Efficiency evaluation of a DC transmission system based on voltage source converters

The efficiency of a VSC-HVDC transmission system used to transmit wind farm power to the network is investigated. The losses associated with the operation of the VSC-HVDC system are the conversion losses (conduction and switching losses) in converters and the transmission losses due to I²R (in the converter transformers, smoothing reactors, and DC cables). An analytical method based on the average and root mean square of the semiconductors' current is used to estimate the conversion losses in the converters. The remaining power losses are evaluated using I²R. The results obtained using the analytical method are confirmed by the measured losses obtained from simulation studies.