arms for te elimination oarmonics orders of t, 3 t, above. DC bus is regulated at 62V wit DC capacitance C 35 F. APF interface DC filter inductance is cosen as L.37 mh. interface Te IGBT switces are driven by an 8 Hz PWM pulse generator. Passive components effectively reduce current THD from 33.6% to 3.5% by trapping 5 t 7 t armonics (see Figure 8). In order to avoid overloading, due to parameter discrepancy, 5 t 7 t filter brances do not resonate at exactly 25 Hz 35 Hz but rater Hz Hz. Consequently, 5 t 7 t armonics are not entirely eliminated. In addition, te current transient occurs at s is caracteristic of capacitor switcing Figure 8 Nonlinear current being filtered by te passive components Figure 9 Nonlinear current being compensated wit te passive components te active component 5 Figure 7 HPAPF wit active passive components installed In Figure 9, te active component is switced on at.3s after te source current becomes stable. Hig frequency fluctuation is considerably reduced since t 3 t are eliminated current THD is furter decreased to.%.

5 5 Min Hoang Hac Le et al. / Jurnal Tenologi (Sciences & Engineering) 72: (25) 6 Figure sows power factor correction from.85 to.95 by connecting te passive components at.3s. At.7s, te active component is connected improves te power factor to Figure Power factor correction of te joint topology, active component connected at.7 s A comparison between a typical sunt APF te joint topology is done by measuring te amount of compensating current produced by eac type of device. Figure sows te reduction of RMS current rating of te active component wen te active component RMS rating to only 32% of a sunt APF s (22 Arms compared to 68 Arms) for tis case study. Irms (A) Time (s) Figure Comparison of compensation RMS current between pure sunt APF HPAPF 5. CONCLUSION Traditional APF HPAPF Te paper demonstrates te effectiveness of te proposed HPAPF in te armonics cancellation te dynamic reactive compensation in a VFD system. Te obtained results sow tat te active component RMS current rating in te HPAPF system is only 32% of te traditional APF rating wile producing te same armonics filtering performance. Tis reduction in rating implies a great economic advantage of te proposed HPAPF compared to te traditional APFs. Moreover, te proposed HPAPF sows significant potential in installation footprint reduction, wic is important in space constraint sites suc as cruise sips, oil rigs, etc. Future wors involves termal design of te active component a detailed transient analysis of HPAPF system. Furtermore, an electrical prototype will also be developed to verify real-world performance. Acnowledgement Tis wor is partially supported by te PowerMore Ltd. Company, Vietnam. References [] Aagi, H. 26. Modern active filters traditional passive filters. Bulletin of te Polis Academy of SciencesTecnical Sciences. 54(3). [2] Nguyen, K.A. Bui, Q.K. 29. An active filters design for te reduction of current armonic te compensation of reactive power for induction melting furnace power. Journal of science & Tecnology, te University of Danang. 4(33): [3] Yasir, M., Kazemi, S., Letonen, M. Fotui-Firuzabad, M. 22. Optimal selection of voltage sag mitigation solution based on event tree metod. Proc. on Electric Power Quality Supply Reliability Conference (PQ).-6. [4] Grady, W. M., Samotyj, M. J. Noyola, A. H Te application of networ objective functions for actively minimizing te impact of voltage armonics in power systems. IEEE Transactions on Power Delivery. 7(3): [5] Godbole, P. 24. Effect oarmonics on active power flow apparent power in te power system. IOSR Journal of Electronics Communication Engineering (IOSR-JECE): [6] Sing, B., Al-Haddad, K. Cra, A A Review of Active Filters for Power Quality Improvement. IEEE Transactions On Industrial Electronics. 46(5). [7] Tupsa-ard, J., Camcoy, C. Tayjasanant, T. 2. Hig voltage passive armonic filter design. Proc. on Electrical Engineering/Electronics, Computer, Telecommunications Information Tecnology (ECTI-CON) International Conference [8] Das, J. C. 23. Passive filters-potentialities limitations. Proc. on Pulp Paper Industry Tecnical Conference, Conference Record of te 23 Annual, IEEE [9] Tang, Y., et al. 22. Generalized design oig performance sunt active power filter wit output LCL filter. IEEE Transactions on Industrial Electronics 59(3): [] Aagi, H., Aira N. Satosi A Control strategy of active power filters using multiple voltage-source PWM converters. IEEE Transactions on Industry Applications. 3: [] Bavaraju, V. B. Prasad, N. E Analysis design of an active power filter for balancing unbalanced loads. IEEE Transactions on Power Electronics. 8(4): [2] Demirdelen, T., et al. 23. Review oybrid active power filter topologies controllers. Proc. of Fourt International Conference on Power Engineering, Energy Electrical Drives (POWERENG), IEEE. [3] Kim, S. Prasad N. E. 22. A new ybrid active power filter (APF) topology. IEEE Transactions on Power Electronics. 7(): [4] Luo, A. et al. 29. Development oybrid active power filter based on te adaptive fuzzy dividing frequencycontrol metod. IEEE Transactions on Power Delivery. 24(): [5] Tzung-Lin, L., Yen-Cing, W., Jian-Ceng, L. Guerrero, J.M. 25. Hybrid Active Filter Wit Variable Conductance for Harmonic Resonance Suppression in Industrial Power Systems. IEEE Transactions on Industrial Electronics. 62(2): [6] Susila, D.J. Rajaty, R. 23. Power Quality Enancement Using Hybrid Active Filter. International Journal of Engineering Science Innovative Tecnology (IJESIT). 2(3). [7] Asadi, M. Jalilian, A.R. 22. A Hybrid Active Power Filter Comprising an Active Electromagnetic Filter. PRZEGLĄD ELEKTROTECHNICZNY (Electrical Review), ISSN R. 88 NR a. [8] Peeran, S.M., Creg, W.P.C 995. Application, design, specification oarmonic filters for variable frequency drives. IEEE Transactions on Industry Applications. 3(4):