Analyzing Method for Transient Active Power Difference Between Parallel Grid-Connected Gridforming Converter

For a power station consisting of parallel gridforming (GFM) converters that are connected to a point of common coupling (PCC), it is necessary to match the transient output active power of the GFM converters to reduce circulating current losses. Therefore, it is essential to establish a method to evaluate transient active power difference (TAPD) between parallel grid-connected GFM converters, which might be affected by the mismatch of line impedance (the impedance between the converter output terminals and the PCC) or steady-state operating points. In this paper, we propose an index to quantify the severity of TAPD based on the difference in transient synchronizing power coefficients and verify the coincidence between the proposed index and the TAPD under different scenarios. The results show that the proposed evaluation method effectively analyzes the potential TAPD in a GFM power station, and solutions to mitigate TAPD are proposed.