Review of the Application of Short Circuit Ratio in the Stability of Power Electronic Systems Connected to Grid

The foundations of the power system are changing. Increasingly, power electronic converters are being integrated into the power grid to connect renewable energy and high-voltage direct current transmission systems. In renewable energy power system as the main source, power system strength evaluation is very important to ensure the safe operation of whole system. There is a positive correlation between short circuit ratio and system strength, and whole system with low short circuit ratio is usually a weak power network, which is prone to a variety of instability problems such as wide frequency oscillation. In this paper, the construction methods of different short circuit ratio indexes are analyzed from the field of multi-frequency small-signal stability of power electronic systems connected grid. The application status of short circuit ratio in evaluating the strength of grid-connected power electronic systems is reviewed.