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CHAPTER:1
Introduction
The STPS(solar thermal power system) is one form of solar thermal utilizations which uses solar thermal energy converted by solar radiation by concentrator and receiver to drive the steam turbine to generate electricity according to the thermal circuit. It is one of the major modes to make use of solar power on a large scale in the future. But up to now, the Solar Thermal Power System (STPS) still has the disadvantages which restrict seriously its commercial application, namely the high investment and cost in the unit capacity and the low system integrated efficiency.
Researches show that when the operation temperature of the STPS is below 360C, the system is in low technical difficulties, low construction costs and high photo-thermal transformation efficiency. However, under such condition, it has the defects of low efficiency of the generating system, which resulted in the high cost of power generation. In order to improve the efficiency of the generating system and the integrated efficiency of the entire system, the system operating temperature should be increased to make sure the system has the high efficiencies of photo-thermal transformation and thermal circulation.
In conventional thermal power plant, the techniques of design and construction, the equipment manufacturing, and the maintenance experiences are quite well-developed in high or super-high temperature system, and the comprehensive efficiency of system is pretty high. However, simultaneously, a large amount of fossil fuels need be consumed and serious pollution would be resulted. According to the analysis on the whole process of converting the fuel energy into the steam heat energy by the boiler of the conventional thermal power plant, the energy absorbed by the cycle working fluid, which is heated from the condensate water to the superheated steam of 360C, is more than 70% of the total heat absorbed in the whole thermal circulation.
Therefore, based on the consideration of above-mentioned characteristics of STPS and conventional thermal power plant, the scheme of the construction of an integrated operation system was proposed in this file . This developed system can not only use solar power effectively to generate low or middle temperature steam, but also has the high comprehensive efficiency as the conventional thermal power generation unit. Moreover, the technical choke points in high temperature STPS can be avoided. Therefore, the combined operation of solar thermal power and conventional thermal power could be one of the most important modes to utilize the solar power in the future
The increasing instability of fossil fuel costs has led the world in a quest for exploiting the free and naturally available energy from the Sun to produce electric power .A performance evaluation and simulation of a Solar Thermal Power Plant is conducted for Puerto Rico, with local solar data, for determining the viability of this file. several of the simulation studies that have been performed rely on parabolic troughs, costly software packages and on prototype system measurements usually conducted where solar radiation is the highest in the world. This model will show how system behavior is affected during solar transients in tropical regions taking into account solar variability throughout the day.
The use of the compound parabolic concentrator proves useful due to its non-imaging characteristics. This allows the solar collection system to concentrate direct, as well as diffuse radiation energy, as opposed to the parabolic trough which can only concentrate direct solar energy . Since PR lies on a tropical region, solar energy is highly scattered mainly due to atmospheric phenomena such as: clouds, water vapor and dust particles .For the present study, an optical and thermal analysis of the CPC and absorber was conducted in Microsoft® Excel® and MATLAB®. The results were used in the Simulink® model constructed. These parameters can, however, be: estimated, taken from literature or from manufacturer’s data.
The implementation of advanced control systems to optimize the overall performance of Central Receiver Solar Thermal Power System is nowadays a priority research line. The development of dynamic models for use in simulation and control of this kind of power plants is presented in this article, focused on the CESA-I solar plant. The developed model is based in the thermo hydraulic modeling framework Thermo Fluid, and the main components of the system are presented as well as the respective modeling assumptions. The work is mainly oriented to the development of dynamic models of solar energy plants to be used in the design of automatic control systems aimed at optimizing global performance.
In this article also focus The Heat exchangers and other power plant related equipment represent critical operational and maintenance concerns. Scale formation and bio fueling in power plant steam condenser tubes, in service water piping, and in process-liquid piping (manufacturing) are wide spread phenomena.' Befouling and the resultant corrosion can be major factors in reducing the operating capacity of these systems. Chemical treatment, either for removal by acid treatment or for prevention by water chemistry control, is a typical remedy.
One new remediation method utilizes pulsed acoustic waves at intensities ,above the cavitations threshold to remove accumulated scale and/or biofouling from the inside walls of piping and other enclosed structures. The pulsed acoustic wave successively removes accumulated deposits as the arc-discharge source is moved down the tube by an operator. This technique has the advantages of chemical removal, namely no physical contact with the tube walls, and the advantages of mechanical removal via scrapers, namely no chemical waste stream. As will be described , the effect is based on physical mechanisms as opposed to chemical, and thus should have minimal environmental impact.
A brief overview of differential evolution in solar thermal power system, and shows its uses in two applications are also consider in this file. The first application is using differential evolution in a reference governor to generate optimal set points for the control of a power plant. The second application uses differential evolution as a gain tuning algorithm for the same power plant. Both applications include a comparison of multiple differential evolution strategies as well as a comparison with prominent particle swarm optimization techniques.
Intelligent predictive control to govern the dynamics of a solar power plant System are also given to this file.. This system is highly nonlinear process; therefore, a nonlinear predictive method, e.g., new fuzzy predictive control, ran be a better match to govern the system dynamics. In our proposed method, The first value of this sequence is applied la the plant. Using the proposed intelligent predictive controller, the performs née of temperature tracking problem in a solar power plant is investigated. Simulation results demonstrate the effectiveness and superiority of the proposed approach.
Model based predictive control (MBPC) is now widely used in industry and a large number of implementation algorithms due to its ability to handle difficult control problems which involve multivariable process interactions, constraints in the system variables, time delays, etc. In recent years, the use of neuro-fuzzy models for nonlinear system identification has proved to be extremely successful. In this file, we will use an Evolutionary Programming (EP) algorithm to minimize the cost function and obtain the control input. The analyses of a neuro-fuzzy based nonlinear predictive controller for a solar power plant, which is a highly nonlinear process. The procedure is based on construction of a neuro-fuzzy model for the process and the proper use of that in the optimization process.
In this Article also focus The utilization of solar energy can be made by photovoltaic (PV) cells to generate electric power directly and solar thermal panels can be applied to generate heat power. The power generated by utilizing the solar energy absorbed by a given solar panel can be increased if the two technologies, PV and T cells, are combined in such a way that the resulting unit will be capable of co-generation of heat and electric power. In the article a part of the simulation studies, carried out to determine the energy balance in the electric energy conversion section of the system.