Mhj. Bollen, METHOD OF CRITICAL DISTANCES FOR STOCHASTIC ASSESSMENT OF VOLTAGE SAGS, IEE proceedings. Generation, transmission and distribution, 145(1), 1998, pp. 70-76
A fast method is presented for obtaining a first estimate of the expec
ted number of spurious trips due to voltage sags. The method is based
on an expression for the so called critical distance (the radius of th
e exposed area in which faults lead to equipment trips) in radial syst
ems. Extensions of the method for nonradial systems, and transfer of s
ags due to single-phase and phase-to-phase faults to lower voltages ar
e also presented.