Multi pulse AC-DC Converter Analysis for RL Load

Transcription

1 Mult pulse D onerter nalyss for RL Load D. Snh, Prof. H. Mahala, Prof. P. Kaur Department of Electrcal & Electroncs Enneern, N.R.I.I.I.S.T., hopal deependra_2n@yahoo.com, hemantmahala@yahoo.co.n, paramjeet_2@yahoo.com bstract Ths paper presents the analyss of current wae shapn D conerters for effecte harmonc mtaton under smlar loads. The proposed conerters consst of a starconnected phase shftn transformer based multpulse D conerters. The proposed D conerters elmnate the most domnant adjacent harmoncs and also reduce the hher order harmoncs; thereby, resultn n an mproed power qualty at man supply. To aldate the approach, same machne ndces are presented under all loads. Expermental results obtaned are en to aldate the model and desn of the multpulse conerter. Index Terms Multpulse, Total Harmonc Dstorton,, Form factor, Rpple ontent. 6 I. INTRODUTION In the past few years a lot of work has been done for the reducton of Total Harmonc Dstorton usn dfferent concepts and applcatons. Ths thess work deals wth the reducton of Total Harmonc Dstorton usn Multpulse to D onerson scheme. The results are obtaned for both uncontrolled and controlled conerters for RL Load. The threephase multpulse to D conerson system employs a phaseshftn transformer and a threephase conerter between the supply and load sde of the system. Eery such conerter prodes 6pulse to D conerson, so n order to produce more sets of 6pulse systems, a unform phaseshft s requred and hence wth proper phaseshftn anle, 2, 8, 24, 3, and hher pulse systems can be produced []. Dfferent rectfers are used for conerson of supply nto D supply. For uncontrolled conerson, dodes hae been preferred, whle for the controlled conerson, thyrstors hae been mplemented. The performance mproement of multpulse conerter s acheed for total harmoncs dstorton () n supply current, D oltae rpples and form factor. ll the smulatons hae been done for smlar ratns of RL Load, for all the multpulse conerters confuratons, so as to represent a far comparson amon controlled and uncontrolled contnuatons of multpulse conerters. The presented smulaton results show the reduced at supply sde. These results aree wth the IEEE Standards [2]. Effect of ncrease n number of pulses n conerter crcuts for uncontrolled and controlled multpulse conerter on nput supply current and D sde oltae and current has been presented n ths paper. II. OJETIVE OF PRESENT STUDY The present work s an effort towards analyzn the dfferent multpulse to D conerters n soln the harmonc problem n a threephase conerter system. The effect of ncreasn the number of pulses on the performance of to D conerters has been analyzed. For performance comparson the major factors consdered are the rpple percentae, form factor and the total harmonc dstorton (). The effects of load araton on multpulse to D conerters hae also been nestated [2]. III. MULTIPULSE METHODS Multpulse methods nole multple conerters connected so that the harmoncs enerated by one conerter are cancelled by harmoncs produced by other conerters. y ths means, certan harmoncs related to number of conerters are elmnated from the power source. In multpulse conerters, reducton of nput lne current harmoncs s mportant as reards to the mpact the conerter has on the power system [3]. Multpulse methods are characterzed by the use of multple conerters or multple semconductor deces wth a common load. F. & F. 2 en below depct the arous technques used wdely for the reducton of harmoncs [4]. F.. Varous Harmonc Reducton Technques

2 Zza Phase Shftn Transformer (5 de) ontnuous F. 2. MultPulse onerter onfuratons Zza Phase Shftn Transformer (5 de) F. 5. twele pulse conerter poweru FFT wndow: of cycles of selected snal IV. SIMULTION OF UNONTROLLED MULTIPULSE ONVERTERS. SxPulse onerter The sx pulse conerter brde shown n F 3. as the basc conerter unt of HVD transmsson s used for rectfcaton, where electrcal power flows from the sde to the D sde and nerson where the power flow s from the D sde to the sde. Thyrstor ales operate as swtches whch turn on and conduct current when fred on recen a ate pulse and are forward based. The characterstc sde current harmoncs enerated by 6pulse conerters are 6n±, haracterstc D sde oltae harmoncs enerated by a 6pulse conerter are of the order 6n±. Zza Phase Shftn Transformer ( de) F. 3. SxPulse onerter FFT wndow: of cycles of selected snal ontnuous poweru Tme (s) F. 6. for nput current Fundamental (Hz) = 76.73, =.63% Harmonc order. Ehteen Pulse onerter In ths 8pulse topoloy, the manetc crcut noled s same as that of a 6pulse conerter. Therefore ths topoloy s comparately a preferred one. The smulated results are n close areement wth any result obtaned from an 8 pulse conerters. phase shft of 2 has been proded between all three phase shft transformers wth star connected secondary. Zza Phase Shftn Transformer ( de) Tme (s) Zza Phase Shftn Transformer (2 de) ontnuous poweru.8.7 Fundamental (Hz) = 68.5, =.7% Zza Phase Shftn Transformer (2 de) F. 7. ehteen pulse conerter Harmonc order F. 4. for nput current FFT wndow: of cycles of selected snal. Twele Pulse onerter Twelepulse conerter s a seres connecton of two fully controlled sx pulse conerter brdes and requres two 3 phase systems whch are spaced apart from each other by 3 electrcal derees. The phase dfference effected to cancel out the 6pulse harmoncs on the and D sde Tme (s) Fundamental (Hz) = 8.63, =.4% Harmonc order 62 F. 8. for nput current

3 Zza Phase Shftn Transformer (2 de) Zza Phase Shftn Transformer (. de) Zza Phase Shftn Transformer (2 de) Zza Phase Shftn Transformer (24 de) Zza Phase Shftn Transformer (24 de) ontnuous poweru Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (25 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (25 de) FFT wndow: of cycles of selected snal D. TwentyFour Pulse onerter The connecton for 24pulse conerter and the correspondn connectons are shown n f. 9. Four sx pulse conerters phase shfted by 5 derees from each other, can prode twenty four pulse rectfcaton, obously wth much lower harmoncs on and D sde. Its output oltae would hae 24n± order harmoncs.e., 23 rd, 25 th, 47 th, 49 th harmoncs wth mantudes of /23 rd, /25 th, /47 th,/49 th, respectely, of the phase shft. Zza Phase Shftn Transformer ( de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (3 de) F. 9. twenty four pulse conerter ontnuous poweru Tme (s) Fundamental (Hz) = 83.43, =.36% Harmonc order F. 2. for nput current F. ThrtySx Pulse onerter The connecton for 36pulse conerter and the correspondn connectons are shown n f. 3 Fe sxpulse conerters phase shfted by from each other, can prode thrtysx pulse conerson, and obously wth much lower harmoncs on and D sde. Its output oltae would hae 3n±order harmoncs FFT wndow: of cycles of selected snal ontnuous poweru Tme (s) Fundamental (Hz) = 82.4, =.6% F. 3. ThrtySx Pulse onerter Harmonc order F.. for nput current FFT wndow: of cycles of selected snal E. ThrtyPulse onerter The connecton for 3pulse conerter and the correspondn connectons are shown n f. sx pulse conerters phase shfted by 2 derees from each other, can prode thrtypulse conerson, and obously wth much lower harmoncs on and D sde. Its output oltae would hae 3n± order harmoncs.e., 29 th, 3 st, 59 th, 6 st harmoncs wth mantudes of /29 th, /3 st, /59 th, /6 st, respectely, of the phase shft. F.. thrty pulse conerter Tme (s) Fundamental (Hz) = 84.2, =.7% Harmonc order F. 4. for nput current G. FortyEht Pulse onerter For hh power FTS controllers, from the pont of ew of the systems een a twentyfour, thrty or thrtysx pulse conerter wthout flters could hae oltae harmoncs, whch are hher than the acceptable leel. The alternate of course s o to 48 pulse operaton wth eht sx pulse roups wth one set of transformers of one 24 pulse conerters phase shfted conerter from 7.5 derees all 8 transformer prmares may be connected n seres. 63

4 Zza Phase Shftn Transformer ( de) Zza Phase Shftn Transformer (7.5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (22.5 de) Zza Phase Shftn Transformer (7.5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (22.5 de) ontnuous poweru. nalyss of D Voltae Form Factor Table 3: Form Factor Obsered on Smulaton No. of Pulses Form Factor Zza Phase Shftn Transformer (3 de) F. 5. FortyEht Pulse onerter FFT wndow: of cycles of selected snal VI. SIMULTION OF ONTROLLED MULTIPULSE ONVERTERS For the smulaton of controlled mult pulse conerters nstead of the dode brde we use the Thyrstor rde and the correspondn pulses are en Tme (s). SxPulse onerter.8 Fundamental (Hz) = 85.2, =.% Harmonc order F. 6. for nput current Zza Phase Shftn Transformer ( de) onn onn2 onn3 ontnuous poweru V. UNONTROLLED MULTIPULSE ONVERTERS FOR RL LOD F. 7. ontrolled sxpulse onerter. nalyss of Supply urrent Table : Total Harmonc Dstorton Obsered on Smulaton No. of Pulses nalyss of D Voltae Rpple ontent Table 2: % Rpple ontent Obsered on Smulaton No. of Pulses Rpple ontent FFT wndow: of cycles of selected snal Tme (s) Fundamental (Hz) = 68.58, =.44% Harmonc order F. 8. for nput current 64

5 Zza Phase Shftn Transformer ( de) Zza Phase Shftn Transformer (2 de) Zza Phase Shftn Transformer (2 de) onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 ontnuous poweru frn anle frn anle Zza Phase Shftn Transformer ( de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (3 de) Zza Phase Shftn Transformer (2 de) Zza Phase Shftn Transformer (. de) Zza Phase Shftn Transformer (2 de) Zza Phase Shftn Transformer (24 de) Zza Phase Shftn Transformer (24 de) onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 PWM PWM PWM2 PWM3 PWM4 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 PWM PWM PWM2 PWM3 ontnuous poweru. Twele Pulse onerter Zza Phase Shftn Transformer (5 de) onn onn2 onn3 onn onn2 onn3 ontnuous poweru Zza Phase Shftn Transformer (5 de) F. 9. ontrolled Twele Pulse onerter F. 23. ontrolled twenty four pulse conerter FFT wndow: of cycles of selected snal FFT wndow: of cycles of selected snal Tme (s) Tme (s).9.8 Fundamental (Hz) = 82.43, =.3%.7 Fundamental (Hz) = 76.86, =.3% Harmonc order.2. F. 24. for nput current Harmonc order F. 2. for nput current E. Thrty Pulse onerter. EhteenPulse onerter F. 2. ontrolled ehteen pulse conerter F. 25. ontrolled Thrty Pulse onerter ontnuous poweru FFT wndow: of cycles of selected snal FFT wndow: of cycles of selected snal Tme (s).8 Fundamental (Hz) = 8.64, =.% Tme (s) Fundamental (Hz) = 83.55, =.% Harmonc order F. 22. for nput current D. TwentyFour Pulse onerter Harmonc order F. 26. for nput current 65

6 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 onn onn2 onn3 F. ThrtySx Pulse onerter FFT wndow: of cycles of selected snal frn anle PWM Zza Phase Shftn Transformer (5 de) PWM Tme (s) Zza Phase Shftn Transformer (5 de) PWM Fundamental (Hz) = 85.6, =.6% Zza Phase Shftn Transformer (25 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (5 de) PWM3 PWM4 PWM5 RL ranch ontnuous poweru Harmonc order F. 3. for nput current Zza Phase Shftn Transformer (25 de) F. 27. ontrolled ThrtySx Pulse onerter VII. ONTROLLED MULTIPULSE ONVERTERS FOR RL LOD FFT wndow: of cycles of selected snal Tme (s) Fundamental (Hz) = 84.23, =.6% nalyss of Supply urrent Table 4: Total Harmonc Dstorton Obsered on Smulaton No. of Pulses Harmonc order F. 28. for nput current G. FortyEht Pulse onerter frn anle Zza Phase Shftn Transformer ( de) Zza Phase Shftn Transformer (7.5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (22.5 de) Zza Phase Shftn Transformer (7.5 de) Zza Phase Shftn Transformer (5 de) Zza Phase Shftn Transformer (22.5 de) Zza Phase Shftn Transformer (3 de) F. 29. ontrolled FortyEht Pulse onerter PWM PWM PWM2 PWM3 PWM4 PWM5 PWM6 PWM7 ontnuous poweru. nalyss of Rpple ontent Table 5: % Rpple ontent Obsered on Smulaton No. of Pulses Rpple ontent nalyss of Form Factor Table 6: Form Factor Obsered on Smulaton No. of Pulses Form Factor VIII. ONLUSION 66

7 . Smulaton The arous solated multpulse confuratons were smulated usn the software MTL/SIMULINK [5] and the results hae been presented n ths chapter n Table to Table 6. The effect of load araton on dfferent multpulse conerters reeals that wth RL load because of nductance there s smoothn effect on current, therefore current decreases. The effect s smlar for dfferent multpulse conerters,.e. t ncreases current dscontnuty and hence affectn the harmonc spectrum adersely pulse conerter.4 ontrolled. ontrolled ontrolled. Performance nalyss nd omparson (c) Ehteen Pulse onerter ll the data obtaned after smulaton of aforesad models usn MTL/SIMULINK has been collected here so as to ease the comparson of factors accounted for.e., Rpple ontent and Form Factor between & ontrolled Multpulse conerters. ll the results obtaned hae been collected from Tables 5. to 5.6 and cateorsed on the bass of Load proded so as to ease the comparson ontrolled ontrolled ) Total Harmonc Dstorton.2 ontrolled 24 pulse conerter.6 ontrolled.3 (d) Twenty Four Pulse onerter ontrolled ontrolled pulse conerter.7 ontrolled.44 (a) Sx Pulse onerter.7 ontrolled ontrolled. (e) Thrty Pulse onerter 3 pulse conerter ontrolled.6.5 ontrolled ontrolled pulse conerter.63 ontrolled.3 (b) Twele Pulse onerter pulse conerter.7 ontrolled.6 (f)thrty Sx Pulse onerter ontrolled 67

8 RIPPLE % GE RIPPLE % GE RIPPLE % GE RIPPLE % GE RIPPLE % GE RIPPLE % GE RIPPLE % GE ontrolled ontrolled ontrolled ontrolled pulse conerter.4 ontrolled.9 () Forty Eht Pulse onerter F. 3. % for RL Load: (a) () 24 pulse conerter.588 ontrolled (d) Twenty Four Pulse onerter 2) Percentae Rpple ontent ontrolled ontrolled ontrolled 4 ontrolled pulse conerter ontrolled 2.3 (a) Sx Pulse onerter.33 ontrolled 2.56 (e) Thrty Pulse onerter 3 pulse conerter ontrolled ontrolled 2.5 ontrolled 4 ontrolled pulse conerter.9479 ontrolled (b) Twele Pulse onerter 36 pulse conerter.2739 ontrolled 2.27 (f) Thrty Sx Pulse onerter ontrolled ontrolled ontrolled.8.6 ontrolled pulse conerter.582 ontrolled (c) Ehteen Pulse onerter.2 48 pulse conerter.2988 ontrolled.66 () Forty Eht Pulse onerter F. 32. %Rpple ontent for RL Load: (a) () 68

9 FORM FTOR FORM FTOR FORM FTOR FORM FTOR FORM FTOR FORM FTOR FORM FTOR 3) Form Factor ontrolled ontrolled ontrolled ontrolled pulse conerter. ontrolled.7 (a) Sx Pulse onerter ontrolled (e) Thrty Pulse onerter 3 pulse conerter ontrolled ontrolled ontrolled ontrolled pulse conerter ontrolled.2 (b) Twele Pulse onerter. 36 pulse conerter ontrolled (f) Thrty Sx Pulse onerter ontrolled ontrolled ontrolled ontrolled pulse conerter ontrolled. (c) Ehteen Pulse onerter 48 pulse conerter ontrolled () Forty Eht Pulse onerter F. 33. Form Factor for RL Load: (a) () ontrolled ontrolled. Result Of Smulaton pulse conerter ontrolled. The objecte of the present work s to nestate the performance of controlled and uncontrolled multpulse conerters. These conerters are studed n terms of harmonc spectrum of supply current, Total Harmonc Dstorton, Rpple ontent & form factor n the mans. It s concluded therefore that n eneral wth ncrease n number of pulses n multpulse case the performance parameters of these conerters are remarkably mproed. (d) Twenty Four Pulse onerter IX. FUTURE SOPE backtoback asynchronous te comprsed of VS conerters employn PWM may well represent the ultmate HVD system. esdes controlln the throuh power flow, 69

10 t can supply reacte power and prode ndependent dynamc oltae control at ts two termnals. The two conerters can be paralleled to double the reacte power capablty suppled to one sde or the other. The backtoback conerters can be used for black start or to supply a passe load. Hher oltae desns can be used wth transmsson lnes or cables to form ponttopont or multtermnal transmsson lnks. More sophstcated controls can be used to prode addtonal network benefts. Wth the Eale Pass project, SW has realzed the system adantaes of deployn a VS based backtoback asynchronous Te wth standby dynamc oltae control durn network contnences. The controlled power transfer capablty allows the exchane of power between the two networks whle the oltae control stablzes the oltae follown lne outaes especally durn peak load perods. The future scope of work could be the smulaton of 6, 2, 8, 24, 3, 36, 48 mult pulse conerter topoloes n closed loop. Wth ths technque, ths work can be further extended to:. Number of pulses can be ncreased. Een hher pulse conerters can be used for hh oltae and hh power applcatons such as HVD conerson. usn dfferent combnatons of transformer wndns such as star, delta, zza, fork, polyon, etc. REFERENES [] N.Mohan, T.M.Undeland, W.P.Robbns, Power Electroncs: onerters, pplcatons, and Desn, 3rd Edton, 22 [2] D..Pace, Power Electronc onerter Harmoncs Multpulse Methods for lean Power. New York, IEEE Press, 996. [3].Snh, S.Garola,.N.Snh,.handra, and K..Haddad, Multpulse D onerter for Impron Power Qualty: Reew, IEEE Transactons, On Power Delery, Vol.23 No. January 28. [4] G.K.Dubey, S.R.Doradla,.Josh, R.M.K.Snha, Thyrstorsed Power ontrollers, New e Internatonal publshers, July 996. [5] Mathworks, Matlab Users Gude, Mathworks. Inc. orporaton. losed Loop Multpulse conerson can be worked out for enhanced controlln and effcency.. Other method of ncreasn the pulses can be used n place of phase shftn transformers as to dere multphase supply from three phase mans 7