The increased demand for electrical energy due to increased industrialization andrnpopulation growth of Dire Dawa and nearby cities has become a challenge to supplyrnadequate power using the national grid to Eastern region of Ethiopia. One reason forrnthese power shortages is the insufficient current carrying capacity of existing high voltagernalternating current, (HVAC), transmission lines supplying the area. High voltage directrncurrent (HVDC) transmission lines are a possible solution as they provide more powerrnthan HVAC lines.rnNew parallel HVAC lines, or converting the existing HVAC line to HVDC lines arernpossible solutions to improve power delivery in the area. This thesis investigates therntechnical feasibility of upgrading existing HVAC lines to HVDC. This option allows thernpower transmission rating to be more than doubled and the specific transmission losses tornbe substantially reduced without having to widen the right-of-way. What is more, suchrnconversions cost only a one third the cost of building a new line. Thus main contributionrnof this thesis work is the evaluation of a HVDC system including study of technicalrncompatibility of existing system conversion to HVDC as a solution to overcom powerrndelivery shortages to Eastern region of Ethiopia.rnFrom the technical performance the bipolar HVDC lines has a loss as much as 69.75%rnlower compared to the existing transmission lines and the monopolar HVDC line has arnloss as much as 83.02% lower compared to the existing transmission lines. On the otherrnhand, the transmission powers of the bipolar HVDC line at Â± 500 kV increase by 217%rnand the monopolar HVDC line at Â± 500 kV increase by 75.8% from the power transferrncapacity of the existing HVAC line. From the cost analysis the cost of conversion isrnapproximately 36% of cost of new HVAC line. Moreover, conversion of the existingrntransmission line to DC line is both financially and economically feasible.rnKey Words: HVAC, HVDC,LLC,HVDC control, Transmission line efficiency, coronarnloss, investment cost, internal rate of return.