Study on AC Voltage Range of VSC-HVDC Systems in Steady-State Operation Conditions Based on a Point-by-Point Scanning Method

VSC-HVDC technologies are widely introduced into long-distance and large-scale power transmission systems in various countries around the world owing to its advantages, such as high flexibility and easy controllability. Due to the primacy of system stabilization, the determination of steady-state range of the VSC is essential for the operation of a VSC-HVDC system. This paper presents a point-by-point scanning method of calculating the voltage operating range under different active power, which takes into consideration the filter in AC system. On the basis of a one-terminal VSC-HVDC system, the impacts of different factors on the steady-state operation of VSC are analyzed and the corresponding constraints are written. To verify the accuracy and effectiveness of the proposed method, detailed electromagnetic simulations using PSCAD are conducted. The simulation results indicate that the analysis based on the proposed model is accurated, and the range of AC voltage is mainly limited by modulation ratio and transformer capacity, and decreases with the increase of active power.