Optimal Power Flow
The optimal power flow (OPF) problem was defined in early 1960, in connection with the economic dispatch of power. The OPF problem can be described as the cost of minimization of real power generation in an interconnected system where real and reactive power, transformer taps, and phase-shift angles are controllable and a wide range of inequality constraints are imposed. In the OPF problem, the basic definitions of state variable, control vector, and input demand vector are retained. During a real power OPF subproblem, the reactive power control variables are kept constant, and in reactive power OPF, the real power controls are held constant at their previously set values. The solution method for the real and reactive power OPF subproblem can be different. OPF methods can be broadly classified into two optimization techniques: Linear programming–based methods and nonlinear programming–based methods.