FAST ALGORITHM FOR CONTINGENCY EVALUATION IN POWER SYSTEM PLANNING AND OPERATION.

This paper describes a very fast, although approximate, algorithm for contingency studies in power system planning and operation. It requires one iteration starting from the power flow data of the base system. The proposed algorithm is based on decoupled power flow methods with variables in rectangular form. Power flow methods with variables expressed in rectangular form have shown some advantages, concerning convergence and speed of solution, over other existing methods in polar form. The algorithm uses the concept of simulating a line or transfomer outage by injecting power (both active and reactive) equal to that flowing into the outaged element at appropriate buses. It exploits matrix sparsity and uses few elements of the sensitivity matrix corresponding to the terminal buses of the outaged elements. The proposed algorithm determines post contingent network voltages (magnitude and angle) and power flows (active and reactive), should the contingency occur, very fast and in a most economical way.