Voltage-source-controlled high-voltage direct-current（VSC-HVDC） transmission technology is an advanced one with voltage-source converters

self-closing-devices and pulse width modulation as a base and has such advantages as flexible power distribution adjustment without almost harmonic and reactive power compensation etc

and can be used widely in such fields as new power interconnection

urban power supply

interconnection of islands and access of distributed power. In this paper

the operation situation of VSC-HVDC transmission technology in the existing projects of domestic grid is studied and the advantage and disadvantage of the VSC-HVDC transmission technology is analyzed. As for Nanjing western-loop power grid during the fourth Five Year planning period

grid strengthening schemes based on VSC-HVDC and conventional AC transmission technologies respectively are proposed. The bottlenecks to be broken through and development suggestion of popularization and application of VSC-HVDC transmission on the actual project is summarized through technical/economic comparison of the two grid strengthening scheme.