Filtered Power-Based Frequency Coupling Suppression Control for Three-Phase Voltage-Source Converter Under Weak Grids

Frequency coupling suppression control (FCSC) emerges as a promising technique for three-phase voltage source converters (VSCs), streamlining system modeling and stability analysis. In this article, a filtered power-based FCSC (FP-FCSC) is presented for three-phase grid-tied VSCs. By constructing power filtering dynamics and incorporating reactive power regulation, a symmetrical dclink voltage controller (Sym-DVC) is developed, eliminating asymmetric dynamics associated with conventional DVCs. The frequency coupling is fully suppressed by the FP-FCSC, allowing the system to be accurately modeled as a simple single-input single-output (SISO) admittance. Admittance analysis demonstrates that the VSC using FP-FCSC can adapt to a wide range of short circuit ratios (SCRs) from stiff to ultra-weak grids. Simulation and experimental results confirm the stability enhancement of the FP-FCSC under weak grid conditions.