A lifetime-extending model-based predictive control for scheduling in concentrating solar power plants

Abstract

In this work, a model-based predictive control (MPC) approach with turbine protection is proposed to face the scheduling problem in concentrating solar power (CSP) plants with thermal energy storage (TES). This approach allows rescheduling the generation at regular periods taking advantage of the most recent energy prices and weather forecast, and of the current plant's state. Moreover, a more workable generation schedule for the next day is carried out as a result of that rescheduling. The turbine protection is based on the penalization for changes of the turbine output and the limitations of the number of daily turbine startups. These mechanisms aim to preserve the turbine lifetime. However, these constraints limit the flexibility of the electricity generation, therefore they could worsen the economic profits derived from sales of electricity. In conclusion, the proposed scheduling method provides a trade-off between the economic profits obtained from energy sales and the protection of the generation block. The proposed approach is applied, in a simulation context, to a 50 MW parabolic trough collector-based CSP with TES under the assumption of participation in the Spanish day-ahead energy market. A case study based on a one-month period is performed. The simulation results show, for several levels of turbine protection, the changes in generation profiles and the reduction of economic profits. It can also be observed that the reduction of economic profits is not significant. This result encourages the use of the turbine protection in the MPC approach.