THIS PAPER DEALS WITH OBTAINING SUITABLE DC MODEL OF PHASE SHIFTERS, AND A BRIEF DISCUSSION ABOUT THEIR EFFECTS ON POWER SYSTEM OPERATION AND SECURITY. TO DETERMINE THE OPTIMAL PHASE SHIFTERS’ ANGLES MAXIMIZING THE NETWORK SECURITY, A SET OF LINEAR EQUATIONS IS OBTAINED IN THE FORM OF A MATRIX EQUATION, AS A RESULT OF USING A CONTINUOUS AND DERIVABLE INDEX FOR REFLECTING THE NETWORK SECURITY. THIS FAST OPTIMIZATION PROCEDURE, MAKES IT SUITABLE TO USE IN COMBINATORIAL ALGORITHMS, TO SOLVE PHASE SHIFTER ALLOCATION OPTIMIZATION PROBLEMS. THIS PAPER ALSO PRESENTS A NEW ALGORITHM FOR PHASE SHIFTER ALLOCATION IN POWER SYSTEMS, BY MIXING THE ABOVE PROCEDURE WITH GENETIC ALGORITHM. IEEE 14 BUS AND 118 BUS SYSTEMS ARE USED AS TEST CASES.