IEEE 1547-2018 significantly expanded requirements for distributed energy resources (DER). Passive anti-islanding alone no longer meets the bar — modern inverters must provide voltage/frequency ride-through and volt-VAR/volt-Watt support.
Islanding Detection Categories
- Passive: under/over voltage, under/over frequency, ROCOF
- Active: Sandia frequency shift, impedance measurement
- Communication-based: transfer trip, PLCC
Category II & III Ride-Through
Cat III (utility-scale) inverters must remain connected during voltage sags to 0.5 pu for 1 second, and during frequency excursions of 57.0-61.2 Hz for 299 s.