ASSESSMENT TECHNICAL LOSSES IN DISTRIBUTION SYSTEM

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1 ASSESSMENT TECHNICAL LOSSES IN DISTRIBUTION SYSTEM AHMED HAMZAH KADHIM Electrical Power Engineering, Universiti Tenaga Nasional (UNITEN), Selangor, Malaysia ABSTRACT This research study is aimed at reducing the technical losses in Al Muthanna city in Iraq. This is carried out in the distribution system using PSS/adept program as tool for simulation. The techniques considered for the reduction of losses are the reconfiguration and switching optimization of distribution network with the addition of new 11KV feeders or addition new 33/11KV substation based on optimal power flow and benefit cost analysis, which enables the benefit cost analysis and objective function assessment of energy loss reduction, which supports the investments. The costs considered are economic costs associated with loss reduction sources. The benefit is the reduction in energy loss costs in the distribution system. The benefits will be worked out against the costs which will show the economic justification of the investments in loss reduction sources. Keywords: Three Phase Power Flow, Technical Loss, PSS/Adept Program 1. INTRODUCTION In recent years, electrical energy distribution companies have invested substantial amounts for purposes to identify and calculate the technical losses in terms of energy in a distribution system within a network. Despite these efforts, most of the approaches in identifying and solving the related problems are still rather inefficient. For most electrical distribution companies, accuracy in identification and the precision in the calculation of electrical losses are of utmost important. This is become the clear specification of the critical points and segments in the networks enable the effective prioritization of actions and interventions that consequently reduce electricity losses and problems in distribution system. The other concern is the minimization of power losses within the network. The loss of energy may occur in the electrical system for both the electrical energy distribution companies and regulators. Therefore, minimization of energy losses is important as it not only leads higher revenues, but it also brings about more improvement on the quality of the products offered to consumers. In addition, the companies can expect to gain new markets and to expand network capacity Technical losses in term of energy are inevitable physical phenomenon these losses during the transfer of energy from generating plants to load centers [1]. During this transfer process, some of the input energy is dissipated in conductors and transformers along the delivery route. The losses that occur in all conductors may be of any of the three types copper, dielectric and induction radiation losses of the three, copper losses record the highest of total transmission losses. Copper losses make up the losses that are inherent in all conductors. This is because of the finite resistance of the conductors. These losses occur due to the current flowing in the electrical network. In alternating current (AC) system, the copper losses are higher due to skin effect [2]. This research was to analyze technical loss in Al Muthanna city in Iraq. This is carried out in the distribution system using PSS/Adept 5.3.2program as tool for simulation. The techniques considered for the reduction of losses are the reconfiguration or switching optimization of distribution network with the addition of new 11KV feeders or addition new 33/11KV substation. Finally to the comparison between finally the investment costs of operations of the options available in this project by using economic analysis based on present worth method. 2. THEORIES 2.1 POWER FLOW The load flow analysis is characteristic analysis of power system at steady state to find appropriate work point. In general, use power system model and distribute loads constant [3] [4]. The power flow equations take the form When we consider voltage both magnitude and phase angle. We can write equation for find active power and reactive power at bus: So we can calculate power flow in Jacobian matrix INTERNATIONAL JOURNAL OF SCIENCE, ENGINEERING AND TECHNOLOGY

: Real power mitmach : Reactive power mitmach Given an initial set of bus voltages, the real and reactive powers are calculated from the power flow equations.

2 : Real power mitmach : Reactive power mitmach Given an initial set of bus voltages, the real and reactive powers are calculated from the power flow equations. The changes in power are the differences between the scheduled and calculated values Figure 1: PSS/Adept program 2.3 SCENARIO DEVELOPMENT We can analyze magnitudes and phase angle voltage for bring to find new result, until real power error is admit section which is The process is until and for all buses are within a specified tolerance. 2.2 TECHINCAL LOSS Technical losses occur due to the current flowing in a conductor that generates heat (losses= ); hence affects resistance, causing electricity loss. The following are losses that occur in all the conductors [5]. They are: Dielectric losses, Copper losses, and Induction/radiation losses DISTRIBUTION LINE LOSS Distribution losses (kwh) = LLF * energy losses * period (3) Which from model PSS/Adept PSS/Adept Program Energy losses Program which brought to calculate technical losses was PSS/Adept of Power Technologies, INC.A Shaw Group Company which has step to use: 1. Model transmission lines or distribution lines 2. Feed parameter in model A scenario represents all the possible outcomes in the future. It is usually conducted to improve the performance of the system. In this research project, the scenario implemented to reduce power losses. It can be performed by build and install new 33/11KV substation or build new 11KV feeders at a practical region to suit the loads SCENARIO 1 (BUILD NEW FEEDER) In this scenario, one or more build new 11KV feeders are proposed for sharing some of the load of the heavy loaded feeders. Then, network reconfiguration is implemented for the distribution of minimization of power loss and load balancing under normal operating conditions. After this, the whole Distribution network is under study once more but this time, it is modeled using PSS/adept. Finally, the data gathered are analyzed to show the results of the power losses SCENARIO 2 (BUILDING NEW SUBSTATION) The second scenario involves the addition of new 33/11KVsubstations to the existing. The location of the installation of the substation is determined by the findings obtained from load study (over load feeders). Then, network reconfiguration is implemented for the distribution of minimization of power loss and load balancing under normal operating conditions. After this, the whole Distribution network is under study once more but this time, it is modeled using PSS/adept. Finally, the data gathered are analyzed to show the results of the power losses. 3. ECONOMIC ANALYSIS The optimization of technical losses in electricity distribution system is engineering issue that involves classic tools of power systems planning and modeling [6]. The main criterion is the minimization of the net present value of the total investment cost of the distribution system plus the total cost of technical losses. All the recommendation proposed in this research project are supported by economic analysis using the Present worth method with consideration of a life cycle of 20 years. 3. Run Program INTERNATIONAL JOURNAL OF SCIENCE, ENGINEERING AND TECHNOLOGY

As such, it is necessary to define the present value money (P) and the future value of money (F). The number of periods is assumed to be n, while the interest rate is assumed to be i (%).

3 3.1 PRESENT WORTH METHOD (NPW) According to [6], all input and output cash flow of a project are converted to the present values. The one with a net negative flow (Net Present Worth, NPW) is considered to be viable. From those viable, the one with the lowest net flow is the best plan. As such, it is necessary to define the present value money (P) and the future value of money (F). The number of periods is assumed to be n, while the interest rate is assumed to be i (%). Mathematically, the present value of future cash flow is defined the following formula: transformers connected to three 11 kv feeders and (19) static load. Also this network consists of (34) switches that can be opened or closed. The total power load connected to distribution network is MVA. (4) (5) Where is named as a uniformed series of present worth factor, that is donated by (P/A, i %, n), whereby is a payment in time worth of n year. 3.2 ECONOMIC ASSUMPTIONS The economic evaluation is based on assumptions provided by the industry as listed in Table 1. Table 1: Economic Assumptions interest rate 2% Life cycle (n) in year 20 Initial cost of 11KV 3*150 underground cable ($/meter) Annual O&M cost of 11KV 3*150 underground cable ($/Km in a month) Initial cost of 1*31.5MVA substation ($) 1,320, Figure 2: Single line diagram of Al Muthanna distribution system Distribution network data technically is be converted to meet with PSS/ADEPT parameter requirements. Then model of the present Al Muthanna network is simulated, run load flow by using the model. Hence, determine power losses in each branch of the network. Also the candidate places for loss reduction supports were defined. The identification of the candidate locations is made according to where the highest power loss flows in the network. The following results in Figure 3 were the power loss and load at every feeder in the test network. The results show that the total energy loss of network is 48, MWh/year. The results show that the rate of energy losses is higher around the mean of 12.2% for the 11 kv system Annual O&M cost of 1*31.5MVA substation ($/MW in month) Initial cost of 33KV 1*400 underground cable ($/meter) Annual O&M cost of 33KV 1*400 underground cable ($/km in a month) Tariff cost ($/KWh) ANALYSIS The network of Al Muthanna Iraq distribution system was chosen as a test distribution system, the test system for the case study consisting of 68 bus radial system. The system is under in base of 11 kv distribution systems. Normally the network is fed by eight 11 kv underground feeders from two substations located in the area named as Al Samawah Substation and Al Western Substation. Al Samawah Substation consists of (2) units of 61.5 MVA, 132/33/11 kv transformers connected to five 11 kv feeders and (48) static load. While, The Western Substation consists of 2 units of 31.5 MVA, 33/11 kv Figure 3: details of energy loss in the network. 4.1 CALCULATION FOR DISTRIBUTION LOSSES WITH SCENARIO 1 In this scenario, we installed 7 new 11 KV feeders (using XLPE power cable, 3x150mm^2,copper conductor) are proposed for sharing of the load of the heavy loaded feeders is show in figure 4, then we can found losses by PSS/Adept program. Figure 5 shows resulting of the INTERNATIONAL JOURNAL OF SCIENCE, ENGINEERING AND TECHNOLOGY

total losses in the network before and after installation of 7 feeders. Figure 7: Result of the losses in the network before and after implementation of the new two substations.

Simulation network after implementation of new 7 feeders. 4.

in table 6. The following steps are used to calculate the cost 1 Using the calculated the power losses (kw), the total annual energy (kwh) is obtained by equation (3).

4 total losses in the network before and after installation of 7 feeders. Figure 7: Result of the losses in the network before and after implementation of the new two substations. Figure 4: Simulation network after implementation of new 7 feeders. 4.3 ECONOMIC EVALUATION OF TECHNICAL LOSSES IN THE SELECTED SCENARIOS The present value of the two scenarios, which are presented in Table 4 and 5, is calculated, to compare between two scenarios show in table 6. The following steps are used to calculate the cost 1 Using the calculated the power losses (kw), the total annual energy (kwh) is obtained by equation (3). 2 The cost of power losses ( ) in ($/year) for the distribution network is determined by using the formula: Figure 5: Result of the losses in the network before and after implementation of the new 7 cables 4.2 CALCULATION FOR DISTRIBUTION LOSSES WITH SCENARIO 2 The second scenario involves the addition of 2 new 33/11KV substations to the network, as shown figure 6. We chose the location of the installation of the substation by the findings obtained from load density (over load feeders). Figure 7 shows resulting of the total losses in the network before and after installation of two substations. 3 Revenue in ($/year) for the distribution network is obtained by equation (7). 4 Benefit in ($/year) for the distribution network is obtained by equation (8). 5 Determined NPW in ($) is obtained by equation (5), the one with the lowest net flow is the best scenario. Table 2 shows details of the scenarios according to economic analysis. Table 2: cost calculation result case Scenario 1 Scenario 2 Calculated losses (KW) Annual loss cost (M$/year) Figure 6: Simulation network after implementation of new two substations. Investment cost (M$ ) Benefit (M$ /year) INTERNATIONAL JOURNAL OF SCIENCE, ENGINEERING AND TECHNOLOGY

NPW (M$) 36.68 39.77 From the above results, one can conclude the following: 1 Using scenario 1, the technical losses are costing the system owner about $479,444 annually.

5 NPW (M$) From the above results, one can conclude the following: 1 Using scenario 1, the technical losses are costing the system owner about $479,444 annually. Over a 20 year evaluation period, the NPW of this scenario is $36.68 million. 2 Using scenario 2, the technical losses are costing the system owner about $237,522 annually. Over a 20 year evaluation period, the NPW of this scenario is $39.77million. The results show that scenario 1 is best plan. 5. CONCLUSION This research provided a detailed discussion for the assessment of technical losses in the distribution system. Initially, this research was to analyze technical loss in of al Muthanna city in Iraq. This is carried out in the distribution system using PSS/Adept 5.3.2program as tool for simulation. The data show high level of losses that requires remedial corrective actions in metering and reporting process. The discussion also includes the solutions to reduce technical losses that can be minimizing by two scenarios: 1 Scenario 1, additional and fed 8 new 11KV feeders with (using XLPE power cable, 3x150m, copper conductor. No of feeders= 8, total length is 16.6km) see figure in the original network by using also simulation depending on the load flow at each feeder, as shown in figure 4. 2 Scenario 2, building and fed 2 new 33/11KV substation with capacity is 1*31.5MVA each in the original network by using the simulation, as shown in figure 6. [2] R. Herawan, "ANALYSIS OF TECHNICAL ENERGY LOSSES BY USING SIMULATION," MAKARA Journal of Technology, 10(1) [3] B. Euraporn, "Basic Power System Analysis,," Chulalongkorn University publisher, [4] H. Saadat, " Power system analysis.," WCB/McGraw Hill, [5] IE Davidson, "tevhnical losses computation and economic dispatch model for T&D system in deregulated ESI,," Power Engineering Journal, p. p 55, [6] S. Seifi, " Electric Power System Planning.," Springer., AUTHOR PROFILE Ahmed Hamzah Kadhim was born in Iraq in He received the B.S. degree in Electrical Engineering from Almustansiria University, Iraq in During , he employed in Al Muthanna Office, DG of Electricity Distribution South, Ministry of Electricity in Iraq. He worked in Electrical O&M Department. Then in 2012 Iraqi government sent him to Malaysia to study M.S. degree in Electrical Power engineering Uniten University. Now he is doing a dissertation and its topic: Assessment Technical Losses in Distribution System. The last section of this research is the calculation of investment costs for the both scenarios using Net Present Method (NPW). Using scenario 1, the technical losses are costing the system owner about $479,444 annually. Over a 20 year and 2% interest rate evaluation period, the NPW of this scenario is $36.68 million. In this work, it was found that a 72% reduction in power losses which can be achieved through scenario 1 presents an annual benefit of $2.8 million annually. While, using scenario 2, the technical losses are costing the system owner about $1141.1annually. Over a 20 year and 2% interest rate evaluation period, the NPW of this scenario is $39.7 million. In this work, it was found that an 85% reduction in power losses which can be achieved through scenario 2 presents an annual benefit of $2.98 million annually. Furthermore, the case study reveals that building substation have the lowest power losses; therefore, the highest energy cost saving, also requires the highest investment. REFERENCE [1] Y. J & N. YU, " Analysis on Technical Line Losses of Power Grids and Countermeasures to Reduce Line Losses [J].," Power System Technology, 18, 014., INTERNATIONAL JOURNAL OF SCIENCE, ENGINEERING AND TECHNOLOGY

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