Determining reasonable reactive power balance and switching strategy of the converter station is the basis for safe and stable operation of the HVDC transmission system.In this paper

the reactive power demand of AC/DC systems and the capacity determination of reactive power compensation equipment are described.The CDC6 DC quasi-steady state model is established in the PSS/E software

and its self-defined analysis function is used to simulate the reactive power switching strategy of the converter station with both inductive and capacitive reactive power compensation equipment from such two aspects as start-up and outage of the DC system.The start-up process follows the principle of firstswitching-out inductive reactive power equipment

followed by switching-in capacitive reactive power equipment

while the stop process follows the principle of firstswitching-out capacitive reactive power equipment

followed by switching-an inductive reactive power equipment.Finally

through the simulation example

the reactive power exchange between the converter station and the AC system is always within the limited range

which verifies the effectiveness of the method.