Salehi Poor - Electrical and Computer Engineering Department University of Tehran, Tehran, Iran MATN International Company
Sanaye-Pasand - Electrical and Computer Engineering Department University of Tehran, Tehran, Iran MATN International Company
Kahrobaee - Electrical and Computer Engineering Department University of Tehran, Tehran, Iran MATN International Company

Power system protective relays protect electric systems against system faults and abnormalities. Due to increasing advantages of digital relay algorithms, nowadays modern power system protective relays are mostly microprocessor based. Digital based algorithms are used in these relays to implement different relaying schemes. In this paper a new combined method using combination of both differential equation and least square error algorithms is presented. The proposed method is explained analytically and modeled appropriately. Simulation results are performed using two powerful power system softwares, MATLAB and PSCAD, and some simulation results are presented as well. The efficiency and reliability of this method could be perceived by the obtained simulation results.

Distance Protection, Digital Relay, Differential Equation Algorithm, Least Error Squared