Application of a line constant impedance magnitude method for the investigation of the accuracy of a mathematical voltage index

A developed voltage sag index based on power flow equations is presented and investigated in this paper. The index supervises the power quality of a system, through predicting voltage sags caused by an increase in reactive demand due to induction motor starting. The accuracy of the index is investigated for a range of distribution X/R ratio values and various motor loading levels through simulation. The constant impedance magnitude technique is introduced, and applied in order to validate the mathematical index. Results demonstrate the effectiveness and applicability of the proposed index under the investigated load and line impedance variation conditions. (4 pages)