Loss Minimization of Power Distribution Network using Different Types of Distributed Generation Unit

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1 Internatonal Journal of Electrcal and Computer Engneerng (IJECE) Vol. 5, o. 5, October 2015, pp. 918~928 ISS: Loss Mnmzaton of Power Dstrbuton etwor usng Dfferent Types of Dstrbuted Generaton Unt Su Hlang Wn*, Pyone La Swe ** * Department of Electrcal Power Engneerng, Mandalay Technologcal Unversty, Myanmar ** The Republsh of the Unon of Myanmar, Myanmar Artcle Info Artcle hstory: Receved May 9, 2015 Revsed Jul 10, 2015 Accepted Jul 21, 2015 Keyword: Dstrbuted generaton Exact loss formula Four types of DG Optmal locaton and szng Power loss mnmzaton ABSTRACT A Radal Dstrbuton networ s mportant n power system area because of ts smple desgn and reduced cost. Reducton of system losses and mprovement of voltage profle s one of the ey aspects n power system operaton. Dstrbuted generators are benefcal n reducng losses effectvely n dstrbuton systems as compared to other methods of loss reducton. Szng and locaton of DG sources places an mportant role n reducng losses n dstrbuton networ. Four types of DG are consdered n ths paper wth one DG nstalled for mnmze the total real and reactve power losses. The obectve of ths methodology s to calculate sze and to dentfy the correspondng optmum locaton for DG placement for mnmzng the total real and reactve power losses and to mprove voltage profle n prmary dstrbuton system. It can obtan maxmum loss reducton for each of four types of optmally placed DGs. Optmal szng of Dstrbuted Generaton can be calculated usng exact loss formula and an effcent approach s used to determne the optmum locaton for Dstrbuted Generaton Placement. To demonstrate the performance of the proposed approach 36-bus radal dstrbuton system n Beln Substaton n Myanmar was tested and valdated wth dfferent szes and the result was dscussed. Copyrght 2015 Insttute of Advanced Engneerng and Scence. All rghts reserved. Correspondng Author: Su Hlang Wn, Department of Electrcal Power Engneerng, Mandalay Technologcal Unversty Emal: suhlangwn24@gmal.com 1. ITRODUCTIO In recent years, envronmental concerns, fuel cost uncertantes, lberalzaton of electrcty marets and advances n technology have resulted n ncreasng DG unts n dstrbuton system. Ths trend has offered great opportuntes but created several challenges n plannng and operatons of dstrbuton systems. The prmary purpose of DG unts s energy necton; however, strategcally placed and operated DG unts can yeld several other benefts to utltes. A typcal example of such beneft s the applcaton of DG unts for loss reducton [1 3]. Voltage and load ablty enhancement, relablty mprovement and networ upgrade deferral are other benefts [4, 5]. Dstrbuted Generaton s an emergng technology n ths new era and t provdes clean electrc power. Dstrbuted Generaton should be located at or near an electrcal load Centre. Installaton of Dstrbuted Generaton at optmal places provdes the clean electrc power to the customer [6]. Dfferent ssues have been mentoned to defne the Dstrbuted generaton more mportantly.some of the ssues of DG s Dstrbuted Generaton Ratng, then other are Technology, szng, sttng, mode of operaton, Dstrbuted Generaton penetraton [7].Dstrbuted Generaton s a small generatng unt located n the effectve pont of the electrc power system near to the load centre. DG systems are small power sources that connect to dstrbuton systems. Wth the ncreasng demand for electrcal power and the techncal, economc, and envronmental constrants n the constructon Journal homepage:

2 919 ISS: of new power plants and new transmsson lnes, DG can effcently respond to system requrements. DG has predomnant specfcatons. There are a number of DG technologes avalable n the maret today and few are stll n research and development stage. Some currently avalable technologes are recprocat ng engnes, mcro turbnes, combuston gas turbnes, fuel cells, photovoltac, and wnd turbnes. Each one of these technologes has ts own benefts and characterstcs. Among all the DG, desel or gas recprocatng engnes and gas turbnes mae up most of the capacty nstalled so far. Smultaneously, new DG technology le mcro turbne s beng ntroduced and an older technology le recprocatng engne s beng mproved [8]. Fuel cells are technology of the future. However, there are some proto-type demonstraton proects. In ths paper exact loss formula method s used to calculate optmal DG unt s sze and proper locaton. So that the real power losses, reactve power losses were mnmzed and the correspondng voltage profle values were mproved. The proposed approach has been tested on 36-bus dstrbuton system n Beln Substaton n Myanmar. Result obtan from ths approach clearly explans the optmal locaton and szng of DG there by mnmzes the power losses of the system. The remander of ths paper s structured as follows Secton II presents Problem Formulaton, Secton III explans about Proposed Methodology, Secton IV descrbes about Smulaton Results and Dscussons, and fnally Secton V explans about Concluson. 2. PROBLEM FORMULATIO The obectve of problem s to fnd the locaton of DGs and ts sze for type-1, type-2, type-3 and type-4 DG to mnmze the real and reactve power losses and to mprove the voltage profle. Real Power loss n the system can be calculated by equaton (1), gven the system operatng condton, Where, P P Q Q β Q P P Q P α (1) L 11 α r cos δ δ (2) V V β r sn δ δ (3) V V The mnmze reactve power loss wll have sgnfcant mpact on voltage stablty of the power system. The reactve power loss formula s gven by equaton (4), Where, P P Q Q ζ Q P PQ Q γ (4) L 1 1 X cos (5) V V X sn δ δ (6) V V P s real power flow at bus n MW Q s reactve power flow at bus n MVAR P s real power flow at bus n MW Q s reactve power flow at bus n MVAR IJECE Vol. 5, o. 5, October 2015 :

3 IJECE ISS: R s resstance of the lne connectng bus and n Ohms X s Reactance of the lne connectng bus and n Ohms V and V are bus voltage magntude at bus and n PU δ and δ are bus voltage angle at bus and 2.1. Type-1 DG Photo voltac, mcro turbnes, fuel cells whch are ntegrated to man grd wth the help of converters/nverters are good examples of type1. For type-1 DG, the optmal sze of DG at each bus for mnmzng losses s gven by equaton (7). 1 P DG PD β Q α P β Q (7) α 1, P =P DG - P D (8) Real power loss reducton by DG, PLoss PLoss PLR 100% (9) P Loss DG 2.2. Type-2 DG Synchronous motors such as gas turbnes are examples for type2. For type-2 DG, the optmal sze of DG at each bus for mnmzng losses s gven by equaton (9), Q DG Q D 1 α β P 1, Q P (10) Q Q Q (11) DG Reactve power loss reducton by DG, D QLoss QLoss QLR 100% (12) Q Loss DG 2.3. Type-3 DG DG unts that are based on synchronous machne fall n type 3. The combnaton of both P DG and Q DG nected at the same bus can produce the optmal sze of Type 3 DG, S DG 2 2 P DG Q (13) DG 2.4. Type-4 DG The DG wll supply real power and n turn wll absorb reactve power. In case of the wnd turbnes, nducton generator s used to produce real power and the reactve power wll be consumed n the process. Q DG P (14) DG The optmal szes at varous locatons have been calculated for dfferent types of DG and the losses are calculated wth optmal szes for each case. The case wth mnmum losses s selected as optmal locaton for each type DG. Loss Mnmzaton of Power Dstrbuton etwor usng Dfferent Types of Dstrbuted (Su Hlang Wn)

4 921 ISS: PROPOSED METHODOLOGY A computer program has been wrtten n MATLAB to calculate the optmal szes of DG at varous bus and approxmate total losses wth DG at dfferent locatons dentfy the best locaton. A ewton-raphson algorthm based load flow program s used to solve the load flow problem. The 36-bus dstrbuton system s extracted from 230/33/11V Beln Substaton n Kyause area of Myanmar. Ths radal dstrbuton system conssts of sx man feeder. The total real and reactve power loads are 200MW and 198 MVAr, respectvely. The Beln dstrbuton system, s as shown n Fgure 1. Incomng lne of Beln staton s 230 V lne. There are thrty fve outgong lnes. Ther rated voltage s 33 V lne. Analytcal method s appled for optmal sze and locaton of dstrbuted generaton. Fgure 1. Sngle lne dagram of Beln Substaton n Myanmar 4. SIMULATIO RESULTS AD DISCUSSIOS The Proposed Methodology s tested on 36-bus dstrbuton system n Beln Substaton n Myanmar wth dfferent szes are smulated n MATLAB envronment to calculate the optmum DG szes for varous buses and approxmate total power loss wth DG at varous locaton. The lne parameters and load data are lsted n Appendx. The data are based on 100 MVA Optmum Sze Allocaton Based on the proposed approach optmum szes of DG s are determned usng equaton (7) and (10) at varous nodes for Beln dstrbuton system n Myanmar. In Beln dstrbuton system optmum szes of DG rangng from 4.6 MW to 97.2 MW and 1.67 MVAR to 72.2 MVAR. After connectng DG s one by one t s mportant to note that the total power loss s lowest at the correspondng buses. IJECE Vol. 5, o. 5, October 2015 :

IJECE ISS: 2088-8708 922 Sze of DG 100 90 80 70 60 50 40 30 20 10 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 Bus umber DG Sze n MW DG Sze n MVAR Fgure 2.

real and reactve power loss s mnmum at the respectve buses. Fgure 2 shows the optmum real and reactve power szes of type 1 and type 2 DG at 36- bus Beln dstrbuton system.

5 IJECE ISS: Sze of DG Bus umber DG Sze n MW DG Sze n MVAR Fgure 2. Optmum real and reactve power szes of type 1 and type 2 DG at 36 bus dstrbuton system at Beln Substaton n Myanmar Based on ths result of DG szng the optmal locaton of DG s determned where the total real and reactve power loss s mnmum at the respectve buses. Fgure 2 shows the optmum real and reactve power szes of type 1 and type 2 DG at 36- bus Beln dstrbuton system. Fgure 3 shows the optmum sze of type 3 DG at varous nodes for 36 bus dstrbuton system. As far as one locaton s concerned, n a dstrbuton system, Fgure 3 would gve the value of DG sze to have a possble mnmum total loss. The range of optmum szes of type 3 DG s from 0.3 MW to 3.9 MW. ow, t s mportant to dentfy the locaton n whch the total power loss wll be mnmal. Optmum DG Sze (MW) Bus umber Fgure 3. Optmum sze of type 3 DG at 36 bus dstrbuton system at Beln Substaton n Myanmar Fgure 4 shows the bar representaton of optmal szes of type 4 DG at all buses for 36 bus system. From fgure, t can be observed that the DG sze do not follow a regular manner and the sze s ndependent of locaton of bus. Loss Mnmzaton of Power Dstrbuton etwor usng Dfferent Types of Dstrbuted (Su Hlang Wn)

6 923 ISS: Optmum DG Sze (MW) Bus umber Fgure 4. Optmum sze of type 4 DG at 36 bus dstrbuton system n Beln Substaton 4.2. Selecton of Optmum Locaton Wth the help of optmum DG szes obtaned at varous nodes t s best enough to fnd out the optmum locaton that would leads to calculate the least total power losses. In Beln dstrbuton system bus 24 s located as optmal placement of DG. After DG placement total real and reactve power losses are reduced and average real power loss s reduced from MW to MW and average reactve power loss s reduced to the range of MVAR to MVAR. Table 1 shows the result of average real and reactve power loss after connectng DG at Beln dstrbuton system n Myanmar. Table 1. Result of average real and reactve power loss after connectng DG at Beln dstrbuton system Bus umber at whch DG Connected Sze of DG n MW Sze of DG n MVAR Average Real Power Loss n MW Average Reactve Power Loss n MVAR IJECE Vol. 5, o. 5, October 2015 :

IJECE ISS: 2088-8708 924 Fgure 5 shows the real power losses of the system are reduced by optmal placement of type 3 DG, type 4 DG and wthout DG.

Real power losses at buses DG Type 4, DG Type 3 and wthout DG Fgure 6 shows the total reactve power losses of the system for dfferent locatons of DG wth the sze obtaned from the prevous secton.

7 IJECE ISS: Fgure 5 shows the real power losses of the system are reduced by optmal placement of type 3 DG, type 4 DG and wthout DG. 7 6 Real Power Losses Base Case DG Type 4 DG Type Bus umber Fgure 5. Real power losses at buses DG Type 4, DG Type 3 and wthout DG Fgure 6 shows the total reactve power losses of the system for dfferent locatons of DG wth the sze obtaned from the prevous secton. Reactve Power Losses (MW) Base Case Base Case DG Type 4 DG Type 3 Bus umber Fgure 6. Reactve power losses at buses DG Type 4, DG Type 3 and wthout DG Table 2 shows the optmal locaton and the optmal sze of type-1 DG at 36 bus dstrbuton system n Myanmar. Loss Mnmzaton of Power Dstrbuton etwor usng Dfferent Types of Dstrbuted (Su Hlang Wn)

8 925 ISS: Table 2. Optmal DG Type-1 Placement of the System DG nstalled DG Type 1 DG Type 1 DG Type 1 DG Type 1 Locaton PDG sze, MW Ploss, MW Ploss reducton, % 60.31% 39.31% 22.89% 15.14% Table 3 shows the optmal placement and the optmal sze of type-2 DG nstalled nto the system. Table 3. Optmal DG Type-2 Placement of the System DG nstalled DG Type 2 DG Type 2 DG Type 2 DG Type 2 Locaton QDG sze, MW Qloss, MW Qloss reducton, % 39.69% 52.65% 47.84% 40.59% Table 4 shows the optmal locaton and the optmal sze for type-3 DG at 36 bus dstrbuton system n Myanmar. Table 4. Optmal DG Type-3 Placement of the System DG nstalled DG Type 3 DG Type 3 DG Type 3 DG Type 3 Locaton PDG sze, MW Ploss, MW Ploss reducton, % 29.56% 9.429% 83.17% 24.86% Table 5 shows the optmal locaton (bus number) and sze (P DG sze and Q DG sze are real and reactve capacty of DG nstalled, respectvely) for dfferent types of DG nstalled nto the system. Table 5. Optmal DG Placement of the System for DG Placement DG nstalled DG Type 1 DG Type 2 DG Type 3 DG Type 4 Locaton PDG sze, MW QDG sze, MVAr 35.3 Ploss, MW Qloss, MVAr Ploss reducton, % 60.31% 52.65% 83.17% 50.49% Qloss reducton, % 74.39% 66.5% 94.16% 34.39% These tables also present the nformaton of real (Ploss reducton) and reactve power loss reducton (Qloss reducton) n term of percentage, and total real (Ploss) and reactve power loss (Qloss) n term of MW and MVAR, respectvely. The results n these tables show the sgnfcant real and reactve power loss reducton after nstallaton of DG n the system. In addton, optmal sze and locaton of DG are also changed wth dfferent type of DG nstalled n the system. DG type 1 can reduce the real and reactve power loss by 60.31% & 74.39% compared to 52.65% & 66.5%, 83.17% & 94.16%, and 50.49% & 34.39% for DG type 2, DG type 3, and DG type 4, respectvely. a. Optmum Bus Voltage Profle The Voltage at varous buses should be mantaned wthn the acceptable lmts to meet out the power system demand. But the Bus voltage may reach the permssble lmt when DG s not connected to the IJECE Vol. 5, o. 5, October 2015 :

9 IJECE ISS: dstrbuton system or the bus voltage may lac due to some dsturbances. For ths reason Dstrbuted Generaton should be placed and szed at the relevant bus locaton n radal Dstrbuton system so that the bus voltage profle gets mproved. The mprovement of voltage profle of the system for dfferent types of DG nstalled s shown n Fgure V oltage (p.u) Base Case DG Type 1 DG Type 2 DG Type 3 DG Type Bus umber Fgure 7. Varaton of voltage profle for 36 bus dstrbuton system 5. COCLUSIO Dfferent types of DG nstalled n the system have dfferent mpacts on reactve power loss reducton. Optmal sze and locaton of DG are also changed wth dfferent type of DG nstalled n the system. Exact loss formula s used to determne optmal sze and the locaton for type-1, type-2, type-3 and type-4 DGs. The four types of DGs effectvely reduced the real power loss, reactve power loss and voltage profle are also mproved. DG type 3 has the most effectve way of reducng real and reactve power loss, followng by DG type 1, DG type 2, and DG type 4, respectvely. It s also nterestng to note that DG type 3 has the hghest loss reducton snce t can generate both real and reactve power and DG type 4 has the lowest loss reducton snce t consumes reactve power n the system. The methodology of fndng proper locaton and sze of DG n order to mnmze real and reactve power losses n radal dstrbuton system s more effectve n term of voltage mprovement than that of fndng proper locaton and sze of DG n order to mnmze real and reactve power losses. Loss Mnmzaton of Power Dstrbuton etwor usng Dfferent Types of Dstrbuted (Su Hlang Wn)

10 927 ISS: From Bus o. Appendx A Lne Parameters and Load Data of 36-bus Dstrbuton System Lne Parameters Load Data To Bus o. R (p.u) X (p.u) Bus o. P (p.u) Q (p.u) ACKOWLEDGEMET The authors are deeply grateful to U Kyaw Wn and Daw Ky Htay for ther supports and encouragement to attan her destnaton wthout any trouble and all the persons who share the trouble of the author on any stuaton n tryng ths paper. REFERECES [1] nam T, Taher SI, Aghae J, Tabatabae S, ayerpour M. A modfed honey bee matng optmzaton algorthm for multobectve placement of renewable energy resources. Appl Energy 2011; 88(12): [2] Taher. A new HBMO algorthm for multobectve daly Volt/Var control n dstrbuton systems consderng dstrbuted generators. Appl Energy 2011; 88(3): [3] Martnez-Roas M, Sumper A, Goms-Bellmunt O, Sudrà-Andreu A. Reactve power dspatch n wnd farms usng partcle swarm optmzaton technque and feasble solutons search. Appl Energy 2011; 88(12): [4] Manfren M, Caputo P, Costa G. Paradgm shft n urban energy systems through dstrbuted generaton: Methods and models. Appl Energy 2011; 88(4): [5] Baos GC. Dstrbuted power generaton: a case study of small scale PV power plant n Greece. Appl Energy 2009; 86(9): [6] W.El-Khattam, M.M.A.Salama, Dstrbuted Generaton Technologes, defntons and benefts, Electrc Power Systems Research, Vol. o.71, pp , [7] Thomas Acermann, Goran Andersson, Lennart Soder, Dstrbuted Generaton: a defnton, Electrc Power Systems Research, Vol. o. 57, pp , [8] Carmen L.T. Borges, Dalma M. Falcao, Optmal Dstrbuted Generaton allocaton for relablty, losses and voltage mprovement, Electrcal power and Energy systems, Vol. o. 28, pp , IJECE Vol. 5, o. 5, October 2015 :

IJECE ISS: 2088-8708 928 BIOGRAPHIES OF AUTHORS Ms. Su Hlang Wn. She was born on 24 th August 1983. I am thrty two years old. She studed BE and ME at Technologcal Unversty (Monywa).

11 IJECE ISS: BIOGRAPHIES OF AUTHORS Ms. Su Hlang Wn. She was born on 24 th August I am thrty two years old. She studed BE and ME at Technologcal Unversty (Monywa). And she s worng as an assstant lecturer at Technologcal Unversty (Kyause). ow, she s Ph.D canddate at Electrcal Power Engneerng Department at Mandalay Tecnologcal Unversty. She got ICSE paper that held n Inyar lae hotel n Myanmar and Internatonal paper of ICTAEECE Conference that held n Bango durng ths year. Her emal s suhlangwn24@gmal.com. Pyone La Swe, Assocate Professor Department of Electrcal Power Engneerng, Mandalay Technologcal Unversty, Mandalay, Myanmar. emal: pyonela@gmal.com Loss Mnmzaton of Power Dstrbuton etwor usng Dfferent Types of Dstrbuted (Su Hlang Wn)

Chapter - 2. Distribution System Power Flow Analysis

Chapter - 2. Distribution System Power Flow Analysis Chapter - 2 Dstrbuton System Power Flow Analyss CHAPTER - 2 Radal Dstrbuton System Load Flow 2.1 Introducton Load flow s an mportant tool [66] for analyzng electrcal power system network performance. Load