  Inverter based renewable generation (RG), especially at the distribution
level, is supposed to trip offline during an islanding situation. However,
islanding detection is done by comparing the voltage and frequency measurements
at the point of common coupling (PCC), with limits defined in the form of
ride-through curves. Current practice is to use the same limit throughout the
year independent of the operating conditions. This could result in the tripping
of RG at times when the system is already weak, thereby posing a threat to
voltage security by heavily limiting the load margin (LM). Conversely, heavily
relaxing these limits would result in scenarios where the generation does not
go offline even during an islanding situation. The proposed methodology focuses
on optimizing low-voltage ride-through (LVRT) settings at selective RGs as a
preventive control for maintaining a desired steady-state voltage stability
margin while not sacrificing dependability during islanding. The proposed
process is a multi-stage approach, in which at each stage, a subset of
estimated poor-quality solutions is screened out based on various
sensitivities. A full continuation power flow (CPFLOW) is only run at the
beginning and in the last stage on a handful of remaining candidate solutions,
thereby cutting down heavily on the computation time. The effectiveness of the
approach is demonstrated on the IEEE 9-bus system.
