Dynamic modelling of concentrated solar field for thermal energy storage integration

Concentrated solar power (CSP) can offer solutions to overcome many problems related to fossil fuel consumption and fast growing share of intermittent solar and wind generation. As intermittent renewable energy generation is increasing, energy storages have an important role in balancing the increasing gap between power generation and consumption. Thermal energy storage (TES) integration into solar fields is a proven technology. The importance of CSP field dynamics for energy storage operations is evident. Dynamic performance simulation of CSP field under varying conditions is an important tool to plan, predict and finally optimize thermal energy storage operations. CSP technologies considered in this paper, parabolic trough (PT) and linear Fresnel reflector (LFR) are both proven line-focusing CSP technologies, PT having better sun tracking ability but more complex design. Solar irradiation is a time and location dependent variable energy source, and thus dynamic modelling is needed to investigate plant behavior for storage operations. In this paper solar field models based on both PT and LFR technologies are configured in Apros simulation software. Apros has the capability to dynamically simulate solar field behavior with varying collector dimensions and field layouts under intermittent irradiation conditions. In this paper design and performance calculation of PT and LFR collector modules configured in Apros and two entire solar field configurations, including collector modules, solar radiation and solar irradiation processor modules, and field control, are presented. Both solar fields represent recirculation boiler and apply direct steam generation (DSG). Solar modules are used to define solar position and beam and diffusive radiation on the tilted surface according to time and location and taking into account sun tracking on a single-axis. Dynamic performance of both models based on two different CSP technologies was investigated under different conditions. Thermal performance of two models was compared to each other at different dates at the selected location by simulating full 24 hours at each case. Similar control strategies were applied to both fields. Dynamic model development of different solar fields is essential in order to augment the utilization of CSP technologies and to evaluate suitability of thermal energy storage integration into solar field in certain location, and to further evaluate integration feasibility. The results show an obvious difference in performance between technologies at different operational conditions. The performance investigation reveals the dynamic charge and discharge needs for storage operations in varying conditions.