2026/06/02 by Shan Jiang, Ye Zhu, Georgios Konstantinou
Engineering · Computer Science · #Microgrid Control and Optimization #Nonlinear Dynamics and Pattern Formation #Control and Stability of Dynamical Systems
paper · doi:10.1109/tpel.2026.3699436
Power synchronization control (PSC) plays a critical role in shaping the frequency response of grid-forming (GFM) converters. However, existing PSC implementations are developed with diverse control structures, which hinders a unified interpretation of their dynamic characteristics and associated design trade-offs. This paper demonstrates that common PSC methods, i.e., constant power, droop, and virtual synchronous generator (VSG) control, can be unified by a first-order transfer function (termed the complex droop factor) with four coefficients and up to three degrees of freedom. This unified representation reveals how PSC inherently governs both primary frequency response (PFR) and virtual inertial response (VIR). In particular, constant power control provides only VIR, droop control provides only PFR, and VSG control provides both. However, VSG control is prone to synchronization instability as it is essentially a proportional–derivative controller. To overcome these limitations, a fractional VSG control is proposed to bridge the gap between droop and VSG control. By independently regulating three degrees of freedom, the proposed method enables flexible shaping of droop, inertia and damping characteristics, allowing simultaneous consideration of power overshoot, frequency deviation, and response speed during disturbances. Furthermore, a three-step tuning guideline is developed to facilitate practical parameter design while maintaining consistency with classical VSG control principles, followed by an adaptive control law that yields adaptive virtual inertia. The proposed method is validated through experimental studies under various network transients and operating conditions with different system strengths.