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 to transfer 200MW power. Themost economical solution for the conductor type from the design was Aluminium Conductor Steel Reinforced (ACSR) Finch type. The conductor diameter being 32.85mm. Moreover, the other basic considerations in HVDC like design of line parameters, converter transformer, and harmonic filters were conducted. The designed and modelled transmission line required two converter stations; one at Karuma in Kiryandongo district and another at kawanda in Wakiso district. Furthermore, during the conversion of Alternating Current (AC) to Direct Current (DC) or vice versa harmonic contents were generated because of nonlinear loads like rectifiers, but these contents were mitigated by using harmonic filters and smoothing reactors coordinately. Design, simulation and experimental studies using dig-silent software were carried out for the coordinated control as well as independent control of AC and DC power transmissions.