Advanced Materials Research Vols. 945-949

Abstract: At present, with the development of wind’s energy application and disaster prevention, the windspeed uncertainty must be estimated because of the existing large gap between the requirement of prediction performance and current techniques owing to it’s strong random fluctuation. In this paper, a new method for windspeed uncertainty estimation is proposed on the base of physical mechanism, the inherent amplitude modulation effect in windspeed. According to the the atmosphere motion power spectrum in low-layers, the actual windspeed is usually decomposed into the hourly average windspeed and the turbulent residual error by many researchers. And the turbulent residual error and the turbulent standard deviation is modulated by the hourly average windspeed. Moreover experiments further show that the confidence interval of windspeed random fluctuation uncertainty based on it’s amplitude modulation effect is more rigorous than that obtained by general statistical model. As a result, this uncertainty estimation method has certain physical academic meaning and engineering application value both in the electric system and the other wind domain.

Abstract: By using AVL FIRE code, three-dimensional numerical simulations of the diesel-natural gas injection characteristics in a direct injection diesel-natural gas engine were conducted. The effects of the start of injection (SOI) of the pilot diesel and natural gas injection velocity on combustion and emission performance were investigated. The results showed that diesel-natural gas injection characteristics have an important influence on the subsequent combustion and emission. NO and Soot emission performance is better when the SOI was 36°BTDC (Before Top Dead Center), and a larger natural gas injection velocity usually leads to a lower engine economical efficiency.

Abstract: Turbine Air Powered Engine (TAPE) is a new type engine which has the character of zero emission, no pollution. Mathematical models of TAPE were established by the method of exergy analysis, the overall exergy and the exergy loss after reduced pressure with throttling were simulated in this paper. The results show that the maximum exergy loss of system is 60% during the process of reduced pressure with throttling, so the type of throttling decompression is not suitable for the system of TAPE which has bigger pressure reducing ratio. The results of bench test indicate that output power increases with the increase of inlet pressure within the scope of less pressure, and the regulation is similar to the simulating result. In the hybrid system of pneumatic internal-combustion engine, the measure which the air powered system is used in low-speed stage and the internal combustion engine powered system is adopted in high-speed stage can effectively solve the problem which the fuel consumption of the internal combustion engine is too bigger at low speed.

Abstract: In order to explore the influence of temperature and illumination strength to photovoltaic cells, we establish the photovoltaic (PV) generation system which contains PV array, boost converter, maximum power point tracking (MPPT) and so on. By changing of the illumination strength and temperature according to the actual environment, we simulate the PV generation system under the MATLAB 7 simulation environment, and the results indicate that the stronger of illumination strength and the higher of temperature, the better output characteristics of the system and the higher of the generation efficiency.

Abstract: For the case of ground-source heat pump in severe cold regions in winter, the heat transfer situation of the ground and ground heat exchanger was dynamically simulated according to the statistics of a project in Changchun to analysis the change of the ground heat, which provided references for the initial design and operation and management of the ground-coupled heat pump in severe cold regions.

Abstract: Excavated foundation is a basic type of foundation that has been widely applied in recent transmission line construction in China. Making full use of the bearing capacity of undisturbed soil and reducing the amount of excavation are its advantages. Rotary drilling rig is a piling machine that is widely used in fields such as civil engineering with high working efficiency. Using mechanized construction can significantly reduce the workload and safety risks of construction and produce better direct and indirect economic benefits. This paper considers introducing rotary drilling rig to the construction of transmission and focuses on the adaptability of rotary drilling rig in excavated foundation construction.

Abstract: Logistics supplier selection is the source of wind power manufactures enterprise product quality assurance,while the evaluation and selection of suppliers are affected by a number of uncertainty factors. In order to be more accurate and comprehensive evaluate the logistics supplier of wind power manufactures enterprise, a set of vendor evaluation index system is established in this paper. For the status quo of wind power manufactures enterprise directly scoring, an evaluation model is proposed which use fuzzy comprehensive evaluation method to evaluate and select logistics supplier for wind power manufactures enterprise. The actual case shows that the method can be objective and accurate selection of suppliers and overcome the shortcomings of the previous evaluation methods.

Abstract: In this paper, a minimal common-mode voltage peak value rule is defined due to the problem of common-mode voltage that current source converters (CSCs) usually exist. Base on this rule, two methods of hybrid sequence modulation (HM2/HM3) are proposed which can recompose the arrangement of traditional zero vectors to decrease common-mode voltage and reduce harmonics. The effectiveness of the optimal method (HM3) for CSCs is verified in theoretical research and simulation experiment.

Abstract: With the development of the power system, wind energy was applied to micro-grid system as a distributed generation. The output of the wind farms has the characteristic of intermittence and fluctuation, which would influent the stability of micro-grid system and can be solved effectively by compressed air energy storage system, a new energy storage technology. Because of the advantage of fast response, high economic performance and small environmental impacts, it has an extensive application prospect. This paper builds a micro-grid system with wind power generator, and control the output of micro-grid system by using compressed air energy storage system. The simulation result verifies that the compressed-air energy storage system can effectively suppress power fluctuation and improving the stability of the micro-grid system.

Abstract: This research proposes a new parallel-type short-circuit current limit adjustment device. A unified power quality control strategy is provided to solve the typical issues of the power system. Meantime，when short-circuit fault occurs in the load side，short-circuit current can be limited to minimal range. The parallel-type short-circuit current limit adjustment device simulation model is established based on PSCAD/EMTDC simulation software. By doing some experiments on the parallel short-circuit current limit adjustment device, the correctness and validity of the proposed main circuit topology and control strategy is validated.