Screening the sensitivity of Least Square Algorithm implemented in digital protective relays

Fault in the transmission line network initiates a number of unpredictable parameters. These parameters influence the Least Square Algorithm (LSA) implemented in digital protective relays for estimating fundamental frequency phasor. The sensitivity analysis method is applied for analyzing the degree of influential parameters since the investigated parameters are unpredictable. The Morris sensitivity analysis method is selected to screen input unpredictable parameters to identify the high influential parameters, also known as important parameters, on the LSA output. The result of this Morris method identifies three important parameters namely: the amplitude of the decaying DC offset and its time constant, as well as the fundamental frequency variation.