IOSR Journal of Engineering (IOSRJEN ISSN: 50-301 Volume, Issue 6 (June 01, PP 09-15 www.iosrjen.org Sensitivity pproah for the Effetive loation of in a Deregulated Eletriity Market B.Likhitha 1, J.Srinivasa Rao 1, J.marnath 1 Department of Eletrial and Eletronis Engineering, QIS College of Engg & Tehnology, Ongole. Department of Eletrial and Eletronis Engineering, JNTUH College of Engg & Tehnology, Hyd. BSTRCT: - In a deregulated eletriity market it may always not be possible to dispath all of the ontrated power transations due to ongestion of transmission orridors. In a ompetitive eletriity market, ongestion ours when transmission network is unable to aommodate all of the desired transations due to the violation of system operating limits. Congestion relief an be handled using FCTS devie suh as, where transmission apability will be improved. Based on redution of total system reative power loss optimal loation for the plaement of these devies. Congestion management by Transmission Line Relief (TLR sensitivity method was also eamined for IEEE 9 bus system. The approah for this problem was arried out with the help of Power World Simulator software. Keywords: Congestion, Deregulated power system,, Redution of reative power losses, Transmission Line Relief (TLR sensitivity. 1. INTRODUCTION Power industry is moving rapidly from regulated onventional setup to a deregulated environment. The main objetive of the deregulation of power industry is to introdue ompetition among the power produers and prevent monopolies. Congestion is a onsequene of network onstraints haraterizing a finite network apaity that preludes the simultaneous delivery of power from an assoiated set of power transations [5]. When the produers and onsumers of the eletri energy desire to produe and onsume in amounts that would ause the transmission system to operate at or beyond one or more transfer limit, the system is said to be ongested. Congestion is also defined as when the transmission network is unable to aommodate all of the desired transations due to the violation of system operating limits. Line outages or higher load demands are the auses of ongestion in the transmission network. Congestion ours in both vertially bundled and unbundled systems but the management in the bundled system is relatively simple as generation, transmission and in some ases, distribution systems are managed by one utility. The management of ongestion is somewhat more omple in ompetitive power markets and leads to several disputes. Different tehniques are used in many papers for solving the ongestion problem. In [5] oordination between and SVC is investigated via Real Geneti lgorithm tehnique to inrease the power transfer. In [6] shwini kumar proposed a Zonal based ongestion management approah based on Real and Reative power Resheduling. In [11] an algorithm for ongestion management based on optimal power flow framework and using has been proposed. In [14] modelling of and a sensitivity based approah for optimal loation of is proposed. In [15] two methods suh as LMP differene method and ongestion rent ontribution methods are proposed for the Plaement of series FCTS devies like to redue ongestion. FCTS devies are utilized as one of the method whih an redue the transmission ongestion and leads to better using of eisting grid infrastruture. FCTS devies, espeially series FCTS devies like are onsidered one suh tehnology whih redues transmission ongestion. Transmission Line Relief (TLR sensitivities an also be used for the purpose of ongestion alleviation by load urtailment. In this paper a method for Congestion management have been suggested based on Load Curtailment using TLR sensitivity method and based on redution of total system reative power losses with the use of FCTS devies.. PROBLEM FORMULTION.1 Stati modelling of Thyristor ontrolled series ompensators ( are onneted in series with the lines. The effet of a on the network an be seen as a ontrollable reatane inserted in the related transmission line that ISSN: 50-301 www.iosrjen.org 9 P a g e
ompensates for the indutive reatane of the line. This redues the transfer reatane between the buses to whih the line is onneted. This leads to an inrease in the maimum power that an be transferred on that line in addition to a redution in the effetive reative power losses. The series apaitors also ontribute to an improvement in the voltage profiles. Figure 1. Shows a model of a transmission line with a onneted between buses i and j. The transmission line is represented by its lumped π-equivalent parameters onneted between the two buses. During the steady state, the an be onsidered as a stati reatane -j. This ontrollable reatane,, is diretly used as the ontrol variable to be implemented in the power flow equation. Fig.1. Model of in a transmission line. The following equations are used to model the. Let the voltages at bus i and bus j are represented by V i δ i and V j δ j respetively. The omple power from bus i to j is P i = V i G V i V j [ G Cosδ + B Sinδ i ]... (.1 P j = V j G V i V j [ G Cosδ + B Sinδ ]... (. G = ( r r ( r (... (.3 B i = ( r ( r r (... (.4. Redution of total system VR power loss Here it is looked at a method based on the sensitivity of the total system reative power loss (Q L with respet to the ontrol variables of the FCTS devies. For the devie onsidered the following ontrol parameter: Net line series reatane (X for a plaed between buses i and j, sensitivity fators with respet to the ontrol variable may be given as follows: Loss sensitivity with respet to ontrol parameter X of plaed between buses i and j, a Q L....(.5 X The loss sensitivities with respet to X an be omputed as: QL a X R X V i V j VV i j os( i j...(.6 ( R X 3. SELECTION OF OPTIML PLCEMENT OF FCTS DEVICES Using the loss sensitivities as omputed in the previous setion, the riteria for deiding devie loation might be stated as follows: 1. must be plaed in the line having the most positive loss sensitivity inde a. The proedure is shown in below flow hart fig. ISSN: 50-301 www.iosrjen.org 10 P a g e
Fig:3.1 Flow hart for proposed method in effetive loation of 4. LOD CURTILMENT BSED ON TLR SENSITIVITIES TLR sensitivities an be used for the purpose of ongestion alleviation by load urtailment. TLR sensitivities are onsidered as inverse of power transfer distribution fators (PTDFs. PTDFs are used to determine the sensitivities of transmission line flow to a single power transfer where as TLR sensitivity of the flow on single transmission element to various transations in the system. In the method of ongestion alleviation using load urtailment, TLR sensitivities at all the load bases for the most over loaded line are onsidered. TLR sensitivity at a bus k for a ongested line i-j is given by equation S k =.(4.1 Where is the eess power flow on line i-j = -... (4. Where : tual power flow through line i-j : Flow limit of transmission line i-j The new load at bus k an be obtained by (4.3 =load after urtailment at bus K = load before urtailment at bus K S k =sensitivity of power flow on line i-j due to load hange at bus k N= total number of load buses. 5. SIMULTION RESULTS In this study an IEEE 9 bus system has been analysed for ongestion management by the optimal loation of FCTS devie suh as using the power world simulator software based on sensitivity indies approah Fig 5.1. Indiates the single line diagram of an IEEE 9 bus system drawn in power world simulator. ISSN: 50-301 www.iosrjen.org 11 P a g e
MV MV MV MV MV MV MV 7 MW 35 Mvar slak 85 MW 1 Mvar slak 90 MW 30 Mvar 3 4 5 6 MV 9 10% MV 8 7 15 MW 50 Mvar 100 MW 35 Mvar 163 MW 0 Mvar Fig. 5.1. Modified IEEE 9 bus system From the above figure it was found that the line 8-9 in the system is in ongested ondition.in order to relieve the system from ongested ondition FCTS devie suh as Thyristor ontrolled series ompensator ( is plaed in one of the lines. reative power loss sensitivity based approah is used here for optimal plaement of this devie. The sensitivity indies for the ongested 9 bus system were tabulated below. Table 5.1 OPF result without LINES FROM BUS TO BUS LODBILITY (% 1 1 4 66.69 4 5 39.13 3 5 6 61.08 4 3 6 71.58 5 4 9 53.60 6 8 7 77.09 7 8 65.68 8 8 9 10.0 9 6 7 31.95 The result of the OPF run on the test network is shown in the above table 3.1. From the OPF it was found that the real power flow in line 8 was 10.0 whih is more than line loading limit. 5.1 Reative power loss sensitivity inde of IEEE 9 bus system LINE FROM BUS Table 5. sensitivity fators TO BUS SENSITIVITY INDEX (a (0%omp (40%omp 1 1 4-0.64546-0.65990-0.66714 (60%omp 4 5-0.1684-0.1385-0.10357 3 5 6-0.35638-0.34761-0.616 4 3 6-0.7407-0.73801-0.74401 5 4 9-0.6500-0.6851-0.5751 6 7 8-0.59930-0.6059-0.57969 7 8 -.6885 -.68448 -.675 8 8 9-0.75807-0.75434-0.6786 9 6 7-0.075-0.0790-0.07835 ISSN: 50-301 www.iosrjen.org 1 P a g e
From the above table the lines having the most positive loss sensitivity inde is hosen for the plaement of devies. Hene lines and 9 are seleted from the table. devie in the indutive mode of operation are onneted in series with these two lines, with indutive reatane of 60% of the line reatane eah have been onsidered. lines Power flow without (MW Table5.3 Power flow list. with 0% omp with 40% omp with 60% omp 1 7.09 7.09 7.09 7.11 31.03 9.54 8.0 7.00 3 60.9 6.5 63.64 64.90 4 85 85.00 85.00 85.00 5 41.06 4.55 43.89 45.10 6 76.9 77.86 79.7 80.54 7 163 163 163 163 8 86.71 85.14 83.73 8.46 9 4.31.75 1.36 0.10 Fig 5.. Comparison of power flows with (0%omp and without. Fig 5.3 Comparison of power flows with (40%omp and without. Fig 5.4 omparison of power flows with (60%omp and without. ISSN: 50-301 www.iosrjen.org 13 P a g e
When (0% is plaed in the lines 4-5 and 6-7, it removes the ongestion present in the line 8-9 from 10% to 100%. gain when the lines 4-5 and 6-7 were being ompensated by 40%, the ongestion in the line 8-9 got relieved from 100% to 99% and the ongestion in the line 8-9 is relieved to 97% when the lines 4-5 and 6-7 were ompensated by 60%. From the results we an observe that plaing the in the optimal loation relieves the ongestion in the modified IEEE 9 bus system. 5. Transmission line relief (TLR sensitivity method This transmission line relief method is based on load urtailment. In this method of ongestion management, TLR sensitivities at all the load buses for the most overloaded line are onsidered. n IEEE 9 bus ongested system is onsidered here. 36 MW 38 MVR 85 MW 1 MVR slak 3 4 5 6 80% 99 MW 150 MVR 9 8 97% 163 MW 181 MVR 49 MW 15 MVR 7 Fig5.5 Congested IEEE 9 bus system. The TLR values of ongested lines of a 9 bus system are tabulated below. Table: 5.4 TLR sensitivities BUSES LINE (4-9 LINE (7-8 LINE (7-6 1 0 0 0 0.639-0.361 0.361 3 0.385 0.385-0.385 4 0 0 0 5 0.135 0.135-0.135 6 0.385 0.385-0.385 7 0.533 0.533 0.467 8 0.639-0.361 0.361 9 0.875-0.15 0.15 Load urtailment is to be done at the bus having most positive value. From the table the TLR sensitivity at bus 9 for the line 4-9 is most positive. So load urtailment of 9MW at bus 9 relieves the ongestion of line 4-9 and similarly load urtailment at bus 7 relieves ongestion from 97% to 90% of the line 8-. 6. CONCLUSION Congestion management is the important issue in the deregulated power system.tlr sensitivity approah have been eamined by load urtailment and redution of total system reative power loss sensitivity indies are proposed for loating devie to manage the ongestion in deregulated eletriity market. power injetion Π-model is developed for and then redution of reative power loss sensitivity inde is modified for the network ontaining a. The proposed methodologies are based on sensitivity that are by-produt of OPF problem formulation. The proposed method was tested on modified IEEE 9 bus system. CKNOWLEDGMENT The authors would like to thank QISCET, Ongole for providing the omputer lab faility with neessary software. ISSN: 50-301 www.iosrjen.org 14 P a g e
REFERENCES 1..S. Bawnakar, V.P. Rajderkar, Third International Conferene on Emerging Trends, Thyristor Controlled Series Compensator To Resolve Congestion Caused Problems.. L.Rajalakshmi, M.V.Suganyadevi, S. Parameswari, Congestion management in deregulated power system by loating series FCTS devies. International Journal of Computer ppliations (0975 8887 Volume 13 No.8, January 011. 3. De Oliveira E.J., Lima W.M., 1999 lloation of FCTS devies in a ompetitive environment, 13 th PSCC, 1184-1190. 4..R.bhyankar, Prof.S..Khaparde, IIT Bombay, Introdution to deregulation in power industry. 5..H.Iranmahesh, M. Rashidi-Nejad nd Gharaveisi, M. Shojaee, Congestion Relief Via intelligent Coordination Of & SVC. 6. Kumar a., Srivatsava S.C., singh S.N., 004. Zonal Congestion Management pproah using Real and Reative Power Resheduling, IEEE Transations on Power systems, vol. 19, No. 1. 7. Ch. Shaffner, G. ndersson, Swiss Fedaral Institute of Tehnology(ETH, zurih, Switzerland, Use of FCTS devies for ongestion management in liberalized eletriity market. 8. G.Glanzmann*, G.ndersson, ETH Zurih, Switzerland. Using FCTS devies to resolve ongestionin transmission grids. 9. N.G. Hingaroni and L. Gyugyi. Understanding FCTS onepts and tehnology of fleible a transmission systems. IEEE Press, New York, 000. 10. Seyed Mohammad Hosseini Nabavi, Nazanin lsadat Hosseinipoor,Somayeh Hajforoosh, International Journal of Computer ppliations(0975-8887 vol6-no.6, September 010. Soial Welfare Maimization by optimal loating and sizing of for Congestion Management in Deregulated power markets. 11. Huuan Li, Fanging Li, Pei Zhang, Xiayang. Presentation at 009 IEEE BuharestPower Teh onferene, June 8 th july nd,buharest, Romania. Optimal utilization of Transmission Capaity to Redue Congestion with Distributed FCTS. 1. Manasarani Mandala and C.P. Gupta, 16 th National Power systems Conferene, 15 th -17 th Deember,010. Comparative Studies of Congestion Management in Deregulated Eletriity Market. 13. Shmuel S. Oren, University of California at berkely. Transmission Priing and Congestion Management : Effiieny, Simpliity and Open ess. 14. H. singh, S. Hao,and.papaleopoulos, Transmission ongestion management in ompetitive eletriity markets, IEEE Trans. on power systems, 1998, vol. 13, No.,pp. 67-680. 15. Naresh harya, M. Mithulananthan, Loating Series FCTS devies For Congestion Management In Deregulated Eletriity Market. 16. Power World Simulator, Power World Corporation, version 11.0, Evaluation and University Eduational Use, URBN, IL 61801. ISSN: 50-301 www.iosrjen.org 15 P a g e