  This paper explores the stability of nonsynchronous hybrid ac/dc power grids
under the grid-forming hybrid angle control strategy. We formulate dynamical
models for the ac grids and transmission lines, interlinking converters, and dc
generations and interconnections. Next, we establish the existence and
uniqueness of the closed-loop equilibria for the overall system. Subsequently,
we demonstrate global attractivity of the equilibria, local asymptotic
stability of the desired equilibrium point, and instability and
zero-Lebesgue-measure region of attraction for other equilibria. The theoretic
results are derived under mild, parametric, and unified stability/instability
conditions. Finally, relying on the intermediate results, we conclude the
almost global asymptotic stability of the hybrid ac/dc power grids with
interlinking converters that are equipped with hybrid angle control. Last, we
present several remarks on the practical and theoretical aspects of the problem
under investigation.
