Differential Evolution based Optimal Control of Induction Motor Serving to Textile Industry

Transcription

1 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 Differential Evolution baed Optial Control of Induction Motor Serving to Textile Indutry C. Thanga Raj, Meber, IAENG, S. P. Srivatava, and Praod Agarwal Abtract Thi paper illutrate the iportance of controller on energy aving opportunity of partial loaded three-phae induction otor in textile ill (ring pinning frae) application. The econoic of a calar controlled 00 HP induction otor i invetigated with three topologie naely tar-delta (S/D) connection, contant Volt/frequency (V/f) controller and Differential Evolution (DE) controller in teady-tate condition. In thi tudy, the flux level in a achine ha been conidered to adjut to give iniu operating cot for the textile ill load. The flux controller iprove the econoic in ter of operating cot (energy cot and deand charge cot) and the tet reult how that the flux level in the ot econoic otor will be adjuted according to load and peed, particularly at light load. Standard benchark proble (Ratingin and Griewank) have been conidered for validation of the propoed DE controller for induction otor operating cot iniization. Cae tudy alo preented in thi paper. Index Ter Differential evolution, econoic, induction otor, lo iniization. I. INTRODUCTION Three-phae induction otor (IM) are the ot frequently ued achine in variou electrical drive. About 70% of all indutrial load on a utility are repreented by induction otor []. Recently oil price, on which electricity and other public utility rate are highly dependent, are rapidly increaing. It, therefore, becoe iperative that ajor attention be paid to the efficiency of induction otor []. Textile indutrie are found to be energy-intenive (4% energy cot in total input cot) copared to other indutrie like cheical, food, coputer anufacturing, etc., and hence extenive reearch ha been focued on uch indutrie in the pat to reduce the energy cot and the total input cot [3]. Generally, induction otor have a high efficiency at rated peed and torque. However, at light load, iron loe increae draatically, reducing coniderably the efficiency [4 ]- [5]. The efficiency and power factor can be iproved by aking the otor excitation a onotone increaing function of the load. To achieve thi goal, the induction otor hould either be redeigned or fed through an inverter [6]. Siply, the flux ut be reduced, obtaining a balance between copper and iron loe o that efficiency will be axiized. In general, there are three different approache to iprove the induction otor efficiency epecially under light-load condition [4], naely, lo odel controller (LMC), earch controller (SC), and lookup table chee. Many reearcher have been reported everal trategie uing different variable to iniize loe in IM. Soe algorith ue lip peed [4], [5], rotor flux [0], [6], [7], power input [0], [8], and voltage [9]. Thi paper conider rotor flux a a variable and earche it optiu by DE. The DE [] algorith wa introduced by Storn and Price in 995. It i a population baed algorith uing utation, croover and election a like a Genetic Algorith. The ain difference in contructing better olution i that Genetic Algorith relie on croover while DE relie on utation operation []. Thi paper i organized a follow. Section II, dicue the textile ring pinning frae and it load diagra, ection III review oe of the preent ethod of efficiency optiization technique, ection IV and V derive the lo and operating cot odel of the IM, ection VI briefly dicue DE algorith and it objective function, ection VII preent the iulation reult of 00 hp otor and analyze the econoical coparion of DE controller in energy aving opportunitie in the ae induction otor for a textile ill load diagra. Validation of DE and cae tudy are preented in ection VIII and IX repectively. II. TEXTILE SPINNING MACHINE A ring pinning frae anufacture the cotton into yarn that winded in pindle (Fig. ) and ued to feed cone winding achine. After that it can be ued to ake end product uch a clothing with the help of weaving achine. The ain drive, with a power rating in the range of 5 kw to 75 kw and it haft load deterine by the quantity of yarn in the pindle. The quantity of the yarn in the pindle varie fro zero (when the proce tart) to full (when proce coplete), hence the otor haft load varie fro zero to rated. Manucript received January 9, 008. C. Thanga Raj i with Departent of Electrical Engineering, Indian Intitute of Technology Roorkee, India (e-ail: ctrajdee@iitr.ernet.in ). S.P. Srivatava i with Departent of Electrical Engineering, Indian Intitute of Technology Roorkee, India (e-ail: atyafee@iitr.ernet.in). P. Agarwal i with Departent of Electrical Engineering, Indian Intitute of Technology Roorkee, India (e-ail: pragfee@iitr.ernet.in). Fig.. Textile pinning ring frae In thi paper, 00 hp otor ha been conidered for (Advance online publication: 0 May 008)

2 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 econoical analyi. In order to illutrate the iportance of efficient controller in the indutrial procee, conidered the real load diagra of ring pinning frae in a textile indutry (Fig. ). T i the tie conuption for the copletion of one proce. Fig.. Average load diagra of a typical pinning ring frae drive otor III. METHODS FOR EFFICIENCY OPTIMIZATION The induction achine hould operate with the rated flux for the rated value of load torque, where a for load torque le than rated, the reduction of flux caue a reduction in iron loe and agnetizing current. For a very low load torque (up to about 5% of the rated value), energy aving work can reduce power lo by even 70-90% [3]. In thi ection, dicu three type of controller which are ued to operate the otor with reduced operating cot at partial load. Thee are a follow, (a) (b) Keep the otor connection in tar reult reduced power conuption. When the otor run in tar ode, the voltage applied to tator phae winding i reduced by the factor.73. Since the torque developed in the otor i directly proportional to quare of the voltage, the developed torque in tar ode i alo reduced by the factor 3. Therefore, the otor can be operated in tar ode up to 0.33 p.u load. In thi cae, the torque developed hould be eaured and find ufficient to drive the connected yte and alo eaure the teperature to be noral. Thi ethod i not uitable for wide range of partial load. Thi controller i not offering converter loe due to the abence of power electronic circuit and i hown in figure 3 (a). B. Lo Model Controller The lo odel controller eaure the peed and tator current and through the otor lo odel deterine the optial air-gap flux [0]. The ain proble of thi approach i that it require the exact value of achine paraeter which include core loe and ain inductance flux aturation [4]. The inner part control algorith ay be in calar or vector. Optial earching technique like DE hown in Fig. 3 (c), particle war optiization, and genetic algorith can be ued for earching optial flux level. Contant V/f control i the calar (variable are controlled in agnitude only) type control hown in Fig. 3(b) for iniizing the loe of induction otor at light load. The idea i to calculate, for pecific operating point, the optial V/f ratio (in other word the optial flux), that aure iniu loe till allowing the required peed and torque [5]. Scalar control technique i oewhat iple to ipleent, but the inherent coupling effect reult luggih repone and the yte i eaily prove to intability becoe of higher order yte effect [6]. In vector control, the variable are controlled in agnitude and phae. Thi technique of control need ore calculation than the tandard V/f control [7]. In thi control, the coplex induction otor can be odeled a a DC otor by perforing iple tranforation. The field oriented controller generate the required reference current to drive the otor. Thee current are baed on the reference torque. C. Search Controller for Miniu Input Power Thi controller eaure the input power of the achine drive continuouly and earche for an optial flux value which reult in iniu power input to the otor for given value of peed and torque. Thi technique i low for reaching the optiu value and a ripple in teady tate torque i alway preent [4]. (c) Fig. 3. Efficiency optiization controller (a) tar/delta, (b) v/f control, (c) DE controller A. Operate the Motor at Star Mode Induction otor operate at light load, require le torque. IV. INDUCTION MOTOR LOSS MODEL The equivalent circuit of the induction otor i iilar to that for a tranforer and it i alo called a rotating tranforer. Moreover induction otor paraeter are derived fro no-load and blocked rotor tet and can be eaily repreented by per-unit quantitie. Stator and rotor circuit can be erged by adjuting the value of the rotor coponent in accordance with the effective turn ratio a like a the tranforer [8]. (Advance online publication: 0 May 008)

3 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 Noenclature: R Stator reitance ' R r Rotor reitance X l Stator leakage reactance X lr Rotor leakage reactance X Magnetizing reactance R c Cable reitance ω Speed T e Electroagnetic torque ϕ Air-gap flux E Air-gap voltage a, w e Supply frequency Slip a Slip frequency ω r Rotor peed ω b Bae peed I Stator current ' I r Rotor current I Magnetizing current P c Copper loe in Stator and Rotor P i Iron loe P conv Converter loe P cable Cable loe P lo Total loe k h, k e Eddy current and hyterei coefficient S, S, S Magnetizing curve coefficient 3 C Mechanical lo coefficient fw C tr Stray lo coefficient K, K Switching lo coefficient I E / a Φ = = X X The rotor current reflected in to the tator in ter of the air gap flux i given by Φ I r = (3) Rr ( ) + X lr a Equation can alo be written including agnetic aturation effect a I 3 5 Φ + SΦ + S3Φ () = S (4) The tator current in ter of rotor current and agnetizing current i given by 3 5 X lr Te I = ( S Φ + SΦ + S3Φ ) + ( + ) X Φ (5) The equation of efficiency i given by output η = (6) input In cae of IM drive, the output i the power upplied by the otor to drive the load (product of haft load and it peed) and the input i the power conued by the total yte including otor, converter circuit and cable. Since the efficiency of IM or any yte i depend on the total loe aociated with it, (6) rewritten a output η = (7) output + loe The per-phae IM equation () (5) are given in the per-unit yte [0] ωe ω a = = ω b The agnetizing current in ter of the air-gap flux and the agnetizing reactance i given by () The loe in the IM drive yte are divided into a nuber of lo ter, connected with pecific part of the achine. The total loe hown in Fig. 4 coprie of copper loe in tator and rotor, iron loe due to eddy current and hyterei, tray loe arie on the copper and iron of the otor, friction loe, converter loe due to the reitance offered by the olid tate witche and finally the cable loe due to the reitance offered by the cable. Power output i the product of haft load and it peed. Fig. 4. Loe in the IM drive yte (Advance online publication: 0 May 008)

4 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 Copper and iron loe in the tator and rotor are ore evere than other. The individual lo equation in the IM are given by [0] Copper loe P c RI + Rr I r i [ Ke( + ) a + Kh ( + ) a] Φ tr Ctr Ir = (8) Iron loe P = (9) Stray loe P = ω (0) Mechanical loe P = C fw ω () The approxiate loe in the converter and inverter of the IM drive i given by [4] = K I K I () Pconv + The approxiate loe in the cable to connect otor drive yte to the upply ain (grid), i given by P = I * R (3) cable c B. Deand cot Deand charge cot conued by the otor over the whole life of the otor can be calculated by uing the equation (8) and i given below D = Cd ** N * P lo (8) where D Deand cot for the life period C d Deand cot per onth (US $) The total energy cot (TEC) of the otor for the coplete life i the uation of two individual energy cot and i given by TEC = P N *(( C * T ) + ( C *)) (9) lo * e d Fro (9), TEC = function (Flux), which can be iniized by earching optial flux value. Fro Equation (8)-(3), the total loe in IM drive yte i given by P = P + P + P + P + P + P (4) lo c i tr conv cable The total loe in ter of air-gap flux i given by P lo = R I r I r r + + R + [ Ke ( + ) a + Kh ( + ) a] Φ fw + KI + KI + I Rc + C trω I C ω * (5) VI. DE FOR MOTOR S ENERGY COST MINIMIZATION Many recent developent in cience, econoic and engineering deand nuerical technique for earching global optia to correponding optiization proble [9]. DE i a parallel direct earch ethod [0], which firt et the initial value of the paraeter in the population. Fig. 5 how the flow of DE algorith. V. OPERATING COST MODEL OF INDUCTION MOTOR Fro (5), loe can be iniized by electing optial value of flux level. There are two ain type of operating cot in the induction otor related to energy conuption by the otor. Energy cot and deand cot are thee two. A. Energy cot The energy cot of the induction otor hould be calculated over the whole life cycle of the otor [4] and i given below. Power factor penalty i not conidered in thi paper becaue alot all the indutrie have centralized power factor correction equipent. S = Ce * T * N * P out *( ) (6) η where S Energy cot for life period C e Energy cot (US $/KWH) T Total operating hour/year N Motor evaluation life in year P out Output power of the otor (KW) η Efficiency of the otor Equation (6) can be rewritten in ter of total loe (KW) which i given below S = C * T * N * (7) e P lo Fig. 5 Flow of DE algorith. The utation operator chooe three different vector fro the population and create the utant vector, i given by [], (Advance online publication: 0 May 008)

5 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 v i, g + = x, + F *( x, x, ) (0) r g, r, r3 r g r g 3 where r {,,..., NP} are randoly choen integer, ut be different fro each other and alo different fro the running index i. F (>0) i a caling factor. To do the recobination tep, the following equation i ued [] v if ( rand CR) ( j j ) ji, g + j or = u ji g + = rand, () x ji, g if ( rand j > CR) and ( j jrand ) where j =,,, D; rand [0,] ; CR i the croover contant take value in the range [0, ] and j rand (,,..., D) i the randoly choen index. Selection i the tep to chooe the vector between the target vector and the trial vector with the ai of creating an individual for the next generation. Thee operator will continue up to an optiu olution i found or the nuber of axiu iteration (et by uer) ha been reached. Energy cot iniization of the induction otor can be forulated a hown in () by conidering (9) a objective function. j Miniize TEC (Te, w, Φ ) () VII. SIMULATION RESULTS AND DISCUSSION In thi ection, a 00 HP otor operating with the given load diagra (Fig. ) in textile ill application (ring pinning frae) ha conidered for econoic analyi. Referring to the induction otor (00 hp) paraeter preented in [0], total energy cot coparion i perfored with three type of controller. The otor paraeter are ' R =0.09, R r =0.00, X =.88, X lr =0.067, k e =0.006, k h =0.006, C tr =0.05, C fw =0.00, S =0.4, S =-0.30, S 3 =0.45, K = , K = 0.05, R c = The block diagra of propoed controller i hown in Fig. 6. In thi controller, optiu lip peed i earched by DE o that otor will be operated with optiu flux. Total loe, energy cot, and tator current coparion of the contant peed (rated) IM for a textile ill load diagra with the following electricity tariff (Tail Nadu Electricity Board, HT tariff I for the indutrie ituated in rural area) and auing 5 procee repeated per day (otor running period = 0 hour per day), 355 day of operation/year and life tie of the otor (N) i aued a 5 year are uarized in Table I, and II. Individual loe coparion i hown in Table III. Maxiu deand (KVA) charge: US $ 6.66/onth Energy (kwh) charge: US $ 0.077/kWh ( US $= Indian Rupee 45 approxiately). All the load S/D offered low TEC due to abence of converter loe and DE perfored uch better than V/f. Fig. 7 how the variation of TEC (T i aued a 8000) by adjuting flux level in the otor at variable load and peed application and it reveal that iniu TEC occurred at rated flux (pu) for rated load and rated peed application but need to adjut the ae at lightly loaded condition. Hence flux adjutent i ainly required in the otor at lightly loaded condition for energy aving. VIII. VALIDATION OF DE WITH STANDARD BENCHMARK PROBLEMS To validate the perforance of DE progra, tandard benchark proble, Ratringin (f ) and Griewank (f ) function are ued, hown in Table IV. Fig. 8 and 9 how the convergence graph of the above benchark proble repectively. Fro the convergence graph, we coe to conclude that DE i working properly. IX. CASE STUDY A privately owned ediu ize pinning and ewing thread indutry in Tail Nadu, producing 5 ton of yarn and 0 ton of ewing thread/ day, i having 96 ring frae [3] ha conidered in thi ection. For thi textile ill, the econoical benefit of pinning drive otor by uing different controller are hown in Table V. Fig. 6. Propoed controller for operating cot iniization (Advance online publication: 0 May 008)

6 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 (A) w r = 0.5 (B) w r = 0.5 (c) w r = Fig. 7. TEC vere flux at variable peed and variable load of induction otor TABLE TOTAL LOSSES, FLUX AND STATOR CURRENT IN 00 HP IM FOR A TEXTILE MILL LOAD DIAGRAM (W R=) Tie Te Φ (pu) I (pu) P lo (KW) (hr) (pu) S/D V/f DE S/D V/f DE S/D V/f DE t t t t t TABLE II OPERATING COST OF 00 HP MOTOR TEXTILE MILL LOAD DIAGRAM (w r =) Tie Te S (US $) D (US $) TEC (US $) (hr) (pu) S/D V/f DE S/D V/f DE S/D V/f DE t t t t t TABLE III INDIVIDUAL LOSS TERMS OF 00 HP IM FOR TEXTILE MILL LOAD DIAGRAM (W R=) P Te P c (KW) P i (KW) tr + P + P conv + P cable (KW) (pu) S/D V/f DE S/D V/f DE S/D V/f DE (Advance online publication: 0 May 008)

7 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 TABLE IV BENCHMARK PROBLEMS Function Di Range Mini. Value f ( x) = ( x i 0 co( π x i ) + 0 ) i = [-5.,5.] f (0) = 0 n ( ) n x f x = x co( i ) i [-600,600] f ) i= 0 i = 0 i + = 0 TABLE V CASE STUDY IN A TYPICAL SPINNING RING FRAME FOR ECONOMIC COMPARISON Sl. No. Controller No. of Ring Frae TEC (US $) Saving (US $) Star/ Delta V/f DE Fig. 8 Convergence graph for Ratringin function Fig. 9 Convergence graph for Griewank function X. CONCLUSION Thi tudy invetigated the influence of controller in the econoic of a calar controlled 00 hp pinning drive otor (induction otor) in textile ill application. It i noted that DE produced better reult than V/f in all intance (otor load). Cable loe alo accounted in the total loe etiation of the IM. Fro the cae tudy, US $ can be aved in a typical ediu cale textile indutry when ued DE controller over v/f controller to elect optiu flux level of the IM. Although S/D offered iniu TEC copared to other, it cannot be applied wide range of variable load and peed application. To validate DE algorith, tandard benchark proble Ratringin and Griewank function were ued in thi paper. C++ code i ued for DE ipleentation. ACKNOWLEDGMENT Firt author would like to thank Minitry of Huan Reource and Developent (MHRD), Governent of India for giving financial upport to hi reearch work. REFERENCES [] Z. Maljkovic, M. Cettolo, et.al, The ipact of the induction otor on hort-circuit current, IEEE Ind. Application Magazine, 00, pp.-7. [] M. K. Yoon, C. S. Jeon, S. K. Kauh,. fficiency increae of an induction otor by iproving cooling perforance, IEEE Tran. Energy Converion, 00, pp. -6. [3] C. Palanichay, C. Nadarajan, P.Naveen, N. S. Babu, Dhanalakhi, Budjet contrained energy conervation- An experience with a textile indutry, IEEE Tran. Energy Converion, Vol. 6, No. 4, 00, pp [4] R. H. A. Haid, A. M. A. Ain, R. S. Ahed, A. El-Gaal, New technique for axiu efficiency of induction otor baed on PSO, IEEE conference proceeding, 006, pp (Advance online publication: 0 May 008)

8 IAENG International Journal of Coputer Science, 35:, IJCS_35 03 [5] D. H. Ki, GA-PSO baed vector control of indirect three phae induction otor, Applied Soft Coputing, Vol. 7, No., 006, pp [6] B. Pryyak, et al., Neural network baed flux optiization uing a odel of loe in induction otor drive, Matheatic and coputer in iulation, Vol. 7, 006, pp [7] S. Li, K. Na., Lo iniization control chee for induction otor, IEE proc. Electr. Power appli., Vol. 5, No. 4, 004, pp [8] S. Ghozzi, K. Jelai, X. Roboa, Energy optiization of induction otor drive, IEEE conference on Indutrial Technology (ICIT), 004, pp [9] K. undarewaran et al, Artificial neural network baed voltage controller for energy efficient induction otor drive, IEEE Int. conference, Dec. 998, pp [0] I. Kiokeidi, N. Margari, Lo iniization in calar controlled induction otor drive with earch controller, IEEE Tran. Power Electronic, Vol., No., 996, pp [] K. V. Price, Differential evolution: A practical approach to global optiization, Springer, Berlin, 005. [] D. Karaboga, etal, A iple and global optiization algorith for engineering proble: Differentila evolution algorith, Turki J of Elec. Engin., Vol., No., 004, pp [3] P. Gnacinki, Energy aving work of frequency controlled induction cage achine, Energy Converion and Manageent, Vol. 48, 007, pp [4] R. H. A. Haid, A. M. A. Ain, R. S. Ahed, A. El-Gaal, New technique for axiu efficiency and iniu operating cot of induction otor baed on PSO, IEEE conference proceeding IECON, 006, pp [5] M. Cacciato, A. conoli, G. Scarcella, G. Seelba, A. Teta, Efficiency optiization technique via contant optial lip control of induction otor drive, IEEE conference proceeding on Power Electronic, Electric Drive, autoation, and Motion, 006, pp [6] L. Raeh, S.P. Choudhury, S. Choudhury, A.K Saha, Y. K. Sung, Efficiency optiization of induction otor uing a fuzzy logic baed optiu flux earch controller, IEEE conference proceeding, PEDES, 006, New Delhi (digital object identifier: 0.09/PEDES ). [7] H. M. B. Metwally, f. E. Abdul-Kader, H. M. El-Shewy, M. M. El-Kholy, Propoed torque optiized behavior for digital peed control of induction otor, Energy Converion and Manageent, Vl. 43, 006, pp [8] R. Krihnan., Electric otor drive- Modeling, Analyi, and Control, Prentice Hall of India publication, 003 [9] Fang Wang, Yuhui Qiu, A odified particle war optiizer with Roulette election operator, IEEE conference proceeding of NLP-KE, 005, pp [0] R. Storn, K. price, Differential evolution- A iple and efficient heuritic for global optiization over continuou pace, Journal of global optiization, Vol., 997, pp [] A. Kele, Binary differential evolution for the unit coitent proble, GECCO 07 international conference, 005, pp Thanga Raj Chelliah received the diploa in Electrical and Electronic Engineering fro the Governent Polytechnic College, Nagercoil, India in 996, Bachelor degree in Electrical and Electronic Engineering fro Bharathiar Univerity, Coibatore, India in 00 and the Mater degree in Power Electronic and Drive fro Anna Univerity, Chennai, India in 005. He i currently working toward the Ph. D degree at Indian Intitute of Technology Roorkee, India. Fro 996 to 00, he wa with Haitia Textile Liited, Coibatore, a an Aitant Electrical Engineer. While there, he wa involved in energy conervation activitie in the electrical equipent. Fro 00 to 003, he wa with PSN College of Engineering and Technology, Tirunelveli, a a Lecturer. S. P. Srivatava received the Bachelor and Mater degree in Electrical Technology fro I.T. Banaru Hindu Univerity, Varanai, India in 976, 979 repectively and the Ph. D degree in Electrical Engineering fro the Univerity of Roorkee, India in 993. Currently he i with Indian Intitute of Technology (IIT) Roorkee, India, where he i an Aociate Profeor in the Departent of Electrical Engineering. Hi reearch interet include power apparatu and electric drive. Praod Agarwal received the Bachelor, Mater and Ph. D degree in Electrical Engineering fro the Univerity of Roorkee (now, Indian Intitute of Technology Roorkee), India in 983, 985, and 995 repectively. Currently he i with Indian Intitute of Technology Roorkee, India, where he i a Profeor in the Departent of Electrical Engineering. Hi pecial field of interet include electrical achine, power electronic, power quality, icroproceor and icroproceor-controlled drive, active power filter, high power factor converter, ultilevel inverter, and dspace-controlled converter. (Advance online publication: 0 May 008)