  Reliable and secure operation of power systems becomes increasingly
challenging as the share of volatile generation rises, leading to largely
changing dynamics. Typically, the architecture and structure of controllers in
power systems, such as voltage controllers of power generators, are fixed
during the design and buildup of the network. As replacing existing controllers
is often undesired and challenging, setpoint adjustments, as well as tuning of
the controller parameters, are possibilities to counteract large disturbances
and changing dynamics. We present an approach for fast and computationally
efficient adaptation of parameters of structured controllers based on
H-infinity optimization, also referred to as structured H-infinity controller
synthesis, tailored towards power systems. Conditions are established that
guarantee that the approach leads to stability.The results are verified in a
testbed microgrid consisting of six inverters and a load bank, as well as
simulation studies. The proposed method improves the system robustness, as well
as the time-response to step disturbances and allows structured controller
tuning even for large networks.
