Distributed Generation Placement in Unbalanced Distribution System with Seasonal Load Variation

Transcription

1 Distriuted Genertion Plement in Unlned Distriution System with Sesonl Lod Vrition Rvi Tej Bhimrsetti Dept. of Eletril Engg., NT Kurukshetr Kurukshetr, ndi Ashwni Kumr, Memer, EEE Dept. of Eletril Engg., NT Kurukshetr Kurukshetr, ndi Astrt To minimize power losses, it is importnt to determine the optiml lotion nd size of Distriuted Genertion (DG to e pled in distriution system. npproprite lotion nd size my led to inese the system losses nd d effet on voltge profile. This pper proposes method for finding optiml size nd lotion of DG for loss redution in unlned rdil distriution network (URDN. n this pper, the impt of sesonl (summer lod vrition with ZP lod model is onsidered. ZP lod model onsists of residentil, industril nd ommeril hs een onsidered for study of test system. The proposed tehnique hs een tested on us URDN. Keywords DG plement; unlned rdil distriution; optiml lotion nd size, sesonl lod vrition. NTRODUCTON The losses in the distriution system re out -3% of totl generted power. So the redution of tive power loss in distriution systems is very importnt to improve the overll effiieny of eletril power system. There re mny wys to redue the losses s like Distriuted Genertion plement, pitor plement, lod mngement, Network Reonfigurtion nd so on. Due to the glol nxious out energy isis nd glol wrming, the distriuted genertion tehnology ttrts more ttention []. For loss minimiztion, there re vrious pprohes to ple the optimum DG nd those re: the geneti lgorithm nd Hereford rnh lgorithm [], tu serh [3], fuzzy-ga method [], seond-order lgorithm method [] nd sensitivity sed pprohes [6]. V.V.S.N.Murty, et l [7] proposed omined power loss sensitivity sed pproh nd modified novel method for optiml plement of DG in lned rdil distriution system. K. Ngrju, et l [] proposed novel method to find the optiml lotion nd size of DG sed on rel power loss minimiztion t unity power ftor. T. Rmn, et l [9] presented method for otining optiml lotion nd size of DG in three-phse unlned rdil distriution system for power loss minimiztion. By penetrting the DG of size % of totl feeder lod t eh node, uthors first identified the voltge sensitive nodes nd the node t whih voltge index in minimum is seleted s est lotion for DG plement. Vritionl lgorithm is used to find the optiml size. This pper proposes method of minimizing the losses ssoited with tive omponent of nh urrents y pling optiml DG t proper lotion. n this method, the optiml size of DG t eh node n e otined y optimizing the loss sving eqution. The node t whih the loss sving is mximum will e onsidered s ndidte node of DG plement nd the orresponding size is the optiml size. The lod flow of unlned rdil distriution system hs een implemented from Ref. []. The impt of summer lod vrition [] with ZP lod model hs een tken for nlysis of us URDN [9].. PROPOSED METHODOLOGY Let us onsider the following TPL =Totl rel power loss. TQL =Totl retive power loss. Sloss = TPL j TQL,, re the nh urrents in three phses. r,, re the tive (rel omponent of nh urrents in three phses. i, i, i re the retive (imginry omponent of nh urrents in three phses. Z is the nh impedne. α is the set of nhes from soure us to the us where DG is onneted. The totl power loss in n unlned distriution system is given y [] Z ( ( ( Z Z Sloss = Z ( Z ( Z ( ( nhes Z ( ( ( Z Z Where = r j i ( 3 = j i j ( 3 = j i j TPL ssoited with oth tive nd retive omponent of nh urrents n e given s //$3. EEE

2 Sloss= nhes R R R R ( r i R ( i R ( i ( r ii 3 ri 3 i ( ii 3 i 3i ( r ii 3 i 3 ir TPL n e divided into two prts: TPL due to tive omponent of nh urrent nd TPL r due to retive omponent of nh urrent. TPL = TPL TPL r (3 Power loss ssoited with tive omponent of nh urrents n e minimized y supplying prt of tive power demnd lolly with the help of DGs. When unity power ftor DG is instlled t node k, the urrent DG flows towrds the susttion nd the urrent flowing through the respetive nhes redues, wheres, the urrent in the remining nhes remins unltered. Let α e the set of nhes from soure us to the k th us. Then the urrents of ll nhes in set α will e hnged. The urrent of other nhes ( α is unffeted y the DG. At unity power ftor, DG n supply only tive omponent of urrent. Hene fter instlling DG, rel power loss ssoited with tive omponent of nh urrent will e hnged. The simple distriution system is shown in Fig.. f the DG is pled t us, then the set α onsist of,, nd nhes. Fig.. Simple distriution system Rel power loss ssoited with tive omponent of urrent is TPL = nhes R R R R R R r ( r 3 ri 3i 3i 3i ( r 3i 3ir After pling DG t node k, new urrents of ll nhes in set α re given y r ( new ( new ( new = = = r D DG D DG D DG Where D=; if nh α =; otherwise ( ( The rel power loss for the ompensted system n e written s, R ( ( ( r DG R DG R DG ( r DG ( DG R ( ( 3 r DG i 3i DG ( DG TPL = ( DG ( DG nhes R ( ( 3 DG i 3 i DG ( ( DG r DG R ( ( 3 DG i 3i r DG The loss sving TPL sving is the differene etween eqns. & nd is given y DG TPL = TPL TPL (6 TPL sving sving = nhes R R R R D R D R D DG r DG DG DG DG DG (7 3i DG 3 i DG r 3 i DG DG to get the mximum loss DG DG DG DG DG DG DG DG DG DG DG DG i Current to e supplied y DG ( r i i 3 DG D 3 DG D 3 DG D sving n e otined y differentiting the eqn. (7 nd is given y R ( D DG D r TPLsving = R [ ( D D DG D 3i ] = ( DG nhes R ( D D DG D 3 i ] R ( D DG D TPLsving = R [ ( D r D DG D 3 i ] = (9 DG nhes R [ ( D D DG D 3 i ] R ( D DG D TPLsving = R [ ( D D DG D 3 i ] = ( DG nhes R [ ( D r D DG D 3 i ] Arrnging the eqns. (- in mtrix form, For mximum loss sving, required urrent to e supplied y DG is DG DG = [ MATRX ] *[ MATRX ] ( DG R Where [ ] MATRX = R [ MATRX ] = j α j α R R r R R 3R i 3R i R r R 3R i 3R i R r R 3R i 3R i //$3. EEE

3 α is the set of nhes from soure us to the us where DG is onneted. The orresponding DG size is, PDG = DG * V ( PDG = PDG = PDG (3 Here V is the voltge mgnitude of phse-a t k th us. The ove proedure n e repeted for ll nodes nd the node t whih loss svings is mximum will e onsidered s ndidte node for DG plement nd the orresponding size is the optiml size of DG.. ALGORTHM Step. Run the se se lod flow nd otin the nh urrents. Step. Selet us nd then find the urrent to e supplied y DG using eqn. ( to get mximum loss svings. Step 3. With the help of DG urrents ( DG = DG = DG, find the mximum loss sving using eqn. (7 nd the orresponding size y using eqns. (-3. Step. Repet steps -3 for ll uses exept t soure us nd identify the us t whih the loss sving is highest. Step. Compenste the seleted us with the orresponding DG size. V. RESULTS AND DSCUSSONS The proposed method of loss redution y optiml plement of DG hs een tested on us URDN [9]. The results t norml loding ondition hve een ompred with the existing method [9]. A. DG plement t Norml Loding At Norml loding ondition, without instlltion of DGs the totl rel nd retive power losses re.79 kw nd 67.7 kvar respetively nd the minimum us voltges (p.u re found tht.9,.939 nd However fter instlltion of DG of size kw t eh phse of us 7, the rel nd retive power losses re redued y 6.99 % nd 7.7 % respetively. Minimum us voltges (p.u re inesed to.969,.96 nd.969. The results show tht the redution in power losses is more with the proposed method when ompred to Ref [9]. Tle shows the results for DG plement in URDN nd Fig. shows voltge profile under Norml lod ondition B. DG plement with summer sesonl loding n this setion, dily lod urve whih is more prtil to rel distriution system is onsidered. Voltge dependent lod model (ZP hs een onsidered for this pper work nd the vrition of three tegories of lods i.e. residentil, ommeril, nd industril with respet to time is lso onsidered. Figs. 3- show the voltge profile of us URDN without instlltion of DG with hours sesonl (summer lod vrition. Figs. 6- show the voltge profile of us URDN fter instlltion of DG with hours sesonl (summer lod vrition. t n e oserved form Figs. 3- tht the voltge profile hs een inesed fter instlltion of DGs. Fig. 9 shows the minimum voltge profile of us URDN efore nd fter instlltion of DG onsidering hours lod vrition. Fig. shows the rel nd retive power loss profile without nd with DG. From Fig., it is oserved tht the rel power losses re redued y round % nd retive power losses re redued y round 6% t eh hour. For summer lod vrition, the optiml lotion for plement of DG is 7 t ll hours nd the optiml DG size t eh hour is shown in Fig.. TABLE. RESULTS BUS URDN UNDER NORMAL LOADNG CONDTON Node Before DG Plement After DG Plement t UPF Ref [9] V (p.u V (p.u V (p.u V (p.u V (p.u V (p.u V (p.u V (p.u V (p.u //$3. EEE

4 Min V (p.u DG Size (kw lotion - 7 PLoss (kw QLoss (kvar TPL (kw TQL (kvar Voltge (p.u Fig.. Voltge profile of us URDN under Norml lod ondition.9 Bus numer Time (hrs 6 Fig.. profile of Phse C without DG Voltge (p.u Bus Numer Time (hrs 6 Voltge (p.u Bus Numer 6 Time (hrs Fig. 3. Voltge profile of Phse A without DG Fig. 6. Voltge profile of Phse A with DG Voltge (p.u Voltge (p.u Bus Numer Time (hrs Bus Numer Time (hrs 6 Fig.. Voltge profile of Phse B without DG Fig. 7. Voltge profile of Phse B with D //$3. EEE

5 Voltge (p.u Bus Numer Time (hrs 6 proper lotion hs een proposed in this pper. The method first finds the optiml size of DG t eh node y mximizing the loss sving eqution nd then the node t whih the loss sving is mximum will e onsidered s ndidte node of DG plement nd the orresponding size is the optiml size. The proposed method hs een tested on us unlned distriution system with relisti ZP lod y onsidering hour sesonl (summer lod vrition. The results show tht the proposed method is showing etter results ompred to existing method. ACKNOWLEDGMENT This is prt of the work tht hs een ried out under the projet sponsored y the Deprtment of Siene nd Tehnology, DST, New Delhi under the projet grnt: SR/S3/EECE/3/, SERB, New Delhi. The uthors knowledge DST, New Delhi for the grnt of the projet. Fig.. Voltge profile of Phse C with DG Fig. 9. Minimum voltge profile of us URDN Fig.. Rel nd Retive power loss profile without nd with DG Fig.. Optiml DG sizes t eh hour V. CONCLUSONS A simple method for minimizing the losses ssoited with tive omponent of nh urrents y pling optiml DG t REFERENCES [] W. El-Khttm nd M.M.A. Slm, Distriuted genertion tehnologies, definitions nd enefits, Eletri Power Systems Reserh, Vol. 7, ssue, pp. 9-,. [] K.H. Kim, Y.J. Lee, S.B. Rhee, S.K. Lee nd S.K.You, Dispersed genertor plement using fuzzy-ga in distriution system EEE PES Summer Meeting, Vol. 3, pp. -3,. [3] K. Nr, Y. Hyshi, K. ked nd T. Ashizw, Applition of tu serh to optiml plement of distriuted genertors EEE PES Winter Meeting, Vol., pp. 9-93,. [] J.O. Kim, S.W. Nm, S.K. Prk nd C. Singh, Dispersed genertion plnning using improved Hereford Rnh lgorithm Eletril Power Systems Reserh, Vol. 7, ssue, pp. 7-, 99. [] S. Ru nd Y.H. Wn, Optiml lotion of resoures in distriuted plnning EEE Trnstion in Power Systems, Vol. 9, ssue, pp. -, 99. [6] C. Wng nd M.H. Nehrir, Anlytil pprohes for optiml plement of DG soures in power systems EEE Trnstions on Power Systems, Vol. 9, ssue, pp. 6-76,. [7] V.V.S.N.Murthy nd Ashwni Kumr, Comprison of Optiml DG Allotion Methods in Rdil Distriution systems sed on Sensitivity Approhes, Eletril Power nd Energy Systems, Vol. 3, pp. 67, 3. [] K. Ngrju, S. Sivngrju, T. Rmn, S. Stynryn nd P.V. Rmn, A novel method for optiml distriuted genertion plement in rdil distriution systems Distriuted Genertion & Alterntive Energy Journl, Vol. 6, ssue, pp. 7-9,. [9] T. Rmn, V. Gnesh nd S. Sivngrju, Distriuted genertor plement nd sizing in unlned rdil distriution system Cogenertion & Distriuted Genertion Journl, Vol., ssue, pp. - 7,. [] J.H. Teng, A diret pproh for distriution system lod flow solutions EEE Trnstions on Power Delivery, Vol., No. 3, pp. -7, 3. [] K. Qin, C. Zhou, M. lln nd Y. Yun, Effet of lod models on ssessment of energy losses in distriution genertion plnning Eletril Power nd Energy Systems, Vol. 33, ssue 3, pp. 3-,. [] T.E. MDermott,. Drezg nd R.P. Brodwter, A heuristi nonliner onstrutive method for distriution system reonfigurtion EEE Trns on Power Syst., Vol., ssue, pp. 7-3, //$3. EEE