Single-phase SOGI-PLLs for fast and accurate frequency ramp tracking

This letter explores accurate frequency and phase tracking for single-phase power grid applications. While the conventional type-2 phase-locked loop (PLL) offers fast dynamic response, it exhibits steady-state tracking error in the presence of frequency ramp caused by rapid changes in power generation and/or consumption. The higher-order type-3 PLL can address this, albeit with slower dynamics. Our contribution introduces quasi-type-2 PLLs, which excel at accurate phase tracking during frequency ramps, outperforming conventional type-2 PLLs and maintaining a faster dynamic response than type-3 counterparts. This enhancement relies on linear phase error forward compensation. Experimental validation across four test scenarios underscores the superiority of our proposed PLLs over traditional methods. Achieving zero tracking error during frequency ramps, our methods prove useful for controlling grid-connected power converters.