The control system design of grid-forming (GFM) converters requires prior knowledge of grid parameters such as grid impedance, grid equivalent electromagnetic force (EMF), and short-circuit ratio (SCR), which are normally time-variant and preferably estimated in real time. However, existing estimation methods are either unable to estimate multiple parameters simultaneously or involve complex calculation algorithms for nonintrusive estimations. To address this issue, this study proposes a real-time grid parameter estimation method for GFM converters. Without introducing disturbances into the system, multiple parameters can be simultaneously estimated during the transient state with a simple algorithm, while the effects of the virtual impedance of the GFM converter and the output filter are both considered. In addition, a parameter estimation-based adaptive synchronous power control (SPC) is proposed, which exhibits improved dynamic performance and enhanced robustness of the GFM converter under various grid conditions. The validity of the proposed method is verified by simulation and hardware-in-loop-simulation (HILS) results. [ABSTRACT FROM AUTHOR]