Managing wind variability with pumped hydro storage and gas turbines

Load and wind energy profiles are totally uncorrelated, therein lies the problem of variable energy sources. Managing load with increasing wind penetration may call for operational ranges that conventional systems cannot readily access. Storage technologies could allow tolerating the unsteadiness of renewable sources with smaller fossil fuel plants capacity. In this paper, we analyze the operational requirements of about 1 GW nameplate wind farm to provide firm power to the grid when Pumped Hydro Storage (PHS) is compound with Gas Turbines (GTs) to smooth out wind variability. GTs and PHS operational constrains are included in the system model in order to correctly demonstrate how wind variability influences GTs and PHS performance. Taking into account different days of wind generation, integrated system behavior has been analyzed comparing different strategies: i) an in-house control strategy and ii) an optimal control strategy based on Dynamic Programming. The latter requires a careful approach to system modeling, aimed at reducing its complexity and the consequent computational load. The challenge is to implement only the smallest set of state and control variables needed to define the optimization problem. For the selected days of analysis, GTs and PHS output profile, fuel consumption and storage reservoir operation are presented.