  This work explores the stability, behavior, variants, and a
controller-hardware-in-the-loop (C-HiL) verification of the recently proposed
grid-forming (GFM) hybrid angle control (HAC). We revisit the foundation of GFM
HAC, and highlight its behavioral properties in relation to the conventional
synchronous machine (SM). Next, we introduce the required complementary
controls to be combined with the HAC to realize a GFM behavior. The
characterization of the analytical operating point and nonlinear energy-based
stability analysis of a grid-connected converter under the HAC is presented.
Further, we consider various output filter configurations and derive an
approximation for the original control proposal. Moreover, we provide details
on the integration of GFM HAC into a complex converter control architecture and
introduce several variants of the standard HAC. Finally, the performance of GFM
HAC is verified by several test scenarios in a C-HiL setup to test its behavior
against real-world effect such as noise and delays.
