• • The proposed decentralized transient damping control reduces angular frequency deviations in multi-parallel GFM-VSC systems by introducing supplementary mutual damping torque, directly mitigating power-frequency oscillations that otherwise trigger protection misoperations and cascading disconnections under grid power flow variations or rapid frequency fluctuations.
• • Root locus and Bode analyses identify inertia (J), damping (D), and line impedance (X) disparities as the primary oscillation drivers in dual-machine parallel systems, with the characteristic equation denominator as³ + bs² + cs + d where a = ω₀(K₁+K₂)J₁J₂, b = ω₀(K₁+K₂)(D₁J₂+D₂J₁), c = ω₀(K₁+K₂)D₁D₂ + K₁K₂(J₁+J₂), and d = K₁K₂(D₁+D₂), providing explicit parameter sensitivity for industrial tuning.
• • Lyapunov function analysis formally proves the control strategy's correctness, establishing a rigorous mathematical foundation for stability guarantees that is often absent in heuristic damping approaches, thereby reducing certification risk for grid-code compliance in renewable integration projects.
• • The impedance-based small-signal modeling approach overcomes the flexibility limitations and parameter-variation modeling difficulties of state-space methods for high-dimensional multi-machine systems, enabling scalable extension to multi-area decentralized control architectures without requiring full-system state information.