MODIFICATIONS TO NEWTON-RAPHSON LOAD FLOW FOR ILL-CONDITIONED POWER-SYSTEMS

This paper presents the effects of five different modifications to the standard Newton-Raphson (NR) method for the solution of load flows in ill-conditioned power systems. The proposed modifications to the NR method are: (1) NR method with decelerated convergence; (2) accelerated method for Newton's method at singular points (two-step algorithm and three-step algorithm); (3) Broyden's Jacobian-updating procedure for the NR method; (4) constant positive shift algorithm; (5) increasing positive shift algorithm. All the proposed modifications are based on the numerical technique to get a stable and feasible solution at singular points. The results of the proposed algorithms are presented for 11-, 13- and 43-bus ill-conditioned test systems and for a 25-bus test system while performing single-line contingency studies, for those cases where the NR algorithm fails to converge. © 1990.