Research on the control strategy of VSC based HVDC system supplying passive network

In this paper, the transient mathematical model for the VSC-HVDC system in d-q synchronous reference frame is developed and its controllers are designed. A decoupled controller based on input-output variable feedback linearization is adopted in the rectifier, which uses a voltage vector corresponding to the system voltage and can control the active and reactive power separately. A constant AC voltage controller is used in the inverter, which is based on the steady state mathematical model of the converter. Simulation tests realized by PSCAD/EMTDC are performed to verify the effectiveness of the controllers under different operating conditions. The results show that the controllers can be applied in real systems with its simple, robust and high performance.