IDENTIFICATION AND MITIGATION OF POWER QUALITY DISTURBANCES USING IUPQC BASED ON PSODV TECHNIQUE

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1 Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 IDENTIFICATION AND MITIGATION OF POWER QUALITY DISTURBANCES USING IUPQC BASED ON PSODV TECHNIQUE SK.Abdul Khaleel, B.MaheshBabu, Dr.L.Rav Srnvas 3, Dr.S.S.Tulas Ram 4 M-Tech Scholar [PEED] Dept.of EEE, Gudlavalleru Engneerng College, Gudlavalleru, Andhra Pradesh, Inda Assstant Professor, Dept. of EEE, Gudlavalleru Engneerng College, Gudlavalleru, Andhra Pradesh, Inda Professor, Dept. of EEE, Gudlavalleru Engneerng College, Gudlavalleru, Andhra Pradesh, Inda 3 Professor, Dept. of EEE, JNTU Hyderabad, Hyderabad, Telangana, Inda *** Abstract: The concept of power qualty has become one of the major concern n today s electrcal power system. The man causes of dstorton n power qualty s wth voltage varatons and harmonc currents. To mtgate these power qualty problems, usage of Actve power condtoner n utlty power systems s one of the soluton. Interlne unfed power qualty condtoner (IUPQC) was wdely studed by many researchers as an eventual actve power condtoner to mprove power qualty of two feeders n a transmsson lne of a power system. The nterlne unfed power qualty condtoner (IUPQC) conssts of seres and shunt actve flters connected n between two transmsson lne. The reference current generaton s carred out by nstantaneous actve power (PQ) theory for shunt actve flter and synchronous reference frame (SRF) theory for seres actve flter. Further the effectve s enhanced wth partcal swarm optmzaton wth dfferental velocty (PSO+DE) optmzaton technque. The gatng pulses for VSI s of actve power condtoner are generated by hysteress band current control. The effectve smulatons are carred out n Mat lab/smulnk. generated wth the control strategy nstantaneous actve and reactve power (PQ) theory n one feeder lne. and the synchronous reference frame (SRF) theory n another feeder lne. The p controller can be optmzed wth new optmzaton technque partcle swarm optmzaton wth dfferental velocty (PSO+DE).Ths paper can be explaned by a new connecton of UPQC to mprove the power qualty of two feeder lnes n a dstrbuton system. The UPQC s connected between two dfferent feeders (lnes), ths connecton of UPQC wll be called an IUPQC. II.INTERLINE UNIFIED POWER QUALITY CONDITIONER (IUPQC): IUPQC s relatvely new member of custom power devce. It s a combnaton of shunt and seres compensators. Keywords: Power Qualty (PQ),Total Harmonc Dstorton (THD),Interlne Unfed Power Qualty Condtoner(IUPQC), Partcle Swarm Optmzaton wth Dfferental Velocty (PSODV). I. INTRODUCTION power qualty problems have receved a great attenton nowadays are manly named as harmonc currents and voltage varatons. The non-lnear loads lke (power electronc devces) s connected n load sde harmonc currents wll occurred. voltage varatons (sag & swell) are occurred due to energzaton of heavy loads. These harmonc currents & voltage varatons are mtgated by shunt & seres actve power flters. The reference currents are Fg:. typcal IUPQC connected n a dstrbuton system ISSN: All Rghts Reserved 5 IJARCET 3654

2 Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 Interlne unfed power qualty condtoner conssts of two voltage source converters (VSC- and VSC-) whch are connected back to back through a common dc capactor C dc. VSC- s connected n shunt nstantaneous actve and reactve power (PQ) theory wth feeder- whle VSC- s placed n seres synchronous reference frame (SRF) theory wth feeder. In ths fg. the feeder mpedances are denoted by the pars (R s, L s ) and (R s, L s ) t can be seen that the two feeder supply loads L- and L-. The load L- s assumed to have non-lnear load. It s further load L- s assumed to have lnear load. The shunt VSC- s connected to bus B-at the end of feeder-.whle the seres VSC- s connected to bus B- at the end of feeder-. and across senstve load termnals Vt and Vt respectvely. III.CONTROL STRATAGY FOR IUPQC PQ theory s a nherently 3-phase theory and These control strategy can be used for the generaton of reference source currents. Inputs of the Instantaneous actve and reactve power theory (p q theory) are load sde harmonc currents, source voltages and loss component current from the dc lnk voltage control. The concept of nstantaneous reactve power theory (p-q theory) method bascally conssts of a varable transformaton from the a, b, c reference frame of the nstantaneous power, voltage and current sgnals to the α β reference frame. The converson formulae of voltages and currents are gven be sde u u cos cos( ) cos( ) a / 3 sn sn( ) sn( ) b c u cos cos( ) cos( ) a / 3 u sn sn( ) sn( ) b u c The nstantaneous actve and reactve power can be expressed by the followng system: p l ql u u u u 3 Fg : sngle lne dagram of IUPQC The sngle lne dagram of IUPQC s shown n fg.. Bascally IUPQC s nothng but the devce UPQC kept n between two ndvdual feeders lke feeder- and feeder-. Whch are connected to two dfferent substatons, Supply the system loads L- and L-. The supply voltages are denoted by V s and V s. The voltages whch are denoted by V t and V t, respectvely. The IUPQC s to hold the voltages V t and V t constant aganst voltage sag and voltage swell etc. n ether of the two feeders t has been demonstrated that the IUPQC can absorb power from one feeder (say feeder-) to hold V l constant n case of a sag n the voltage V s. Ths can be accomplshed as the two VSCs are suppled by a common DC capactor. The nstantaneous actve and reactve power can be decomposed n terms of the dc components plus the ac components, that s Where: p p ~ p q q q~ p : s the dc component of the nstantaneous power p, and s related to the conventonal fundamental actve current. p~ : s the ac component of the nstantaneous power p, t does not have average value, and s related to the harmonc currents caused by the ac component of the nstantaneous real power. ISSN: All Rghts Reserved 5 IJARCET 3655

3 Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 q : s the dc component of the magnary nstantaneous power q, and s related to the reactve q ~ : s the ac component of the nstantaneous magnary power q, and s related to the harmonc currents caused by the ac component of nstantaneous reactve power. v v v v v p v q 4 The reference currents based on the nstantaneous actve and reactve power are determned accordng to the flowng equaton: power generated by the fundamental components of voltages and currents. * a * b * c ~ ~ The block dagram of Instantaneous Actve and Reactve Power Theory (P-Q theory) s shown n Fg.. 5 Fg.3: Instantaneous Actve and Reactve Power Theory for Reference Current Generaton. B. SERIES CONTROL FOR SRF THEORY SRF theory can acheve fast and accurate extracton of the harmonc content. and These control strategy can be used for the generaton of reference currents and voltages. Applyng an angle transformaton s to convert from a statonary reference frame (a-b-c) to a synchronously rotatng frame (d-q-o) t s nothng but Parks transformaton. And these are converted nto DC quanttes. The sne and cosne functons are due to mantan the synchronzaton wth supply voltage and current wth the help of closed loop feedback control sgnal (PLL). That generates sgnal wth the same frequency and phase angle of the nput sgnal. PI controller s used n ths theory. Ths (d-q-o) frame s agan converted nto (a-b-c) frame to get requred reference currents and voltages. ISSN: All Rghts Reserved 5 IJARCET 3656

4 Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 V qs V ds V os 3 cos cos( /3) cos( 4 /3) sn sn( /3) sn( 4 /3) / / / V as V bs V cs (6) * a ds sn qs cos (9) I ds = /3 (I a sn θ+i b sn( θ * )).(7) sn( ) cos( ) () b ds qs qs /3( cos cos( ) cos( )) (8) a b c * c ds sn( ) qs cos( ) () Fg.4: control block of synchronous reference frame theory ISSN: All Rghts Reserved 5 IJARCET 3657

5 Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 C.HYSTERESIS BAND CURRENT CONTROL Hysteress current control technque s employed to desgn the control part of the APF [8].The hysteress band current controller for actve power flter can be carred out to generate the swtchng pattern of the nverter. In ths controller actual current s forced to track the sne reference wthn hysteress band by back and forth (or bang-bang) swtchng of the upper and lower swtches. So the nverter then becomes a current source, whch s controlled wthn the band and makes the source current to be snusodal. ntegral gans of the dc bus voltage PI controller. The placement of PI controller s shown n Fg. [5]. IV.DESIGN SPECIFICATIONS Desgn parameters of IUPQC: DC bus voltage, Dc bus capactance, KVA ratng of transformer and voltage ratng of seres actve power flter, and flter desgn. a) DC capactor voltage: The DC capactor voltage s calculated based on followng relaton V dc ( * V ) / (3* m)) () LL Where m s modulaton ndex (m=) b) DC bus capactance of the VSC: Fg.5: Hysteress band current control The swtchng takes place when carrer sgnals crosses the error sgnal of ref and act. Comparson of carrer sgnals wth the error sgnal of ref and act realzes the PWM swtchng law descrbed below: If (act) > (ref + hb) upper swtch of a leg s ON and lower swtch s OFF If (act) < (ref + hb) upper swtch of a leg s OFF and lower swtch s ON D. PI CONTROLLER The reason behnd the use of proportonal ntegral controller s ts effectveness n the control of steady-state error of a system and also ts easy mplementaton [6]. However, one dsadvantage of ths conventonal compensator s ts nablty to mprove the transent response of the system. In ths crcut, the actual DC capactor voltage s detected and compared wth the reference value, and the error s amplfed then added to the lo`ss, the output of hgh-pass flter. Therefore, actve power allowed nto the capactor s beng changed and the dc voltage s controlled. loss( n) loss( n ) kp( vsn vs( n ) ) kv Where, ( v sn vs( n ) ) s the error between the reference (Vdc*) and sensed (Vdc) dc voltage at the nth samplng nstant. Kp and K are the proportonal and the sn The DC bus capactance s calculated based on how much of energy s requred durng the change n load, t s calculated as E / * C dc ( V dc Vdc ) (3) Where V dc s DC bus voltage and V dc s the mnmum voltage level of dc bus. Where C dc V * dc V s P* t / C dc ( V V dc dc P* t = /*C dc (V dc V dc ) P 3* V s * I *( p * t ) /( V s dc ) Vdc ) (4) c) kva ratng of transformer: The kva ratng of transformer s calculated as S ( 3V s * I )/ (5) s d) Voltage ratng of seres actve power flter: The voltage ratng of VSC depends on maxmum voltage to be njected under the case any voltage varatons of the load..the njected voltage s calculated as a V nj ( V s V L ) V DVR (6) e) Rpple Flter: In order to elmnate the swtchng frequency rpples from njected ISSN: All Rghts Reserved 5 IJARCET 3658

6 Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 voltage the rpple flter s desgned. Rpple flter conssts a seres connected R r and C r. f r /( * R * C ) (7) Where f r s taken as half of the Swtchng frequency. The range of swtchng frequency s from 5KHz KHz. Parameters Table: Parameters of IUPQC r Ratngs r selected randomly. The dfference between ther postonal coordnates s taken as a dfference vector: X k X j (8) Then the d-th velocty component ( < d < n) of the target partcle s updated as AC lne voltage Reference dc lnk capactance Reference dc voltage Lne mpedance Rpple flter DC voltage of seres apf PWM frequency Seres Transformer swtchng 45V,5Hz µf 88V L s =3mH,R s =.Ω C f =μf,r f =4.8Ω 3V khz kva,v/3v V d ( d d t ). V ( t). C..( P V ( t) d gd otherwse X ( t)), d f rand(,) CR ( 9) where CR s the crossover probablty, d s the d-th component of the dfference vector defned earler, and s a scale factor n [, ]. In essence, the cogntve part of the velocty update formula s replaced wth the vector dfferental operator to produce some V. OPTIMIZATION OF PI CONTROLLER USING PARTICLE SWARM OPTIMIZATION WITH DIFFERENTIAL VELOCITY(PSODV) PSO-DV ntroduces a dfferental operator (borrowed from the dfferental evoluton) n the velocty-update scheme of PSO. The operator s nvoked on the poston vectors of two randomly chosen partcles (populatonmembers), not on ther ndvdual best postons. Further, unlke the PSO scheme, a partcle s actually shfted to a new locaton only f the new locaton yelds a better ftness value,.e., a selecton strategy has been ncorporated nto the swarm dynamcs. In the proposed algorthm, for each partcle n the swarm two other dstnct partcles, say j and k ( j k), are addtonal exploraton capablty. Clearly, for CR, some of the velocty components wll retan ther old values. Now, a new tral locaton Tr s created for the partcle by addng the updated velocty to the prevous poston X: T r X ( t) V ( t ) () The partcle s placed at ths new locaton only f the coordnates of the locaton yeld a better ftness value. Thus f we are seekng the mnmum of an n dmensonal functon f (X ), then the target partcle s relocated as follows: X X ( t ) T ( t ) X r f ( t) f ( T r ) f ( X ( t)) otherwse () ISSN: All Rghts Reserved 5 IJARCET 3659

7 Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 Therefore, every tme ts velocty changes, the partcle ether moves to a better poston n the search space or stcks to ts prevous locaton. The current locaton of the partcle s thus the best locaton t has ever found wth respect to the prevous locatons. In other words, unlke the classcal PSO, n the present scheme, P ld always equals X d. So the cogntve part of the algorthm nvolvng P ld -X d s automatcally elmnated n our algorthm. If a partcle gets stagnant at any pont n the search space (.e., f ts locaton does not change for a predetermned number of teratons), then the partcle s Fg.6. Tunng of PI wth PSODV The flow chart representaton of PSODV algorthm s as shown n Fg (7) shfted by a random mutaton (explaned below) to a new locaton. Ths technque helps escape local mnma and also keeps the swarm movng : f (( X ( t) X ( t ) X ( t )... X ( t N) and f ( X ( t N))) then for (r=to n) X r ( t N ) X mn randr (,) ( X max X mn) () where f * s the global mnmum of the ftness functon, N s the maxmum number of teratons up to whch stagnaton can be tolerated and (X max, X mn ) defne the permssble bounds of the search space. Prce and Storn formulated the workng prncple of the DE wth a smple strategy n [3]. Later on, they suggested ten dfferent strateges of the DE [49]. Strategy-7 (DE/rad//bn) s the most successful and wdely used strategy. The key control parameters n DE are populaton sze (NP), scalng factor (F) and crossover constant (CR). Tunng of PI controller wth PSODV s represented as below Fg (6) Fg (7):flowchart of PSODV algorthem ISSN: All Rghts Reserved 5 IJARCET 366

8 harmonc compensatng current(amps) Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 VI. SIMULATION RESULTS OF IUPQC WITH PSODV In the above fgure s nterlne unfed power qualty condtoner smulated n MATLAB software here one of the transmsson lne connected n shunt PQ theory of non lnear load and another transmsson lne connected n seres SRF theory of lnear load n that smulaton of matlab results are shows n below Tme(n seconds) Fg: harmonc compensatng currents after the applcaton of upqc A 3-phase supply of 45v lne to lne 5hz wth dfferent dsturbances at source end, Non-lnear load (whether dode rectfer feedng an RL load ) njects current harmoncs n to the system. IUPQC s able to reduce the harmoncs from enterng nto the system usng shunt control after the applcaton of IUPQC wth harmonc compensatng currents. ISSN: All Rghts Reserved 5 IJARCET 366

9 source current(amps) njected harmonc currents Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September Tme(n seconds) Fg: njected currents of statcom Tme(n seconds) Fg:3 source current The shunt actve flter (PQ) theory and seres actve flter (SRF) theory has to appled n IUPQC wth the help of PSODV technque the source current s snusodal. ISSN: All Rghts Reserved 5 IJARCET 366

10 dc lnk voltage load voltage(p.u) njected voltage source voltage(p.u) Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September Tme(n seconds) Fg:4 Mtgatng the effect of sag of. p.u wth duraton.sec to. sec usng PSODV technque wth p controller A 3-phase supply voltage (45v-5hz) wth momentary sag of. pu magntude wth the duraton about -3 cycles s taken.wth the system operatng n the steady state. %<vdc> Tme(n seconds) Fg:5 capactor voltage(vdc) n order to supply the balanced power requred to the load,the dc capactor voltage rases as soon as the sag occurs. as the sag s removed the capactor voltage returns some tmes to the steady state. The total harmonc dstorton (THD) at load sde s found to be.9%.the source current thd was effectvely found to be 3.3%. ISSN: All Rghts Reserved 5 IJARCET 3663

11 Mag (% of Fundamental) Mag (% of Fundamental) Mag (% of Fundamental Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September 5 Mag (% of Fundamental) VII. DEVELOPING OF PROPOSED ALGORITHM The proposed algorthm ensures that the mnmum VA loadng s obtaned by controllng the voltage sag usng PSODV wth constrants on THD of load voltage and THD of source current. The man objectve of controllng the njected voltage s accomplshng the precse compensaton of the harmonc component. Ths secton descrbes the total harmonc dstorton of IUPQC wth PI regulator the source current THD s 5.45% whch s shown n fg (8). Fg..THD of source current wth IUPQC usng PI- PSODV controller. Wth IUPQC PI-PSODV controller the llustraton of THD n load voltage whch s reduced to.9% by makng K P =.5 K I =.47 shown n fg () Selected sgnal: 5 cycles. FFT wndow (n red): 5 cycles Tme (s) Selected sgnal: 5 cycles. FFT wndow (n red): 5 cycles Fundamental (5Hz) =.7897, THD=.9% Tme (s) Fundamental (5Hz) = 5.76, THD= 5.45% Frequency (Hz) Frequency (Hz) Fg.8.THD source current wth IUPQC usng controller In these another secton descrbes the total harmonc dstorton of IUPQC wth PI regulator the load voltage THD s.37% whch s shown n fg (9) Selected sgnal: 5 cycles. FFT wndow (n red): 5 cycles Tme (s) PI Fg..THD of load voltge wth IUPQC usng PI- PSODV controller. The convergence of THD n load voltage and source current IUPQC wth PSODV s llustrated as shown n fg () and fg(). The optmzaton has been run for to teratons. The parameters of PSO are gven n table 3. Parameters Table3: Parameters of PSODV Populaton sze Values Fundamental (5Hz) =.9397, THD=.37% Frequency (Hz) No.of teratons C R and C F.8 and.5 Fg.9.THD load voltage wth IUPQC usng controller Wth IUPQC PI-PSODV controller the llustraton of THD n source current whch s reduced to 3.3% by makng K P =7.333 K I = shown n fg () Selected sgnal: 5 cycles. FFT wndow (n red): 5 cycles Tme (s) Fundamental (5Hz) =.8, THD= 3.3% PI From the knowledge of PQ theory & SRF theory the kp and k values are tunng wth PSODV optmzaton technque. No of populatons=5 No of teratons= Cr=.8 f=.5 (constant) C and c are varyng C C GLOB LE FIT (THD). 5 Table4: Results of PSODV KP KI KP KI Frequency (Hz) ISSN: All Rghts Reserved 5 IJARCET 3664

12 percentage of thd Internatonal Journal of Advanced Research n Computer Engneerng & Technology (IJARCET) Volume 4 Issue 9, September The mult objectve functon s F = f(thd of source current)+f(thd of load voltage) For K p =.438; K =3.534; K P =8.8; K =.8377 The overall THD has been reduced to.9 for CR=.8, F=.5 for populaton sze and number of teratons are taken as. snusodal voltage and current at load sde. Fnally the conventonal PI controller and Partcle Swarm Optmzaton wth Dfferental Evoluton (after runnng better result of tmes) showed that PSODV has been proved to be better n terms of harmonc reducton n source current. The man am of IUPQC s to mtgate the current harmoncs n one of the feeder lne and to control the voltage sag n another feeder lne. Fnally the source current wll be snusodal and load voltage also snusodal usng IUPQC devce based on PSODV optmzaton technque. for all types of dsturbances (nterruptons) the total harmonc dstorton (THD)after compensaton s to be lessthan 5% whch s as per IEEE standereds. IX. REFERENCES [] F. Z. Peng and J. S. La, Generalzed nstantaneous reactve power theory for three-phase power systems, IEEE Trans. Instrum. Meas., vol. 45, no., pp , Feb [] G. Ledwch and A. Ghosh, A flexble DSTATCOM operatng n voltage and current control mode, Proc. Inst. Elect. Eng., Gen., Transm. Dstrb., vol. 49, no., pp. 5 4, C=3.5 C=.5 C= C=3 C=.5 C=.5 C=.5 C=.5 CR=.8 F=.5(CONT) [3] M. K. Mshra, A. Ghosh, and A. Josh, Operaton of a DSTATCOM n voltage control mode, IEEE Trans. Power Del., vol. 8, no., pp , Jan. 3. [4] N. H. Woodley, L. Morgan, and A. Sundaram, Experence wth an nverter-based dynamc voltage restorer, IEEE Trans. Power Del., vol. 4, no. 3, pp. 8 86, Jul Controller no of teratons Fg.. THD convergence graph Table4: THD of IUPQC wth PSODV THD of source current THD of load voltage Wth PI [5] A. Ghosh, A. K. Jndal, and A. Josh, Desgn of a capactorsupported Dynamc Voltage Restorer (DVR) for unbalanced and dstorted loads, IEEE Trans. Power Del., vol. 9, no., pp , Jan. 4. [6] F. Kamran and T. G. Habetler, Combned deadbeat control of a seresparallel converter combnaton used as a unversal power flter, IEEE Trans. Power Electron., vol. 3, no., pp. 6 68, Jan [7] H. M. Wjekoon, D. M. Vlathgumuwa, and S. S. Cho, Interlne dynamc voltage restorer: an economcal way to mprove nterlne power qualty, Proc. Inst. Elect. Eng., Gen., Transm. Dstrb., vol. 5, no. 5, pp. 53 5, Sep. 3. Wth PSODV.37.9 [8] A. Ghosh, A. K. Jndal, and A. Josh, A unfed power qualty condtoner for voltage regulaton of crtcal load bus, n Proc. IEEE Power Eng. Soc. General Meetng, Denver, CO, Jun. 6, 4. VIII. CONCLUSION A sutable mathematcal model of the IUPQC ha been developed wth shunt (p) controller and seres voltage controller the smulated results have been descrbed. the smulated results shows that p controller of the shunt actve flter, seres actve flter compensates of all types of nterruptons n the load current and source voltage, so as to mantan [9] A. Ghosh and G. Ledwch, A unfed power qualty condtoner (UPQC) for smultaneous voltage and current compensaton, Elect. Power Syst. Res., vol. 59, no., pp ,. [] A. Ghosh, G. Ledwch, O. P. Malk, and G. S. Hope, Power system stablzer based on adaptve control technques, IEEE Trans. Power App. Syst., vol. PAS-3, no. 8, pp , Aug ISSN: All Rghts Reserved 5 IJARCET 3665