A Multi-Objective Hybrid Heuristic Approach for Optimal Setting of FACTS Devices in Deregulated Power System

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1 IOSR Journal of Electrcal and Electroncs Engneerng (IOSR-JEEE) e-issn: ,p-ISSN: , Volume, Issue 4 Ver. I (Jul. Aug. 206), PP A Mult-Objectve Hybrd Heurstc Approach for Optmal Settng of FACTS Devces n Deregulated Power System Sa Ram Inkollu and Venkata Reddy Kota 2 Dept. of Electrcal and Electroncs Engneerng, Dhanekula Insttute of Engneerng & Technology, Vjayawada 52 39, Andhra Pradesh, Inda 2 Dept. of Electrcal and Electroncs Engneerng, Jawaharlal Nehru Technologcal Unversty, Kaknada , Andhra Pradesh, Inda Abstract: Improvement of power system performance n terms of ncreased voltage profle and decreased transmsson loss s becomng one of the challengng tasks to the system operators under open access envronment. Apart from tradtonal power flow controllng devces, use of Flexble AC Transmsson System (FACTS) devces can gve an attractve soluton for the operaton and control of deregulated power system. The type, sze, locaton and number of FACTS devces are to be optmzed approprately n order to get the targeted benefts. In ths paper, two FACTS devces, and IPFC are selected to obtan the requred performance. To search the optmal locaton and optmal ratng of the selected FACTS devces, a hybrd algorthm whch formulated wth PSO and GSA s proposed. At the frst step, the optmzaton problem s solved for fndng the optmal locaton of FACTS devces usng PSO wth an objectve of voltage profle mzaton and later GSA s mplemented to optmze ther parameters wth an objectve of transmsson loss mnmzaton. The proposed method s mplemented on IEEE 30-bus test system and from the smulaton results t can be proved that ths technque s well suted for real-tme applcaton. Keywords: Deregulated power system, open access,, IPFC, PSO-GSA I. Introducton The practcal lmtatons to expanson and ever ncreasng electrcty demand are causng to operate transmsson system at ts bottleneck under compettve envronment n deregulated power system. In addton, the randomness n power njecton and wthdrawals wth the strategc behavor of market partcpants are further causng to decrease the securty margn of transmsson system. Under ths scenaro, the prmary objectves to ntroduce Flexble AC Transmsson System (FACTS) devces are redefned by many researchers durng last decade. Some of the major areas focused wth FACTS devces are lke securty margn enhancement [-3], stablty enhancement [4-0], relablty management [], system performance mprovement [2-9], congeston management [20-24] and electrcty market economc effcency mzaton [25-30] etc. As per the controllng attrbute n power system, the type, sze, locaton, number etc. are requred to optmze very precsely. Many researchers have attempted to solve ths problem by heurstc algorthms due to ther adoptablty for mult-objectve complex problems. Usng Genetc Algorthm (GA), the optmal locaton and number of thyrstor-controlled phase shfters are optmzed n [3, 32]. In [33], hybrd TS/SA approach has been proposed to solve OPF problem ncorporatng FACTS devces. An evolutonary algorthm based evoluton strateges (ES) technque s proposed to mze system loadablty va optmzng type of FACTS devce, ther locaton and settngs [34]. Smlarly, the ABC algorthm and PSO algorthm applcaton for optmzng IPFC locaton can be found [35, 36]. On other sde, the conventonal approach lke mxed-nteger nonlnear programmng (MINLP) s adopted to fnd the optmal settng of FACTS devces used n the optmal power-flow problem. [37].It s worthwhle to notfy the role of heurstc algorthms used to solve n all these complex problems. The objectve of ths paper s not only to resolve mult-objectve optmzaton problem but also to nvestgate the effectveness wth the use of FACTS devces for the mprovement of the performance of transmsson system. Ths s an extenson of our exstng works [38] under open access envronment. Under open access, the blateral or multlateral transactons are executed wth an assumpton of unconstraned transmsson system. Wth ths new generaton and loadng levels, the ablty of varous FACTS devces for the mprovement of the transmsson system performance s analyzed. Two FACTS devces, and IPFC devces are used n ths work. To dentfy the most sutable locatons, the Partcle Swarm Optmzaton (PSO) s appled frst. Later, the Gravtatonal Search Algorthm (GSA) s mplemented to fnd the optmal parameters of the FACTS devces. The overall voltage devaton ndex () s consdered whle optmzng the locaton and the transmsson loss s consdered whle optmzng the parameters of FACTS devces. Ths paper s arranged as follows: secton gves ntroducton, secton 2 shows the power njecton modelng of varous FACTS devces. Secton 3 explans the objectve functon n the necessary mathematcal DOI: / Page

2 A Mult-Objectve Hybrd Heurstc Approach for Optmal Settng of FACTS Devces n Deregulated.. equatons. In secton 4, the proposed hybrd algorthm s explaned brefly. Secton 5 deals wth varous case studes on standard IEEE test systems and secton 6 concludes the paper. II. Modelng of FACTS Devces 2.. Thyrstor Controller Phase Shft Transformer As far as the statc modelng s concerned, the power njecton equatons are as follows: Pnj, r VV j sn j tcpst X se Q r V r VV cos 2 2 nj, j j tcpst Xse Xse P P nj, j nj, Q r VV cos nj, j j j tcpst X se where, tan tcpst s the phase angle adjustment by between, 2 2, r s the rato between the magntude of the nduced seres voltage and magntude of the th bus voltage. It s varable n the range 0, r, 2 and j are the load angles of buses, j respectvely. In addton, X se xse n xsh, where xse and xsh are the seres and shunt reactances of transmsson lne/transformer and n s the varable of the phase shft angle. The detaled nformaton can be found n [39] Interlne Power Flow Controller By assumng IPFC locaton between buses, j and k, the power njectons are as follows [5, 6]. Here V se n and se n P V V b sn nj, sen n sen n j, k Q V V b cos nj, sen n sen n j, k Pnj, n Vj Vse b sn n n j se n n j, k Qnj, n Vj Vse bn cosj se n j, k n are the magntude and angle of seres njected voltage source. III. Problem Formulaton The transmsson system performance can be mathematcally formulated n terms of two terms: voltage devaton of the system, f x, u, and transmsson losses, f2 x, u. Therefore the major objectve functon can be defned as: F x, u f x, u, f2x, u The frst objectve s to optmze the overall system voltage profle.e., mnmze the voltage devaton at load buses, whch can be defned as,, DOI: / Page NLB f x u x u V V ref where L s the number of load buses, V s the pre-specfed reference magntude at th load bus, whch usually wth magntude of.0 p.u. The second objectve s to mnmze the total real power loss of the lnes, whch s wrtten as:, loss, NL f x u P x u P n ref 2, loss where P, loss s the real power loss n transmsson lne, and NL s the total number of transmsson lnes. In both the objectve functons, x denotes the vector of dependent varables such as slack bus power P G, generator reactve power outputs Q G, load bus voltages V L and apparent power flows n transmsson lnes S L. Therefore x can be defned as: T x P, Q,... Q, V,... V, S,... S G G NGB L NLB L NL 2

3 A Mult-Objectve Hybrd Heurstc Approach for Optmal Settng of FACTS Devces n Deregulated.. where NGB s the number of generator buses. Smlarly, u denotes the vector of control varables such as generator bus voltages V G, locaton of FACTS devces L, and real and reactve power njectons P nj & Q nj at FACTS devce ncdent buses, j respectvely. Therefore u can be expressed as: T u VG,... VNGB, L,... LNL, Pnj,, Qnj,, Pnj, j, Q nj, j As per the type of FACTS devce, the power njectons agan controlled wth ther respectve controllng parameters. a) Equalty constrants The equalty constrants whch are the real and reactve power balance equatons for all the buses except buses p and q wth UPFC are shown n the followng equatons. P P P V V Y cos g, d, k k k j k g, d, k k k j k DOI: / Page Q Q Q V V Y sn,2,..., ; but p, q For buses p and q, the equalty constrants can be wrtten as P P P V V Y cos P p g, p d, p p k pk pk p j p, nj k Q Q Q V V Y sn Q p g, p d, p p k pk pk p j p, nj k P P P V V Y cos P q g, q d, q q k qk qk q j q, nj k Q Q Q V V Y sn Q q g, q d, q q k qk qk q j q, nj k b) Inequalty constrants Real power generaton lmts: The upper and lower lmt of the real power generated by the generators can be shown as mn P P P,,2,..., NG g, g, g, Reactve power generaton lmts: The upper and lower lmt of the reactve power can be shown as mn Q Q Q,,2,..., NG g, g, g, Voltage lmts: The upper and lower lmt of the bus voltage magntude can be shown as mn V V V,,2,..., NG Phase angle lmts: The upper and lower lmts on the bus voltage phase angle can be shown as mn,,2,..., NG Tap-Changers lmts: The upper and lower lmts on the tap postons n tap-changng transformer lnes can be shown as mn a a a,,2,..., NTCL MVAr njecton lmts: The upper and lower lmts on the MVAr njectons at voltage controlled buses can be shown as mn Q Q Q,,2,..., NVCB nj, nj, nj, Lne flow lmts: The mum MVA power flow n a transmsson lne can be shown as S S, l,2,..., NL l l IV. Proposed Hybrd Approach The hybrd algorthm adopted here s smlar to our prevous works and the detaled algorthm can be found [38]. The pseudo code of the procedure nvolved n PSO-GSA s as follows: PSO for Optmal Locaton. For each partcle. Intalze partcle, End Do GSA for Optmal Parameters. Search space dentfcaton, t=0; 2. Random ntalzaton, X(t); For =,, N

4 A Mult-Objectve Hybrd Heurstc Approach for Optmal Settng of FACTS Devces n Deregulated.. 2. For each partcle. Calculate ftness value If t s better than the best ftness value (pbest) n hstory. Set current value as the new pbest End 3. Choose the partcle wth the best ftness value of all the partcles as the gbest 4. For each partcle. Calculate velocty. Update poston End - whle mum teratons or mnmum error crtera s not attaned. 3. Ftness evaluaton of objects; 4. Update the parameters of G, best, worst and M; For =,, N 5. Calculaton of the force on each object; 6. Calculaton of the acceleraton and the velocty of each object; 7. Update the poston of the agents by (4) to yeld X(t+); t=t+; 8. Repeat steps 3 to 7 untl the stop crtera s reached; 9. End V. Case Studes The GSA-PSO algorthm s appled for optmal placement of each FACTS devce on the IEEE 30-bus test system. The real load of the system s MW. We have allocated MW for generator 2 and the rest of load s allocated to generator. Snce the test system has consstng of 6 generator buses and 2 load buses. Hence each generator can treat as source bus and smlarly each load bus can be lke a snk bus n open access envronment. Snce the partcpants and ther requred MW quanttes are unpredctable n real-tme, we have determned by usng random numbers theory. It means, the algorthm wll decde the source bus and snk bus as well as ther contracted power. For each smulaton, we can have ether blateral or multlateral contracts and hence numerous case studes can generate. Here we have gven some lmted transactons. 5. Wth 5... Sngle Source Sngle Snk Smulaton Results wth The base case transmsson loss before transacton s MW. It has been ncreased durng tractons and the controls n lne 2 6 are mnmzed that ncreased loss at every transacton. Smlarly, the voltage devaton ndex () s hgh wthout TCSC and t s also decreased wth. Fnally, the transmsson losses as well as are optmzed at every blateral transacton as gven n Table 3. The performance characterstcs of PSO-GSA for frst transacton are llustrated for voltage profle as well as transmsson loss n each transmsson lne are llustrated n Fg. and Fg. 2 respectvely. Table 3. mpact on losses and for sngle source sngle snks transactons Source Snk Contracted Transmsson losses (MW) Power (MW) Before transacton After transacton Wth Wthout Wth Sngle Source Multple Snks Smulaton Results wth In secton 5., we have executed only wth one source bus and one snk bus. In ths secton, one source bus and two snk buses are consdered for each transacton. The combned ncreased load at two snk buses s suppled by one source bus. The multlateral contracts and system performance wth are gven n Table 4 and Table 5 respectvely. For multple sources sngle snk transactons and correspondng mpact on system performance are gven n Table 6 and Table 7 respectvely. Smlarly, for multple sources multple snks and correspondng mpact on system performance are gven n Table 8 and Table 9 respectvely. Table 4. Multlateral transactons for sngle source multple snks smulatons Source Snks Contracted Power (MW) At snk At snk 2 At snk 3 Total DOI: / Page

5 Bus Voltage A Mult-Objectve Hybrd Heurstc Approach for Optmal Settng of FACTS Devces n Deregulated.. Table 5. mpact on losses and voltage for sngle source multple snks smulatons Transmsson losses (MW) Before Transacton After transacton Wth Wthout Wth Multple Sources Sngle Snk Smulaton Results wth Table 6. Multlateral transactons for multple sources sngle snk smulatons Sources Snk Contracted Power (MW) At source At source 2 At source 3 Total Table 7. mpact on losses and voltage for multple sources sngle snk smulatons Transmsson losses (MW) Before Transacton After transacton Wth Wthout Wth Multple Sources Multple Snks Smulaton Results wth Table 8. Multlateral transactons for multple sources multple snks smulatons Sources Snks Contracted Power (MW) At source At source 2 At snk At snk 2 Total Table 9. mpact on losses and voltage for multple sources multple snk smulatons Transmsson losses (MW) Before Transacton After transacton Wth Wthout Wth N-R Method Transacton GSA Bus No Fg.. Bus System voltage profle wth DOI: / Page

6 BUS voltage Power Loss n MW A Mult-Objectve Hybrd Heurstc Approach for Optmal Settng of FACTS Devces n Deregulated N-R Method Transacton Proposed method wth Transmsson Lne Fg. 2. Loss n each transmsson lne wth 5.2. Wth IPFC Multple Sources Multple Snks Smulaton Results wth IPFC The base case transmsson loss before transacton s MW. It has been ncreased durng tractons and the IPFC controls n lne are mnmzed that ncreased loss at every transacton. Smlarly, the voltage devaton ndex () s hgh wthout IPFC and t s also decreased wth IPFC. Fnally, the transmsson losses as well as are optmzed at every multlateral transacton as gven n Table 0 and Table respectvely. The voltage profle as well as transmsson loss n each transmsson lne are llustrated n Fg. 3 and Fg. 4 respectvely...08 performence of IPFC bus no vs bus voltage N-R Method Transaton GSA BUS NO Fg. 4. Bus voltage profle wth IPFC Table 0. IPFC mpact on losses and for sngle source sngle snks transactons Source Snk Contracted Transmsson losses (MW) Power (MW) Before After Wth Wthout Wth IPFC transacton transacton IPFC IPFC DOI: / Page

7 Power Loss n MW A Mult-Objectve Hybrd Heurstc Approach for Optmal Settng of FACTS Devces n Deregulated N-R Method Transaton Proposed method wth IPFC Transmsson Lne Fg. 5. Loss n each transmsson lne wth IPFC VI. Concluson In open access transmsson system, the transactons can take place at any tme among varous market partcpants. Some transactons can cause to decrease total transmsson losses due to counter flows and some are cause to ncrease due to domnant flows. Irrespectve of transactons and ther volumes, the major responsblty of power system engneers s to decrease net transmsson losses as well as to mantan good voltage profle for the better performance of system. In ths paper, the mpact of and IPFC on system performance s analyzed for both blateral and multlateral transactons. It has been observed that the transmsson losses are decreased and voltage profle s ncreased sgnfcantly wth FACTS controllers n the network. The adopted hybrd algorthm GSA-PSO s proved ts ablty to solve complex optmzaton problem wth multple objectves. References [] Gerbex, S., R. Cherkaou, and A. J. Germond. "Optmal locaton of FACTS devces to enhance power system securty." Power Tech Conference Proceedngs, 2003 IEEE Bologna. Vol. 3. IEEE, [2] Ongsakul, Weerakorn, and Peerapol Jrapong. "Optmal allocaton of FACTS devces to enhance total transfer capablty usng evolutonary programmng." Crcuts and Systems, ISCAS IEEE Internatonal Symposum on. IEEE, [3] Zhang, Jun, and Akhko Yokoyama. "Applcaton of nterlne power flow controller to ATC enhancement by optmal power flow control." Power Tech, 2007 IEEE Lausanne. IEEE, [4] Hammad, A. E. "Analyss of power system stablty enhancement by statc VAR compensators." Power Systems, IEEE Transactons on.4 (986): [5] Mohanty, Alok Kumar, and Amar Kumar Bark. "Power System Stablty Improvement Usng FACTS Devces." Internatonal Journal of Modern Engneerng Research (IJMER).2 (20): [6] Kumkratug, Prechanon. "Applcaton of nterlne power flow controller to ncrease transent stablty of power system." Journal of Computer Scence 6.2 (200): 490. [7] Mohanty, Alok Kumar, and Amar Kumar Bark. "Power System Stablty Improvement Usng FACTS Devces." Internatonal Journal of Modern Engneerng Research (IJMER).2 (20): [8] Zhang, Jun, and Akhko Yokoyama. "Power System Transent Stablty Improvement by the Interlne Power Flow Controller (IPFC)." 電気学会論文誌 B ( 電力 エネルギー部門誌 ) 28. (2008): [9] Karam, A., M. Rashdnejad, and A. A. Gharaves. "Voltage Securty Enhancement and Congeston Management va STATCOM & IPFC usng Artfcal Intellgence*." Iranan Journal of Scence and Technology 3.B3 (2007): 289. [0] Gupta, Sandeep, R. K. Trpath, and Rshabh Dev Shukla. "Voltage stablty mprovement n power systems usng facts controllers: State-of-the-art revew." Power, Control and Embedded Systems (ICPCES), 200 Internatonal Conference on. IEEE, 200. [] Moghadas, S-M., et al. "Composte system relablty assessment ncorporatng an nterlne power-flow controller." Power Delvery, IEEE Transactons on 23.2 (2008): [2] Bhaskar, M. Arun, et al. "Voltage profle mprovement usng FACTS devces: A comparson between SVC, TCSC and." Advances n Recent Technologes n Communcaton and Computng, ARTCom'09. Internatonal Conference on. IEEE, [3] Snagham, Rajshekar, and K. Vjay Kumar. "Role of Interlne Power Flow Controller for Voltage Qualty." Internatonal Journal of Advances n Electrcal and Electroncs Engneerng,(IJAEEE), ISSN (203): [4] Fardanesh, B. "Optmal utlzaton, szng, and steady-state performance comparson of multconverter VSC-based FACTS controllers." Power Delvery, IEEE Transactons on 9.3 (2004): [5] Babu, AV Naresh, et al. "Mult-Lne Power Flow Control usng Interlne Power Flow Controller (IPFC) n Power Transmsson Systems." World Academy of Scence, Engneerng and Technology, Internatonal Journal of Electrcal, Computer, Energetc, Electronc and Communcaton Engneerng 4.3 (200): [6] Babu, AV Naresh, and S. Svanagaraju. "Mathematcal modellng, analyss and effects of nterlne power flow controller (IPFC) parameters n power flow studes." Power Electroncs (IICPE), 200 Inda Internatonal Conference on. IEEE, 20. DOI: / Page

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