Unit commitment in fully renewable, hydro-wind energy systems

This paper presents the solutions to the Unit Commitment problem for fully renewable energy systems. Today in Spain there is a small and isolated system of completely renewable electrical energy sources. Specifically we are talking about the island of El Hierro in the Canarian archipelago. There is only a wind farm and a hydro pure-pump station. As well as some small thermal units, which are used only in emergency. We apply the Unit Commitment tool for operation planning in this system. There are several novelties in the Unit Commitment problem both in the model and the methodological solution. In the part of the model, what is original are the specific and unusual characteristics of the hydro pure-pump station. In the part of the methodology, we need to introduce artificial costs for coordination between the wind farm and the pure-pump station. We used mixed-integer linear programming (MILP) methodology to find the optimal scheduling of a multiunit pump-storage hydro power station. In this paper we explain in detail the model and methodologies used and we present the results obtained with the software tool developed for this purpose.