Advanced Materials Research Vols. 860-863

Abstract: Photoanodes are critical parts of dye-sensitized solar cells (DSSCs), which are composited of TCO (transparent conductive oxide) glasses and nanocrystalline semiconductor film deposited on them. Post-treatment of porous TiO₂ film after sintering for the first time was important for the enhancement of the performance of DSSCs. A novel method to modify the surface of TiO₂ film was investigated in our work. Photoanodes of DSSCs were treated with the isopropanol solution containing 0.05mol/L La (NO₃)₃. After the post-treatment, there was an obvious increase of the overall performance of DSSCs. The photoelectric conversion efficiency (PCE) reached 9.33%, with a raise of 3.3%, compared with the traditional TiCl₄ thermal treating method at 70°C for 40min.

Abstract: This paper presents the simulation of a solar-powered continuous adsorption air-conditioning system with the working pair of silica gel and water. In order to make the adsorption system more suitable to use solar energy to supply cooling continuously during daytime, a new adsorption system without refrigerant valves is being developed in SJTU recently. By using this system, the problem such as pressure drop along refrigerant circuit can be resolved. The frequent switches of refrigerant valves can also be omitted. The daytime long simulation results (ranging from 6:00 to 18:00) demonstrate that the solar-powered adsorption system can supply a fairly steady cooling output all the time. Based on the results, parametric study is also undertaken to optimize the design.

Abstract: This paper analyzes the potential of the integration of solar water heater systems and high-rise residential buildings in a perspective of Ecological Civilization and raised issues specific to high-rise residential. Against the prospect the use of solar energy for high-rise residential buildings, the author points out the appropriate solution. The paper stresses that the process of the integration of high-rise residential and solar water heater systems, is a multi-phase technology system and building system integration process, is the inevitable trend to achieve ecological modern urban development.

Abstract: It analyses the model of wake effect of wind farm in detail. Considering the energy loss caused by wake effect on the wind speed of wind turbine in different locations, the output of whole wind farm can be evaluated via the model, including the wind speed distribution. Then, it determines a kind of equivalent method of wind farm based on the output characteristic of the port of wind farm.

Abstract: Applied superconductivity technology has been thought of being utilized in manufacturing large capacity wind turbines for several years. It is regarded as the only way to minify the volume and mass for large electric motors. Cryogenic system for the generator is fatally important, to create the necessary low temperature maintaining field windings superconducting state. Aiming at designing a reliable cryogenic system for large capacity as 12 MW superconducting generators field winding, in this paper, thermal numerical calculation and analysis for the superconducting coil with cold shield with multilayer insulation (MLI) are done, a dynamic model is established with finite element method (FEM) to verify the previous analysis. Optimization is also done to reduce the thermal loss. Proposal for the numbers of Cryocoolers needed and their layout in generator are given.

Abstract: Wind machine high speed shaft bearing in high speed and light load conditions,it is prone to produce skidding.Skidding damage often becomes one of the main damage forms.According to EHD lubrication theory,this paper establishes the interacting model among rolling-elements,which includes gyroscopic and centrifugal effects,to study the skidding characteristics of angular contact ball-bearings.The model will enable engineers to improve bearing reliability at the design stage.

Abstract: The present paper evaluates the tip vortex evolution of a horizontal axis wind turbine model using the stereo particle image velocimetry technology. The measurements of the wake region up to 2.7 diameters downstream are first conducted using the phase locked technique based on two high speed CCD cameras. Parameters that describe the helical vortex wake, such as the velocity, helicoidal pitch and vortex vorticity, are presented at two tip speed ratios. The vortex interaction and stability of helical vortex filaments within wind turbine wake are seen throughout the measurement domain. The results show the wake structure varies with tip speed ratio, and the helicoidal pitch of tip vortex trajectory reduces while the diffusion of tip vortex is faster with increasing tip speed ratio.

Abstract: Wind power is intermittent and volatility. Some new problems would arise to power system operation when Large-scale wind farm is connected with power systems. One of the most important effect is the influence on the grid dispatch. An aggregated wind power prediction method for a region is presented. By means of analyzing power characteristics and correlation, then the greater correlation is selected as model input. Based on grey correlation theory, a least squares support vector machine prediction model is established. Finally, this method is executed on a real case and integrated wind power prediction method can effectively improve the prediction accuracy and simplify the prediction step are proved.

Abstract: Reactive and active power variation of large scale wind farms always lead to the instability of voltage and frequency. To solve this problem, this paper proposed a method of joining with frequency and voltage control loop of Voltage Source Converter HVDC (VSC-HVDC). Control loop of VSC-HVDC converter WFVSC (Wind Farm Side VSC) and GSVSC (Grid Side VSC) were detailed designed. By the frequency loop of WFSVSC, transient stability is greatly improved. Finally, based on the DIgSILENT/Power Factory simulation, the results show its validity and effectiveness.

Abstract: For the optimal sizing problem of solar-wind-diesel-battery hybrid microgrid, the economic model of optimal sizing was built with the objective that takes daily costs of equipment, operation and maintenance, fuels, environment protection into account. Meanwhile the blackout penalty fee and wasted energy penalty fee also are included in the economic model. The optimal capacity configurations of different power sources in the system were solved by genetic algorithm under optimal investment condition and considering constraints of the reliability of power supply, the complementary of wind and solar, battery charge and discharge times. The reasonableness of the proposed models is verified by case study results.