Voltage Feedforward Damping Control Based on Duffing–Hopf Oscillator for Parallel Grid-Forming Inverters

Oscillator-based grid-forming (GFM) control, such as dispatchable virtual oscillator and Andronov-Hopf oscillator control, offers a rigorous analytical framework with enhanced synchronization, lower harmonic, and faster dynamic response but lacks effective inertia support. Insufficient inertia will impair the stability and reliability of the power system, especially in the system with parallel inverters. To fundamentally solve the issue of insufficient inertia in traditional oscillator-based GFM control, a Duffing-Hopf oscillator control is proposed. The second-order Duffing-Hopf oscillator control ensures inertia and damping properties within the active power control loop. Furthermore, a q-axis component of the point of common coupling (PCC) voltage feedforward damping control is proposed to suppress active power oscillation during load fluctuations in the parallel system. The feedforward component provides extra damping power by indirectly incorporating the grid frequency into the active power control loop without relying on a phase-locked loop (PLL). The experimental results show that compared with the traditional oscillator-based GFM control, the Duffing-Hopf oscillator control provides enough inertia and damping ratio to alleviate the rate of change of frequency, and the q-axis component of PCC voltage feedforward control can effectively suppress the power oscillations caused by inconsistent control parameters.