Analysis of plant performance with improved turbine flexibility: Test case on a parabolic trough configuration

Parabolic trough configurations account for 95% of the current installed concentrating solar power (CSP) capacity. Certainly this technology is considered as the most mature among other CSP types. However, regardless of its maturity, the pursuit of cost competitiveness with respect to fossil fuels and other renewables is still a dire need.

One way to maximize profitability and improve performance is flexibility through fast starts. In this regard, the steam turbine has been identified as a key limiting component to the start-up process. This work focuses on analyzing the influence of steam turbine start-up parameters on the overall annual performance of a CSP plant.

For this, a detailed parabolic trough power plant (PTPP) performance model was developed including a control strategy to account for turbine transient start-up constraints. The PTPP model was developed in accordance to the latest state-of-the-art of the technology. As such, the first part of the results consisted of validation studies of the model with respect to the actual power plant.

The results obtained in this regard showed that the model correlates to the rated performance of the power plant with maximum errors of 12% and of 14% to the dynamic operation of the power plant. The second part of this work consisted of using the validated model in a series of sensitivity studies concerning the variation of different turbine start-up parameters.

Results showed that improvements of up to 1.8% in the annual electricity production are possible with only 0.3% increase in fuel consumption.