Applied Mechanics and Materials Vols. 341-342

Abstract: Liquefied natural gas (LNG) is a kind of clean and efficient energy. On one hand import LNG may diversify the energy structure and safeguard energy security for energy consumers, on the other hand the expansion in LNG export may well develop natural gas resources, increase foreign exchange income and promote national economic for energy producers. Therefore, LNG trade is becoming a new hot spot in the global energy market. In this paper, LNG consumption market structure was analyzed based on the popularization ratio of urban gas and consumption concentration of GDP worth of ten thousand yuan. LNG market present situation in China was explained accurately and reasonably.

Abstract: A design idea of power supply for aircraft battery charger is proposed, which is based on the thought of aircraft batteries characters such as small capacity and same working voltage range. The crucial parameters of the power supply are set depended on analyzing the capacity and voltage range of aircraft batteries. After analyzing the features of power converters, the ZVS phase shifted full-bridge soft-switching circuit is chose and then crucial components are designed. The experiment results show that the design scheme of the power supply can meet using-requirements. The design scheme of general-purpose power supply solve the problem that aircraft battery charger has bad general-using ability.

Abstract: For nuclear power plant, station black-out (SBO) is the events that contribute significantly to the level-I core damage risk. For an SBO, it is assumed that both the off-site power and on-site diesel generators fail to supply alternating-current power for the plant systems. SBO induced steam generator tube rupture (SGTR) is a concern because the steam generator (SG) tubes are parts of the reactor coolant pressure boundary and failure of the SG tubes may lead to fission products bypassing the containment. The SG tube integrity may be challenged by high temperature and high pressure conditions and may have a potential to fail due to creep rupture. This study focuses on the probability of SBO induced SGTR accidents under the station blackout (SBO) with RCS integrity, seal LOCA and steam relief valves remaining stuck open for the reference plant. At last, the sensitivity of the tube thick is studied.

Abstract: Uniform velocity of primary air is very important in the operation of utility boilers. Regulation of the resistance of each pipe was done without pulverized coal to achieve equal flow velocity. The mass flow rate of pulverized coal and the length difference of pipes would lead to velocity variation of primary air. By the research of primary air flow and the regulation process, model of the velocity variation was built to calculate the velocity of each pipe and their difference. The arrangement of pipes and the operation parameters were taken into consideration. With the experimental data, calculation of velocity under different states was made. The velocity difference of different pipes was estimated. The length difference between pipes and the variation of the mass flow rate of pulverized coal play the most important role that affects the velocity of primary air.

Abstract: SCHC is a new kind of insulator coating designed to enhance the pollution flashover voltage, and more importantly, to reduce contamination accumulation on insulators. SCHC has good performance in laboratory, but its operating effect has not been studied. In this paper, sample insulators with SCHC coating having operated for a year are tested concerning its hydrophobicity, NSDD, ESDD, and voltage withstanding capability. The result shows that the hydrophobicity doesnt change after a years operation and contamination accumulation on SCHCs surface is much less than that on the RTVs surface. The SCHC has better performance than RTV overall and still needs to be improved in the future.

Abstract: Multilevel DC/AC Inverters have various structures. They have many advantages. Unfortunately, most existing inverters content too many components (independent/floating batteries/sources, diodes, Capacitors and switches). The author introduces the "Laddered Multilevel DC/AC Inverters in this paper that is new approach of the development in this area. Their simple structure and clear operation are obviously different from the existing inverters. Its application in Solar Panel Energy Systems is successful. The simulation and experimental results strongly support our design. We believe that these inverters will draw much attention over the world, and be applied in other renewable energy systems.

Abstract: The evaluation results of power system are greatly influenced by the reliability parameters and uncertainty of system components. The connection number assessment model and an approach have been presented to assess the occurrence frequency due to voltage sags. The proposed method had been applied to a real distribution system. Compared with the interval number method, the simulation results have shown that this method is simple and flexible.

Abstract: A power quality analysis method based on electromechanical-electromagnetic hybrid simulation is proposed. The hybrid simulation for power quality analysis can not only enhance the simulation accuracy, and can realize power quality simulation of large scale power system. Then power quality simulation and assessment system is developed based on ADPSS. The system provides plenty of power quality models and achieves power quality simulation based on electromechanical-electromagnetic hybrid simulation. It will provide guidance and reference for power quality study. The hybrid simulation model of an actual large scale power system is built and voltage sag problems caused by short circuit tests are simulated based on the developed system. Simulation result shows the practicality and effectiveness of power quality simulation and assessment system.

Abstract: With different element models and parameters in power system, the transient stability analysis results are also different, especially the model of generator and load. Based on the actual parameters of Hunan power grid, this paper builds the synthesis load model of the distribution network with small hydropower considered, and then the Hunan simulation network can also be got. Using PSASP, analyses the transient stability of Hunan power system with distributed small hydropower under different operation modes systematically and comprehensively. Through an overall check of the stability level in each Hunan area, and then compared with the analysis results of Hunan power grid based on the currently used load model , the influences of the distributed small hydropower on the safe and stable operation of the large power network are summarized.

Abstract: It is difficult to evaluate and analyze power supply reliability of large-scale medium voltage distribution network by detailed modeling method. The paper proposes a power supply reliability evaluation method of large-scale medium voltage distribution network, which is based on the network reliability characteristics model. Lines with similar structural characteristics are designated as one model. The reliability index of each mode can be represented by the typical lines. The assessment principle, process and the advantages of this method are elaborated. The medium voltage distribution network of Nanjing area is taken as an example to evaluate power supply reliability. And the results are compared with historical statistics. The result shows that the method can greatly reduce the workload and has high accuracy. It can be used to evaluate the reliability of large-scale medium voltage distribution network.