Optimal Placement of TCSC and SVC Using PSO

Transcription

1 IOSR Journa of Eectrica and Eectronics Engineering (IOSR-JEEE) e-issn: ,p-ISSN: , Voume 7, Issue (Ju. - Aug. 013), PP 45-5 Optima Pacement of and Using PSO K.Kavia #1, Dr.R.Neea * # Assistant Professor,Department of Eectrica engineering, Annamaai University Chambaram, Tami nadu, India. * Professor,Department of Eectrica engineering, Annamaai University Chambaram, Tami nadu, India. Abstract: Fexibe AC Transmission System (FACTS) devices pay a vita roe in improving e static as we as dynamic performance of e power system. They serve to mae e oerwise rig, conventiona AC systems fexibe ones as ey mae it possibe to adjust e bus votage magnitudes, phase anges and ine impedances at faster rates in e required directions which wi resut in e improvement of stabiity and bus votage profies and reduction of rea and reactive power osses. In order to tap imum benefits out of eir instaation, e ocation and ratings of e FACTS devices are to be chosen optimay. In is paper a PSO based technique has been presented for soving e probem of device pacement and an objective function comprising e weighted sum of e indicators of ine oadings, bus votage deviations and device cost functions has been formuated. The objective function is soved rough e appication of PSO technique and testing has been done using IEEE 14, 30 and 57 bus systems Keywords: FACTS devices, Thyristor Controed Series Capacitor (), Static Var Compensator (), Partice Swarm Optimization (PSO), Security enhancement. I. INTRODUCTION Present day power systems are highy compex interconnected systems, so it becomes necessary to operate e power systems in a secure and reiabe manner. Due to e dynamic oad pattern and ever increasing oad demand, power fows in some of e transmission ines are we above eir norma imits whie some of e ines are not oaded upto eir fu capacity. As a resut of is uneven oad distribution, e votage profie of e system gets deteriorated which poses a reat for e security of e system. Taing into conseration e factors such as ever increasing oad demand, economica and technica constraints invoved in setting up new power generation faciities and imitations faced in purchasing right of ways to reaize new transmission corrors it becomes highy essentia to utiize e existing generation and transmission faciities in e most efficient manner. FACTS controers are found to be an effective aternative for e compex tas of buing up new transmission corrors [1]. Moduating and reversing e power fow rough e transmission ines in a fast, accurate and precise manner was made possibe rough e FACTS (Fexibe Aternating Current Transmission System) concept introduced by N.G.Hingorani []. FACTS devices are very effective in improving e votage profie, reducing e ine oadings and ine osses, proving reactive power support over a we range of operating votages and enhancing e stabiity of e system. They can as we be used wi e existing ines in order to enhance eir power transfer capabiity. The power fow rough e networ can be controed wiout modifying e generation and carrying out any switching operations in e networ. [3]. In order to achieve imum benefits rough e instaation of e FACTS devices, devices of suitabe ratings need to be instaed at optima ocations [4]. The proposed wor deas wi e pacement of muti-type FACTS devices namey and. (Static Var Compensator) was e first device to be reeased in e maret, when e concept of generating controabe reactive power rough switching power converters was introduced. It is a shunt connected device and is instaed parae wi a bus. It has e abiity to generate or absorb reactive power at e point where it is connected. More an 800 s are being instaed wordwe bo for utiity and industria purposes. (especiay in eectric arc furnace and roing mis)[5]. (Thyristor Controed Series Capacitor) is a type of series compensator at can prove many benefits for a power system incuding contro of power fow in e ine, damping power osciations and mitigating sub synchronous resonance [6]. is a variabe impedance type series compensator. It consists of a series compensating capacitor shunted by a yristor controed reactor. By controing e firing ange of yristor, can change e ine reactance smooy and rapy. has one of e two possibe characteristics eier capacitive or inductive, can be used for increasing or decreasing e reactance of e ine X [7]. Moreover to avo e over compensation of e ine, e imum vaues of capacitance and inductance are fixed at 0.8X and 0.X [8]. Word s first 3 phase, *165 MVAR, was instaed in 199 in Kayenta substation, Arizona. It raised e transmission capacity of transmission ine by 30% and effectivey damped eectromechanica power osciations [9]. Optima pacement of FACTS devices is essentia to tap e imum benefits in terms of system performance and cost effectiveness. A oss sensitivity index wi respect to e contro parameters of FACTS devices has been suggested and wi e computed oss sensitivity index, e FACTS devices are paced on e most sensitive bus or ine [10]. Fuzzy based approach for e optima pacement of FACTS device for enhancing e system security under norma and networ contingencies has been discussed in [11]. The optima ocation of a given number of FACTS devices is a probem of combinatoria anaysis. 45 Page

2 Optima Pacement Of And Svc Using PSO To sove such ind of probems, heuristic meods can be used [1]. They permit to obtain acceptabe soutions wiin a imited computation time. The appication of Genetic Agorim for e optima ocation of muti type FACTS devices in order to imize e system oadabiity is anaysed in [13]. A Differentia Evoution based agorim to dece e optima ocation and device rating has been suggested in [14] wi an objective of enhancing e system security under singe ine contingencies. The Partice Swarm Optimization (PSO) is appied for e optima ocation of FACTS devices to achieve minimum cost of instaation and to improve system oadabiity, by consering erma imit for e ines and bus votage imit for e oad buses as constraints [15]. Sensitivity anaysis approach for finding e optima ocation and PSO for e optima parameter setting of has been suggested in [16] so as to imize e oadabiity. In is paper, PSO technique is appied to find e optima pacement and capacity of muti type FACTS devices ( & ). The objective function to be minimized comprises of cost of e device, ine oadings and votage deviations at e oad buses. II. PROBLEM FORMULATION A. Objective of e optimization As e cost of e FACTS devices is high, in order to achieve e imum benefit, e devices are to be instaed at e optima ocations. The objective function has ree terms, e first term represents e instaation cost of e devices, e second and ird terms represent e oad bus votage deviations and ine oadings respectivey. The minimization of e proposed objective function has to ead to a cost effective security oriented device pacement. The objective function is formuated as MinF W ( C * S) C S W LVD W LL (1) 1 * 3 F is e objective function; C is e cost of device in US $/KVar; C is e cost of device in US $/KVar; S is e operating range of e FACTS device; LVD is e Load votage deviation; LL is e Line oading; W 1,W & W 3 are e weight factors. (i) Cost ( C ) & ( C ) The first term of e objective function C represents e instaation cost of device and cost of in e networ, which are given by e foowing equations. C s s () C is e instaation C s s (3) (ii) Load votage deviation LVD Excessive high or ow votages can ead to an unacceptabe service quaity and can create votage instabiity probems. FACTS devices connected at appropriate ocations pay a eading roe in improving votage profie ereby avoing votage coapse in e power system. The second term consered represents e oad votage deviations in order to prevent e under or over votages at networ buses. LVD nb m1 Vmref V V mref m V is e votage magnitude at bus m m mref n V is e nomina votage at bus m & is consered as 1.0 pu. m refers to e oad buses, where (iii) Line oading LL V m is ess an (4) V mref. is ocated in order to remove e overoads and to distribute e oad fows uniformy. To achieve is, ine oading is consered as e ird term in e objective function. 46 Page

3 Optima Pacement Of And Svc Using PSO LL n S S 1 n (5) S is e apparent power in e ine. S is e apparent power rating of ine. B. The optimization variabes The optimization variabes consered in is wor are (a) The number of FACTS devices ( & ) to be instaed is taen as e first variabe. (b) The ocation of ese devices is consered as e second variabe to be optimized. is paced on a ine and is connected at a oad bus. s are not instaed in e ines where e transformers exist. (c) Type of e device ( or ) to be instaed is consered as e ird variabe. (d) The rating of e device is consered as e four variabe. Ony one FACTS device per ine or bus is permitted C. Modeing of FACTS devices (i) Modeing is a series compensator. It consists of a series compensating capacitor shunted by a yristor controed reactor as shown in figure(a).wi e power fow contro can be done by increasing or decreasing e overa ines effective series transmission impedance, by adding a inductive or capacitive reactance correspondingy. The is modeed as a variabe reactance as shown in figure (b). The woring range of is consered as foows. ocated. 0.8X X 0. X (6) X is e reactance added to e ine by pacing. X is e reactance of e ine where is (ii) Modeing is a shunt connected static var generator or absorber whose output is adjusted to exchange capacitive or inductive current so as to maintain or contro specific parameters of e eectrica power system. The is a genera term for a TCR (Thyristor Controed Reactor), a TSC (Thyristor Switched Capacitor) or a combination of bo as shown in figure (c). It wors in two modes, capacitive or inductive mode. In inductive mode, it absorbs reactive power and in capacitive mode it injects reactive power. It is modeed as an ea reactive power injection at bus i, where it is connected as depicted in figure (d). is paced in ony at oad buses. The reactive power is imited as foows min Q Q Q (7) Where min Q 100MVar Q 100MVar III. OVERVEIW OF PSO TECHNIQUE 47 Page

4 Optima Pacement Of And Svc Using PSO Partice swarm optimization is a heuristic search technique deveoped by Eberhart and Kennedy [17] based on e concept of swarm inteigence exhibited by e foc of birds, schoo of fish etc in which each member of e group adjusts its behaviour based upon its own experience and e experience of e swarm..this sort of socia behaviour is used to simuate e probem soving environment in which a swarm is randomy generated in terms of soution variabes of e probem. The indivuas in a swarm are caed partices. After generating e swarm, e fitness vaues of e partices P are evauated and compared against e vaues obtained from e previous iteration. The partices wi e vaues of fitness function in e next generation P are retained. G is e vaue attained so far by e swarm of partices. G of e previous iteration and whichever is ower is In each iteration, G of e current swam is compared wi e retained aong wi e corresponding partice. The position update of partices is carried out rough e expression (8) in which e veocity is cacuated using (9). X X V (8) V 1 1 K1 WV K c r 1 1 P X c r G X The inertia weight in (7) is cacuated using e foowing expression. W Wmin W W * iter iter (10) (9) This iterative procedure is repeated ti a specified number of swarms are reached or unti a predefined amount of time has eapsed or unti ere is no conserabe difference between e outcomes of a few subsequent iterations. - V -Veocity of e 1 iteration. 1 V -Veocity of e X - Position of e 1 X - Position of e P G r 1, c c 1, - Best position of e i indivua at i indivua at i indivua at iteration iteration. i indivua at 1 i indivua. - Best position among e indivuas. iteration. r - Random numbers distributed wiin e interva [0, 1] - Positive constants caed acceeration constants. W - Inertia weight. W W iter - Initia vaue of inertia weight. min - Fina vaue of inertia weight. - Maximum number of iterations. iter - Current iteration number. d 1,,...D i 1,,...m, D is e number of members in a partice., m is e size of e swarm. IV. ALGORITHM The agorim of e proposed wor is expained beow. Step1: The system data and e oad factor are initiaized. Step: PSO parameters such as e size of swarm m, imum number of iterations, e number of variabes to be optimized, imits of each variabes in e partice, c 1 & c vaues, W min & W, D, veocity imits, P and G are initiaized. Step3: An initia popuation is randomy generated consering e variabes to be optimized. [The number of devices, ocation of e device, type of device, rating of e device] Step4: For each partice i [i = 1, m] in e popuation, e objective function is evauated. Stpe5: The cacuated vaue of each partice is compared wi its P and P of each partice is updated. Step6: G is cacuated, en compared wi e G in e previous iteration and it is updated. Step7: A new popuation is created by changing e veocity and position of e partice. 48 Page

5 Step8: If stopping criterion is satisfied, e indivua is printed, ese repeated from step 4. Step9: Steps from to 8 are repeated for different oad factors. Optima Pacement Of And Svc Using PSO V. SIMULATED RESULTS The proposed meod has been tested on standard IEEE 14 bus, 30 bus and 57 bus test systems and e resuts are presented in tabes 1 to 9. To study e effect of e instaation of and on oad bus votages and ine oadings under overoad conditions, e oads on e system were increased in a step by step manner; e rea and reactive power oads connected at various oad buses were increased eeping e oad power factor constant. The imum number of FACTS devices is imited to on a 14 bus system, 3 on a 30 bus system and 5 on a 57 bus system. The test resuts are tabuated and an equivaent bar chart representation of e resuts is aso presented for each of e oad conditions. The resuts are presented here for ree different cases namey, variations of oad bus votages and ine oadings under various oading conditions when no FACTS devices are present in e system, wi ony s connected to e system and wi bo as we as connected. Case (I) 14 bus system Tabe1: Line oading for different oad factors Tabe: Load votage deviation for different oad factors Tabe3: Location of FACTS devices Fig. 1: Line oading VS percentage of oad Fig. : Load votage deviation VS percentage of oad A. Case (II) 30 bus system 49 Page

6 Optima Pacement Of And Svc Using PSO Tabe4: Line oading for different oad factors Tabe5: Load votage deviation for different oad factors Tabe6: Location of FACTS devices Fig. 3: Line oading VS percentage of oad B. Case (III) 57 bus system Fig. 4: Load votage deviation VS percentage of oad Tabe7: Line oading for different oad factors Tabe8: Load votage deviation for different oad factors Tabe9: Location of FACTS devices 50 Page

7 Optima Pacement Of And Svc Using PSO Fig.5: Line oading VS percentage of oad Fig. 6: Load votage deviation VS percentage of oad It has been observed at for e IEEE 14 bus system, ere is a significant reduction in e ine oadings when s are connected at optima ocations. When s are used aong wi s, ine oadings are furer reduced ereby improving e eve of system security. It is aso observed at e oad votage deviations are reduced when s are connected at appropriate ocations and when s were used aong wi s e oad bus votages improve significanty ereby resuting in a better votage profies roughout e system under norma and overoad conditions. Simiar resuts were obtained for IEEE 30 bus and 57 bus systems. The variations of ine oadings and bus votage deviations under various oad conditions are presented in e form of bar charts in Figures1 to 6 for better understanding. VI. CONCLUSIONS A new meod has been suggested for seecting e optima ocation and size of s and s under norma and overoad conditions. The objective function formuated consists ree terms, first term indicating e instaation cost of e devices, e second term indicating e ine oadings and e ird one indicating e oad votage deviations. The objective function has been soved by e appication of PSO technique which is basicay a heuristic search agorim which is we suited for compex, noninear probems. It has been found at e pacement of s and s of optima ratings at suitabe ocations resuts in conserabe improvement in bus votage profies and ine oadings are reduced significanty. REFERENCES [1] Sureha Manoj, Dr. Puttaswamy P.S., Importance of FACTS Controers in power systems, Internationa Journa of Advanced Engineering Technoogy, vo.ii, Issue III, juy-sep, 011, pages [] N.G.Hingorani and L.Gyugyi, Understanding FACTS, IEEE Press, [3] S.N.Singh, A.K.Dav, Optima ocation of FACTS devices for congestion management, Eectric Power Systems Research vo 58, 001, pages [4] R.Benab, M.Boudour, M.A. Abo, Optima ocation and setting of and devices using non-dominated sorting Partice Swarm Optimization, Eectric Power Systems Research vo 79, 009, pages [5] K.Sundareswaran, P.Srinivasarao Naya, Durga Venatesh Ch, Hariharan B, Optima pacement of FACTS devices using probabiistic Partice Swarm Optimization, IEEE PES Innovative Smart Gr Technoogies, 011, pages1-6. [6] Hugo Ambriz-Perez, Enrique Acha, Caudio R. Fuerte- Esquive, -firing ange mode for optima power fow soutions using Newton s meod, Eectric Power Systems Research vo 8, 006, pages [7] Naresh Acharya, N.Miuanaan, ocating series FACTS devices for congestion management in dereguated eectricity marets, Eectric Power Systems Research vo 77, 007, pages [8] Ghamgeen I.Rashed, Yuanzhang Sun, Kai-Pei Liu, Optima pacement of Thyristor Controed Series Compensation in Power System based on Differentia Evoution Agorim IEEE, seven Internationa Conference on Natura Computation, 011, pages Page

8 Optima Pacement Of And Svc Using PSO [9] S.Meiandasivam, Rajesh Kumar Nema, Shaiendra Kumar Jain, Behaviora Study of device- A matab / simuin Impementation Word Academy of Science, Engineering and Technoogy, 008. Pages [10] Preecha Preedavichit, S.C. Srivastava, Optima reactive power dispatch consering FACTS devices Eectric Power Systems Research vo 46, 1998, pages [11] K.Visaa, D.Thuaram, Lawrence Jenins, Appication of UPFC for system security improvement under norma and networ contingencies eectric power systems research-003, pages [1] Sung-Hwan Song, Jung-U Lim, Seung-II Moon, Instaation and operation of FACTS devices for enhancing steady state security Eectric Power Systems Research vo 70, 004, pages [13] Stephane Gerbex, Rach Cheraoui, Aain J. Germond, Optima ocation of muti-type FACTS devices in a power system by means of genetic agorims IEEE Transactions on power systems, vo. 16. Aug. 001, pages [14] Husam I.Shaheen, Ghamgeen I.Rashed, S.J. Cheng, Optima ocation and parameter setting of UPFC for enhancing power system security based on differentia evoution agorim, Eectric Power Systems Research vo 33, 010, pages [15] M.Saravanan, S.Mary Raja Sochana, P.Venatesh, J.Prince Stephen Abraham, Appication of partice swarm optimization technique for optima ocation of FACTS devices consering cost of instaation and system oadabiity, Eectric Power Systems Research vo 77, 007, pages [16] K.Satyanarayana, B.K.V.Prasad, G.Devanand, N.Siva Prasad, optima ocation of wi minimum instaation cost using PSO, Internationa Journa of computer science and technoogy, vo, dec 011, pages [17] James Kennedy, Russe Eberhart Partice Swarm Optimization, in Proceedings of IEEE Internationa Conference on Neura Networs, vo14, 1995, pages [18] 5 Page