Browsing by Author "Tesfaye, Yohannes"

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    [Application of Micro-Hydro Pv/Battery off- Grid Hybrid Energy System for Ethiopian Rural Area]
    (Addis Ababa University, 2014-08) Tesfaye, Yohannes; Edessa, Dribssa (PhD)
    Ethiopia is a developing country with a total access to electricity not exceeding 41% (in 2012) and the number of household connected to this access is 17%. About 85% of the population lives in places where access to electricity is less than 2%. The village for this study, Mogno Keshenbel Village (8.570N, 37.450E) has a total population of 4526 and 874 households (CSA, 2007, Guder Wereda Health Office). The village is about 68km from Guder substation; whicht makes the extension of the grid not yet practical and off grid electrification is the best option for the village. The community in the Mogno Keshenbel village uses Kerosene for lighting, water for milling and biomass for cooking and dry cells for radios. Nothing has been done so far in developing the renewable energy resources, such as small-scale hydro, solar and wind energy in the village. In this study, feasibility of micro hydro/PV/battery hybrid electric supply system to the village is analyzed using HOMER software (hybrid optimization model for electrical renewable) as optimization and sensitivity analysis tool. The logic behind HOMER selection is that it is proven and worldwide used for micro power design. Hydro potential of the village is analyzed by measuring the gross head of the river with the help of GPS (Geographical Position System) and stream flow data obtained from Ministry of Water, Irrigation and Energy and also Meteorological data of the village is collected from National Meteorological Agency of Ethiopia and NASA. Surface Metrology is used for the estimation of solar energy potentials. Electric load for the basic needs of the community, such as, for lighting, radio, television, ‘injera Mittad”, water pumps, milk processing and flour mills is estimated. One primary school and one health posts are also considered for the community. Additionally three Protestant churches and two Orthodox churches also considered. As a result, many feasible hybrid system combinations are generated, and accordingly, total net present cost (NPC) of the hybrid configuration and cost of energy (COE) for PV/ micro hydro/ battery hybrid system is $394,819 and $0.044/kWh, respectively, which is much lower than previously studied Micro hydro/wind hybrid system and PV/hydro/wind hybrid systems, and this value is less than the current grid price of Ethiopian ($0.06) [EPCO]. Index terms: Hybrid energy systems, Photovoltaic, Micro - hydro, off - grid system, HOMER
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    Assessment of Power Interruptions in Addis Ababa
    (Addis Ababa University, 2015-07) Tesfaye, Yohannes; Seid, Mohammed (PhD)
    This research project is done for the primary purpose of assessing electric power interruptions in Addis Ababa. Power interruption becomes a serious problem in the city in everywhere. The number of outages is very high and it takes long time for service restoration. Due to this every aspects of business and non business activities and day to day lives of the city residents are negatively affected and highly complained with this problem. Moreover the power interruptions cause wastage of power or power losses significantly. The objective of this research project is identifying the root causes of power interruption and identifying and forwarding the appropriate remedies for the identified problems. For this end primary and secondary data are collected, a subsequent four year power interruptions secondary data are collected from the service provider. A primary data is collected through open ended and close ended questionnaires, interviews and observations. Questioner is developed for electric power customers, for the service provider distribution and transmission operation staffs. Representative sample is determined based on random sampling method at 95% confidence level and at 5% margin of error. As per this 384 samples is determined out of 523,944 electric power customers and 184 sample employees from a total 362 employees. The analysis is done based on descriptive research analysis by using both qualitative and quantitative methods. Problems identifications are also done through SWOT analysis and root cause analysis. Root cause identifications are done through problem tree analysis. The research analysis find outs that power interruptions, power drops and poor customer services are major problems in electric power service. The root causes of the existing power interruptions are infrastructure capacity limitations, poor infrastructure & design, infrastructure management problem, poor planning & forecasting, exposure of infrastructures for theft & accidents, natural accident and water shortages. The company can minimize the power interruption problems by upgrading power supply infrastructure capacity, improving power infrastructure & design, improving infrastructure management practices, developing effective planning & forecasting practices: establishing preventive maintenance systems, applying power infrastructure rehabilitations works, supplying adequate and standard quality inputs, minimizing operational interruptions, developing infrastructure capacities, improving human resource management Practices and by making further studies. Electric power interruption is power outages and blackouts due to various reasons. Frequency of power interruption indicates the rate of occurrence or the number of repetition of the power interruptions in the grid systems. Whereas interruption duration indicates the length of time the power interruption continues or exists in the power grid systems.