A Cascaded Hybrid Synchronization Control for Grid-Connected Inverters

This letter revisits vector voltage control (VVC) and finds that by introducing a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$P-E_{q}$</tex-math></inline-formula> droop into the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$q$</tex-math></inline-formula>-axis voltage reference, a conventional phase-locked loop (PLL) can effectively substitute the power synchronization control for replicating the power-frequency (angle) dynamics of grid-forming (GFM) inverters. Consequently, a simple GFM control strategy that retains the traditional PLL and VVC is proposed. In contrast to recently reported PLL-based GFM approaches, the method eliminates the need for virtual admittance control and offers higher stability robustness across a wide range of grid short-circuit ratios (SCRs).