Optimal scheduling in concentrating solar power plants oriented to low generation cycling

In a one-day ahead energy market, power plant owners have to provide a generation schedule in advance. A scheduling strategy for concentrating solar power plants with thermal energy storage is studied in this paper. The strategy is based on a mixed-integer linear programming model which approximates the plant operation. The main novelty of the method is the inclusion in the optimization model of a penalty term for generation variation (cycling) with different intensities depending on the power block situation, i.e., normal operation, startup or shutdown. This distinction increases the search space for schedules with reduced cycling and high energy sale profits. Cycling reduction leads to higher lifetimes of the power block elements, lower maintenance costs, and easier plant operability. A simulation case study, based on a 50 MW plant participating in the Spanish market, is included. The main conclusion of this study is that an important reduction of the generation cycling can be achieved without reducing profits. Other advantages of the method are also shown. By means of historical data, it is possible to estimate the lowest level of generation cycling which maintains profits. Moreover, lower generation deviations are obtained, facilitating the tasks of the electric system operator.