###### Abstract  
The present work focuses on the development of a detailed dynamic model of an existing parabolic trough solar power plant (PTSPP) in Spain. This work is the first attempt to analyse the dynamic interaction of all parts, including solar field (SF), thermal storage system (TSS) and power block (PB), and describes the heat transfer fluid (HTF) and steam/water paths in detail. Advanced control circuits, including drum level, economiser water bypass, attenperator and steam bypass controllers, are also included. The parabolic trough power plant is modelled using Advanced Process Simulation Software (APROS). An accurate description of control structures and operation strategy is necessary in order to achieve a reasonable dynamic response. This model would help to identify the best operation strategy due to DNI (direct normal irradiation) variations during the daytime. The operation strategy used in this model has also been shown to be effective compared to decisions made by operators on cloudy periods by improving power plant performance and increasing operating hours. parabolic trough power plant; dynamic simulation; APROS; operation strategy; comparative study +
Footnote †: journal: Applied Sciences  
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A Comparison Study on the Improved Operation Strategy for a Parabolic trough Solar Power Plant in Spain  
[PERSON], [PERSON], [PERSON], [PERSON]. There are several commercial programs for power plant modelling used in solar thermal applications, namely TRNSYS, EcoSimPro, EBSILON Professional, IPSEpro, GATE-CYCLE, MATHEMATICA, DYMOLA and APROS [5; 7; 8]. In general, there are few researchers who have studied the dynamic simulation of parabolic trough power plants. In particular, most researchers have not addressed optimising the performance of these plants. For this reason, we will review the most important works that have dealt with parabolic trough power plants. [PERSON] et al. [9] developed a control predictive model to optimise thermal power on a large scale for solar parabolic trough plants. The power plant is divided into several subsystems. They are controlled by their loop control valves to improve the performance and reduce the computation time of control inputs. The operation strategy is evaluated by decentralised and centralised control predictive models in two simulated solar fields. [PERSON] and [PERSON] [10] optimised the solar field of a parabolic trough power plant using a centralised predictive model. The best operating strategy of the power plant is implemented by regulating a group of control valves installed at the beginning of each collector loop. This leads to improving the response obtained from classic control processes for this type of power plant. The implemented control model is applied for a small parabolic trough power plant. The simulated control models are evaluated based on the data of the collector of solar fields for ACUREX (Almeria, Spain) over two hours. The results of the suggested algorithm showed a good agreement with the centralised algorithm. [PERSON] et al. [11] performed a control predictive model for analysis of deconcentrating control for different collector loops. The HTF temperature is controlled by deconcentrating two and four collector loops in different cases. The results showed better performance when four complexes were not concentrated in addition to maintaining the deconcentrating procedures in the areas with high control power. [PERSON] et al. [12] developed dynamic models of a 50 MW parabolic trough power plant using Modelica language to assess the behaviour of stored energy and its mechanism of action with the solar field (SF) and the power block (PB). The steady-state results were compared with the original plant data. Regarding dynamic behaviour, the response of the PB showed good behaviour because the chosen days were clear. [PERSON] et al. [13] implemented a thermal model to evaluate the reserve part required for 100 MW\({}_{\text{el}}\) hybrid-fossil-solar PTSPP.