  During the last decades, significant advances have been made in the area of
power system stability and control. Nevertheless, when this analysis is carried
out by means of decentralized conditions in a general network, it has been
based on conservative assumptions such as the adoption of lossless networks. In
the current paper, we present a novel approach for decentralized stability
analysis and control of power grids through the transformation of both the
network and the bus dynamics into the system reference frame. In particular,
the aforementioned transformation allows us to formulate the network model as
an input-output system that is shown to be passive even if the network's lossy
nature is taken into account. We then introduce a broad class of bus dynamics
that are viewed as multivariable input/output systems compatible with the
network formulation, and appropriate passivity conditions are imposed on those
that guarantee stability of the power network. We discuss the opportunities and
advantages offered by this approach while explaining how this allows the
inclusion of advanced models for both generation and power flows. Our analysis
is verified through applications to the Two Area Kundur and the IEEE 68-bus
test systems with both primary frequency and voltage regulation mechanisms
included.
