  This paper presents an extensive framework focused on the control design,
along with stability and performance analysis, of Grid-Following Inverters
(GFL). It aims to ensure their effective operation under both stiff and weak
grid conditions. The proposed framework leverages the coupled algebraic
structure of the transmission line dynamics in the $dq$ frame to express and
then mitigate the effect of coupled dynamics on the GFL inverter's stability
and performance. Additionally, we simplify the coupled multi-input,
multi-output (MIMO) closed-loop system of the GFL into two separate
single-input, single-output (2-SISO) closed-loops for easier analysis and
control design. We present the stability, robust stability, and performance of
the original GFL MIMO closed-loop system through our proposed 2-SISO
closed-loop framework. This approach simplifies both the control design and its
analysis. Our framework effectively achieves grid synchronization and active
damping of filter resonance via feedback control. This eliminates the need for
separate phase-locked loop (PLL) and virtual impedance subsystems. We also
utilize the Bode sensitivity integral to define the limits of GFL closed-loop
stability margin and performance. These fundamental limits reveal the necessary
trade-offs between various performance goals, including reference tracking,
closed-loop bandwidth, robust synchronization, and the ability to withstand
grid disturbances. Finally, we demonstrate the merits of our proposed framework
through detailed simulations and experiments. These showcase its effectiveness
in handling challenging scenarios, such as asymmetric grid faults, low voltage
operation, and the balance between harmonic rejection and resonance
suppression.
