Configuration Method of Grid-Forming Converters to Enhance Multiconverter System Stability

Abstract

The grid-forming control is a promising solution to address the instability issues induced by the voltage source inverters (VSIs) based on grid-following control under weak grid conditions. Nonetheless, the placement of VSIs based on grid-forming control (GFM-VSIs) and its capacity configuration method have not been theoretically revealed. To fill this gap, this article proposes the placement and capacity configuration strategies for GFM-VSIs based on participating factor (PF) and power flow analysis. By establishing the unified αβ-frame complex-valued node admittance model, the active node with the largest PF is chosen as the placement of GFM-VSIs. It is revealed that the system stability can be guaranteed even if the active power reference of GFM-VSIs is set to 0, thereby, the system stability can be improved by implementing the GFM-based static synchronous compensator (GFM-STATCOM). Furthermore, the optimal capacity of GFM-STATCOM under different control strategies is obtained by the power flow analysis within the stability constraints as the active node type is determined after accessing GFM-STATCOM. The proposed method is performed based on the three-machine test system, and the hardware-in-the-loop and physical experiments validate the theoretical analysis.