Energy Loss Reduction in a 20-kV Distribution Network Considering Available Budget

Transcription

1 Journal of Applied Science and Engineering, Vol. 20, No. 1, pp (2017) DOI: /jase Energy Loss Reduction in a 20-kV Distribution Network Considering Available Budget Mehdi Izadi 1 * and Farzad Razavi 2 1 Young Researchers and Elite Club, Qazvin Branch, Islamic Azad University, Qazvin, Iran 2 Faculty of Electrical and Biomedical Engineering Qazvin Branch, Islamic Azad University, Qazvin, Iran Abstract The present paper is a report on a study which tried to determine the best way of allocating the budget available to the Qazvin Electric Distribution Company in Iran in order to optimally decrease energy loss in an affiliated distribution network. Five methods of loss reduction were compared in terms of the degree of loss reduction and cost-effectiveness. The budget to be assigned to each method was determined. The results show that the budget should only be appropriated to capacitor placement, replacement of dilapidated conductors, and load imbalance adjustment, in that order. Key Words: Available Budget, Loss Reduction, Load Imbalance Adjustment, Capacitor Placement, Dilapidated Conductors 1. Introduction Preservation of energy is very important from the point of view of environmental issues, high fossil fuel prices, formation of private power utilities, and the cost of developing power plants. It follows that loss of electrical energy generated for sale would mean many charges on power utilities and the industry. This has led many governments to considerably invest in reducing energy loss. Various approaches have been used in the past few decades for reducing loss. Study [1] summarizes a list of such methods at the distribution level: Reconductoring in primary and secondary feeders Reconfiguring feeders Using high-efficiency distribution transformers Reducing secondary network length by adding and optimally placing distribution transformers Using distributed generation Placing subtransmission substations near load centers Load balancing *Corresponding author. mehdiizadi_eeikiu@yahoo.com Improving load factor Improving voltage profile. Loss stems from, among other things, load imbalance, reactive power, dilapidated transformers, dilapidated conductors, and weak connections. Adjusting load imbalance will decrease loss in the lines and transformers. Optimally placing a capacitor in a network improves power factor and reduces reactive power. Replacing overworked and dilapidated transformers reduces copper and iron loss. Dilapidated cables and conductors should be replaced as their increased resistance results in energy loss. And finally, correcting the connections weakened over time will reduce line resistance and energy loss. A review of previous studies on loss reduction follows. Study [2] tried to reduce loss by removing load imbalance. Study [3] used evolutionary fuzzy programming algorithm and dynamic information structure to optimally place capacitors in a 69-bus radial distribution system. Genetic Algorithm (GA) was used by [1] for capacitor placement in a 69-bus system. Study [4] placed capacitors using the particle swarm optimization (PSO) algorithm.

2 22 Mehdi Izadi and Farzad Razavi Study [5] found that loss in a transformer decreases if the transformer works at half the nominal load and if harmonics filters are installed. The algorithm proposed in [6] for reducing network loss and determining the optimum conductor for a radial distribution network drew upon a new load flow. Study [7] studied the impact of fixing weak connections on loss reduction in Hormozgan power network in Iran regarding the relevant operating costs. This study is innovative in the following ways; first of all determining the efficiency of different methods of loss reduction in Sharif-Abad s 20-kV feeder will be considered and then tries to evaluate methods of loss reduction on the basis of the available budget. However, these studies that were mentioned in advance did not pay serious, if any, attention to the expenses involved in the method they employed. The present research attempts to evaluate several ways of reducing energy loss in the 20-kV distribution network of Sharif- Abad, which is part of the Qazvin Electrical Distribution Company in Iran, in terms of the operating costs involved, method efficiency, and the available budget. For this purpose, we first measured energy loss at the peak hour of the period spanning annual. Then, energy loss for the period under study was calculated. Having the data for power loss and energy loss, we obtained the loss factor of the network for the year-long period. The objective functions used in the research was then minimized using the Genetic Algorithm. 2. Model Formulation It is worth noting that the authors of [8] did not have any idea about power loss at peak and the energy loss in the year under study and thus did not know the loss factor. For this reason, they considered the loss factor in the feeder under investigation to be 0.52 on the basis of the loss factor in the adjacent feeders in Qazvin Electrical Distribution Company. However, in the present research, the loss factor was calculated to be Another point that makes the current work different from [8] is that the main objective here is budget allocation. 2.1 Fixing Load Imbalance Fixing load imbalance requires that the current of each phase be close to the average current of the three phases. Load imbalance was adjusted as described below [8]: The percentage of imbalance was determined for each phase (Eq. (1)). A certain percentage (from 0 to 100) was randomly assigned to each load by means of GA. The cost of imbalance adjustment for each phase equals the integral of the area under the curve of the A/x graph in the interval [a new, a old ]. The cost of imbalance adjustment for each load is equal to the sum of the costs related to imbalance adjustment for the three phases. The total cost of imbalance adjustment is equal to the sum of the costs associated with imbalance adjustment for all the loads in the feeder at issue (Eq. (2)). (1) where I p (A) is the phase current, and I ave (A) is the average of the three phase currents. (2) where C imbalance is the cost of adjusting imbalance ($). A is a constant set at $70 according to our empirical work. a oldpi is the old percentage of load imbalance for the p th phase of the i th load. a newi is the new percentage of load imbalance for the i th load. The cost of reducing load imbalance from 60% to 50% is less than the cost associated with decreasing imbalance from 30% to 20% (Figure 1). Figure 2 is the flowchart related to fixing load imbalance. 2.2 Capacitor Placement Capacitors were placed considering the following [8]: Capacitors were only placed where loads were. Loads were adjusted before capacitor placement. Use was made of 12.5-kvar capacitors. GA determined the number of capacitors. A gene was considered for each load. The total number of capacitors multiplied by the price

3 Energy Loss Reduction in a 20-kV Distribution Network Considering Available Budget 23 Figure 1. The A/x diagram. phase angle between the current and voltage after the installing capacitor. Given that the transformer operates at its nominal apparent power, then P max = 504 kw, cos 1 =0.8,and tan 1 = As this work aims to increase the power factor from 0.8 to 0.955, the capacitor to be installed in the feeder will have a maximum capacity of 222 kvar. The cost of capacitor placement for the whole network is obtained from Eq. (4). Additionally, the cost of capacitor placement for each bus and the variable cost of placing capacitors for each bus are calculated from Eqs. (5) and (6), respectively. (4) where C cap : the cost of capacitor placement ($). C capi : cost of placing capacitors on the i th bus ($). (5) where C capfixdi fixed cost of placing capacitors on the i th bus ($). C capvariablei variable cost of placing capacitors on the i th bus ($). (6) where n cap : number of capacitors on the i th bus. p cap : price of each capacitor ($/unit). Figure 2. The flowchart of fixing load imbalance. of each capacitor and the fixed costs related to capacitor placement were added up in the objective function. Fixed costs in this study were of three types: (a) 16 steps; (b) 712 steps; and (c) 1318 steps. The maximum number of steps was determined by the transformer with the highest capacity (Eq. (3)). (3) where Q c : is the capacity of the installed capacitor (kvar). Q 1 : reactive power before installing the capacitor (kvar). Q 2 : reactive power after installing the capacitor (kvar). P: active power (kw). 1 : phase angle between the current and voltage before the installing capacitor. 2 : 2.3 Replacing Dilapidated Transformers Dilapidated transformers were replaced with the following in mind [8]: The transformers used in the feeder under study had the apparent power values of 25, 50, 100, 200, 250, 315, 500, and 630 kva. A gene was considered for each transformer. If a transformer is replaced, its copper and iron losses decrease by 20%, according to Qazvin Electrical Distribution Company. The costs involved in replacing all transformers were addeduptoobtainthetotalcostoftransformerreplacement. The cost of transformer replacement is the sum of all the expenses associated with replacing the transformers, as determined by GA.

4 24 Mehdi Izadi and Farzad Razavi 2.4 Replacing Dilapidated Lines Dilapidated lines were replaced on the basis of the following [8]: A gene was considered for each line. If a line is replaced, its resistance decreases by 10%, according to Qazvin Electrical Distribution Company. The costs associated with replacing all dilapidated lines were added up to obtain the total cost of line replacement. The cost of conductor replacement is the sum of all the expenses associated with replacing the conductors, as determined by GA. 2.5 Correcting Weak Connections Weak connections in the network were corrected in the following way [8]: The length of the lines connecting buses was calculated using computer software. It was assumed that there was a connection at each end of each line. A connection was added if the line connecting every two buses was longer than 480 m. A gene was considered for each connection. The assumed number of connections is for singlewire lines only. For three-wire lines, the number should be multiplied by three. If a weak connection is corrected, line resistance decreases by ohms, according to Qazvin Electrical Distribution Company. In order to calculate the total cost of correcting weak connections, the operating costs associated with correcting each connection was multiplied by the total number of connections (Eq. (7)). (7) where C connection : the cost of correcting weak connections ($). n connection : the total number of weak connections. p connection : the cost of fixing each weak connection ($/unit). 2.6 The Benefit Obtained from Loss Reduction The benefit to be obtained from reducing power loss is calculated using Eq. (8). (8) where B loss_reduction : the benefit resulting from loss reduction ($). P lossafter : loss after the application of the methods (kw). P lossbefore : loss before the application of the methods (kw). T: the period, in hours, for which energy loss was calculated. This covered the full length of a year (8760 hours). LSF: loss factor. p energe :priceof energy ($/unit) [8]. 2.7 Objective Function without Considering the Budget The objective function without considering the budget was calculated from Eq. (9): (9) where OF 1 : objective function regardless of the budget ($). C imbalance : the cost of adjusting imbalance ($). C cap : the cost of placing capacitors ($). C trans : the cost of replacing transformers ($). C line : the cost of replacing conductors ($). C connection : the cost of correcting weak connections ($). B loss_reduction : the benefit resulting from loss reduction ($) [8]. The flowchart of OF 1 is portrayed in Figure New Method: Budget Allocation The objective function defined above (OF 1 ) can be rewritten as Eq. (10) below: OF 1 = a + b (10) where OF 1 : objective function regardless of the budget ($). a: The total cost associated with employing loss reduction methods ($). b: The benefit resulting from loss reduction ($). Since loss before the reduction methods were employed is less than post-reduction loss, b is always a negative value. However, this objective function needs to be modified because the present research aims to determine how much of the budget available to the company under study should be allocated to each method of reducing loss and also because the entire budget considered for loss reduc-

5 Energy Loss Reduction in a 20-kV Distribution Network Considering Available Budget 25 Figure 3. The flowchart of the OF1 for each iteration. tion is expected to be spent. The procedure used to reduce loss considering available budget is as follows: First, the amount of the budget considered for loss reduction is given to the software, which calculates the total cost associated with each method of reducing. The objective function is optimized when the cost is equal to the available budget. The proposed objective function is presented as Eq. (11) below. Figure 4. This Feeder is radial and it fed from 63 to 20 substation. Type of loads of this feeder are: agricultural, domestic and commercial. Figure 5 is the expanding of marked area in Figure 4. In Figure 5 electrical tower and lines are clarified and information mentioned. Information and description of equipment of this feeder given in Tables 1 to 5 are as following: Information about transformers (apparent power and number) Information about lines (length and types of conductors, resistance, reactance and weight) Operating costs of equipment and services Table 1 presents different levels of apparent power as used in the network under study and the number of transformers or each level. There are nine agricultural transformers in this feeder. Table 2 gives the number of transformers associated with different levels of apparent power used in the network. The specifications of this feeder can be seen in Tables 3 and 4. (11) where n: available budget. a: all the costs associated with power loss. b: the benefit to be obtained from loss reduction. :averylargeconstant(e.g.,10 10 ). OF 2 :the objective function for the available budget. An important consideration in this objective function is that the available budget must be less than the total cost of fully implementing all the methods of loss reduction (n a). Figure 4. The schematic representation of Sharif-Abad Feeder. 4. Simulation 4.1 Case Study The distribution network studied in this research was the 20-kV Feeder of Sharif-Abad in northwestern Iran. The schematic represenation of this feeder is given in Figure 5. The enlargement of the area marked in Figure 4.

6 26 Mehdi Izadi and Farzad Razavi Table 5 summarizes the operating costs of the methods applied to the network under discussion. Table 1. Levels of apparent power and the number of associated transformers Apparent power (kva) Number of associated transformers Table 2. The number of agricultural transformers associated with levels of apparent power Levelofapparentpower (kva) Number of associated transformers Table 3. A sample of the length of line between every two terminals Terminals i j Length (km) T59-T T60-T T62-T T64-T T65-T T66-T T67-T T68-T T69-T T70-T T71-T T72-T T73-T T74-T T75-T T76-T Software DIgSILENT Power Factory 13.2 was used to develop the proposed algorithm for the objective functions and to analyze the system. This application can calculate load flow, short-circuit level, active losses of the network, and the network parameters. The main feature of DIgSILENT is DPL (DIgSILENT Programming Language), which simplifies the application of the proposed method. The objective functions were optimized using GA on MATLAB R2008a Software. A text file connected the two applications. 4.3 Proposed Algorithm In the proposed algorithm, GA determines the following for each load: The percentage of imbalance, which is a number from 0 to 100. The quantity of 12.5-kvar capacitors, which is a number from 0 to 18. In addition, each transformer, line, and loose connection is assigned a value of either 0 or 1, denoting the necessity (1) or lack thereof (0) of fixing/replacement. The above-mentioned are only done if constraints are not violated. The details of the proposed method are given below: (1) DIgSILENT writes the zero in the text file to flag the beginning of the initial calculation. Detecting this flag, GA will not begin the associated program. Table 4. Conductor types Type Resistance (/km) Reactance (/km) Weight (kg/km) Table 5. Operational costs Equipment and services Capacitor 12.5 kvar Fixed cost 1 Fixed cost 2 Fixed cost 3 Trans 25 kva Trans 50 kva Trans 100 kva Trans 200 kva Trans 250 kva Trans 315 kva Trans 500 kva Trans 630 kva Conductor type1 Conductor type2 Energy Cost ($/unit) 100 ($/unit) 200 ($/unit) 300 ($/unit) ($/unit) ($/unit) ($/unit) ($/unit) ($/unit) ($/unit) ($/unit) ($/unit) ($/kg) ($/kg) ($/kwh)

7 Energy Loss Reduction in a 20-kV Distribution Network Considering Available Budget 27 (2) 1 n vars nvar simbalance DIgSILENT writes the matrix n in varscap population_ size Generation the text file. The first row is the flag which shows the program must begin its operation. When the flag is set to 1, GA must run. n vars, n varsimbalance, and n varscap respectively identify the total number of the genes within the chromosome, those related to load imbalance, and those associate with the capacitors. (3) GA writes the matrix [2 B 1 B n C 1 C n T 1 T n L 1 L m X 1 X k ] in the text file. In this matrix, B 1,, B n are the new percentages of imbalance for each load, C 1,, C n are the number of 12.5-kvar capacitors for each load, T 1,, T n are the values of 0 or 1 related to each transformer, L 1,, L m are the values of 0 or 1 associated with each line, X 1 X k are the values of 0 or 1 pertinent to the loose connections of each line, and Flag 2 indicates that DIgSILENT must restart its operation. (4) Upon seeing Flag 2 at the beginning of the text file, DIgSILENT commences operation and calculates the OF using the chromosome given in that file. The application, then, inserts in the text file Flag 3 and the 3 quantity of the OF in the form of a matrix OF, where Flag 3 is an indicator of the temporary termination of the operation of DIgSILENT and the restart of the operation of the GA. (5) If the maximum number of iterations is not reached, the process described above reverts to stage 3. Otherwise, the process goes on to stage 6 below. (6) The GA is finished, so it inserts Flag 4 in the text file, denoting the end of the process. (7) Upon seeing Flag 4 in the text file, DIgSILENT realizes that the process is over. 5. Results and Discussion In this research, loss factor was considered to be , and the following items were calculated with regard to attendant costs: (1) Adjusting load imbalance (2) Placing capacitors (3) Replacing transformers (4) Replacing line conductors (5) Correcting weak connections (6) All the above carried out together without regard to the available budget (7) All the above carried out together with regard to the available budget 5.1 Adjusting Load Imbalance Table 6 summarizes the results of adjusting load imbalance in transformers. Power loss was kw after load imbalance was corrected, indicating a drop of kw, which equals 10.16% of the total loss of the network. The cost of balancing all the loads was obtained from Eq. (2). The quantity of phase current R was 1.5 times as large as that of the average current. The quantities of phase currents S and T were respectively 0.8 and 0.7 times those of the average current. Phase current R was 50% more than the average current. Phase currents S and T were 20% and 30% less than the average current, respectively. Now, by reducing the surplus of phase current R to 30%, we can reduce the deficit of phase currents S and T to 10% and 20%, respectively, at a cost of $ The loss reduction thus obtained will be 21 MWh, and the resultant benefit will be $3700 a year. 5.2 Placing Capacitors Unless load imbalance had been adjusted, capacitors could not be placed. Hence, loss should have a different amount before capacitor placement than before the deployment of any of the other methods. The results of allocating capacitors in the network are given in Table 7. Different capacitors were placed at different busses Table 6. Fixing load imbalance Item Quantity Loss after run kw Loss reduction kw Cost $ Benefit $ OF 1 $

8 28 Mehdi Izadi and Farzad Razavi Table 7. Capacitor allocation Item Quantity Loss before run kw Loss after run kw Loss reduction kw Cost $ Benefit $ OF 1 $ as follows: 12.5-kvar capacitors at busses T18, T28, T kvar capacitors at busses T2, T4, T10, T20, T kvar capacitors at busses T26, T30, T40, T46, T48, T kvar capacitors at bus T kvar capacitors at bus T kvar capacitors at busses T38, T44, T kvar capacitors at bus T kvar capacitors at bus T52. Before capacitor installation and at the peak moment, the apparent power input was kva, the reactive power input was kvar, and power loss was kw. After placing capacitors and at the peak moment, the apparent power input was kva, the reactive power input was kvar, and power loss was kw. This shows that the apparent power input was reduced by kva(equal to 9.03%), the reactive power input by kvar (or 43.24%), and power loss by kw (i.e., 16.90%). The total capacity of all the capacitors added to the network under investigation was 950 kvar at the peak moment of the year. Capacitor installation increased the usable capacity of the network by kva (equal to 9.03%) at the peak moment of the year. 5.3 Replacing Transformers Zero transformers had to be changed. This finding can be explained as follows: There were 28 transformers in the feeder studied in this research. The loss of the transformers consists of copper and iron loss. At the peak moment of the year, the total loss of all the transformers was 31 kw, with the total iron loss being 19 kw, and the total copper loss being 12 kw. The total loss of all the transformers was equal to 54.82% of the total loss of the network. Iron loss was 60.29% of the total loss of the transformers and 33.05% of the total loss of the network. Copper loss was amounted to 39.71% of the total loss of the transformers and 21.77% of the total loss of the network. Replacing dilapidated transformers will reduce the total loss of transformers by 20%. That is to say, a reduction of 55.4 MWh will bring the total loss of transformers to MWh. It follows that the total loss of the network will reduce by 10.96%. Given that the benefit of loss reduction resulting from replacing dilapidated transformers will be $7523 a year, and that replacing all the transformers will cost $152633, the benefit to be obtained from replacing dilapidated transformers will be not be significant. 5.4 Replacing Line Conductors The total loss of lines was MWh, equaling 45.18% of the total loss of the network. Replacing the dilapidated conductors of a line diminishes its resistance by 10%. This correspondingly reduces the loss of the lines as loss is positively related to resistance. Thus, replacing all dilapidated conductors will result in a reduction of about 4.52% in the total loss of the network. Loss will be reduced by MWh. The benefit to be obtained will be $ a year. Replacing all the conductors will be approximately $ given that all the lines in the network are about 19 km in length. In consequence, the benefit to be obtained from replacing dilapidated conductors will be insignificant. Table 8 summarizes the results of line conductor replacement. 5.5 Correcting Weak Connections Weak connections should not be corrected. The explanation is as follows: As mentioned above, the resistance of a weak connection in the network under study was ohm. The Table 8. Replacing line conductors Item Quantity Loss after run kw Loss reduction kw Cost $ Benefit $ OF 1 $23.698

9 Energy Loss Reduction in a 20-kV Distribution Network Considering Available Budget 29 resistance of the weak connections in a km line was ohm. The resistance of a km line was found to be ohm. The resistance emanating from weak connections is equal to 0.08% of the total resistance of the line. Fixing weak connections in a line will cost $ The benefit to be obtained from fixing weak connections seems trivial in comparison with the costs involved. 5.6 All the Methods Applied Simultaneously Different capacitors were installed at different busses as follows: 12.5-kvar capacitors at busses T4, T kvar capacitors at busses T20, T38, T40, T kvar capacitors at busses T8, T16, T26, T30, T kvar capacitors at busses T14, T kvar capacitors at busses T32, T kvar capacitors at buss T kvar capacitors at busses T8, T16, T26, T30, T kvar capacitors at bus T kvar capacitors at bus T52. Table 9 presents the results of simultaneous application of all the five methods of loss reduction, only placing capacitors and fixing load imbalance seem cost-effective. More specifically, simultaneously applying all the methods reduces power loss by 18.10%, with the ratio of benefit to cost being 47 to 40. The total capacity of the capacitors added to the network was 1050 kvar. Table 9. All the methods applied simultaneously Item Quantity Loss after run kw Loss reduction kw Cost $ Benefit $ OF 1 $ Cost of Fixing load imbalance $ Prioritizing Methods of Loss Reduction According to the Degree of Reduction and the Amount of Available Budget Tables 10 and 11 summarizes the ratio of benefit to cost and percentage of loss reduction, respectively. The best method of loss reduction will be fixing load imbalance providing that the decision is based on the benefit-cost ratio. However, if the percentage of loss reduction forms the basis of the decision, capacitor placement will be the best method. As the budget available to Qazvin Electrical Distribution Company (n) was $19000, running OF 2 gave the results presented in Table 12. All the five methods were concurrently used to reduce loss in the network. According to the results, only adjusting load imbalance, placing capacitors, and replacing dilapidated conductors are advisable considering the available budget. In addition, a comparison of Tables 9 and 12 reveals that running OF 1 showed capacitor placement and load imbalance adjustment to be the best of the five alternative methods. Running OF 2 showed that replacing dilapidated conductors can be a good alternative as well. The difference lies in the fact that OF 2 was run with a $19,000 budget in mind. From Table 12, it can be seen that 2.95% of the available budget should be allocated to adjusting load imbalance, 76.59% to placing capacitors, and 20.46% to replacing dilapidated conductors. 6. Conclusions This study proposed a way for allocating the budget Table 10. Cost-benefit ratio Method Benefit-cost ratio Fixing load imbalance 6.85 Placing capacitors 1.16 Replacing line conductors 1.14 Table 11. Percentage of loss reduction Method Percentage of loss reduction Fixing load imbalance Placing capacitors Replacing line conductors Table 12. The results of running OF2 Item Quantity Loss after run kw Amount of loss reduction kw OF 2 = Benefit $ Cost of adjusting load imbalance $ Cost of placing capacitors $ Cost of replacing dilapidated conductors $

10 30 Mehdi Izadi and Farzad Razavi available to the Qazvin Electric Distribution Company to different approaches to loss reduction in an attempt to obtain maximum loss reduction. For this purpose, an actual feeder was subjected to five methods of reducing loss. These methods were studied in terms of the degree of loss reduction brought about and the amount of costs involved. Then, the budget to be assigned to each method was determined using the proposed objective function. The results showed the available budget should be assigned to capacitor placement, replacement of dilapidated conductors, and load imbalance adjustment in that order. This finding can help power utilities better allocate their loss reduction budget. A limitation of the present research is that only the five methods discussed were applicable to the network under study. Thus, it seems advisable to evaluate some other methods. Finally, when the model is put into operation, load imbalance adjustment should always be performed prior to capacitor placement. No particular order is needed for the other methods of loss reduction. References [1] Haghifam, M. R. and Malik, O. P., Genetic Algorithm-based Approach for Fixed and Switchable Capacitors Placement in Distribution Systems with Uncertainty and Time Varying Loads, IET Generation, Transmission & Distribution, Vol. 1, pp (2007). doi: /iet-gtd: [2] Lin, C.-H., Chen, C.-S., Chuang, H.-J., Huang, M.-Y. and Huang, C.-W., An Expert System for Threephase Balancing of Distribution Feeders, IEEE Transactions on Power Systems, Vol. 23, pp (2008). doi: /TPWRS [3] Venkatesh, B. and Ranjan, R., Fuzzy EP Algorithm and Dynamic Data Structure for Optimal Capacitor Allocation in Radial Distribution Systems, IEE Proceedings-Generation, Transmission and Distribution, Vol. 153, pp (2006). doi: /ip-gtd: [4] Etemadi, A. H. and Fotuhi-Firuzabad, M., Distribution System Reliability Enhancement Using Optimal Capacitor Placement, IET Generation, Transmission & Distribution, Vol. 2, pp (2008). doi: /iet-gtd: [5] Senior, A. H. A.-B., Elmoudi, A., Metwally, I., Al- Wahaibi, A., Al-Ajmi, H. and Bulushi, M. A., Losses Reduction in Distribution Transformers, Proceedings of International MultiConference of Engineers and Computer Scientists, Hong Kong, pp (2011). [6] Sivanagaraju, S., Sreenivasulu, N., Vijayakumar, M. and Ramana, T., Optimal Conductor Selection for Radial Distribution Systems, Electric Power Systems Research, Vol. 63, pp (2002). doi: / S (02) [7] Nemati, G. and Nasr, K. S., Reducing Operation Costs and Losses Using Thermography, Presented at the 21st International Conference on Electricity Distribution, Frankfurt Germany (2011). [8] Izadi, M., Razavi, F., Gandomkar, M., Najafi, A. and Soleimani, M., Power Loss Reduction in Distribution Systems through an Intelligent Method Considering Operational Costs, J. Basic Appl. Sci. Res., pp (2012). Manuscript Received: Jun. 27, 2016 Accepted: Oct. 14, 2016