This paper treats a nonlinear dynamical system with both continuous-time an
d discrete-time variables as a differential-difference-algebraic equation (
DDA) or a hybrid dynamical system, presents a fundamental analyzing method
of such a DDA system for local sampling, asymptotical stability, singular p
erturbations and bifurcations, and further shows that there exist four type
s of generic codimension-one bifurcations at the equilibria in contrast to
two types in continuous-time dynamical systems and three types in discrete-
time dynamical systems. Finally the theoretical results are applied to digi
tal control of power systems as an example. Numerical simulations demonstra
te that our results are useful.