Short Circuit Calculation Aggregated Model of Power Grid with Grid-forming Converter

With the rapid development of new power grid, proportion of grid-forming converters will increase continually. The characteristics of its current output when outer short-circuit fault occurred are significantly different from those of traditional generators and grid-following converters, which resulting in deviations in short-circuit calculation considering new power grid, and the lack of relevant research will bring safety hazards to operation of power grid. This paper proposes an aggregation model considers grid-forming converters for grid calculation in short-circuit. A unified structure of aggregation short circuits model is proposed for power grid side, including numerous grid-forming converters and synchronous generators on power side. Three voltage sources of different sizes and attenuation speeds are used to represent the overall output of different synchronous generators on equivalent power side, and a variable impedance series connected constant voltage source is used to represent the overall output of a large number of grid-forming converters on equivalent power side. Further research focuses on the method of obtaining model parameters, leveraging detailed model simulation data to identify key parameters. The correctness and accuracy of aforementioned model are verified by short-circuit fault cases. During a fault, this aggregated model can represent the steady-state output of synchronous generators and grid-forming converters, fulfilling the requirements for power grid short-circuit calculations.