Browsing by Author "Abiy, Atakure"

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    Studies on Applications of FACTS Devices to Improve Overloading and Unbalanced Power System Operating Conditions
    (Addis Ababa University, 2019-04) Abiy, Atakure; N.P., Singh (PhD)
    An important issue in today’s power system is the need to analyze and determine the adequacy of transmission capacity. There is a need for approaches to increase transmission system capacity without construction of new transmission facilities, all while assuring secure operation of the grid. Smart grid technologies such as FACTS and DSRs can enhance capacity utilization and increase flexibility in controlling power flows on transmission lines. Distributed Series Reactor (DSR) control is a new smart grid technology that can be applied to control flows in the transmission system. DSRs can be used to balance flows in a single line as well as to control the distribution of power flows in parallel lines. This thesis investigates the application of Distributed Series Reactors (DSRs) on Ethiopian National Grid transmission systems to control power flow and to improve the overloaded line capacity and shifting power to other parallel branches which are under loaded. Simulation studies are carried out on Ethiopian grid using power system simulation for Engineers (PSS/E). 400kV, 230kV and 132 kV transmission lines of the Ethiopian gird are considered for simulation studies. Placement of a DSR having its reactance value 20% of the overloaded line enhances the existing transmission capacity utilization of the 400kV lines by 89.22%, for the 230kV lines by 81.28% and the same for 132kV lines by 83.79%. Moreover, the overloading condition of the 132kV line is improved by 95%. Placement of a DSR having its reactance value 30% of the overloaded line enhances the existing transmission capacity utilization of the 400kV lines by 89.22%, the 230kV lines by 81.32% and the same for 132kV lines by 82.42%. Moreover, the overloading condition of the 132kV line is improved by 85%. Placement of a DSR having its reactance value 50% of the overloaded line enhances the existing transmission capacity utilization of the 400kV lines by 89.22%, the 230kV lines by 81.31% and the 132kV lines by 80.13%. Moreover, the overloading condition of the 132kV line is improved by 79%. In this study cost benefit analysis of DSR placement having its reactance value 20% of the overloaded line is performed. The cost benefit analysis for the construction of new transmission line for 84.76% capacity improvement needs 12.25M$ and the total cost for the same capacity improvement using DSRs are deployed on the overloaded line needs 3.33M$. Comparing this total cost of DSRs which is 3.33M$ with that of building new lines which is 12.25M$, it appears that the DSRs implementation cost reduced by 27.18 % relative to the traditional approach of building new lines.