Electrical Computer Engineering

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    DISTRIBUTION SYSTEM RELIABILITY IMPROVEMENT USING DISTRIBUTED GENERATION AND NETWORK RECONFIGURATION
    (Hawassa University, 2021-10-28) MEKLIT GIRMA
    Power supply reliability is the basic issue for economic and technology development of the country. The sufficient or adequate and secure supply of power will assure the reliability of the system. Unreliability of the system occur due to high outage frequency and duration, system overload and unsecure system or protection system. When the distribution system is reliable, it has capacity to meet the demand of customer and operate under adverse condition. Arbaminch distribution system has encountered frequent power interruption and power quality problem. The interruptions are mainly caused by system overload and short circuit fault. The reliability of the distribution system is assessed based on the data from Ethiopian Electric Power Corporation. Arbaminich substation of feeder -05 is selected as case study, which has high rate of interruption. Feeder -05 has SAIDI value of 236.8386 Hr./cust. /yr. and SAIFI of 221.6338 f/cust. /yr. The reliability indexes values of feeder -05 are not within the ranges of bench marks of reliability requirement. This thesis focused on reliability improvement of distribution system with better placement of distributed generation and network reconfiguration. Particle swarm optimization algorithm is used for placement of DG, size and network reconfiguration. The algorithm is done using MATLAB 2016 software. Based on the availability in the area, efficiency, cost and emission level, Solar and Microturbine sources are used as distributed generation. The suitable site and size of DG are found at bus 10 with suitable size 4.5 MW. For network reconfiguration sectionalizing switch is used. Before reconfiguration the switch was placed at bus 20, 21, 22,23 and 24. During network reconfiguration switch changed to bus 3, 4,12,24 and 31. The reliability indices SAFI, SAIDI and EENS value improved by 82.81%,78.89% and 78.10% respectively after DG with reconfiguration used. Expected interruption cost before applying the proposed method is 9,758,852$ /year. After the proposed method used expected interruption cost reduced to 2,995,270$ /year. This indicates that, 6,763,582 $/year is saved after using the proposed techniques
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    SALP SWARM ALGORITHM BASED OPTIMAL NETWORK RECONFIGURATION WITH DISTRIBUTED GENERATION FOR POWER LOSS MINIMIZATION AND VOLTAGE PROFILE IMPROVEMENT (CASE STUDY: YIRGALEM SUBSTATION)
    (Hawassa University, 2022-04-26) FIKADU ALEMAYEHU
    In a distribution system, power loss and voltage deviation are the main concern for the customers and utility. The distribution system has a lower voltage level and higher amount of flowing current than the transmission system, so that, the percentage real power loss in the distribution system is higher. Therefore, this thesis work presents optimal network reconfiguration with the distributed generation of yirgalem radial distribution network to minimize the power loss, operation cost, and enhance the voltage profile of the distribution system using the Salp Swarm Algorithm (SSA). The resource feasibility of solar and wind power in yirgalem city was analyzed and the outcomes showed that solar power generation is more desirable. For this reason, the solar-type Distributed Generation (DG) is used. The proposed SSA algorithm was compared with Particle Swarm Optimization (PSO) and Whale Optimization Algorithm (WOA) in three various scenarios (only optimal network reconfiguration, only optimal DG size and site, and simultaneous optimal network reconfiguration and DG allocation) for the abosto feeder. After analysis of the three scenarios in MATLAB-R2016a, it can be concluded that the simultaneous network reconfiguration with DG shows a dominant result over only network reconfiguration and only DG allocation. The simulation result of base case backward forward sweep load flow analysis revealed that the abosto feeder has a base case power loss of 401.3KW. The feeder minimum voltage profile at the base case is 0.87pu. After simultaneous optimal network reconfiguration and DG size and site with SSA, the optimal tie switch open is 11, 25, 16, 42, 14 and the optimal location of the solar-type DG is at bus 23 and its size is found to be 895.3KW. Consequently, power loss of the selected abosto feeder is reduced to 101.5KW from the base case. The power loss reduction of the abosto feeder is 74.7% with respect to the base case loss. The voltage profile after optimal network reconfiguration with DG is improved by 11.4%. As per the economic evaluations, the proposed method is cost-effective. Depending on the findings of this thesis, it is concluded that optimal network reconfiguration with DG reduces power loss, operating cost and enhance the voltage profile of the distribution system.