Power Transfer Improvement on Uganda's Transmission Grid Network from HVAC to HVDC

Abstract

This project report presents the design of High Voltage Direct Current (HVDC) transmission system and shows why it is preferred over High Voltage Alternating Current (HVAC) transmission for power transmission over long distances. The HVDC transmission design presented here originates from karuma and terminates at kawanda. The total length of the transmission line is approximately 248 km. A bipolar dc link configuration was chosen with a standard transmission voltage of +/- 400kV. The other basic considerations in HVDC line design were the converter transformer, and harmonic filters. The designed and modelled transmission line required two converter stations; one at Karuma in Kiryandongo district and another at kawanda in Wakiso district. Design, simulation and experimental studies using DigSilent software were carried out for the coordinated control as well as independent control of AC and DC power transmissions. In conclusion, for the case of cost, HVDC is higher due to the karuma-kawanda transmission line distance being below the breakeven distance which is 800km above which the cost of HVDC becomes cheaper than HVAC. The choice has to be made whether to choose a cheaper transmission line at the expense of high transmission losses or choosing HVDC with high capital cost but with few losses. This report has four chapters which include: Chapter one covers project background, problem statement, objectives, justification, and significance of the research. Chapter two consists of the review of the literature. Chapter three consists of the methodology and discussion of the results. Chapter four consists of conclusion and recommendations.