Evaluation of linear stability operating boundary for voltage source converter under grid faults

Voltage source converters have been used in high voltage direction current systems, which provides various advantages such as reduction in installation cost and space, easy connectivity with renewable energy sources and enhanced power quality. One of the most important issues is how to ride through the grid faults to ensure the stability operation of voltage source converters. In practice, however, there are practical considerations of physical restrictions such as the linear stability operating boundary, beyond which the current would be distorted, even the system would be instable. In this paper, a quantitative analysis and evaluation of the linear stability operating boundary is presented for operating the voltage source converter under grid faults. The proposed method indicates that the operating boundary mainly depends on the circuit parameters and control strategies. Simulation results have provided to verify the proposed quantitative analysis and control strategy. It is expected to provide a useful guidance for designing and controlling the voltage source converter within the linear stability operating boundary, which enhances the system and increased the reliability of the system.