Influence of synchronous condenser transient parameters on voltage stability of HVDC

Large-capacity synchronous condenser can provide a powerful dynamic reactive power for the HVDC transmission system. The dynamic characteristic of reactive power is mainly related to the parameters of synchronous condenser. Therefore, it is very important to study the influence of transient parameters on the voltage stability of AC-DC system. In this paper, the model of HVDC system with the synchronous condenser connected is built. Taking the voltage sag of sending-end system as an example, firstly the paper presents the influences of transient and sub-transient reactance (x′d, x″d) and time constant (F′d0, T″d0) on reactive power characteristic of synchronous condenser and the voltage stability of HVDC. Then the reactive power response speed of synchronous condenser and the recovery time of system voltage are compared and analyzed under the different transient and sub-transient parameters. In addition, the results show that the recovery time of system voltage increases by 0.36s as the transient reactance increasing to 1.3 times actual value, and the recovery time of system voltage increases by 0.43s as the transient time constant changes to 1.3 times actual value. Finally the sub-transient parameters have almost no effect on the system voltage and the results provide an important theoretical basis for the operation of synchronous condenser connected to HVDC.