A Transient Stability Enhanced Andronov-Hopf Oscillator : Analysis and Design

Grid forming control has been widely applied in renewable energy and energy storage systems due to its ability to generate self-synchronous voltage and exhibit superior small-signal stability under weak grid. Andronov-Hopf oscillator (AHO) control is an emerging grid-forming control, while its transient behaviors under grid voltage faults have not been fully explored. Unlike the fixed droop coefficients of droop control, the transient stability of AHO-based converter under grid faults is compromised by the equivalent nonlinear droop coefficients of AHO control. In this paper, a transient stability enhanced Andronov-Hopf oscillator (EAHO) control is proposed. By reconstructing the dynamic equations of traditional AHO control, the monotonically decreasing nonlinear droop coefficients of traditional AHO control are reshaped into monotonically increasing as the voltage magnitude increases. The transient stability features of the droop, AHO, and EAHO control during grid voltage faults are compared and summarized. The theoretical analysis and simulation results show that the transient stability of EAHO control is significantly improved than AHO control.