Linear-programming-based method for optimum schedule of reactive power sources in power systems

This paper proposes a linear-programming optimization-based method for reactive power scheduling using generator terminal voltages and reactive outputs, transformer tap-settings and switchable reactive power sources as control variables. Dual linear programming is applied to minimize a composite objective function consisting of the cost of the adjusted control variables and the system transmission losses. The proposed composite objective function is more economical than that of the minimum total adjustment of the control variables and calls for less adjustments of var sources to meet the desired voltage limits. The proposed method is applicable to practical transmission and distribution networks, 500 kV to 11 kV, of small and large sizes.