  Distributed averaging-based integral (DAI) controllers are becoming
increasingly popular in power system applications. The literature has thus far
primarily focused on disturbance rejection, steady-state optimality and
adaption to complex physical system models without considering uncertainties on
the cyber and communication layer nor their effect on robustness and
performance. In this paper, we derive sufficient delay-dependent conditions for
robust stability of a secondary-frequency-DAI-controlled power system with
respect to heterogeneous communication delays, link failures and packet losses.
Our analysis takes into account both constant as well as fast-varying delays,
and it is based on a common strictly decreasing Lyapunov-Krasovskii functional.
The conditions illustrate an inherent trade-off between robustness and
performance of DAI controllers. The effectiveness and tightness of our
stability certificates are illustrated via a numerical example based on
Kundur's four-machine-two-area test system.
