Advanced Materials Research Vol. 827

Abstract: The issue about choosing the point of interconnection is important to reduce the impact of Photovoltaic generation to the power grid security and investment. Here we present a model to identify the optimal point of Photovoltaic generation interconnection, based on the identification method of the critical elements in the complex network theory. In the model, the critical threshold is used as the measure index which reflects the minimum capacity of power grid to maintain every element stable operation. The simulations are carried out in the IEEE-118 power system, the IEEE-145 power system and the IEEE-162 power system, and the results show that the nodes with relative large electrical betweenness are good choice of the Photovoltaic generation interconnection points and the generation nodes are better choices compared to the transmission nodes. The work may have a certain guiding significance for the selection of Photovoltaic generation interconnection point and the planning of power system.

Abstract: SiC devices have excellent properties such as ultra low loss, high withstand voltage, large capacity, high frequency, and high temperature operation compared with Si devices. The SiC JFET is expected to be appropriate for the power device because a JFET has no oxide-semiconductor interface in the channel region and does not use the low mobility SiC MOSFET inversion layer as a channel. Forward I-V up to 4A for SiC VJFET, Gate voltage from 2V to 3.5V by step 0.5V. Reverse I-V characteristics up to 4500V (VG=-8V) for SiC VJFET, Gate voltage from-4V to-8V by step-2V. Turn-off characteristics are studied and fast turn-off time of 136ns at room temperature under DC voltage of 600V is successfully demonstrated.

Abstract: The output power of photovoltaic (PV) cells would crucially change due to the intensity of solar irradiation and the environment temperature. For the sake of achieving more efficiency of solar power system, the Maximum Power Point Tracking (MPPT) is highly demanded. This paper focuses on analyzing the implemental principle of MPPT with an improved incremental method under the standard conditions. An algorithm is applied to PV system where supper capacitor is chose as energy storage element. Finally, an experimental prototype was designed to verify the validity of the improved increment method. It provides the contrast experiment waveforms between the improved increment method and increment conductance method. The result of experimental shows the effectiveness of the algorithm.

Abstract: nland grid cannot reach and cover the islands, and it is also difficult to complete the construction of the cross-sea grid, for these islands are usually far from the mainland. The research on the island micro-grid (solar/wind/tide/battery) is carried out based on the corresponding practical project on a island. The multi-object optimizing design method mainly based on the Deficiency of Power Supply Probability (DPSP) and the Levelised Unit Electricity Cost (LUEC) which represent the reliability of the power supply and the economical efficiency of the micro-grid system, respectively. The traversal algorithm is employed to obtain the capacity optimization configuration for the distributed generation units and the battery bank in the independent micro-grid. Meanwhile, a software designed for the capacity optimization configuration of the island hybrid system is presented. At last, the specific design for a independent island micro-grid is proposed, which validate the effeteness of the method presented in this paper.

Abstract: The direct evaporative cooling conditioner experimental research is carried out in this paper. Analyze the influence of inlet air dry ball temperature and relative humidity to air conditioner cooling capacity and cooling efficiency, which has certain guiding significance to improve the direct evaporative cooling air conditioner performance.

Abstract: According to the load calculation of blade, the required maximum torque of rotational blade is obtained. A mathematic analysis method can be used to deduce the following results: the thrust of hydraulic cylinder is related to crank length, the connecting rod length, the eccentricity, the installation angle, and the variable-pitch driving force. Finally, the optimal values of pitch-controlled actuator are obtained. Based on three-dimensional modeling, assembly and dynamic simulation analysis, the virtual design of variable blade pitch mechanism is completed by using the software Pro/E. By means of dynamic simulation analysis, the rationality of this design is verified, facilitating the further on development mechanism's optimized design.

Abstract: Based on support vector machines (SVM) theory, the method of fault diagnosis for controlled rectifier circuits is expanded to study in the paper, by the basis we analysis the method can be applied to diode rectifier circuit and verified it through the experiment. In addition to this , the rectifier circuit with different types of loads are also simulated to describe the reason this method is applicable to the different types of loads. In the premise of ensuring the accuracy of the method, through the expansion of research, the fault diagnosis method has broader prospects and higher practical value.

Abstract: ntelligent building with solar-induced ventilation wall and complex cavity system was proposed which combined the solar-induced ventilation wall technology and complex cavity technology. The buildings working pattern was established. The feasibility of utilizing solar energy to heat in winter was analyzed in theory. The kind of energy efficient building was researched in terms of the design, construction and heating methods in order to promote the development of the energy efficient building industry.

Abstract: Steel material is very sensitive to temperature, the physical and mechanical properties at high temperature are distinct with those at room temperature. Taking steel beams as the research objects, based on EUROCODE3 for the steel properties at high temperature, this paper established numerical models and analyzed the carrying capacity of steel beams under different temperatures. According to the analysis, it is concluded that the higher the temperature, the lower the subsequent carrying capacity of the steel beam, and the formulas between them are defined by fitting the data.

Abstract: Buildings with masonry structures in rural areas of China have been the most severely damaged ones in earthquake disasters. This paper has analyzed the failure characteristics of rural masonry buildings in earthquake by summarizing the existing researches of the seismic resistance of masonry structures in rural areas, with its focus on the research of the intensity from VI to X. The constitutive relation model of damage developed by Yang Weizhong is used for the seismic analysis of rural masonry structures in combination with the failure criteria for masonry structures. The finite element software ANSYS is applied for the simulation and the results show that the damage of China's rural masonry structures regularly tends to weaken from the bottom to the top, with the seismic capacity of horizontal walls superior to longitudinal walls. As for vertical walls, due to their weak capacity, damage immediately occurs to them even in medium intensity earthquakes.