Power management in a hydrothermal system considering maintenance using Lagrangian relaxation and augmented Lagrangian methods

Abstract

The maintenance of power system equipment, specifically, the maintenance of generating units, is implicitly related to the reliability and economic operation of the power system. In this study, we established a new technique for the maintenance scheduling of a hydrothermal power system. Two coordination schemes are analysed. The first scheme can be described as a primal optimisation scheme because it maintains a feasible solution at every iteration. The second coordination scheme is defined as a dual optimisation scheme. Two variants of the second scheme are evaluated. These two variants correspond to the Lagrangian relaxation method and augmented relaxation method. The Lagrangian relaxation method uses space dilation to update the system incremental costs. The space dilation method considers the difference of two successive subgradients and aids the Lagrangian relaxation method in producing better convergence and minimum total cost, to date. By realising convergence, hydro maintenance is scheduled. The methodology of economic dispatch is presented and solved for hydrothermal maintenance scheduling. The proposed methodology is applied to modified version of the IEEE–RTS.