Combining loss and cost objectives in daily hydro-thermal economic scheduling

A formulation of optimal hydro-thermal power flow in electric power systems combining the minimum loss objective with the more conventional minimum feel cost objective is considered. The implementation is based on a Newton´s iterative procedure, with special initial guess and sparsity-based matrix manipulations to obtain improved convergence properties. The strategies are developed using three standard test systems. The authors discuss the question of assigning an equivalent cost to the loss objective component and compare results obtained using two proposed mechanisms. The first is based on results of conventional dispatch using Kron´s loss formula and the second uses the bus incremental costs involved in the optimal power flow solution. The effects of varying the relative weights assigned to each objective component on pertinent system variables such as active and reactive power generations as well as voltages are explored