Transient Stability Analysis of Grid-Connected Converter under Remote Voltage Sag with Reactive Power Compensation Devices

The renewable energy system and power grid are usually connected through a grid-connected converter (GCC), whose transient performance is significantly essential during the grid faults. In actual operation, reactive power compensation devices are often connected to the common coupling point (PCC) to improve voltage stability. However, there is a lack of analysis when considering the influence of reactive power compensation devices on GCC’s transient stability. In this paper, the mathematical model of GCC when static var generator (SVG) is adopted for reactive power compensation is established. The AC-side equivalent circuit of the system, the state equation and the output power characteristic curve of GCC are obtained. On this basis, the equal-area criterion (EAC) for GCC is proposed to analyze its transient stability. Finally, the simulation of remote voltage sag under different short circuit ratio (SCR) is carried out to verify the correctness of the theoretical analysis.