Study On The AC System Voltage Stability Effected By The HVDC Transmission Lines

Based on the control system of practical project, basic structure and principle of HVDCcontrol system are introduced in this paper. Modeling of power pole control, tap changercontrol and reactor power control are realized in PSCAD/EMTDC, and applied to CIGREHVDC standard benchmark. Simulation and calculation in different modes, such as steadystate, reduce voltage mode, ac and dc system faults etc., prove that the control system has anability to track the change of reference value. At ac and dc faults, control system will rapidlyactive and prevent faults, and force HVDC system come back to steady state. These prove thecorrectness of the simulation model.The effect of HVDC basic control modes and reactor power compensator on ac systemvoltage stability is discussed in this paper. Case studies on Hunan power grid show the effectsof HVDC on ac system voltage stability by PSASP.