In offshore oil platform of large capacity far away from the land

high voltage and power motors（HV motor）are needed when delivering oil to onshore land.Diesel generators in platform can’t support so much power requirement

so the motors mentioned above must be supplied by onshore AC grid. In general

when there is a long distance between offshore platform and onshore land

DC transmission system is more efficient. This paper proposes a power supply method for these motors

using voltage source converter（VSC）

and carries it on modeling analysis. This method combines motor drive theory and research productions in DC transmission field. This method

which makes full use of the advantages of VSC

can start the HV motor stably and regulate the rotor speed in steady state

showing excellent stableness toward the disturbance of mechanic torque.The simulation test is done in PSCAD/EMTDC

and the results verify the validity of control method.