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Abstract.A new optimization tool for micro-heliostat (MH) geometry and field layout is presented. The method intends simultaneous performance improvement and cost reduction through iteration of heliostat geometry and field layout parameters. This tool was developed primarily for the optimization of a novel micro-heliostat concept, which was developed at Solar-Institut Jülich (SIJ). However, the underlying approach for the optimization can be used for any heliostat type. During the optimization the performance is calculated using the ray-tracing tool SolCal. The costs of the heliostats are calculated by use of a detailed cost function. A genetic algorithm is used to change heliostat geometry and field layout in an iterative process. Starting from an initial setup, the optimization tool generates several configurations of heliostat geometries and field layouts. For each configuration a cost-performance ratio is calculated. Based on that, the best geometry and field layout can be selected in each optimization step. In order to find the best configuration, this step is repeated until no significant improvement in the results is observed.

In this work transient simulation results of a hybrid solar tower power plant with open volumetric receiver technology are presented for several locations in China. The open volumetric receiver uses ambient air as heat transfer fluid and the hybridization can be realized with additional firing. The solar receiver and/or the additional firing heat up the air which is then passed through a boiler of a conventional Rankine cycle. The simulated plant is based on the configuration of the solar thermal test and demonstration power plant located in Jülich (STJ). The investigated plant operates in hybrid -parallel mode which allows a constant power generation. The meteorological data for the different sites in China was taken from the software Meteonorm in a time resolution of one hour. The solar tower power simulation tool was developed in the simulation environment MATLAB/Simulink.

Electricity production costs and overall net efficiency of the system are determining factors regarding the quality and cost effectiveness of a solar tower power plant. These factors are strongly dependent on the quality of heliostats, the receiver and the thermal storage concept. This work describes the optimization of load states of a storage system through applying internal process control strategies for the air circuit of the Solar Tower Jülich which works with open volumetric air receiver technology. A concept for optimal operation of the thermal storage system was formulated and developed. Storage concepts include both technical adjustments of the existing storage system as well as the control process of the thermal storage. For simulating the optimized operating strategy of the power plant systems all main power plant components were modeled in MATLAB ® /Simulink ® and interconnected to form a complete system. The focus of the simulation lies in optimizing the operating strategy of a discretized thermal energy storage model. BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer review by the scientific conference committee of SolarPACES 2014 under responsibility of PSE AG 908 V. Kronhardt et al. / Energy Procedia 69 ( 2015 ) 907 -912