Modelling an automatic controller for parabolic trough solar fields under realistic weather conditions

Noureldin, Kareem; Hirsch, Tobias; Kuhn, Pascal Moritz; Nouri, Bijan; Yasser, Zeyad; Pitz‐Paal, Robert

doi:10.1063/1.5067211

Cited by 10 publications

(7 citation statements)

References 15 publications

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“…It is important to note that these results are obtained assuming perfectly accurate prediction of the DNI maps. Studies in [20,44] show that the controllers are robust to systematic errors in irradiation measurements of up to 10% without significant loss in revenues. However, stochastic errors are expected to have an impact on the benefit of the system.…”

Section: Discussionmentioning

confidence: 99%

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Evaluating the Potential Benefit of Using Nowcasting Systems to Improve the Yield of Parabolic Trough Power Plants with Single-Phase HTF

Noureldin

Hirsch

Nouri³

et al. 2021

Energies

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Solar field developers include innovative solutions to optimize the energy production of their plants. Simulation tools play a significant role in the design and testing phases as they provide estimations of this yield in different conditions. Transient processes, like passing clouds and solar field start-up, are specifically challenging to optimize and estimate using such simulation tools. Solar fields are subject to high degree of both temporal and spatial variability in the energy input and a detailed estimation can be achieved by simulating subsystems within acceptable time and computational power. Hence, such simulation tools cannot be utilized for tests under realistic operation conditions. The Virtual Solar Field is a computationally efficient simulation tool that allows a detailed transient simulation of parabolic trough solar fields based on single-phase fluids. Using this tool, developers could reproduce a transient test case with exactly the same disturbances to provide fair comparisons between different configurations. In this paper, an evaluation process based on numerical simulations using the Virtual Solar Field is presented. The economic benefit of novel innovative control concepts can be assessed according to the presented scheme. This is demonstrated by evaluating the potential benefit of availability of spatial DNI nowcasts on the control of parabolic trough solar fields. Results show that nowcasting can increase the economic revenue of commercial power plants by up to 2.5% per day. This proves the feasibility of installing such systems.

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Section: Discussionmentioning

confidence: 99%

“…The goal is to develop controllers that are robust to various realistic irradiation conditions. This has been introduced in [44] and is briefly discussed in this section.…”

Section: Reference Controllermentioning

confidence: 99%

Evaluating the Potential Benefit of Using Nowcasting Systems to Improve the Yield of Parabolic Trough Power Plants with Single-Phase HTF

Noureldin

Hirsch

Nouri³

et al. 2021

Energies

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“…To the best of our knowledge, the presented procedure is the first to provide real-time uncertainties for ASI-based nowcasting systems. A nowcasting system with real-time uncertainties, which considers the current conditions, could be used to optimize solar power plant [1] and electrical grid [2] operations. Operators could assess whether or not the current nowcasting results are sufficiently accurate for their processes at any given time.…”

Section: Discussionmentioning

confidence: 99%

“…Highly variable solar irradiance conditions pose a control challenge for solar thermal power plants and electrical grids of countries with a high solar penetration. All sky imager (ASI)-based nowcasting systems of solar irradiance, with their high temporal and spatial resolution, can be useful to tackle this control challenge [1,2]. In past years, various ASI-based nowcasting systems were developed.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Uncertainty Specification of All Sky Imager Derived Irradiance Nowcasts

Nouri¹,

Wilbert²,

Kuhn³

et al. 2019

Remote Sensing

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The incoming downward shortwave solar irradiance is harvested to an increasing extent by solar power plants. However, the variable nature of this energy source poses an operational challenge for solar power plants and electrical grids. Intra hour solar irradiance nowcasts with a high temporal and spatial resolution could be used to tackle this challenge. All sky imager (ASI) based nowcasting systems fulfill the requirements in terms of temporal and spatial resolution. However, ASI nowcasts can only be used if the required accuracies for applications in solar power plants and electrical grids are fulfilled. Scalar error metrics, such as mean absolute deviation, root mean square deviation, and skill score are commonly used to estimate the accuracy of nowcasting systems. However, these overall error metrics represented by a single number per metric are neither suitable to determine the real time accuracy of a nowcasting system in the actual weather situation, nor suitable to describe any spatially resolved nowcast accuracy. The performance of ASI-based nowcasting systems is strongly related to the prevailing weather conditions. Depending on weather conditions, large discrepancies between the overall and current system uncertainties are conceivable. Furthermore, the nowcast accuracy varies strongly within the irradiance map as higher errors may occur at transient zones close to cloud shadow edges. In this paper, we present a novel approach for the spatially resolved real-time uncertainty specification of ASI-based nowcasting systems. The current irradiance conditions are classified in one of eight distinct temporal direct normal irradiance (DNI) variability classes. For each class and lead-time, an upper and lower uncertainty value is derived from historical data, which describes a coverage probability of 68.3%. This database of uncertainty values is based on deviations of the irradiance maps, compared to three reference pyrheliometers in Tabernas, Andalucia over two years (2016 and 2017). Increased uncertainties due to transient effects are considered by detecting transient zones close to cloud shadow edges within the DNI map. The width of the transient zones is estimated by the current average cloud height, cloud speed, lead-time, and Sun position. The final spatially resolved uncertainties are validated with three reference pyrheliometers, using a data set consisting of the entire year 2018. Furthermore, we developed a procedure based on the DNI temporal variability classes to estimate the expected average uncertainties of the nowcasting system at any geographical location. The novel method can also be applied for global tilted or horizontal irradiance and is assumed to improve the applicability of the ASI nowcasts.

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“…In addition, the model also offers a high degree of flexibility in setting the geometry of the pipes, the number of loops and subfields, the type and optical efficiency of collectors and receivers, and the insulation material in the header and runner pipes. All governing equations and implementation, as well as validation cases against real plant data provided by the commercial power plant Andasol-3 in southern Spain, are described in [4,8,9,10].…”

Section: Used Toolsmentioning

confidence: 99%

Development of training simulator software for molten salt parabolic trough test platform

Hoegemann¹,

Noureldin²,

Bamberger³

et al. 2019

SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems

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Operators of a solar-thermal power plant bear a high responsibility as they are in charge of the plant integrity, the safety of staff and optimal performance. At the same time, the complexity of such plants is very high. Thus, skilled operators are needed to understand what they do and, especially, how to react in non-standard plant conditions. Training the operators for these situations is very important for trouble-free operation. Those items become particularly crucial for testing of parabolic trough plants with molten salt as working fluid, as they inherit the danger of HTF freezing at normal ambient conditions. DLR developed a training simulation software as a platform to train the operators in dealing with various scenarios and test automation concepts for plant control for the test facility in the HPS2 project. The simulator software features a detailed model for transient simulation of the solar field based on DLR's Virtual Solar Field (VSF), a simulator management system and a human-machine interface (HMI). VSF communicates via a standard TCP/IP interface with the simulator management. The plant model features detailed modelling of the hydraulic network and storage system, alarm functions and control logics derived from the functionality of the test plant. The HMI is designed according to the real process control software. Simulations with measured weather data validated the correct behavior of the physical models. To understand the behavior of the plant, the plant model can be completely manually operated. Various weather scenarios can be loaded to show difficulties of transient situations, like a sudden direct normal irradiation (DNI) rise or drop. This enables the trainer to show real operation scenarios of the molten salt plant during the training course without endangering the test facility.

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Modelling an automatic controller for parabolic trough solar fields under realistic weather conditions

Cited by 10 publications

References 15 publications

Evaluating the Potential Benefit of Using Nowcasting Systems to Improve the Yield of Parabolic Trough Power Plants with Single-Phase HTF

Evaluating the Potential Benefit of Using Nowcasting Systems to Improve the Yield of Parabolic Trough Power Plants with Single-Phase HTF

Real-Time Uncertainty Specification of All Sky Imager Derived Irradiance Nowcasts

Development of training simulator software for molten salt parabolic trough test platform

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