ABSTRACT
Power flow* (or load flow) is the solution for the normal balanced three-phase steady-state operating conditions of an electric power system. In general, power flow calculations are performed for power system planning and operational planning, and in connection with system operation and control. The data obtained from power flow studies are used for the studies of normal operating mode, contingency analysis, outage security assessment, and optimal dispatching and stability. Note that, normally it is understood that a “contingency” is the loss of a major transmission element or a large generating unit. When a system is able to withstand any single major contingency, it is now called “N-1 secure” according to the new terminology suggested by National Electric Reliability Council (NERC). A “double contingency” is the loss of two transmission lines, or two generators, or a line and a generator [1]. In this case, it can be said that such system is “N-2 secure.”
