DG Installation in Distribution System for Minimum Loss

Transcription

1 DG Istallatio i Distributio System for Miimum Loss Aad K Padey Om Mishra Alat Saurabh Kumar EE, JSSATE EE, JSSATE EE, JSSATE EE, JSSATE oida,up oida,up oida,up oida,up Abstract: This paper proposes optimal placemet ad optimal size of DG system i the distributed system. Earlier proposal gives aalytical expressio for optimal placemet of DG that is capable of delivery real power oly. This research paper has proposed two other type of DG system also (type 3 ad type 4). 14 test bus systems with stadard IEEE data is used. Result shows optimal locatio for placemet of DG ad its optimal size with some costraits. The result required less computatio ad are verified with the help of illustrated graphs. Keywords: Optimal Locatio, Optimal Size, Power Losses, Distributed Geeratio. I. ITRODUCTIO The objective of power system is to supply electrical eergy to each cosumer with rated coditio with miimum losses ad maximum power trasfer alog with maitaiig stability of the system. There are two types of power techologies: Traditioal techologies ad o-traditioal techologies. Traditioal techologies are o-reewable techologies such as thermal power plat. o-traditioal techologies iclude fuel cells ad reewable eergy based techologies such as wid eergy, solar eergy, geothermal eergy, ocea eergy. For icreasig demad of eergy with miimum cost has led to developmet of may ew techologies. These techologies are also very importat because of growig evirometal cocer aroud the whole world. The fear of depletio of covetioal source of eergy has led to the developmet of o covetioal techologies. Amog them owadays DG system has attracted several researchers to fid ew ideas about how it ca be utilised effectively. Amog these optimal size ad optimal placemet of DG system is very importat. DG (distributed geeratio ) is small scale power statio whose rage may vary from few KW to 50 MW.They are geerally placed at the cosumer side or at the ed of distributio etwork.there are four types of DG system : 1. Type 1 DG, capable of ijectig active power. 2. Type 2 DG, capable of ijectig reactive power 3. Type 3 DG capable of ijectig active ad reactive power. 4. Type 4 DG capable of ijectig active power ad cosumig reactive power. DG system improves reliability of the system. But has also led to may problems. It has foud that if DG is placed at wrog positio i the distributio system the effectiveess of DG decreases. Therefore it is very importat for oe to decide where the DG should be used ad it should be what size. This research paper focuses o this problem oly takig ito cosideratio of all the four types of II. LITERATURE REVIEW I [1] for reducig loss approximate power flow techique was used. As this method is approximate method therefore it ca ot be used i the practical large distributio system. I [2] sigle loop method was used for solvig etwork cofiguratio. I [3] 2/3 are golde rule is used. This method is very effective for uiform load. But this is applicable to ot applicable to o-uiformly distributed load.this rule is simple ad easy to apply. I[4] approach has bee made to fid appropriate locatio to place that DG system i radial as well i loop system this method helps i miimizig losses but here optimal sizig is ot cosidered. Because i practical case differet sizes of DG are preset ad due to ecoomic reaso sometime it becomes difficult to use DG of same size so this method does ot goes well i practical case. I [5] GA method was used to fid optimal placemet ad size of DG it ca solve may problem. But it requires lots of computatioal time. I [6] it used exact loss formula for fidig optimal locatio of DG system i distributed etwork. Here the two load flow calculatio is performed. First of all losses are calculated without the placemet of DG.The the secod load flow calculatio are performed to fid the losses.but this techique gives solutio for type 1 DG oly. Other techique were also used such as dyamic programmig [7], fuzzy expert system which requires lots of aalysis ad have more computatio time [8] ad [9] TS techique is used for fidig the best locatio of placemet of capacitor oly. It does ot give solutio for iductive loads which is the most commo load i distributio system. III. METHODOLOGY Before the placemet of DG system losses of the distributed system are calculated.ow DG system are placed at differet buses ad losses are calculated with the help of exact loss formula. Amog the various cases the locatio which gives miimum loss gives the optimal positio i the distributed system of particular size. This process is repeated for may sizes withi the give costrait The aalytical expressio is give below. P L = [α ij (P i P j + Q i Q j ) + β ij (Q i P j P i Q j )] i=1 1008

2 Where α ij = r ij V i V j cos(δ i δ j ); β ij = r ij V i V j si(δ i δ j ); V i i r ij + x ij = Z ij P i Q i Bus voltage load agle Z bus Active Power ijectio at i bus Reactive Power ijectio at i bus o of buses 3. Type 3 DG: Here Q is positive ad the value of P DG ad Q DG will give the value of total apparet power that determies size of 4. Type 4 DG: The value of Q is egative ad here also we ca calculate the total apparet power to determie the size of DG system. With the help of above expressio we ca ot oly fid the optimal size of DG but also its type which will give miimum loss i the distributed etwork P i = P DGi P Di Q i = Q DGi Q Di = ap DGi - Q Di a=ta -1 (Q/P) Puttig the above two equatio i exact loss formula the ew equatio obtaied is: P L = [α ij ((P DGi P Di )P j + (ap DGi Q Di )Q j ) i=1 + β ij ((ap DGi Q Di )P j (P DGi P Di )Q j )] We will differetiate the followig equatio with respect to P DGi P L = 2 [α P ij (P j + aq j ) + β ij (ap j Q j )] = 0 DGi Fially o substitutio ad simplificatio we get P DGi = α ij(p Di + aq Di ) + β ij (ap Di Q Di ) X i ay i a 2 α ii + α ii Where X i = (α ij P j β ij Q j ) Y i = (α ij Q j + β ij P j ) With the help of above equatio we ca estimate the size of DG as follows- 1. Type 1 DG: For type 1 DG value of a=0 because power factor is uity ad size is: P DGi = P Di 1 [β α ii Q Di + (α ij P j β ij Q j )] i 2. Type 2 DG: I this value of a= because power factor=0: Q DGi = Q Di + 1 α i [β ii P Di (α ij Q j + β ij P j ) ] IV. ALGORITHM This research paper uses the stadard IEEE 14 test bus system ad voltage ad load agle of each buses are also preset accordig to IEEE stadards. The followig steps are followed- 1. Z bus formulatio codig has bee doe to fid the Z bus of IEEE stadards MVA base is take. 3. First of all the total losses of the system is calculated. 4. There is o placemet of 5. May costraits has bee take before the aalysis of system such as size of 6. The loop is performed to fid positio of bus system where miimum losses are preset. 7. We first take miimum size of DG ad the we place at all the 13 bus except the slack bus. 8. Out of all the 13 positio, oly that positio is located which give miimum loss after placemet of 9. This positio is saved i the form of variable. 10. The process is agai repeated util the maximum limit of the size. 11. Several loopig is doe to calculate the optimum positio of differet size of 12. Out of the several size oly that size is chose which gives miimum loss i the distributio system. 13. So we get optimal size ad locatio for type Above process is repeated for two other type of DG also (Type 3 ad Type 4 DG). 15. We get miimum losses for all three types of 16. Out of the three cases that DG type is selected which give the miimum loss. V. THE TEST SYSTEM IEEE 14 bus system is used to check the validity of proposed work ad to fid the optimal size ad locatio of The detail about the test bus system is give i the appedix sectio from where aalysis of DG system is doe. 1009

3 VI. RESULT The below tables shows the values of losses i per uit ad takig 100MVA base ad its variatio o varyig locatio, size ad type of DG ad their correspodig graph are give i appedix sectio. 1. TYPE 1 DG Bus o. Size (p.u.) , (size MW,losses p.u.) 10, 3 10, , , , , , , 9 10, 9 10, , 7 10, 3 Series1 2. TYPE 3 DG Size Bus o. (p.u.)

4 LOSSES 10, (size MW,losses p.u , , , , , , 2 10, 1 10, 6 10, , , , 3 Series BUS Size(p.u.) 3. TYPE 4 DG Bus o LOSSES , , 2 10, , , , (size MW,loss p.u.) 10, , , , LOSSES VS POSITIO 10, , , BUS 1011

5 VII.COCLUSIO The loss i the 14 bus system without the use of DG is calculated to be MW. Usig type 1 DG the loss is calculated to be MW ad the optimal locatio is bus o.4 ad the optimal size is of 10 MW Usig type 3 DG the loss is calculated to be MW ad the optimal locatio is bus o.14 ad the optimal size is of 10 MW Usig type 4 DG the loss is calculated to be MW ad the optimal locatio is bus o.8 ad the optimal size is of 10 MW From above cases type 4 DG is suggested at locatio bus o.8 of size 10 MW which gives miimum loss of MW. VIII. REFERECES [1] M. E.Bara ad F. F.Wu, etwork recofiguratio i distributio systems for loss reductio ad load balacig, IEEE Tras. Power Del., vol. 4, o. 2, pp , Apr IX. [2] J. Y. Fa, L. Zhag, ad J. D. McDoald, Distributio etwork recofiguratio: [3] J. V. Schmill, Optimum size ad locatio of shut capacitors o distributiofeeders, IEEE Tras. Power App. Syst., vol. PAS-84, o. 9,pp , Sep [4] C.Wag adm. H. ehrir, Aalytical approaches for optimal placemetof distributed geeratio sources i power systems, IEEE Tras PowerSyst., vol. 19, o. 4, pp , ov [5] A. Silvestri, A. Berizzi, ad S. Buoao, Distributed geeratio plaigusig geetic algorithms, i Proc. It. Cof. Electr. Power Eg.(PowerTech Budapest), Sep., p [6]. Acharya, P. Mahat, ad. Mithulaatha, A aalytical approach for DG allocatio i primary distributio etwork, It. J. Electr. Power Eergy Syst., vol. 28, o. 10, pp , [7] T. H. Fawzi, S. M. El-Sobki, ad M. A. Abdel-Halim, A ew approach for the applicatio of shut capacitors to the primary distributio feeders, IEEE Tras. Power App. Syst., vol. PAS-102, o. 1, pp , Ja [8] R. A. Gallego, A. J. Moticelli, ad R. Romero, Optimal capacitor placemet i radial distributio etworks, IEEE Tras. Power Del., vol. 16, o. 4, pp , ov APPEDIX Bus o. Bus code Voltage magitude Agle degrees 1. STADARD IEEE DATA Load Geerator Ijected MVAR MW MVAR Qmi Qmax IEEE-14 BUS SYSTEM 1012