Inclusion of Ancillary Services in a Cost-Based Centralized Economic Dispatch Solution for Hydrothermal Systems

In this paper a centralized economic dispatch is developed, where some services are included, associated to frequency control and generation outages. The study can consider thermal machines but hydro turbines as well, both of the run-of-river or regulation type, in whose case the objective function is the present and future thermal cost in the context of the stochastic dual dynamic programming (SDDP), simplified for academic purposes (Pereira, 2002) (Juan, 2005). In this study the immediate plus future thermal cost is minimized, taking into account the primary reserves requirement in each unit (speed governor primary action), plus the AGC reserve, besides the (tertiary) reserves, associated to the outage of any turbine (n-1 criterion). The problem proposed was resolved using a linear programming commercial package. For the sake of clarifying the results, some didactical cases are solved, where comparisons are discussed between the traditional energy-only dispatch and the model herein proposed. This paper extends in a very simple manner the results of a traditional cost-based centralized economic dispatch, of the hydrothermal case, to include the AGC restrictions and spinning reserves requirements.