Assessing Transmission Line Loss in Ethiopian Electric Power System Under Contingency Conditions
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Date
2018-03
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Addis Ababa University
Abstract
Ethiopian Electric Power (EEP) is comprised of large interconnected power systems with far apart and geographically remote generators and loads connected by long transmission lines. This results high transmission line loss and transmission line contingencies frequently. Contingency of any one of transmission line increases the losses in the remaining transmission lines and lead to overloading. This overload triggers their corresponding protection system and thereby result in cascaded tripping lines, transformers and generating units. This in turn leads to total or partial blackout.
In this thesis work, transmission line loss of EEP high voltage 400 kV and 230 kV grid network have been analyzed, under base case condition and each N-1 transmission line contingency condition, using power world simulator software.
From load flow simulation result the base case total transmission loss during peak load is found to be 66.53 MW and the corresponding power loss share obtained for transmission line and transformers are 91.7 % and 8.3% respectively. The annual energy loss due to transmission line power loss is found to be 184.026 Giga Watt hour, amounting to 3.735 million US Dollar financial losses. During N-1 transmission line contingency condition total peak capacity transmission line loss varies with maximum loss of 188.4 MW and minimum loss of 59.37 MW with 10 unsolved simulations. To reduce these; addition of transmission lines and capacitor compensation measures both individually and two methods at a time have been presented. The corresponding transmission line capacity gain obtained form addition of transmission lines, shunt compensation and integrated loss mitigation were 12.86 MW, 4.09 MW and 13.15 MW respectively.
N-1 transmission line contingency analysis before loss mitigation techniques and after integrating loss mitigation techniques of the system network recorded a total of 151 and 52 bus voltage limit violations respectively. Accordingly, the result recorded an appreciable loss reduction and the problem of transmission lines overloading, bus bar voltage limit deviation from the normal limits have been partially solved in normal as well as N-1 transmission line contingency conditions.
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Base case, Contingency, Energy loss, Loss mitigation, Peak load, Power loss